GLK: TADS2: Adding headers

49 files changed, 13987 insertions, 2884 deletions

diff --git a/engines/glk/module.mk b/engines/glk/module.mk
index d84d542825..43c2523b80 100644
--- a/engines/glk/module.mk
+++ b/engines/glk/module.mk
@@ -92,13 +92,22 @@ MODULE_OBJS := \
 	scott/detection.o \
 	scott/scott.o \
 	tads/detection.o \
+	tads/osfrobtads.o \
 	tads/tads.o \
+	tads/tads2/character_map.o \
 	tads/tads2/data.o \
-	tads/tads2/ler.o \
+	tads/tads2/error.o \
+	tads/tads2/error_handling.o \
+	tads/tads2/file_io.o \
+	tads/tads2/memory_cache.o \
+	tads/tads2/memory_cache_heap.o \
+	tads/tads2/memory_cache_loader.o \
+	tads/tads2/memory_cache_swap.o \
 	tads/tads2/os.o \
 	tads/tads2/regex.o \
+	tads/tads2/run.o \
 	tads/tads2/tads2.o \
-	tads/tads2/tads2_cmap.o \
+	tads/tads2/tokenizer.o \
 	tads/tads2/vocabulary.o \
 	tads/tads3/tads3.o
 
diff --git a/engines/glk/tads/os_filetype.h b/engines/glk/tads/os_filetype.h
new file mode 100644
index 0000000000..93b101698f
--- /dev/null
+++ b/engines/glk/tads/os_filetype.h
@@ -0,0 +1,64 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* TADS OS interface file type definitions
+ *
+ * Defines certain datatypes used in the TADS operating system interface
+ */
+
+#ifndef GLK_TADS_OS_DATATYPE
+#define GLK_TADS_OS_DATATYPE
+
+namespace Glk {
+namespace TADS {
+
+/**
+ * File types.  These type codes are used when opening or creating a
+ *   file, so that the OS routine can set appropriate file system metadata
+ *   to describe or find the file type.
+ *   
+ *   The type os_filetype_t is defined for documentary purposes; it's
+ *   always just an int.  
+ */
+enum os_filetype_t {
+	OSFTGAME  = 0,                               /* a game data file (.gam) */
+	OSFTSAVE  = 1,                                   /* a saved game (.sav) */
+	OSFTLOG   = 2,                               /* a transcript (log) file */
+	OSFTSWAP  = 3,                                             /* swap file */
+	OSFTDATA  = 4,      /* user data file (used with the TADS fopen() call) */
+	OSFTCMD   = 5,                                   /* QA command/log file */
+	OSFTERRS  = 6,                                    /* error message file */
+	OSFTTEXT  = 7,                     /* text file - used for source files */
+	OSFTBIN   = 8,          /* binary file of unknown type - resources, etc */
+	OSFTCMAP  = 9,                                /* character mapping file */
+	OSFTPREF  = 10,                                     /* preferences file */
+	OSFTUNK   = 11,         /* unknown - as a filter, matches any file type */
+	OSFTT3IMG = 12,                  /* T3 image file (.t3 - formerly .t3x) */
+	OSFTT3OBJ = 13,                                /* T3 object file (.t3o) */
+	OSFTT3SYM = 14,                         /* T3 symbol export file (.t3s) */
+	OSFTT3SAV = 15,                           /* T3 saved state file (.t3v) */
+};
+
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/osfrobtads.cpp b/engines/glk/tads/osfrobtads.cpp
new file mode 100644
index 0000000000..fbcf1c1050
--- /dev/null
+++ b/engines/glk/tads/osfrobtads.cpp
@@ -0,0 +1,42 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/osfrobtads.h"
+#include "common/file.h"
+
+namespace Glk {
+namespace TADS {
+
+osfildef *osfoprb(const char *fname, os_filetype_t typ) {
+	Common::File f;
+	if (f.open(fname))
+		return f.readStream(f.size());
+	else
+		return nullptr;
+}
+
+int osfrb(osfildef *fp, void *buf, size_t count) {
+	return fp->read(buf, count);
+}
+
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/osfrobtads.h b/engines/glk/tads/osfrobtads.h
new file mode 100644
index 0000000000..2dce84c5ec
--- /dev/null
+++ b/engines/glk/tads/osfrobtads.h
@@ -0,0 +1,267 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* OS-layer functions and macros.
+ *
+ * This file does not introduce any curses (or other screen-API)
+ * dependencies; it can be used for both the interpreter as well as the
+ * compiler.
+ */
+
+#ifndef GLK_TADS_OSFROBTADS
+#define GLK_TADS_OSFROBTADS
+
+#include "common/fs.h"
+#include "common/stream.h"
+#include "glk/glk_api.h"
+#include "glk/tads/os_filetype.h"
+
+namespace Glk {
+namespace TADS {
+
+
+/* Defined for Gargoyle. */
+#define HAVE_STDINT_
+
+#if 0
+#include "common.h"
+#endif
+
+/* Used by the base code to inhibit "unused parameter" compiler warnings. */
+#ifndef VARUSED
+#define VARUSED(var) (void)var
+#endif
+
+/* We assume that the C-compiler is mostly ANSI compatible. */
+#define OSANSI
+
+/* Special function qualifier needed for certain types of callback
+ * functions.  This is for old 16-bit systems; we don't need it and
+ * define it to nothing. */
+#define OS_LOADDS
+
+/* Unices don't suffer the near/far pointers brain damage (thank God) so
+ * we make this a do-nothing macro. */
+#define osfar_t
+
+/* This is used to explicitly discard computed values (some compilers
+ * would otherwise give a warning like "computed value not used" in some
+ * cases).  Casting to void should work on every ANSI-Compiler. */
+#define DISCARD (void)
+
+/* Copies a struct into another.  ANSI C allows the assignment operator
+ * to be used with structs. */
+#define OSCPYSTRUCT(x,y) ((x)=(y))
+
+/* Link error messages into the application. */
+#define ERR_LINK_MESSAGES
+
+/* Program Exit Codes. */
+#define OSEXSUCC 0 /* Successful completion. */
+#define OSEXFAIL 1 /* Failure. */
+
+/* Here we configure the osgen layer; refer to tads2/osgen3.c for more
+ * information about the meaning of these macros. */
+#define USE_DOSEXT
+#define USE_NULLSTYPE
+
+/* Theoretical maximum osmalloc() size.
+ * Unix systems have at least a 32-bit memory space.  Even on 64-bit
+ * systems, 2^32 is a good value, so we don't bother trying to find out
+ * an exact value. */
+#define OSMALMAX 0xffffffffL
+
+#define OSFNMAX 255
+
+/* File handle structure for osfxxx functions. */
+typedef Common::SeekableReadStream osfildef;
+
+/* Directory handle for searches via os_open_dir() et al. */
+typedef Common::FSNode *osdirhdl_t;
+
+/* file type/mode bits */
+#define OSFMODE_FILE    S_IFREG
+#define OSFMODE_DIR     S_IFDIR
+#define OSFMODE_CHAR    S_IFCHR
+#define OSFMODE_BLK     S_IFBLK
+#define OSFMODE_PIPE    S_IFIFO
+#ifdef S_IFLNK
+#define OSFMODE_LINK    S_IFLNK
+#else
+#define OSFMODE_LINK    0
+#endif
+#ifdef S_IFSOCK
+#define OSFMODE_SOCKET  S_IFSOCK
+#else
+#define OSFMODE_SOCKET  0
+#endif
+
+/* File attribute bits. */
+#define OSFATTR_HIDDEN  0x0001
+#define OSFATTR_SYSTEM  0x0002
+#define OSFATTR_READ    0x0004
+#define OSFATTR_WRITE   0x0008
+
+/* Get a file's stat() type. */
+int osfmode( const char* fname, int follow_links, unsigned long* mode,
+             unsigned long* attr );
+
+#if 0
+/* The maximum width of a line of text.
+ *
+ * We ignore this, but the base code needs it defined.  If the
+ * interpreter is run inside a console or terminal with more columns
+ * than the value defined here, weird things will happen, so we go safe
+ * and use a large value. */
+#define OS_MAXWIDTH 255
+#endif
+
+/* Disable the Tads swap file; computers have plenty of RAM these days.
+ */
+#define OS_DEFAULT_SWAP_ENABLED 0
+
+/* TADS 2 macro/function configuration.  Modern configurations always
+ * use the no-macro versions, so these definitions should always be set
+ * as shown below. */
+#define OS_MCM_NO_MACRO
+#define ERR_NO_MACRO
+
+/* These values are used for the "mode" parameter of osfseek() to
+ * indicate where to seek in the file. */
+#define OSFSK_SET SEEK_SET /* Set position relative to the start of the file. */
+#define OSFSK_CUR SEEK_CUR /* Set position relative to the current file position. */
+#define OSFSK_END SEEK_END /* Set position relative to the end of the file. */
+
+
+/* ============= Functions follow ================ */
+
+/* Allocate a block of memory of the given size in bytes. */
+#define osmalloc malloc
+
+/* Free memory previously allocated with osmalloc(). */
+#define osfree free
+
+/* Reallocate memory previously allocated with osmalloc() or osrealloc(),
+ * changing the block's size to the given number of bytes. */
+#define osrealloc realloc
+
+/* Open text file for reading. */
+#define osfoprt(fname,typ) (fopen((fname),"r"))
+
+/* Open text file for writing. */
+#define osfopwt(fname,typ) (fopen((fname),"w"))
+
+/* Open text file for reading and writing, keeping the file's existing
+ * contents if the file already exists or creating a new file if no
+ * such file exists. */
+osfildef *osfoprwt(const char *fname, os_filetype_t typ);
+
+/* Open text file for reading/writing.  If the file already exists,
+ * truncate the existing contents.  Create a new file if it doesn't
+ * already exist. */
+#define osfoprwtt(fname,typ) (fopen((fname),"w+"))
+
+/* Open binary file for writing. */
+#define osfopwb(fname,typ) (fopen((fname),"wb"))
+
+/* Open source file for reading - use the appropriate text or binary
+ * mode. */
+#define osfoprs osfoprt
+
+/* Open binary file for reading. */
+osfildef *osfoprb(const char *fname, os_filetype_t typ);
+
+/* Open binary file for reading/writing.  If the file already exists,
+ * keep the existing contents.  Create a new file if it doesn't already
+ * exist. */
+osfildef*
+osfoprwb( const char* fname, os_filetype_t typ );
+
+/* Open binary file for reading/writing.  If the file already exists,
+ * truncate the existing contents.  Create a new file if it doesn't
+ * already exist. */
+#define osfoprwtb(fname,typ) (fopen((fname),"w+b"))
+
+/* Get a line of text from a text file. */
+#define osfgets fgets
+
+/* Write a line of text to a text file. */
+#define osfputs fputs
+
+/* Write bytes to file. */
+#define osfwb(fp,buf,bufl) (fwrite((buf),(bufl),1,(fp))!=1)
+
+/* Flush buffered writes to a file. */
+#define osfflush fflush
+
+/* Read bytes from file. */
+int osfrb(osfildef *fp, void *buf, size_t count);
+
+/* Read bytes from file and return the number of bytes read. */
+#define osfrbc(fp,buf,bufl) (fread((buf),1,(bufl),(fp)))
+
+/* Get the current seek location in the file. */
+#define osfpos ftell
+
+/* Seek to a location in the file. */
+#define osfseek fseek
+
+/* Close a file. */
+#define osfcls delete
+
+/* Delete a file. */
+#define osfdel remove
+
+/* Access a file - determine if the file exists.
+ *
+ * We map this to the access() function.  It should be available in
+ * virtually every system out there, as it appears in many standards
+ * (SVID, AT&T, POSIX, X/OPEN, BSD 4.3, DOS, MS Windows, maybe more). */
+#define osfacc(fname) (access((fname), F_OK))
+
+/* Rename a file. */
+#define os_rename_file(from, to) (rename(from, to) == 0)
+
+/* Get a file's stat() type. */
+struct os_file_stat_t;
+int os_file_stat( const char* fname, int follow_links,
+                  struct os_file_stat_t* s );
+
+/* Get a character from a file. */
+#define osfgetc fgetc
+
+/* Set busy cursor.
+ *
+ * We don't have a mouse cursor so there's no need to implement this. */
+#define os_csr_busy(a)
+
+/* Update progress display.
+ *
+ * We don't provide any kind of "compilation progress display", so we
+ * just define this as an empty macro.
+ */
+#define os_progress(fname,linenum)
+
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/appctx.h b/engines/glk/tads/tads2/appctx.h
new file mode 100644
index 0000000000..3b3f499777
--- /dev/null
+++ b/engines/glk/tads/tads2/appctx.h
@@ -0,0 +1,248 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_APPCTX
+#define GLK_TADS_TADS2_APPCTX
+
+#include "common/scummsys.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/**
+ *   Application container context.  The TADS run-time is a subsystem that
+ *   can be invoked from different types of applications; in fact, even
+ *   when only the standard stand-alone run-time is considered, multiple
+ *   application containers must be supported because of differences
+ *   between operating systems.  The application container context is an
+ *   optional mechanism that the main application can use to provide
+ *   structured interaction between itself and the TADS run-time subsystem.
+ *   
+ *   The function pointers contained herein are intended to allow the
+ *   run-time subsystem to call the host system to notify it of certain
+ *   events, or obtain optional services from the host system.  Any of
+ *   these function pointers can be null, in which case the run-time
+ *   subsystem will skip calling them.
+ *   
+ *   Note that each function has an associated callback context.  This
+ *   allows the host system to recover any necessary context information
+ *   when the callback is invoked.  
+ */
+struct appctxdef {
+    /**
+     *   Get the .GAM file name.  The run-time will call this only if it
+     *   can't find a game file to load through some other means first.
+     *   The run-time determines the game file first by looking at the
+     *   command line, then by checking to see if a .GAM file is attached
+     *   to the executable.  If none of these checks yields a game, the
+     *   run-time will call this routine to see if the host system wants
+     *   to provide a game.  This routine can be implemented on a GUI
+     *   system, for example, to display a dialog prompting the user to
+     *   select a game file to open.  A trivial implementation of this
+     *   routine (that merely returns false) is okay.
+     *   
+     *   This routine should return true (any non-zero value) if it
+     *   provides the name of a file to open, false (zero) if not.  
+     */
+    int (*get_game_name)(void *appctxdat, char *buf, size_t buflen);
+    void *get_game_name_ctx;
+
+    /**
+     *   Set the .GAM file name.  When the run-time determines the name of
+     *   the file it will use to read the game, it calls this routine.
+     *   The host system should note the game filename if it will need to
+     *   access the game file itself (for example, to load resources).  
+     */
+    void (*set_game_name)(void *appctxdat, const char *fname);
+    void *set_game_name_ctx;
+
+    /**
+     *   Set the root path for individual resources.  By default, we use the
+     *   directory containing the game file, but this can be used to override
+     *   that.  
+     */
+    void (*set_res_dir)(void *appctxdat, const char *fname);
+    void *set_res_dir_ctx;
+
+    /**
+     *   Set the resource map address in the game file.  If the .GAM
+     *   reader encounters a resource map in the file, it calls this
+     *   routine with the seek offset of the first resource.  Each
+     *   resource's address is given as an offset from this point.
+     *   
+     *   fileno is the file number assigned by the host system in
+     *   add_resfile.  File number zero is always the .GAM file.  
+     */
+    void (*set_resmap_seek)(void *appctxdat, unsigned long seekpos, int fileno);
+    void *set_resmap_seek_ctx;
+
+    /**
+     *   Add a resource entry.  The 'ofs' entry is the byte offset of the
+     *   start of the resource, relative to the seek position previously
+     *   set with set_resmap_seek.  'siz' is the size of the resource in
+     *   bytes; the resource is stored as contiguous bytes starting at the
+     *   given offset for the given size.  Note that resources may be
+     *   added before the resource map seek position is set, so the host
+     *   system must simply store the resource information for later use.
+     *   The 'fileno' is zero for the .GAM file, or the number assigned by
+     *   the host system in add_resfile for other resource files.  
+     */
+    void (*add_resource)(void *appctxdat, unsigned long ofs,
+                         unsigned long siz, const char *nm, size_t nmlen,
+                         int fileno);
+    void *add_resource_ctx;
+
+    /**
+     *   Add a resource link entry.  'fname' and 'fnamelen' give the name of
+     *   a local file containing the resource data; 'resname' and
+     *   'resnamelen' give the name of the resource as it appears within the
+     *   compiled game file.  This creates a link from a .GAM resource name
+     *   to a local filename, where the actual binary resource data reside,
+     *   so that we can retrieve a resource by .GAM resource name without
+     *   actually copying the data into the .GAM file.  This is used mostly
+     *   for debugging purposes: it allows the compiler to skip the step of
+     *   copying the resource data into the .GAM file, but still allows the
+     *   game to load resources by .GAM resource name, to create a testing
+     *   environment that's consistent with the full build version (where the
+     *   resources would actually be copied).  
+     */
+    void (*add_resource_link)(void *appctxdat,
+                              const char *fname, size_t fnamelen,
+                              const char *resname, size_t resnamelen);
+    void *add_resource_link_ctx;
+
+    /**
+     *   Add a resource path.  'path' is a string giving a directory prefix
+     *   in local system notation.
+     *   
+     *   This adds a directory to the list of directories that we'll search
+     *   when we're looking for an individual resource as an external file
+     *   (such as a ".jpg" image file or ".ogg" sound file).  This can be
+     *   called zero or more times; each call adds another directory to
+     *   search after any previous directories.  We'll always search the
+     *   default directory first (this is the directory containing the game
+     *   file); then we'll search directories added with this call in the
+     *   order in which the directories were added.  
+     */
+    void (*add_res_path)(void *appctxdat, const char *path, size_t len);
+    void *add_res_path_ctx;
+
+    /**
+     *   Find a resource entry.  If the resource can be found, this must
+     *   return an osfildef* handle to the resource, with its seek position
+     *   set to the first byte of the resource data, and set *res_size to
+     *   the size in bytes of the resource data in the file.  If the
+     *   resource cannot be found, returns null.  
+     */
+    osfildef *(*find_resource)(void *appctxdat,
+                               const char *resname, size_t resnamelen,
+                               unsigned long *res_size);
+    void *find_resource_ctx;
+
+    /**
+     *   Add a resource file.  The return value is a non-zero file number
+     *   assigned by the host system; we'll use this number in subsequent
+     *   calls to add_resource to add the resources from this file.
+     *   
+     *   After calling this routine to add the file, we'll parse the file
+     *   and add any resources using add_resource.  
+     */
+    int (*add_resfile)(void *appctxdat, const char *fname);
+    void *add_resfile_ctx;
+
+    /**
+     *   Determine if a resource exists.  Returns true if the resource can
+     *   be loaded, false if not.  The resource name is in the standard
+     *   URL-style format.  
+     */
+    int (*resfile_exists)(void *appctxdat, const char *res_name,
+                          size_t res_name_len);
+    void *resfile_exists_ctx;
+
+    /**
+     *   Resource file path.  If we should look for resource files in a
+     *   different location than the .GAM file, the host system can set
+     *   this to a path that we should use to look for resource files.  If
+     *   it's null, we'll look in the directory that contains the .GAM
+     *   file.  Note that if the path is provided, it must be set up with
+     *   a trailing path separator character, so that we can directly
+     *   append a name to this path to form a valid fully-qualified
+     *   filename.  
+     */
+    const char *ext_res_path;
+
+    /**
+     *   File safety level get/set.  During initialization, we'll call the
+     *   host system to tell it the file safety level selected by the user on
+     *   the command line; if the host system is saving preference
+     *   information, it should temporarily override its saved preferences
+     *   and use the command line setting (and it may, if appropriate, want
+     *   to save the command line setting as the saved preference setting,
+     *   depending on how it handles preferences).  During execution, any
+     *   time the game tries to open a file (using the fopen built-in
+     *   function), we'll call the host system to ask it for the current
+     *   setting, and use this new setting rather than the original command
+     *   line setting.
+     *   
+     *   Refer to bif.c for information on the meanings of the file safety
+     *   levels.  
+     */
+    void (*set_io_safety_level)(void *ctx, int read, int write);
+    void (*get_io_safety_level)(void *ctx, int *read, int *write);
+    void  *io_safety_level_ctx;
+
+    /**
+     *   Network safety level get/set.  This is analogous to the file safety
+     *   level scheme, but controls access to network resources.  There are
+     *   two components to the network safety setting: client and server.
+     *   The client component controls the game's ability to open network
+     *   connections to access information on remote machines, such as
+     *   opening http connections to access web sites.  The server component
+     *   controls the game's ability to create servers of its own and accept
+     *   incoming connections.  Each component can be set to one of the
+     *   following:
+     *   
+     *.     0 = no restrictions (least "safety"): all network access granted
+     *.     1 = 'localhost' access only
+     *.     2 = no network access
+     *   
+     *   This only applies to the TADS 3 VM.  TADS 2 doesn't support any
+     *   network features, so this doesn't apply.  
+     */
+    void (*set_net_safety_level)(void *ctx, int client_level, int srv_level);
+    void (*get_net_safety_level)(void *ctx, int *client_level, int *srv_level);
+    void *net_safety_level_ctx;
+
+    /**
+     *   Name of run-time application for usage messages.  If this is
+     *   null, the default run-time application name will be used for
+     *   usage messages. 
+     */
+    const char *usage_app_name;
+};
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/built_in.h b/engines/glk/tads/tads2/built_in.h
new file mode 100644
index 0000000000..f5807e61a8
--- /dev/null
+++ b/engines/glk/tads/tads2/built_in.h
@@ -0,0 +1,216 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* Built-in functions interface
+ *
+ * Interface to run-time intrinsic function implementation
+ */
+
+#ifndef GLK_TADS_TADS2_BUILT_IN
+#define GLK_TADS_TADS2_BUILT_IN
+
+#include "glk/tads/tads2/error.h"
+#include "glk/tads/tads2/run.h"
+#include "glk/tads/tads2/text_io.h"
+#include "glk/tads/tads2/regex.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* forward definitions */
+struct vocidef;
+struct voccxdef;
+
+/* maximum number of file handles available */
+#define BIFFILMAX  10
+
+
+/* file contexts for the built-in file handling functions */
+struct biffildef {
+    osfildef *fp;                          /* underyling system file handle */
+    uint      flags;                                               /* flags */
+#define BIFFIL_F_BINARY    0x01                           /* file is binary */
+};
+
+/* built-in execution context */
+struct bifcxdef {
+    errcxdef *bifcxerr;                           /* error-handling context */
+    runcxdef *bifcxrun;                           /* code execution context */
+    tiocxdef *bifcxtio;                                 /* text I/O context */
+    long      bifcxrnd;                               /* random number seed */
+    int       bifcxseed1;                   /* first seed for new generator */
+    int       bifcxseed2;                  /* second seed for new generator */
+    int       bifcxseed3;                   /* third seed for new generator */
+    int       bifcxrndset;                   /* randomize() has been called */
+    biffildef bifcxfile[BIFFILMAX];          /* file handles for fopen, etc */
+    int       bifcxsafetyr;                 /* file I/O safety level - read */
+    int       bifcxsafetyw;                /* file I/O safety level - write */
+    char     *bifcxsavext;        /* saved game extension (null by default) */
+    appctxdef *bifcxappctx;                     /* host application context */
+    re_context bifcxregex;          /* regular expression searching context */
+
+	bifcxdef() : bifcxerr(nullptr), bifcxrun(nullptr), bifcxtio(nullptr),
+		bifcxrnd(0), bifcxseed1(0), bifcxseed2(0), bifcxseed3(0), bifcxrndset(0),
+		bifcxsafetyr(0), bifcxsafetyw(0), bifcxsavext(nullptr), bifcxappctx(nullptr) {
+	}
+};
+
+/*
+ *   argument list checking routines - can be disabled for faster
+ *   run-time 
+ */
+
+/* check for proper number of arguments */
+/* void bifcntargs(bifcxdef *ctx, int argcnt) */
+
+/* check that next argument has proper type */
+/* void bifchkarg(bifcxdef *ctx, dattyp typ); */
+
+#ifdef RUNFAST
+# define bifcntargs(ctx, parmcnt, argcnt)
+# define bifchkarg(ctx, typ)
+#else /* RUNFAST */
+# define bifcntargs(ctx, parmcnt, argcnt) \
+  (parmcnt == argcnt ? DISCARD 0 : \
+   (runsig(ctx->bifcxrun, ERR_BIFARGC), DISCARD 0))
+# define bifchkarg(ctx, typ) \
+  (runtostyp(ctx->bifcxrun) == typ ? DISCARD 0 : \
+   (runsig(ctx->bifcxrun, ERR_INVTBIF), DISCARD 0))
+#endif /* RUNFAST */
+
+/* determine if one object is a subclass of another */
+int bifinh(struct voccxdef *voc, struct vocidef *v, objnum cls);
+
+
+/* enumerate the built-in functions */
+void bifyon(bifcxdef *ctx, int argc);                   /* yorn - yes or no */
+void bifsfs(bifcxdef *ctx, int argc);                            /* setfuse */
+void bifrfs(bifcxdef *ctx, int argc);                            /* remfuse */
+void bifsdm(bifcxdef *ctx, int argc);                          /* setdaemon */
+void bifrdm(bifcxdef *ctx, int argc);                          /* remdaemon */
+void bifinc(bifcxdef *ctx, int argc);                            /* incturn */
+void bifqui(bifcxdef *ctx, int argc);                               /* quit */
+void bifsav(bifcxdef *ctx, int argc);                               /* save */
+void bifrso(bifcxdef *ctx, int argc);                            /* restore */
+void biflog(bifcxdef *ctx, int argc);                            /* logging */
+void bifres(bifcxdef *ctx, int argc);                            /* restart */
+void bifinp(bifcxdef *ctx, int argc);           /* input - get line from kb */
+void bifnfy(bifcxdef *ctx, int argc);                             /* notify */
+void bifunn(bifcxdef *ctx, int argc);                           /* unnotify */
+void biftrc(bifcxdef *ctx, int argc);                       /* trace on/off */
+void bifsay(bifcxdef *ctx, int argc);                                /* say */
+void bifcar(bifcxdef *ctx, int argc);                                /* car */
+void bifcdr(bifcxdef *ctx, int argc);                                /* cdr */
+void bifcap(bifcxdef *ctx, int argc);                               /* caps */
+void biflen(bifcxdef *ctx, int argc);                             /* length */
+void biffnd(bifcxdef *ctx, int argc);                               /* find */
+void bifsit(bifcxdef *ctx, int argc);           /* setit - set current 'it' */
+void bifsrn(bifcxdef *ctx, int argc);               /* randomize: seed rand */
+void bifrnd(bifcxdef *ctx, int argc);         /* rand - get a random number */
+void bifask(bifcxdef *ctx, int argc);                            /* askfile */
+void bifssc(bifcxdef *ctx, int argc);                           /* setscore */
+void bifsub(bifcxdef *ctx, int argc);                             /* substr */
+void bifcvs(bifcxdef *ctx, int argc);          /* cvtstr: convert to string */
+void bifcvn(bifcxdef *ctx, int argc);          /* cvtnum: convert to number */
+void bifupr(bifcxdef *ctx, int argc);                              /* upper */
+void biflwr(bifcxdef *ctx, int argc);                              /* lower */
+void biffob(bifcxdef *ctx, int argc);                           /* firstobj */
+void bifnob(bifcxdef *ctx, int argc);                            /* nextobj */
+void bifsvn(bifcxdef *ctx, int argc);                         /* setversion */
+void bifarg(bifcxdef *ctx, int argc);                             /* getarg */
+void biftyp(bifcxdef *ctx, int argc);                           /* datatype */
+void bifisc(bifcxdef *ctx, int argc);                            /* isclass */
+void bifund(bifcxdef *ctx, int argc);                               /* undo */
+void bifdef(bifcxdef *ctx, int argc);                            /* defined */
+void bifpty(bifcxdef *ctx, int argc);                           /* proptype */
+void bifoph(bifcxdef *ctx, int argc);                            /* outhide */
+void bifgfu(bifcxdef *ctx, int argc);                            /* getfuse */
+void bifruf(bifcxdef *ctx, int argc);                           /* runfuses */
+void bifrud(bifcxdef *ctx, int argc);                         /* rundaemons */
+void biftim(bifcxdef *ctx, int argc);                            /* gettime */
+void bifsct(bifcxdef *ctx, int argc);                          /* intersect */
+void bifink(bifcxdef *ctx, int argc);                           /* inputkey */
+void bifwrd(bifcxdef *ctx, int argc);                           /* objwords */
+void bifadw(bifcxdef *ctx, int argc);                            /* addword */
+void bifdlw(bifcxdef *ctx, int argc);                            /* delword */
+void bifgtw(bifcxdef *ctx, int argc);                           /* getwords */
+void bifnoc(bifcxdef *ctx, int argc);                             /* nocaps */
+void bifskt(bifcxdef *ctx, int argc);                           /* skipturn */
+void bifcls(bifcxdef *ctx, int argc);                        /* clearscreen */
+void bif1sc(bifcxdef *ctx, int argc);                            /* firstsc */
+void bifvin(bifcxdef *ctx, int argc);                           /* verbinfo */
+void bifcapture(bifcxdef *ctx, int argc);                     /* outcapture */
+
+void biffopen(bifcxdef *ctx, int argc);                            /* fopen */
+void biffclose(bifcxdef *ctx, int argc);                          /* fclose */
+void biffwrite(bifcxdef *ctx, int argc);                          /* fwrite */
+void biffread(bifcxdef *ctx, int argc);                            /* fread */
+void biffseek(bifcxdef *ctx, int argc);                            /* fseek */
+void biffseekeof(bifcxdef *ctx, int argc);                      /* fseekeof */
+void bifftell(bifcxdef *ctx, int argc);                            /* ftell */
+
+void bifsysinfo(bifcxdef *ctx, int argc);                     /* systemInfo */
+void bifmore(bifcxdef *ctx, int argc);                        /* morePrompt */
+void bifsetme(bifcxdef *ctx, int argc);                      /* parserSetMe */
+void bifgetme(bifcxdef *ctx, int argc);                      /* parserGetMe */
+
+void bifresearch(bifcxdef *ctx, int argc);                      /* reSearch */
+void bifregroup(bifcxdef *ctx, int argc);                     /* reGetGroup */
+
+void bifinpevt(bifcxdef *ctx, int argc);                      /* inputevent */
+void bifdelay(bifcxdef *ctx, int argc);                        /* timeDelay */
+
+void bifsetoutfilter(bifcxdef *ctx, int argc);           /* setOutputFilter */
+void bifexec(bifcxdef *ctx, int argc);                       /* execCommand */
+void bifgetobj(bifcxdef *ctx, int argc);                    /* parserGetObj */
+void bifparsenl(bifcxdef *ctx, int argc);            /* parserParseNounList */
+void bifprstok(bifcxdef *ctx, int argc);                  /* parserTokenize */
+void bifprstoktyp(bifcxdef *ctx, int argc);            /* parserGetTokTypes */
+void bifprsdict(bifcxdef *ctx, int argc);               /* parserDictLookup */
+void bifprsrslv(bifcxdef *ctx, int argc);           /* parserResolveObjects */
+void bifprsrplcmd(bifcxdef *ctx, int argc);         /* parserReplaceCommand */
+void bifexitobj(bifcxdef *ctx, int argc);                        /* exitobj */
+void bifinpdlg(bifcxdef *ctx, int argc);                     /* inputdialog */
+void bifresexists(bifcxdef *ctx, int argc);               /* resourceExists */
+
+/*
+ *   TADS/graphic functions - these are present in the text system, but
+ *   don't do anything.
+ */
+void bifgrp(bifcxdef *ctx, int argc);            /* g_readpic: read picture */
+void bifgsp(bifcxdef *ctx, int argc);            /* g_showpic: show picture */
+void bifgsh(bifcxdef *ctx, int argc);             /* g_sethot: set hot list */
+void bifgin(bifcxdef *ctx, int argc);                        /* g_inventory */
+void bifgco(bifcxdef *ctx, int argc);                          /* g_compass */
+void bifgov(bifcxdef *ctx, int argc);                          /* g_overlay */
+void bifgmd(bifcxdef *ctx, int argc);                             /* g_mode */
+void bifgmu(bifcxdef *ctx, int argc);                            /* g_music */
+void bifgpa(bifcxdef *ctx, int argc);                            /* g_pause */
+void bifgef(bifcxdef *ctx, int argc);                           /* g_effect */
+void bifgsn(bifcxdef *ctx, int argc);                            /* g_sound */
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/character_map.cpp b/engines/glk/tads/tads2/character_map.cpp
new file mode 100644
index 0000000000..91daa8668c
--- /dev/null
+++ b/engines/glk/tads/tads2/character_map.cpp
@@ -0,0 +1,339 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/character_map.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error.h"
+#include "glk/tads/tads2/os.h"
+#include "glk/tads/tads2/text_io.h"
+#include "glk/tads/osfrobtads.h"
+#include "common/algorithm.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Global variables for character mapping tables 
+ */
+
+unsigned char G_cmap_input[256];
+unsigned char G_cmap_output[256];
+char G_cmap_id[5];
+char G_cmap_ldesc[CMAP_LDESC_MAX_LEN + 1];
+
+
+/* 
+ *   static variables 
+ */
+
+/* 
+ *   flag: true -> a character set has been explicitly loaded, so we
+ *   should ignore any game character set setting 
+ */
+static int S_cmap_loaded;
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize the default character mappings 
+ */
+void cmap_init_default(void)
+{
+    size_t i;
+
+    /* initialize the input table */
+    for (i = 0 ; i < sizeof(G_cmap_input)/sizeof(G_cmap_input[0]) ; ++i)
+        G_cmap_input[i] = (unsigned char)i;
+
+    /* initialize the output table */
+    for (i = 0 ; i < sizeof(G_cmap_output)/sizeof(G_cmap_output[0]) ; ++i)
+        G_cmap_output[i] = (unsigned char)i;
+
+    /* we have a null ID */
+    memset(G_cmap_id, 0, sizeof(G_cmap_id));
+
+    /* indicate that it's the default */
+    strcpy(G_cmap_ldesc, "(native/no mapping)");
+
+    /* note that we have no character set loaded */
+    S_cmap_loaded = FALSE;
+}
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Internal routine to load a character map from a file 
+ */
+static int cmap_load_internal(char *filename)
+{
+    osfildef *fp;
+    static char sig1[] = CMAP_SIG_S100;
+    char buf[256];
+    uchar lenbuf[2];
+    size_t len;
+    int sysblk;
+
+    /* if there's no mapping file, use the default mapping */
+    if (filename == 0)
+    {
+        /* initialize with the default mapping */
+        cmap_init_default();
+
+        /* return success */
+        return 0;
+    }
+    
+    /* open the file */
+    fp = osfoprb(filename, OSFTCMAP);
+    if (fp == 0)
+        return 1;
+
+    /* check the signature */
+    if (osfrb(fp, buf, sizeof(sig1))
+        || memcmp(buf, sig1, sizeof(sig1)) != 0)
+    {
+        osfcls(fp);
+        return 2;
+    }
+
+    /* load the ID */
+    G_cmap_id[4] = '\0';
+    if (osfrb(fp, G_cmap_id, 4))
+    {
+        osfcls(fp);
+        return 3;
+    }
+
+    /* load the long description */
+    if (osfrb(fp, lenbuf, 2)
+        || (len = osrp2(lenbuf)) > sizeof(G_cmap_ldesc)
+        || osfrb(fp, G_cmap_ldesc, len))
+    {
+        osfcls(fp);
+        return 4;
+    }
+
+    /* load the two tables - input, then output */
+    if (osfrb(fp, G_cmap_input, sizeof(G_cmap_input))
+        || osfrb(fp, G_cmap_output, sizeof(G_cmap_output)))
+    {
+        osfcls(fp);
+        return 5;
+    }
+
+    /* read the next section header */
+    if (osfrb(fp, buf, 4))
+    {
+        osfcls(fp);
+        return 6;
+    }
+
+    /* if it's "SYSI", read the system information string */
+    if (!memcmp(buf, "SYSI", 4))
+    {
+        /* read the length prefix, then the string */
+        if (osfrb(fp, lenbuf, 2)
+            || (len = osrp2(lenbuf)) > sizeof(buf)
+            || osfrb(fp, buf, len))
+        {
+            osfcls(fp);
+            return 7;
+        }
+
+        /* we have a system information block */
+        sysblk = TRUE;
+    }
+    else
+    {
+        /* there's no system information block */
+        sysblk = FALSE;
+    }
+
+    /* 
+     *   call the OS code, so that it can do any system-dependent
+     *   initialization for the new character mapping 
+     */
+    os_advise_load_charmap(G_cmap_id, G_cmap_ldesc, sysblk ? buf : "");
+
+    /* read the next section header */
+    if (sysblk && osfrb(fp, buf, 4))
+    {
+        osfcls(fp);
+        return 8;
+    }
+
+    /* see if we have an entity list */
+    if (!memcmp(buf, "ENTY", 4))
+    {
+        /* read the entities */
+        for (;;)
+        {
+            size_t blen;
+            unsigned int cval;
+            char expansion[CMAP_MAX_ENTITY_EXPANSION];
+            
+            /* read the next item's length and character value */
+            if (osfrb(fp, buf, 4))
+            {
+                osfcls(fp);
+                return 9; 
+            }
+
+            /* decode the values */
+            blen = osrp2(buf);
+            cval = osrp2(buf+2);
+
+            /* if we've reached the zero marker, we're done */
+            if (blen == 0 && cval == 0)
+                break;
+
+            /* read the string */
+            if (blen > CMAP_MAX_ENTITY_EXPANSION
+                || osfrb(fp, expansion, blen))
+            {
+                osfcls(fp);
+                return 10;
+            }
+
+            /* tell the output code about the expansion */
+            tio_set_html_expansion(cval, expansion, blen);
+        }
+    }
+
+    /* 
+     *   ignore anything else we find - if the file format is updated to
+     *   include extra information in the future, and this old code tries
+     *   to load an updated file, we'll just ignore the new information,
+     *   which should always be placed after the "SYSI" block (if present)
+     *   to ensure compatibility with past versions (such as this code)
+     */
+
+    /* no problems - close the file and return success */
+    osfcls(fp);
+    return 0;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Explicitly load a character set from a file.  This character set
+ *   mapping will override any implicit character set mapping that we read
+ *   from a game file.  This should be called when the player explicitly
+ *   loads a character set (via a command line option or similar action).  
+ */
+int cmap_load(char *filename)
+{
+    int err;
+    
+    /* try loading the file */
+    if ((err = cmap_load_internal(filename)) != 0)
+        return err;
+
+    /* 
+     *   note that we've explicitly loaded a character set, if they named
+     *   a character set (if not, this simply establishes the default
+     *   setting, so we haven't explicitly loaded anything) 
+     */
+    if (filename != 0)
+        S_cmap_loaded = TRUE;
+
+    /* success */
+    return 0;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Explicitly override any game character set and use no character set
+ *   instead. 
+ */
+void cmap_override(void)
+{
+    /* apply the default mapping */
+    cmap_init_default();
+
+    /* 
+     *   pretend we have a character map loaded, so that we don't try to
+     *   load another one if the game specifies a character set
+     */
+    S_cmap_loaded = TRUE;
+}
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Set the game's internal character set.  This is called when a game is
+ *   loaded, and the game specifies a character set. 
+ */
+void cmap_set_game_charset(errcxdef *ec,
+                           char *internal_id, char *internal_ldesc,
+                           char *argv0)
+{
+    char filename[OSFNMAX];
+    
+    /* 
+     *   If a character set is already explicitly loaded, ignore the
+     *   game's character set - the player asked us to use a particular
+     *   mapping, so ignore what the game wants.  (This will probably
+     *   result in incorrect display of non-ASCII character values, but
+     *   the player is most likely to use this to avoid errors when an
+     *   appropriate mapping file for the game is not available.  In this
+     *   case, the player informs us by setting the option that he or she
+     *   knows and accepts that the game will not look exactly right.)  
+     */
+    if (S_cmap_loaded)
+        return;
+
+    /* 
+     *   ask the operating system to name the mapping file -- this routine
+     *   will determine, if possible, the current native character set,
+     *   and apply a system-specific naming convention to tell us what
+     *   mapping file we should open 
+     */
+    os_gen_charmap_filename(filename, internal_id, argv0);
+
+    /* try loading the mapping file */
+    if (cmap_load_internal(filename))
+        errsig2(ec, ERR_CHRNOFILE,
+                ERRTSTR, errstr(ec, filename, strlen(filename)),
+                ERRTSTR, errstr(ec, internal_ldesc, strlen(internal_ldesc)));
+
+    /*
+     *   We were successful - the game's internal character set is now
+     *   mapped to the current native character set.  Even though we
+     *   loaded an ldesc from the mapping file, forget that and store the
+     *   internal ldesc that the game specified.  The reason we do this is
+     *   that it's possible that the player will dynamically switch native
+     *   character sets in the future, at which point we'll need to
+     *   re-load the mapping table, which could raise an error if a
+     *   mapping file for the new character set isn't available.  So, we
+     *   may need to provide the same explanation later that we needed to
+     *   provide here.  Save the game's character set ldesc for that
+     *   eventuality, since it describes exactly what the *game* wanted.  
+     */
+    strcpy(G_cmap_ldesc, internal_ldesc);
+}
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/character_map.h b/engines/glk/tads/tads2/character_map.h
new file mode 100644
index 0000000000..c61406fd27
--- /dev/null
+++ b/engines/glk/tads/tads2/character_map.h
@@ -0,0 +1,131 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_CHARACTER_MAP
+#define GLK_TADS_CHARACTER_MAP
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+struct errcxdef;
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize the default character mappings.  If no mapping file is to
+ *   be read, this function will establish identify mappings that leave
+ *   characters untranslated. 
+ */
+void cmap_init_default(void);
+
+
+/*
+ *   Load a character map file.  Returns zero on success, non-zero on
+ *   failure.  If filename is null, we'll use the default mapping.
+ */
+int cmap_load(char *filename);
+
+
+/*
+ *   Turn off character translation.  This overrides any game character
+ *   set that we find and simply uses the default translation. 
+ */
+void cmap_override(void);
+
+
+/*
+ *   Set the game's internal character set.  This should be called when a
+ *   game is loaded, and the game specifies an internal character set.  If
+ *   there is no character map file explicitly loaded, we will attempt to
+ *   load a character mapping file that maps this character set to the
+ *   current native character set.  Signals an error on failure.  This
+ *   routine will succeed (without doing anything) if a character set has
+ *   already been explicitly loaded, since an explicitly-loaded character
+ *   set overrides the automatic character set selection that we attempt
+ *   when loading a game.
+ *   
+ *   argv0 must be provided so that we know where to look for our mapping
+ *   file on systems where mapping files are stored in the same directory
+ *   as the TADS executables.  
+ */
+void cmap_set_game_charset(struct errcxdef *errctx,
+                           char *internal_id, char *internal_ldesc,
+                           char *argv0);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Mapping macros 
+ */
+
+/* map a native character (read externally) into an internal character */
+#define cmap_n2i(c) (G_cmap_input[(unsigned char)(c)])
+
+/* map an internal character into a native character (for display) */
+#define cmap_i2n(c) (G_cmap_output[(unsigned char)(c)])
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Global character mapping tables.  The character map is established at
+ *   start-up. 
+ */
+
+/* 
+ *   input-mapping table - for native character 'n', cmap_input[n] yields
+ *   the internal character code 
+ */
+extern unsigned char G_cmap_input[256];
+
+/*
+ *   output-mapping table - for internal character 'n', cmap_output[n]
+ *   yields the output character code 
+ */
+extern unsigned char G_cmap_output[256];
+
+/* the ID of the loaded character set */
+extern char G_cmap_id[5];
+
+/* the full name (for display purposes) of the loaded character set */
+#define CMAP_LDESC_MAX_LEN  40
+extern char G_cmap_ldesc[CMAP_LDESC_MAX_LEN + 1];
+
+/*
+ *   Maximum expansion for an HTML entity mapping 
+ */
+#define CMAP_MAX_ENTITY_EXPANSION  50
+
+
+/* ------------------------------------------------------------------------ */
+/* 
+ *   Signatures for character map files.  The signature is stored at the
+ *   beginning of the file.  
+ */
+
+/* single-byte character map version 1.0.0 */
+#define CMAP_SIG_S100  "TADS2 charmap S100\n\r\01a"
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/data.cpp b/engines/glk/tads/tads2/data.cpp
index c60fcb2c5f..b19f45f1fd 100644
--- a/engines/glk/tads/tads2/data.cpp
+++ b/engines/glk/tads/tads2/data.cpp
@@ -21,7 +21,8 @@
  */
 
 #include "glk/tads/tads2/data.h"
-#include "glk/tads/tads2/types.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/run.h"
 #include "glk/tads/tads2/vocabulary.h"
 #include "common/algorithm.h"
 
diff --git a/engines/glk/tads/tads2/data.h b/engines/glk/tads/tads2/data.h
index 8db2153e1f..8d122c444a 100644
--- a/engines/glk/tads/tads2/data.h
+++ b/engines/glk/tads/tads2/data.h
@@ -47,6 +47,7 @@ enum DataType {
 	DAT_REDIR   = 16,		///< redirection to different object
 	DAT_TPL2    = 17		///< new-style template
 };
+typedef DataType dattyp;
 
 class Data {
 private:
diff --git a/engines/glk/tads/tads2/debug.h b/engines/glk/tads/tads2/debug.h
new file mode 100644
index 0000000000..52695cfb86
--- /dev/null
+++ b/engines/glk/tads/tads2/debug.h
@@ -0,0 +1,589 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_DEBUG
+#define GLK_TADS_TADS2_DEBUG
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/object.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+/* forward declarations */
+struct bifcxdef;
+struct toksdef;
+struct toktdef;
+struct tokcxdef;
+
+/* stack frame record */
+struct dbgfdef
+{
+    struct runsdef *dbgfbp;                        /* base pointer of frame */
+    objnum  dbgfself;             /* 'self' object (MCMONINV for functions) */
+    objnum  dbgftarg;                               /* actual target object */
+    prpnum  dbgfprop;                          /* property being evalutated */
+    int     dbgfargc;                                /* number of arguments */
+    int     dbgfbif;      /* set to built-in function number if in built-in */
+    uint    dbgffr;         /* offset in object of local frame symbol table */
+    uint    dbgflin;                      /* OPCLINE operand of latest line */
+};
+typedef struct dbgfdef dbgfdef;
+
+/* max number of frames to store in debug frame memory */
+#define DBGMAXFRAME  100
+
+/* maximum number of breakpoints set concurrently */
+#define DBGBPMAX 50
+
+/* breakpoint structure */
+struct dbgbpdef
+{
+    objnum dbgbpself;               /* the "self" object for the breakpoint */
+    objnum dbgbptarg;            /* actual target object for the breakpoint */
+    uint   dbgbpofs;                  /* offset in object of the breakpoint */
+    uint   dbgbpflg;                                    /* breakpoint flags */
+#define DBGBPFUSED  0x01                         /* breakpoint has been set */
+#define DBGBPFNAME  0x02                 /* name of address has been stored */
+#define DBGBPFCOND  0x04             /* breakpoint has a condition attached */
+#define DBGBPFDISA  0x08                          /* breakpoint is disabled */
+#define DBGBPFCONDNAME 0x10        /* condition name string has been stored */
+    uint   dbgbpnam;       /* offset of address name within dbgcxnam buffer */
+    uint   dbgbpcondnam;        /* offset of condition string within buffer */
+    objnum dbgbpcond;        /* object containing compiled condition for bp */
+};
+typedef struct dbgbpdef dbgbpdef;
+
+/* maximum number of watch expressions set concurrently */
+#define DBGWXMAX 30
+
+/* watch expression structure */
+struct dbgwxdef
+{
+    objnum  dbgwxobj;              /* object containing compiled expression */
+    objnum  dbgwxself;                         /* 'self' for the expression */
+    uint    dbgwxnam;   /* offset of expression text within dbgcxnam buffer */
+    uint    dbgwxflg;               /* flags for this watch expression slot */
+#define DBGWXFUSED  0x01                            /* watch slot is in use */
+#define DBGWXFNAME  0x02                   /* name of watch has been stored */
+};
+typedef struct dbgwxdef dbgwxdef;
+
+/* amount of space for bp names (original address strings from user) */
+#define DBGCXNAMSIZ 2048
+
+/* debug context */
+struct dbgcxdef
+{
+    struct tiocxdef *dbgcxtio;                          /* text i/o context */
+    struct tokthdef *dbgcxtab;                              /* symbol table */
+    struct mcmcxdef *dbgcxmem;              /* memory cache manager context */
+    struct errcxdef *dbgcxerr;                    /* error handling context */
+    struct    lindef *dbgcxlin;                    /* chain of line sources */
+    int       dbgcxfcn;                          /* number of frames in use */
+    int       dbgcxdep;          /* actual depth (if overflow frame buffer) */
+    int       dbgcxfid;                        /* source file serial number */
+    dbgfdef   dbgcxfrm[DBGMAXFRAME];                        /* stack frames */
+    int       dbgcxflg;                          /* flags for debug session */
+#define    DBGCXFSS   0x01                  /* single-stepping source lines */
+#define    DBGCXFSO   0x02          /* stepping over a function/method call */
+#define    DBGCXFOK   0x04                         /* debugger is linked in */
+#define    DBGCXFIND  0x08     /* in debugger - suppress stack trace on err */
+#define    DBGCXFGBP  0x10                  /* global breakpoints in effect */
+#define    DBGCXFTRC  0x20                        /* call tracing activated */
+#define    DBGCXFLIN2 0x40         /* new-style line records (line numbers) */
+    int       dbgcxsof;                    /* frame depth at step-over time */
+    dbgbpdef  dbgcxbp[DBGBPMAX];                             /* breakpoints */
+    dbgwxdef  dbgcxwx[DBGWXMAX];                       /* watch expressions */
+    struct    prscxdef *dbgcxprs;                        /* parsing context */
+    struct    runcxdef *dbgcxrun;                      /* execution context */
+    uint      dbgcxnamf;               /* next free byte of dbgcxnam buffer */
+    uint      dbgcxnams;                         /* size of dbgcxnam buffer */
+    char     *dbgcxnam;                       /* space for bp address names */
+    char     *dbgcxhstp;                             /* call history buffer */
+    uint      dbgcxhstl;                           /* history buffer length */
+    uint      dbgcxhstf;             /* offset of next free byte of history */
+
+    /* 
+     *   This member is for the use of the user interface code.  If the
+     *   user interface implementation needs to store additional context,
+     *   it can allocate a structure of its own (it should probably do
+     *   this in dbguini()) and store a pointer to that structure here.
+     *   Since the user interface entrypoints always have the debugger
+     *   context passed as a parameter, the user interface code can
+     *   recover its extra context information by following this pointer
+     *   and casting it to its private structure type.  The TADS code
+     *   won't do anything with this pointer except initialize it to null
+     *   when initializing the debugger context.  
+     */
+    void     *dbgcxui;
+};
+typedef struct dbgcxdef dbgcxdef;
+
+
+/* ======================================================================== */
+/*
+ *   Compiler interface.  These routines are called by the compiler to
+ *   inform the debug record generator about important events as
+ *   compilation proceeds. 
+ */
+
+
+/*
+ *   Tell the current line source that we're compiling an executable
+ *   line, and tell it the object number and offset of the code within the
+ *   object. 
+ */
+void dbgclin(struct tokcxdef *tokctx, objnum objn, uint ofs);
+
+/* size of information given to line source via lincmpinf method */
+#define DBGLINFSIZ   4
+
+
+
+/* ======================================================================== */
+/*
+ *   Run-time interface.  These routines are called by the run-time
+ *   system to apprise the debugger of important events during execution.
+ */
+
+
+/*
+ *   Determine if the debugger is present.  Returns true if so, false if
+ *   not.  This should return false for any stand-alone version of the
+ *   executable that isn't linked with the debugger.  If this returns
+ *   true, dbgucmd() must not have a trivial implementation -- dbgucmd()
+ *   must at least let the user quit out of the game.
+ *   
+ *   This can be switched at either link time or compile time.  If DBG_OFF
+ *   is defined, we'll force this to return false; otherwise, we'll let
+ *   the program define the appropriate implementation through the linker.
+ */
+#ifdef DBG_OFF
+#define dbgpresent() (FALSE)
+#else
+int dbgpresent();
+#endif
+
+
+/* add a debug tracing record */
+/* void dbgenter(dbgcxdef *ctx, runsdef *bp, objnum self, objnum target,
+                 prpnum prop, int binum, int argc); */ 
+
+/* tell debugger where the current line's local frame table is located */
+/* void dbgframe(dbgcxdef *ctx, uint ofsfr, ofslin); */
+
+/* 
+ *   Single-step interrupt: the run-time has reached a new source line.
+ *   ofs is the offset from the start of the object of the line record,
+ *   and p is the current execution pointer.  *p can be changed upon
+ *   return, in which case the run-time will continue from the new
+ *   position; however, the new address must be within the same function
+ *   or method as it was originally.
+ */
+/* void dbgssi(dbgcxdef *ctx, uint ofs, int instr,
+               int err, uchar *noreg *p); */
+
+/* pop debug trace level */
+/* void dbgleave(dbgcxdef *ctx, int exittype); */
+#define DBGEXRET   0                                /* return with no value */
+#define DBGEXVAL   1                                 /* return with a value */
+#define DBGEXPASS  2                       /* use 'pass' to exit a function */
+
+/* dump the stack into text output */
+/* void dbgdump(dbgcxdef *ctx); */
+
+/* reset debug stack (throw away entire contents) */
+/* void dbgrst(dbgcxdef *ctx); */
+
+/* activate debugger if possible; returns TRUE if no debugger is present */
+int dbgstart(dbgcxdef *ctx);
+
+/* add a string to the history buffer */
+void dbgaddhist(dbgcxdef *ctx, char *buf, int bufl);
+
+/*
+ *   Find a base pointer, given the object+offset of the frame.  If the
+ *   frame is not active, this routine signals ERR_INACTFR; otherwise, the
+ *   bp value for the frame is returned. 
+ */
+struct runsdef *dbgfrfind(dbgcxdef *ctx, objnum frobj, uint frofs);
+
+
+/* ======================================================================== */
+/*
+ *   User Interface Support routines.  These routines are called by the
+ *   user interface layer to get information from the debugger and perform
+ *   debugging operations. 
+ */
+
+
+/* get a symbol name; returns length of name */
+int dbgnam(dbgcxdef *ctx, char *outbuf, int typ, int val);
+
+/*
+ *   Get information about current line.  It is assumed that the caller
+ *   knows the size of the line information .
+ */
+void dbglget(dbgcxdef *ctx, uchar *buf);
+
+/*
+ *   Get information about a line in an enclosing stack frame.  Level 0 is
+ *   the current line, level 1 is the first enclosing frame, and so on.
+ *   Returns 0 on success, non-zero if the frame level is invalid.  
+ */
+int dbglgetlvl(dbgcxdef *ctx, uchar *buf, int level);
+
+/*
+ *   Set a breakpoint by symbolic address: "function" or
+ *   "object.property".  The string may contain whitespace characters
+ *   around each symbol; it must be null-terminated.  If an error occurs,
+ *   the error number is returned.  bpnum returns with the breakpoint
+ *   number if err == 0.  If the condition string is given (and is not an
+ *   empty string), the condition is compiled in the scope of the
+ *   breakpoint and attached as the breakpoint condition.  
+ */
+int dbgbpset(dbgcxdef *ctx, char *addr, int *bpnum);
+
+/* 
+ *   Set a breakpoint at an object + offset location.  If 'toggle' is
+ *   true, and there's already a breakpoint at the given location, we'll
+ *   clear the breakpoint; in this case, *did_set will return false to
+ *   indicate that an existing breakpoint was cleared rather than a new
+ *   breakpoint created.  *did_set will return true if a new breakpoint
+ *   was set.  
+ */
+int dbgbpat(dbgcxdef *ctx, objnum objn, objnum self,
+            uint ofs, int *bpnum, char *bpname, int toggle,
+            char *condition, int *did_set);
+
+/* 
+ *   Set a breakpoint at an object + offset location, optionally with a
+ *   condition, using an existing breakpoint slot.  If the slot is already
+ *   in use, we'll return an error.  
+ */
+int dbgbpatid(dbgcxdef *ctx, int bpnum, objnum target, objnum self,
+              uint ofs, char *bpname, int toggle, char *cond,
+              int *did_set);
+
+/*
+ *   Determine if there's a breakpoint at a given code location.  Fills in
+ *   *bpnum with the breakpoint identifier and returns true if a
+ *   breakpoint is found at the given location; returns false if there are
+ *   no breakpoints matching the description.  
+ */
+int dbgisbp(dbgcxdef *ctx, objnum target, objnum self, uint ofs, int *bpnum);
+
+/*
+ *   Determine if the given breakpoint is enabled 
+ */
+int dbgisbpena(dbgcxdef *ctx, int bpnum);
+
+/*
+ *   Delete a breakpoint by breakpoint number (as returned from
+ *   dbgbpset).  Returns error number, or 0 for success. 
+ */
+int dbgbpdel(dbgcxdef *ctx, int bpnum);
+
+/* disable or enable a breakpoint, by breakpoint number; returns error num */
+int dbgbpdis(dbgcxdef *ctx, int bpnum, int disable);
+
+/*
+ *   Set a new condition for the given breakpoint.  Replaces any existing
+ *   condition.  If an error occurs, we'll leave the old condition as it
+ *   was and return a non-zero error code; on success, we'll update the
+ *   condition and return zero. 
+ */
+int dbgbpsetcond(dbgcxdef *ctx, int bpnum, char *cond);
+
+/* list breakpoints, using user callback to do display */
+void dbgbplist(dbgcxdef *ctx,
+               void (*dispfn)(void *ctx, const char *str, int len),
+               void *dispctx);
+
+/* enumerate breakpoints */
+void dbgbpenum(dbgcxdef *ctx,
+               void (*cbfunc)(void *cbctx, int bpnum, const char *desc,
+                              const char *cond, int disabled), void *cbctx);
+
+/* call callback with lindef data for each breakpoint currently set */
+void dbgbpeach(dbgcxdef *ctx,
+               void (*fn)(void *, int, uchar *, uint),
+               void *fnctx);
+
+/* 
+ *   Get information on a specific breakpoint.  Returns zero on success,
+ *   non-zero on failure. 
+ */
+int dbgbpgetinfo(dbgcxdef *ctx, int bpnum, char *descbuf, size_t descbuflen,
+                 char *condbuf, size_t condbuflen);
+
+/* 
+ *   Evaluate an expression (a text string to be parsed) at a particular
+ *   stack context level; returns error number.  Invokes the callback
+ *   function repeatedly to display the value string, and ends the display
+ *   with a newline.  If showtype is true, we'll include a type name
+ *   prefix, otherwise we'll simply display the value.  
+ */
+int dbgeval(dbgcxdef *ctx, char *expr,
+            void (*dispfn)(void *dispctx, const char *str, int strl),
+            void *dispctx, int level, int showtype);
+
+/*
+ *   Evaluate an expression, extended version.  For aggregate values
+ *   (objects, lists), we'll invoke a callback function for each value
+ *   contained by the aggregate value, passing the callback the name and
+ *   relationship of the subitem.  The relationship is simply the operator
+ *   that should be used to join the parent expression and the subitem
+ *   name to form the full subitem expression; for objects, it's ".", and
+ *   for lists it's null (because for lists the subitem names will include
+ *   brackets).  'speculative' is passed to dbgcompile; see the comments
+ *   there for information on the purpose of this flag.  
+ */
+int dbgevalext(dbgcxdef *ctx, char *expr,
+               void (*dispfn)(void *dispctx, const char *str, int strl),
+               void *dispctx, int level, int showtype, dattyp *dat,
+               void (*aggcb)(void *aggctx, const char *subname,
+                             int subnamelen, const char *relationship),
+               void *aggctx, int speculative);
+
+/* 
+ *   enumerate local variables at a given stack context level by calling
+ *   the given function once for each local variable 
+ */
+void dbgenumlcl(dbgcxdef *ctx, int level,
+                void (*func)(void *ctx, const char *lclnam, size_t lclnamlen),
+                void *cbctx);
+
+/* 
+ *   Compile an expression in a given frame context.  Returns an error
+ *   number.  Allocates a new object to contain the compiled code, and
+ *   returns the object number in *objn; the caller is responsible for
+ *   freeing the object when done with it.
+ *   
+ *   If 'speculative' is set to true, we'll prohibit the expression from
+ *   making any assignments or calling any methods or functions.  This
+ *   mode can be used to try compiling an expression that the user could
+ *   conceivably be interested in but has not expressly evaluated; for
+ *   example, this can be used to implement "tooltip evaluation," where
+ *   the debugger automatically shows a little pop-up window with the
+ *   expression under the mouse cursor if the mouse cursor is left
+ *   hovering over some text for a few moments.  In such cases, since the
+ *   user hasn't explicitly requested evaluation, it would be bad to make
+ *   any changes to game state, hence the prohibition of assignments or
+ *   calls.  
+ */
+int dbgcompile(dbgcxdef *ctx, char *expr, dbgfdef *fr, objnum *objn,
+               int speculative);
+
+/* display a stack traceback through a user callback */
+void dbgstktr(dbgcxdef *ctx,
+              void (*dispfn)(void *dispctx, const char *str, int strl),
+              void *dispctx, int level, int toponly, int include_markers);
+
+/* format a display of where execution is stopped into a buffer */
+void dbgwhere(dbgcxdef *ctx, char *buf);
+
+/* set a watch expression; returns error or 0 for success */
+int dbgwxset(dbgcxdef *ctx, char *expr, int *wxnum, int level);
+
+/* delete a watch expression */
+int dbgwxdel(dbgcxdef *ctx, int wxnum);
+
+/* update all watch expressions */
+void dbgwxupd(dbgcxdef *ctx,
+              void (*dispfn)(void *dispctx, const char *txt, int len),
+              void *dispctx);
+
+/* switch to a new active lindef */
+void dbgswitch(struct lindef **linp, struct lindef *newlin);
+
+
+
+/* ======================================================================== */
+/*
+ *   User Interface Routines.  The routines are called by the debugger
+ *   to perform user interaction.
+ */
+
+/* 
+ *   Debugger user interface initialization, phase one.  TADS calls this
+ *   routine during startup, before reading the .GAM file, to let the user
+ *   interface perform any initialization it requires before the .GAM file
+ *   is loaded.  
+ */
+void dbguini(dbgcxdef *ctx, const char *game_filename);
+
+/*
+ *   Debugger user interface initialization, phase two.  TADS calls this
+ *   routine during startup, after read the .GAM file.  The debugger user
+ *   interface code can perform any required initialization that depends
+ *   on the .GAM file having been read.  
+ */
+void dbguini2(dbgcxdef *ctx);
+
+/*
+ *   Determine if the debugger can resume from a run-time error.  This
+ *   reflects the capabilities of the user interface of the debugger.  In
+ *   particular, if the UI provides a way to change the instruction
+ *   pointer, then the debugger can resume from an error, since the user
+ *   can always move past the run-time error and continue execution.  If
+ *   the UI doesn't let the user change the instruction pointer, resuming
+ *   from an error won't work, since the program will keep hitting the
+ *   same error and re-entering the debugger.  If this returns false, the
+ *   run-time will trap to the debugger on an error, but will simply abort
+ *   the current command when the debugger returns.  If this returns true,
+ *   the run-time will trap to the debugger on an error with the
+ *   instruction pointer set back to the start of the line containing the
+ *   error, and will thus re-try the same line of code when the debugger
+ *   returns, unless the debugger explicitly moves the instruction pointer
+ *   before returning.  
+ */
+int dbgu_err_resume(dbgcxdef *ctx);
+
+/*
+ *   Find a source file.  origname is the name of the source file as it
+ *   appears in the game's debugging information; this routine should
+ *   figure out where the file actually is, and put the fully-qualified
+ *   path to the file in fullname.  The debugger calls this after it
+ *   exhausts all of its other methods of finding a source file (such as
+ *   searching the include path).
+ *   
+ *   Return true if the source file should be considered valid, false if
+ *   not.  Most implementations will simply return true if the file was
+ *   found, false if not; however, this approach will cause the debugger
+ *   to terminate with an error at start-up if the user hasn't set up the
+ *   debugger's include path correctly before running the debugger.  Some
+ *   implementations, in particular GUI implementations, may wish to wait
+ *   to find a file until the file is actually needed, rather than pester
+ *   the user with file search dialogs repeatedly at start-up.
+ *   
+ *   must_find_file specifies how to respond if we can't find the file.
+ *   If must_find_file is true, we should always return false if we can't
+ *   find the file.  If must_find_file is false, however, we can
+ *   optionally return true even if we can't find the file.  Doing so
+ *   indicates that the debugger UI will defer locating the file until it
+ *   is actually needed.
+ *   
+ *   If this routine returns true without actually finding the file, it
+ *   should set fullname[0] to '\0' to indicate that fullname doesn't
+ *   contain a valid filename.  
+ */
+int dbgu_find_src(const char *origname, int origlen,
+                  char *fullname, size_t full_len, int must_find_file);
+
+
+/* 
+ *   Debugger user interface main command loop.  If err is non-zero, the
+ *   debugger was entered because a run-time error occurred; otherwise, if
+ *   bphit is non-zero, it's the number of the breakpoint that was
+ *   encountered; otherwise, the debugger was entered through a
+ *   single-step of some kind.  exec_ofs is the byte offset within the
+ *   target object of the next instruction to be executed.  This can be
+ *   changed upon return, in which case execution will continue from the
+ *   new offset, but the offset must be within the same method of the same
+ *   object (or within the same function) as it was upon entry. 
+ */
+void dbgucmd(dbgcxdef *ctx, int bphit, int err, unsigned int *exec_ofs);
+
+/*
+ *   Debugger UI - quitting game.  The runtime calls this routine just
+ *   before the play loop is about to terminate after the game code has
+ *   called the "quit" built-in function.  If the debugger wants, it can
+ *   take control here (just as with dbgucmd()) for as long as it wants.
+ *   If the debugger wants to restart the game, it should call bifrst().
+ *   If this routine returns without signalling a RUN_RESTART error, TADS
+ *   will terminate.  If a RUN_RESTART error is signalled, TADS will
+ *   resume the play loop.  
+ */
+void dbguquitting(dbgcxdef *ctx);
+
+/* 
+ *   debugger user interface termination - this routine is called when the
+ *   debugger is about to terminate, so that the user interface can close
+ *   itself down (close windows, release memory, etc) 
+ */
+void dbguterm(dbgcxdef *ctx);
+
+/*
+ *   Debugger user interface: display an error.  This is called mainly so
+ *   that the debugger can display an error using special output
+ *   formatting if the error occurs while debugging. 
+ */
+void dbguerr(dbgcxdef *ctx, int errnum, char *msg);
+
+/* turn hidden output tracing on/off */
+void trchid(void);
+void trcsho(void);
+
+
+/* ======================================================================== */
+/*
+ *   optional debugger macros - these compile to nothing when compiling a
+ *   version for use without the debugger 
+ */
+
+#ifdef DBG_OFF
+# define dbgenter(ctx, bp, self, target, prop, binum, argc)
+# define dbgleave(ctx, exittype)
+# define dbgdump(ctx)
+# define dbgrst(ctx) ((void)0)
+# define dbgframe(ctx, frofs, linofs)
+# define dbgssi(ctx, ofs, instr, err, p)
+#else /* DBG_OFF */
+# define dbgenter(ctx, bp, self, target, prop, binum, argc) \
+   dbgent(ctx, bp, self, target, prop, binum, argc)
+# define dbgleave(ctx, exittype) dbglv(ctx, exittype)
+# define dbgdump(ctx) dbgds(ctx)
+# define dbgrst(ctx) ((ctx)->dbgcxfcn = (ctx)->dbgcxdep = 0)
+# define dbgframe(ctx, frofs, linofs) \
+   (((ctx)->dbgcxfrm[(ctx)->dbgcxfcn - 1].dbgffr = (frofs)), \
+    ((ctx)->dbgcxfrm[(ctx)->dbgcxfcn - 1].dbgflin = (linofs)))
+# define dbgssi(ctx, ofs, instr, err, p) dbgss(ctx, ofs, instr, err, p)
+#endif /* DBG_OFF */
+
+/* ======================================================================== */
+/* private internal routines */
+
+void dbgent(dbgcxdef *ctx, struct runsdef *bp, objnum self, objnum target,
+            prpnum prop, int binum, int argc);
+
+void dbglv(dbgcxdef *ctx, int exittype);
+
+void dbgds(dbgcxdef *ctx);
+
+void dbgss(dbgcxdef *ctx, uint ofs, int instr, int err, uchar *noreg *p);
+
+void dbgpval(struct dbgcxdef *ctx, struct runsdef *val,
+             void (*dispfn)(void *, const char *, int),
+             void *dispctx, int showtype);
+
+int dbgtabsea(struct toktdef *tab, char *name, int namel, int hash,
+              struct toksdef *ret);
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/error.cpp b/engines/glk/tads/tads2/error.cpp
new file mode 100644
index 0000000000..793ddccb1d
--- /dev/null
+++ b/engines/glk/tads/tads2/error.cpp
@@ -0,0 +1,32 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/error.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/error.h b/engines/glk/tads/tads2/error.h
new file mode 100644
index 0000000000..96831068d7
--- /dev/null
+++ b/engines/glk/tads/tads2/error.h
@@ -0,0 +1,390 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* Error handling
+ * This package defines a set of macros that allows code to raise and
+ * handle exceptions.A macro is provided which signals an error, which
+ * does a non - local goto to the innermost enclosing exception handler.
+ * A set of macros sets up exception handling code.
+ * 
+ * To catch exceptions that occur inside a block of code(i.e., in the
+ * code or in any subroutines called by the code), begin the block with
+ * ERRBEGIN.At the end of the protected code, place the exception
+ * handler, which starts with ERRCATCH.At the end of the exception
+ * handler, place ERREND.If no exception occurs, execution goes
+ * through the protected code, then resumes at the code following
+ * the ERREND.
+ * 
+ * The exception handler can signal another error, which will cause
+ * the next enclosing frame to catch the error.Alternatively, if
+ * the exception handler doesn't signal an error or return, execution
+ * continues at the code following the ERREND.Exceptions that are
+ * signalled during exception handling will be caught by the next
+ * enclosing frame, unless the exception handler code is itself
+ * protected by another ERRBEGIN - ERREND block.
+ * 
+ * To signal an error, use errsig().
+ * 
+ * To use a string argument in a signalled error, cover the string
+ * with errstr(ctx, str, len); for example:
+ * 
+ * errsig1(ctx, ERR_XYZ, ERRTSTR, errstr(ctx, buf, strlen(buf)));
+ * 
+ * This copies the string into a buffer that is unaffected by
+ * stack resetting during error signalling.
+ */
+
+#ifndef GLK_TADS_TADS2_ERROR
+#define GLK_TADS_TADS2_ERROR
+
+#include "glk/tads/tads2/lib.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/*
+ *   for compatility with old facility-free mechanism, signal with
+ *   facility "TADS" 
+ */
+#define errsig(ctx, err) errsigf(ctx, "TADS", err)
+#define errsig1(c, e, t, a) errsigf1(c,"TADS",e,t,a)
+#define errsig2(c, e, t1, a1, t2, a2) errsigf2(c,"TADS",e,t1,a1,t2,a2)
+#define errlog(c, e) errlogf(c, "TADS", e)
+#define errlog1(c, e, t, a) errlogf1(c,"TADS",e,t,a)
+#define errlog2(c, e, t1, a1, t2, a2) errlogf2(c,"TADS",e,t1,a1,t2,a2)
+
+
+
+/*---------------------------- TADS Error Codes ----------------------------*/
+/* memory/cache manager errors */
+#define ERR_NOMEM   1                                      /* out of memory */
+#define ERR_FSEEK   2                              /* error seeking in file */
+#define ERR_FREAD   3                            /* error reading from file */
+#define ERR_NOPAGE  4                                 /* no more page slots */
+#define ERR_REALCK  5           /* attempting to reallocate a locked object */
+#define ERR_SWAPBIG 6     /* swapfile limit reached - out of virtual memory */
+#define ERR_FWRITE  7                                 /* error writing file */
+#define ERR_SWAPPG  8                     /* exceeded swap page table limit */
+#define ERR_CLIUSE  9      /* requested client object number already in use */
+#define ERR_CLIFULL 10                      /* client mapping table is full */
+#define ERR_NOMEM1  11   /* swapping/garbage collection failed to find enuf */
+#define ERR_NOMEM2  12            /* no memory to resize (expand) an object */
+#define ERR_OPSWAP  13                          /* unable to open swap file */
+#define ERR_NOHDR   14                     /* can't get a new object header */
+#define ERR_NOLOAD  15   /* mcm cannot find object to load (internal error) */
+#define ERR_LCKFRE  16     /* attempting to free a locked object (internal) */
+#define ERR_INVOBJ  17                                    /* invalid object */
+#define ERR_BIGOBJ  18  /* object too big - exceeds memory allocation limit */
+
+/* lexical analysis errors */
+#define ERR_INVTOK  100                                    /* invalid token */
+#define ERR_STREOF  101                /* end of file while scanning string */
+#define ERR_TRUNC   102                      /* symbol too long - truncated */
+#define ERR_NOLCLSY 103                   /* no space in local symbol table */
+#define ERR_PRPDIR  104               /* invalid preprocessor (#) directive */
+#define ERR_INCNOFN 105                /* no filename in #include directive */
+#define ERR_INCSYN  106                          /* invalid #include syntax */
+#define ERR_INCSEAR 107                         /* can't find included file */
+#define ERR_INCMTCH 108       /* no matching delimiter in #include filename */
+#define ERR_MANYSYM 109                    /* out of space for symbol table */
+#define ERR_LONGLIN 110                                    /* line too long */
+#define ERR_INCRPT  111           /* header file already included - ignored */
+#define ERR_PRAGMA  112                         /* unknown pragma (ignored) */
+#define ERR_BADPELSE 113                                /* unexpected #else */
+#define ERR_BADENDIF 114                               /* unexpected #endif */
+#define ERR_BADELIF 115                                 /* unexpected #elif */
+#define ERR_MANYPIF 116                             /* #if nesting too deep */
+#define ERR_DEFREDEF  117                 /* #define symbol already defined */
+#define ERR_PUNDEF  118                        /* #undef symbol not defined */
+#define ERR_NOENDIF 119                                   /* missing #endif */
+#define ERR_MACNEST 120                         /* macros nested too deeply */
+#define ERR_BADISDEF 121         /* invalid argument for defined() operator */
+#define ERR_PIF_NA  122                           /* #if is not implemented */
+#define ERR_PELIF_NA 123                        /* #elif is not implemented */
+#define ERR_P_ERROR 124                              /* error directive: %s */
+#define ERR_LONG_FILE_MACRO 125              /* __FILE__ expansion too long */
+#define ERR_LONG_LINE_MACRO 126              /* __LINE__ expansion too long */
+
+/* undo errors */
+#define ERR_UNDOVF  200                /* operation is too big for undo log */
+#define ERR_NOUNDO  201                         /* no more undo information */
+#define ERR_ICUNDO  202          /* incomplete undo (no previous savepoint) */
+
+/* parser errors */
+#define ERR_REQTOK  300    /* expected token (arg 1) - found something else */
+#define ERR_REQSYM  301                                  /* expected symbol */
+#define ERR_REQPRP  302                         /* expected a property name */
+#define ERR_REQOPN  303                                 /* expected operand */
+#define ERR_REQARG  304       /* expected comma or closing paren (arg list) */
+#define ERR_NONODE  305                      /* no space for new parse node */
+#define ERR_REQOBJ  306                             /* epxected object name */
+#define ERR_REQEXT  307           /* redefining symbol as external function */
+#define ERR_REQFCN  308                    /* redefining symbol as function */
+#define ERR_NOCLASS 309  /* can't use CLASS with function/external function */
+#define ERR_REQUNO  310                          /* required unary operator */
+#define ERR_REQBIN  311                         /* required binary operator */
+#define ERR_INVBIN  312                          /* invalid binary operator */
+#define ERR_INVASI  313                               /* invalid assignment */
+#define ERR_REQVAR  314                           /* required variable name */
+#define ERR_LCLSYN  315        /* required comma or semicolon in local list */
+#define ERR_REQRBR  316   /* required right brace (eof before end of group) */
+#define ERR_BADBRK  317                          /* 'break' without 'while' */
+#define ERR_BADCNT  318                       /* 'continue' without 'while' */
+#define ERR_BADELS  319                              /* 'else' without 'if' */
+#define ERR_WEQASI  320 /* warning: possible use of '=' where ':=' intended */
+#define ERR_EOF     321                           /* unexpected end of file */
+#define ERR_SYNTAX  322                             /* general syntax error */
+#define ERR_INVOP   323                             /* invalid operand type */
+#define ERR_NOMEMLC 324             /* no memory for new local symbol table */
+#define ERR_NOMEMAR 325              /* no memory for argument symbol table */
+#define ERR_FREDEF  326   /* redefining a function which is already defined */
+#define ERR_NOSW    327      /* 'case' or 'default' and not in switch block */
+#define ERR_SWRQCN  328           /* constant required in switch case value */
+#define ERR_REQLBL  329                        /* label required for 'goto' */
+#define ERR_NOGOTO  330                       /* 'goto' label never defined */
+#define ERR_MANYSC  331                 /* too many superclasses for object */
+#define ERR_OREDEF  332                      /* redefining symbol as object */
+#define ERR_PREDEF  333               /* property being redefined in object */
+#define ERR_BADPVL  334                           /* invalid property value */
+#define ERR_BADVOC  335                    /* bad vocabulary property value */
+#define ERR_BADTPL  336       /* bad template property value (need sstring) */
+#define ERR_LONGTPL 337             /* template base property name too long */
+#define ERR_MANYTPL 338     /* too many templates (internal compiler limit) */
+#define ERR_BADCMPD 339   /* bad value for compound word (sstring required) */
+#define ERR_BADFMT  340     /* bad value for format string (sstring needed) */
+#define ERR_BADSYN  341     /* invalid value for synonym (sstring required) */
+#define ERR_UNDFSYM 342                                 /* undefined symbol */
+#define ERR_BADSPEC 343                                 /* bad special word */
+#define ERR_NOSELF  344                 /* "self" not valid in this context */
+#define ERR_STREND  345            /* warning: possible unterminated string */
+#define ERR_MODRPLX 346    /* modify/replace not allowed with external func */
+#define ERR_MODFCN  347                 /* modify not allowed with function */
+#define ERR_MODFWD  348     /* modify/replace not allowed with forward func */
+#define ERR_MODOBJ  349    /* modify can only be used with a defined object */
+#define ERR_RPLSPEC 350                 /* warning - replacing specialWords */
+#define ERR_SPECNIL 351        /* nil only allowed with modify specialWords */
+#define ERR_BADLCL  353   /* 'local' statement must precede executable code */
+#define ERR_IMPPROP 354          /* implied verifier '%s' is not a property */
+#define ERR_BADTPLF 355                    /* invalid command template flag */
+#define ERR_NOTPLFLG 356      /* flags are not allowed with old file format */
+#define ERR_AMBIGBIN 357          /* warning: operator '%s' could be binary */
+#define ERR_PIA     358           /* warning: possibly incorrect assignment */
+#define ERR_BADSPECEXPR 359               /* invalid speculation evaluation */
+
+/* code generation errors */
+#define ERR_OBJOVF  400     /* object cannot grow any bigger - code too big */
+#define ERR_NOLBL   401                  /* no more temporary labels/fixups */
+#define ERR_LBNOSET 402                 /* (internal error) label never set */
+#define ERR_INVLSTE 403                /* invalid datatype for list element */
+#define ERR_MANYDBG 404  /* too many debugger line records (internal limit) */
+
+/* vocabulary setup errors */
+#define ERR_VOCINUS 450            /* vocabulary being redefined for object */
+#define ERR_VOCMNPG 451          /* too many vocwdef pages (internal limit) */
+#define ERR_VOCREVB 452                             /* redefining same verb */
+#define ERR_VOCREVB2 453            /* redefining same verb - two arguments */
+
+/* set-up errors */
+#define ERR_LOCNOBJ 500           /* location of object %s is not an object */
+#define ERR_CNTNLST 501                /* contents of object %s is not list */
+#define ERR_SUPOVF  502           /* overflow trying to build contents list */
+#define ERR_RQOBJNF 503                     /* required object %s not found */
+#define ERR_WRNONF  504                    /* warning - object %s not found */
+#define ERR_MANYBIF 505     /* too many built-in functions (internal error) */
+
+/* fio errors */
+#define ERR_OPWGAM  600                  /* unable to open game for writing */
+#define ERR_WRTGAM  601                       /* error writing to game file */
+#define ERR_FIOMSC  602              /* too many sc's for writing in fiowrt */
+#define ERR_UNDEFF  603                               /* undefined function */
+#define ERR_UNDEFO  604                                 /* undefined object */
+#define ERR_UNDEF   605                          /* undefined symbols found */
+#define ERR_OPRGAM  606                  /* unable to open game for reading */
+#define ERR_RDGAM   607                          /* error reading game file */
+#define ERR_BADHDR  608     /* file has invalid header - not TADS game file */
+#define ERR_UNKRSC  609               /* unknown resource type in .gam file */
+#define ERR_UNKOTYP 610              /* unknown object type in OBJ resource */
+#define ERR_BADVSN  611     /* file saved by different incompatible version */
+#define ERR_LDGAM   612                   /* error loading object on demand */
+#define ERR_LDBIG   613  /* object too big for load region (prob. internal) */
+#define ERR_UNXEXT  614                 /* did not expect external function */
+#define ERR_WRTVSN  615      /* compiler cannot write the requested version */
+#define ERR_VNOCTAB 616         /* format version cannot be used with -ctab */
+#define ERR_BADHDRRSC 617        /* invalid resource file header in file %s */
+#define ERR_RDRSC   618                /* error reading resource file "xxx" */
+
+/* character mapping errors */
+#define ERR_CHRNOFILE 700          /* unable to load character mapping file */
+
+/* user interrupt */
+#define ERR_USRINT  990       /* user requested cancel of current operation */
+
+/* run-time errors */
+#define ERR_STKOVF  1001                                  /* stack overflow */
+#define ERR_HPOVF   1002                                   /* heap overflow */
+#define ERR_REQNUM  1003                          /* numeric value required */
+#define ERR_STKUND  1004                                 /* stack underflow */
+#define ERR_REQLOG  1005                          /* logical value required */
+#define ERR_INVCMP  1006      /* invalid datatypes for magnitude comparison */
+#define ERR_REQSTR  1007                           /* string value required */
+#define ERR_INVADD  1008              /* invalid datatypes for '+' operator */
+#define ERR_INVSUB  1009       /* invalid datatypes for binary '-' operator */
+#define ERR_REQVOB  1010                            /* require object value */
+#define ERR_REQVFN  1011                       /* required function pointer */
+#define ERR_REQVPR  1012                  /* required property number value */
+
+/* non-error conditions:  run-time EXIT, ABORT, ASKIO, ASKDO */
+#define ERR_RUNEXIT 1013                       /* 'exit' statement executed */
+#define ERR_RUNABRT 1014                      /* 'abort' statement executed */
+#define ERR_RUNASKD 1015                      /* 'askdo' statement executed */
+#define ERR_RUNASKI 1016             /* 'askio' executed; int arg 1 is prep */
+#define ERR_RUNQUIT 1017                                 /* 'quit' executed */
+#define ERR_RUNRESTART 1018                             /* 'reset' executed */
+#define ERR_RUNEXITOBJ 1019                           /* 'exitobj' executed */
+
+#define ERR_REQVLS  1020                             /* list value required */
+#define ERR_LOWINX  1021              /* index value too low (must be >= 1) */
+#define ERR_HIGHINX 1022  /* index value too high (must be <= length(list)) */
+#define ERR_INVTBIF 1023              /* invalid type for built-in function */
+#define ERR_INVVBIF 1024             /* invalid value for built-in function */
+#define ERR_BIFARGC 1025           /* wrong number of arguments to built-in */
+#define ERR_ARGC    1026      /* wrong number of arguments to user function */
+#define ERR_FUSEVAL 1027     /* string/list not allowed for fuse/daemon arg */
+#define ERR_BADSETF 1028      /* internal error in setfuse/setdaemon/notify */
+#define ERR_MANYFUS 1029                                  /* too many fuses */
+#define ERR_MANYDMN 1030                                /* too many daemons */
+#define ERR_MANYNFY 1031                              /* too many notifiers */
+#define ERR_NOFUSE  1032                       /* fuse not found in remfuse */
+#define ERR_NODMN   1033                   /* daemon not found in remdaemon */
+#define ERR_NONFY   1034                  /* notifier not found in unnotify */
+#define ERR_BADREMF 1035    /* internal error in remfuse/remdaemon/unnotify */
+#define ERR_DMDLOOP 1036     /* load-on-demand loop: property not being set */
+#define ERR_UNDFOBJ 1037             /* undefined object in vocabulary tree */
+#define ERR_BIFCSTR 1038            /* c-string conversion overflows buffer */
+#define ERR_INVOPC  1039                                  /* invalid opcode */
+#define ERR_RUNNOBJ 1040     /* runtime error: property taken of non-object */
+#define ERR_EXTLOAD 1041           /* unable to load external function "%s" */
+#define ERR_EXTRUN  1042          /* error executing external function "%s" */
+#define ERR_CIRCSYN 1043                                /* circular synonym */
+#define ERR_DIVZERO 1044                                  /* divide by zero */
+#define ERR_BADDEL  1045      /* can only delete objects created with "new" */
+#define ERR_BADNEWSC 1046    /* superclass for "new" cannot be a new object */
+#define ERR_VOCSTK  1047              /* insufficient space in parser stack */
+#define ERR_BADFILE 1048                             /* invalid file handle */
+
+#define ERR_RUNEXITPRECMD 1049                    /* exited from preCommand */
+
+/* run-time parser errors */
+#define ERR_PRS_SENT_UNK  1200         /* sentence structure not recognized */
+#define ERR_PRS_VERDO_FAIL 1201                         /* verDoVerb failed */
+#define ERR_PRS_VERIO_FAIL 1202                         /* verIoVerb failed */
+#define ERR_PRS_NO_VERDO  1203            /* no verDoVerb for direct object */
+#define ERR_PRS_NO_VERIO  1204            /* no verIoVerb for direct object */
+#define ERR_PRS_VAL_DO_FAIL  1205        /* direct object validation failed */
+#define ERR_PRS_VAL_IO_FAIL  1206      /* indirect object validation failed */
+
+/* compiler/runtime/debugger driver errors */
+#define ERR_USAGE   1500                                   /* invalid usage */
+#define ERR_OPNINP  1501                        /* error opening input file */
+#define ERR_NODBG   1502                 /* game not compiled for debugging */
+#define ERR_ERRFIL  1503               /* unable to open error capture file */
+#define ERR_PRSCXSIZ 1504              /* parse pool + local size too large */
+#define ERR_STKSIZE 1505                            /* stack size too large */
+#define ERR_OPNSTRFIL 1506             /* error opening string capture file */
+#define ERR_INVCMAP 1507                      /* invalid character map file */
+
+/* debugger errors */
+#define ERR_BPSYM   2000                 /* symbol not found for breakpoint */
+#define ERR_BPPROP  2002             /* breakpoint symbol is not a property */
+#define ERR_BPFUNC  2003             /* breakpoint symbol is not a function */
+#define ERR_BPNOPRP 2004              /* property is not defined for object */
+#define ERR_BPPRPNC 2005                            /* property is not code */
+#define ERR_BPSET   2006         /* breakpoint already set at this location */
+#define ERR_BPNOTLN 2007     /* breakpoint is not at a line (OPCLINE instr) */
+#define ERR_MANYBP  2008                            /* too many breakpoints */
+#define ERR_BPNSET  2009            /* breakpoint to be deleted was not set */
+#define ERR_DBGMNSY 2010  /* too many symbols in debug expression (int lim) */
+#define ERR_NOSOURC 2011                   /* unable to find source file %s */
+#define ERR_WTCHLCL 2012        /* illegal to assign to local in watch expr */
+#define ERR_INACTFR 2013 /* inactive frame (expression value not available) */
+#define ERR_MANYWX  2014                      /* too many watch expressions */
+#define ERR_WXNSET  2015                              /* watchpoint not set */
+#define ERR_EXTRTXT 2016               /* extraneous text at end of command */
+#define ERR_BPOBJ   2017              /* breakpoint symbol is not an object */
+#define ERR_DBGINACT 2018                         /* debugger is not active */
+#define ERR_BPINUSE 2019                      /* breakpoint is already used */
+#define ERR_RTBADSPECEXPR 2020            /* invalid speculative expression */
+#define ERR_NEEDLIN2 2021    /* -ds2 information not found - must recompile */
+
+/* usage error messages */
+#define ERR_TCUS1   3000                          /* first tc usage message */
+#define ERR_TCUSL   3024                           /* last tc usage message */
+#define ERR_TCTGUS1 3030                         /* first tc toggle message */
+#define ERR_TCTGUSL 3032
+#define ERR_TCZUS1  3040            /* first tc -Z suboptions usage message */
+#define ERR_TCZUSL  3041
+#define ERR_TC1US1  3050            /* first tc -1 suboptions usage message */
+#define ERR_TC1USL  3058
+#define ERR_TCMUS1  3070            /* first tc -m suboptions usage message */
+#define ERR_TCMUSL  3076
+#define ERR_TCVUS1  3080                /* first -v suboption usage message */
+#define ERR_TCVUSL  3082
+#define ERR_TRUSPARM 3099
+#define ERR_TRUS1   3100                          /* first tr usage message */
+#define ERR_TRUSL   3117
+#define ERR_TRUSFT1 3118                       /* first tr "footer" message */
+#define ERR_TRUSFTL 3119                        /* last tr "footer" message */
+#define ERR_TRSUS1  3150            /* first tr -s suboptions usage message */
+#define ERR_TRSUSL  3157
+#define ERR_TDBUSPARM 3199
+#define ERR_TDBUS1  3200                         /* first tdb usage message */
+#define ERR_TDBUSL  3214                          /* last tdb usage message */
+
+/* TR 16-bit MSDOS-specific usage messages */
+#define ERR_TRUS_DOS_1 3300
+#define ERR_TRUS_DOS_L 3300
+
+/* TR 32-bit MSDOS console mode usage messages */
+#define ERR_TRUS_DOS32_1  3310
+#define ERR_TRUS_DOS32_L  3312
+
+/* TADS/Graphic errors */
+#define ERR_GNOFIL  4001                     /* can't find graphics file %s */
+#define ERR_GNORM   4002                              /* can't find room %s */
+#define ERR_GNOOBJ  4003                   /* can't find hot spot object %s */
+#define ERR_GNOICN  4004                       /* can't find icon object %s */
+
+
+/*
+ *   Special error flag - this is returned from execmd() when preparseCmd
+ *   returns a command list.  This indicates to voc1cmd that it should try
+ *   the command over again, using the words in the new list. 
+ */
+#define ERR_PREPRSCMDREDO  30000             /* preparseCmd returned a list */
+#define ERR_PREPRSCMDCAN   30001    /* preparseCmd returned 'nil' to cancel */
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/error_handling.cpp b/engines/glk/tads/tads2/error_handling.cpp
new file mode 100644
index 0000000000..a2300ee834
--- /dev/null
+++ b/engines/glk/tads/tads2/error_handling.cpp
@@ -0,0 +1,32 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "error_handling.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/error_handling.h b/engines/glk/tads/tads2/error_handling.h
new file mode 100644
index 0000000000..a225bbea74
--- /dev/null
+++ b/engines/glk/tads/tads2/error_handling.h
@@ -0,0 +1,338 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* Library error handling definitions
+ * All of the functions and macros in here are named ERRxxx because
+ * this file was based on the TADS err.h, which used the ERRxxx naming
+ * convention, and it would be a lot of trouble to change.
+ * 
+ * This package defines a set of macros that allows code to raise and
+ * handle exceptions.  A macro is provided which signals an error, which
+ * does a non-local goto to the innermost enclosing exception handler.
+ * A set of macros sets up exception handling code.
+ * 
+ * To catch exceptions that occur inside a block of code (i.e., in the
+ * code or in any subroutines called by the code), begin the block with
+ * ERRBEGIN.  At the end of the protected code, place the exception
+ * handler, which starts with ERRCATCH.  At the end of the exception
+ * handler, place ERREND.  If no exception occurs, execution goes
+ * through the protected code, then resumes at the code following
+ * the ERREND.
+ * 
+ * The exception handler can signal another error, which will cause
+ * the next enclosing frame to catch the error.  Alternatively, if
+ * the exception handler doesn't signal an error or return, execution
+ * continues at the code following the ERREND.  Exceptions that are
+ * signalled during exception handling will be caught by the next
+ * enclosing frame, unless the exception handler code is itself
+ * protected by another ERRBEGIN-ERREND block.
+ * 
+ * To signal an error, use errsig().
+ * 
+ * To use a string argument in a signalled error, cover the string
+ * with errstr(ctx, str, len); for example:
+ * 
+ * errsig1(ctx, ERR_XYZ, ERRTSTR, errstr(ctx, buf, strlen(buf)));
+ * 
+ * This copies the string into a buffer that is unaffected by
+ * stack resetting during error signalling.
+ */
+
+#ifndef GLK_TADS_TADS2_ERROR_HANDLING
+#define GLK_TADS_TADS2_ERROR_HANDLING
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/osfrobtads.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+// TODO: Clean away use of jmp_buf, since ScummVM doesn't allow it
+struct jmp_buf {};
+
+/**
+ * Maximum length of a facility identifier
+ */
+#define ERRFACMAX    6
+
+union erradef {
+    int   erraint;                                      /* integer argument */
+    char *errastr;                                  /* text string argument */
+};
+
+struct errdef {
+    struct errdef *errprv;                          /* previous error frame */
+    int            errcode;        /* error code of exception being handled */
+    char           errfac[ERRFACMAX+1];        /* facility of current error */
+    erradef        erraav[10];                      /* parameters for error */
+    int            erraac;                   /* count of parameters in argc */
+    jmp_buf        errbuf;           /* jump buffer for current error frame */
+};
+
+#define ERRBUFSIZ 512
+
+/**
+ * Seek location record for an error message by number
+ */
+struct errmfdef {
+    uint  errmfnum;                                         /* error number */
+    ulong errmfseek;                       /* seek location of this message */
+};
+typedef struct errmfdef errmfdef;
+
+struct errcxdef {
+    errdef   *errcxptr;                              /* current error frame */
+    void    (*errcxlog)(void *, char *fac, int err, int argc, erradef *);
+                                         /* error logging callback function */
+    void     *errcxlgc;               /* context for error logging callback */
+    int       errcxofs;                        /* offset in argument buffer */
+    char      errcxbuf[ERRBUFSIZ];            /* space for argument strings */
+    osfildef *errcxfp;                /* message file, if one is being used */
+    errmfdef *errcxseek;              /* seek locations of messages in file */
+    uint      errcxsksz;                         /* size of errcxseek array */
+    ulong     errcxbase;   /* offset in physical file of logical error file */
+    struct appctxdef *errcxappctx;              /* host application context */
+};
+
+/**
+ * Begin protected code
+ */
+#define ERRBEGIN(ctx) \
+  { \
+    errdef fr_; \
+    if ((fr_.errcode = setjmp(fr_.errbuf)) == 0) \
+    { \
+      fr_.errprv = (ctx)->errcxptr; \
+      (ctx)->errcxptr = &fr_;
+
+/**
+ * End protected code, begin error handler
+ */
+#define ERRCATCH(ctx, e) \
+      assert(1==1 && (ctx)->errcxptr != fr_.errprv); \
+      (ctx)->errcxptr = fr_.errprv; \
+    } \
+    else \
+    { \
+      assert(2==2 && (ctx)->errcxptr != fr_.errprv); \
+      (e) = fr_.errcode; \
+      (ctx)->errcxptr = fr_.errprv;
+        
+/* retrieve argument (int, string) in current error frame */
+#define errargint(argnum) (fr_.erraav[argnum].erraint)
+#define errargstr(argnum) (fr_.erraav[argnum].errastr)
+
+    
+#define ERREND(ctx) \
+    } \
+  }
+
+/* end protected code, begin cleanup (no handling; just cleaning up) */
+#define ERRCLEAN(ctx) \
+      assert((ctx)->errcxptr != fr_.errprv); \
+      (ctx)->errcxptr = fr_.errprv; \
+    } \
+    else \
+    { \
+      assert((ctx)->errcxptr != fr_.errprv); \
+      (ctx)->errcxptr = fr_.errprv;
+
+#define ERRENDCLN(ctx) \
+      errrse(ctx); \
+    } \
+  }
+
+
+
+/* argument types for errors with arguments */
+#define ERRTINT  erraint
+#define ERRTSTR  errastr
+
+/* set argument count in error frame */
+#define errargc(ctx,cnt) ((ctx)->errcxptr->erraac=(cnt))
+
+/* enter string argument; returns pointer to argument used in errargv */
+#ifdef ERR_NO_MACRO
+char *errstr(errcxdef *ctx, const char *str, int len);
+#else /* ERR_NO_MACRO */
+  
+#define errstr(ctx,str,len) \
+  ((memcpy(&(ctx)->errcxbuf[(ctx)->errcxofs],str,(size_t)len), \
+   (ctx)->errcxofs += (len), \
+   (ctx)->errcxbuf[(ctx)->errcxofs++] = '\0'), \
+   &(ctx)->errcxbuf[(ctx)->errcxofs-(len)-1])
+
+#endif /* ERR_NO_MACRO */
+
+/* set argument in error frame argument vector */
+#define errargv(ctx,index,typ,arg) \
+  ((ctx)->errcxptr->erraav[index].typ=(arg))
+
+/* signal an error with argument count already set */
+#ifdef ERR_NO_MACRO
+void errsign(errcxdef *ctx, int e, char *facility);
+#else /* ERR_NO_MACRO */
+# ifdef DEBUG
+void errjmp(jmp_buf buf, int e);
+#  define errsign(ctx, e, fac) \
+   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
+    (ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
+    (ctx)->errcxofs=0, errjmp((ctx)->errcxptr->errbuf, e))
+# else /* DEBUG */
+#  define errsign(ctx, e, fac) \
+   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
+    (ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
+    (ctx)->errcxofs=0, longjmp((ctx)->errcxptr->errbuf, e))
+# endif /* DEBUG */
+#endif /* ERR_NO_MACRO */
+
+
+/* signal an error with no arguments */
+#ifdef ERR_NO_MACRO
+void errsigf(errcxdef *ctx, char *facility, int err);
+#else /* ERR_NO_MACRO */
+#define errsigf(ctx, fac, e) (errargc(ctx,0),errsign(ctx,e,fac))
+#endif /* ERR_NO_MACRO */
+  
+/* signal an error with one argument */
+#define errsigf1(ctx, fac, e, typ1, arg1) \
+  (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errsign(ctx,e,fac))
+
+/* signal an error with two arguments */
+#define errsigf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
+  (errargv(ctx,0,typ1,arg1), errargv(ctx,1,typ2,arg2), \
+   errargc(ctx,2), errsign(ctx,e,fac))
+
+/* resignal the current error - only usable within exception handlers */
+#ifdef ERR_NO_MACRO
+void errrse1(errcxdef *ctx, errdef *fr);
+# define errrse(ctx) errrse1(ctx, &fr_)
+#else /* ERR_NO_MACRO */
+
+/* void errrse(errcxdef *ctx); */
+# define errrse(ctx) \
+  (errargc(ctx, fr_.erraac),\
+   memcpy((ctx)->errcxptr->erraav, fr_.erraav, \
+    (size_t)(fr_.erraac*sizeof(erradef))),\
+   errsign(ctx, fr_.errcode, fr_.errfac))
+
+#endif /* ERR_NO_MACRO */
+
+/*
+ *   For use in an error handler (ERRCATCH..ERREND) only: Copy the
+ *   parameters from the error currently being handled to the enclosing
+ *   frame.  This is useful when "keeping" an error being handled - i.e.,
+ *   the arguments will continue to be used outside of the
+ *   ERRCATCH..ERREND code. 
+ */
+/* void errkeepargs(errcxdef *ctx); */
+#define errkeepargs(ctx) errcopyargs(ctx, &fr_)
+
+/* 
+ *   copy the parameters for an error from another frame into the current
+ *   frame - this can be used when we want to be able to display an error
+ *   that occurred in an inner frame within code that is protected by a
+ *   new enclosing error frame 
+ */
+/* void errcopyargs(errcxdef *ctx, errdef *fr); */
+#define errcopyargs(ctx, fr) \
+   (errargc((ctx), (fr)->erraac), \
+    memcpy((ctx)->errcxptr->erraav, (fr)->erraav, \
+           (size_t)((fr)->erraac*sizeof(erradef))))
+
+/* log error that's been caught, using arguments already caught */
+#define errclog(ctx) \
+ ((*(ctx)->errcxlog)((ctx)->errcxlgc,fr_.errfac,fr_.errcode,\
+  fr_.erraac,fr_.erraav))
+
+/* log an error that's been set up but not signalled yet */
+#define errprelog(ctx, err) \
+ ((*(ctx)->errcxlog)((ctx)->errcxlgc,(ctx)->errcxptr->errfac,\
+   err,(ctx)->errcxptr->erraac,\
+   (ctx)->errcxptr->erraav))
+
+/* log an error (no signalling, just reporting) */
+#ifdef ERR_NO_MACRO
+void errlogn(errcxdef *ctx, int err, char *facility);
+#else /* ERR_NO_MACRO */
+
+#define errlogn(ctx,err,fac) \
+ ((ctx)->errcxofs=0,\
+  (*(ctx)->errcxlog)((ctx)->errcxlgc,fac,err,(ctx)->errcxptr->erraac,\
+  (ctx)->errcxptr->erraav))
+
+#endif /* ERR_NO_MACRO */
+
+/* log an error with no arguments */
+#ifdef ERR_NO_MACRO
+void errlogf(errcxdef *ctx, char *facility, int err);
+#else /* ERR_NO_MACRO */
+
+/* void errlogf(errcxdef *ctx, char *facility, int err); */
+#define errlogf(ctx,fac,err) (errargc(ctx,0),errlogn(ctx,err,fac))
+
+#endif /* ERR_NO_MACRO */
+
+/* log an error with one argument */
+#define errlogf1(ctx, fac, e, typ1, arg1) \
+ (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errlogn(ctx,e,fac))
+  
+/* log an error with two arguments */
+#define errlogf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
+ (errargv(ctx,0,typ1,arg1),errargv(ctx,1,typ2,arg2),\
+  errargc(ctx,2),errlogn(ctx,e,fac))
+
+
+/*
+ *   Format an error message, sprintf-style, using arguments in an
+ *   erradef array (which is passed to the error-logging callback).
+ *   Returns the length of the output string, even if the actual
+ *   output string was truncated because the outbuf was too short.
+ *   (If called with outbufl == 0, nothing will be written out, but
+ *   the size of the buffer needed, minus the terminating null byte,
+ *   will be computed and returned.)
+ */
+int errfmt(char *outbuf, int outbufl, char *fmt, int argc,
+           erradef *argv);
+  
+/* get the text of an error */
+void errmsg(errcxdef *ctx, char *outbuf, uint outbufl, uint err);
+  
+/* initialize error subsystem, opening error message file if necessary */
+void errini(errcxdef *ctx, osfildef *fp);
+
+/* allocate and initialize error context, free error context */
+errcxdef *lerini();
+void      lerfre(errcxdef *ctx);
+
+/* error message structure - number + text */
+struct errmdef {
+    uint   errmerr;                                         /* error number */
+    char  *errmtxt;                                /* text of error message */
+};
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/file_io.cpp b/engines/glk/tads/tads2/file_io.cpp
new file mode 100644
index 0000000000..581601fbf0
--- /dev/null
+++ b/engines/glk/tads/tads2/file_io.cpp
@@ -0,0 +1,32 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/file_io.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/file_io.h b/engines/glk/tads/tads2/file_io.h
new file mode 100644
index 0000000000..8599c4909f
--- /dev/null
+++ b/engines/glk/tads/tads2/file_io.h
@@ -0,0 +1,137 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/*
+ * file i/o interface
+ */
+
+#ifndef GLK_TADS_TADS2_FILE_IO
+#define GLK_TADS_TADS2_FILE_IO
+
+#include "glk/tads/tads2/lib.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* forward declarations */
+struct voccxdef;
+
+/* load-on-demand context (passed in by mcm in load callback) */
+typedef struct fiolcxdef fiolcxdef;
+struct fiolcxdef
+{
+    osfildef *fiolcxfp;                        /* file pointer of load file */
+    errcxdef *fiolcxerr;                          /* error handling context */
+    ulong     fiolcxst;                          /* starting offset in file */
+    uint      fiolcxflg;                   /* flags from original load file */
+    uint      fiolcxseed;                                    /* fioxor seed */
+    uint      fiolcxinc;                                /* fioxor increment */
+};
+
+/* write game to binary file */
+void fiowrt(struct mcmcxdef *mctx, voccxdef *vctx,
+            struct tokcxdef *tokctx, struct tokthdef *tab,
+            uchar *fmts, uint fmtl, char *fname, uint flags, objnum preinit,
+            int extc, uint prpcnt, char *filever);
+
+/* flag values for use with fiowrt */
+#define FIOFSYM   0x01               /* include symbol table in output file */
+#define FIOFLIN   0x02          /* include source file tracking information */
+#define FIOFPRE   0x04        /* preinit needs to be run after reading game */
+#define FIOFCRYPT 0x08           /* "encrypt" objects prior to writing them */
+#define FIOFBIN   0x10                        /* writing precompiled header */
+#define FIOFFAST  0x20                     /* fast-load records are in file */
+#define FIOFCASE  0x40    /* case folding was turned on in original compile */
+#define FIOFLIN2  0x80                            /* new-style line records */
+
+/* read game from binary file; sets up loader callback context */
+void fiord(struct mcmcxdef *mctx, voccxdef *vctx,
+           struct tokcxdef *tctx,
+           char *fname, char *exename,
+           struct fiolcxdef *setupctx, objnum *preinit, uint *flagp,
+           struct tokpdef *path, uchar **fmtsp, uint *fmtlp,
+           uint *pcntptr, int flags, struct appctxdef *appctx,
+           char *argv0);
+
+/* shut down load-on-demand subsystem, close load file */
+void fiorcls(fiolcxdef *ctx);
+
+/* loader callback - load an object on demand */
+void OS_LOADDS fioldobj(void *ctx, mclhd handle, uchar *ptr,
+                        ushort siz);
+
+/* 
+ *   Save a game - returns TRUE on failure.  We'll save the file to
+ *   'fname'.  'game_fname' is the name of the game file; if this is not
+ *   null, we'll save it to the saved game file so that the player can
+ *   later start the game by specifying only the saved game file to the
+ *   run-time.  'game_fname' can be null, in which case we'll omit the
+ *   game file information.  
+ */
+int fiosav(voccxdef *vctx, char *fname, char *game_fname);
+
+/*
+ *   fiorso() result codes 
+ */
+#define FIORSO_SUCCESS          0                                /* success */
+#define FIORSO_FILE_NOT_FOUND   1                         /* file not found */
+#define FIORSO_NOT_SAVE_FILE    2                  /* not a saved game file */
+#define FIORSO_BAD_FMT_VSN      3       /* incompatible file format version */
+#define FIORSO_BAD_GAME_VSN     4  /* file saved by another game or version */
+#define FIORSO_READ_ERROR       5            /* error reading from the file */
+#define FIORSO_NO_PARAM_FILE    6   /* no parameter file (for restore(nil)) */
+
+/* restore a game - returns TRUE on failure */
+int fiorso(voccxdef *vctx, char *fname);
+
+/*
+ *   Look in a saved game file to determine if it has information on which
+ *   GAM file created it.  If the GAM file information is available, this
+ *   routine returns true and stores the game file name in the given
+ *   buffer; if the information isn't available, we'll return false.  
+ */
+int fiorso_getgame(char *saved_file, char *buf, size_t buflen);
+
+/* encrypt/decrypt an object */
+void fioxor(uchar *p, uint siz, uint seed, uint inc);
+
+/* strings stored in binary game file for identification and validation */
+
+/* file header string */
+#define FIOFILHDR    "TADS2 bin\012\015\032"
+
+/* resource file header string */
+#define FIOFILHDRRSC "TADS2 rsc\012\015\032"
+
+/* CURRENT file format version string */
+#define FIOVSNHDR  "v2.2.0"
+
+/* other file format versions that can be READ by this version */
+#define FIOVSNHDR2 "v2.0.0"
+#define FIOVSNHDR3 "v2.0.1"
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/ler.cpp b/engines/glk/tads/tads2/ler.cpp
deleted file mode 100644
index d996977f0e..0000000000
--- a/engines/glk/tads/tads2/ler.cpp
+++ /dev/null
@@ -1,152 +0,0 @@
-/* ScummVM - Graphic Adventure Engine
- *
- * ScummVM is the legal property of its developers, whose names
- * are too numerous to list here. Please refer to the COPYRIGHT
- * file distributed with this source distribution.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
-
-#include "ler.h"
-
-namespace Glk {
-namespace TADS {
-namespace TADS2 {
-
-#define TRDLOGERR_PREFIX "\n[An error has occurred within TADS: "
-
-int errcxdef::errfmt(char *outbuf, int outbufl, char *fmt, int argc, erradef *argv) {
-	int    outlen = 0;
-	int    argi   = 0;
-	int    len;
-	char   buf[20];
-	const char  *p = nullptr;
-	char   fmtchar;
-
-	while (*fmt != '\0' && outbufl > 1) {
-		switch(*fmt) {
-		case '\\':
-			++fmt;
-			len = 1;
-			switch(*fmt) {
-			case '\0':
-				--fmt;
-				break;
-			case '\n':
-				p = "\n";
-				break;
-			case '\t':
-				p = "\t";
-				break;
-			default:
-				p = fmt;
-				break;
-			}
-			break;
-
-		case '%':
-			++fmt;
-			fmtchar = *fmt;
-			if (argi >= argc) fmtchar = 1;          // too many - ignore it
-			switch(fmtchar) {
-			case '\0':
-				--fmt;
-				len = 0;
-				break;
-
-			case '%':
-				p = "%";
-				len = 1;
-				break;
-
-			case 'd':
-				sprintf(buf, "%d", argv[argi].erraint);
-				len = strlen(buf);
-				p = buf;
-				break;
-
-			case 'u':
-				sprintf(buf, "%u", argv[argi].erraint);
-				len = strlen(buf);
-				p = buf;
-				break;
-
-			case 's':
-				p = argv[argi].errastr;
-				len = strlen(p);
-				break;
-
-			default:
-				p = "";
-				len = 0;
-				--argi;
-				break;
-			}
-			++argi;
-			break;
-
-		default:
-			p = fmt;
-			len = 1;
-			break;
-		}
-
-		/* copy output that was set up above */
-		if (len != 0) {
-			if (outbufl >= len) {
-				memcpy(outbuf, p, (size_t)len);
-				outbufl -= len;
-				outbuf += len;
-			} else if (outbufl > 1) {
-				memcpy(outbuf, p, (size_t)outbufl - 1);
-				outbufl = 1;
-			}
-			outlen += len;
-		}
-		++fmt;
-	}
-
-	// add a null terminator
-	if (outbufl != 0)
-		*outbuf++ = '\0';
-
-	// return the length
-	return outlen;
-}
-
-void errcxdef::errcxlog(void *ctx0, char *fac, int err, int argc, erradef *argv) {
-#ifdef TODO
-	errcxdef *ctx = (errcxdef *)ctx0;
-	char      buf[256];
-	char      msg[256];
-
-	// display the prefix message to the console and log file
-	sprintf(buf, TRDLOGERR_PREFIX, fac, err);
-	trdptf("%s", buf);
-	out_logfile_print(buf, false);
-
-	/* display the error message text to the console and log file */
-	errmsg(ctx, msg, (uint)sizeof(msg), err);
-	errfmt(buf, (int)sizeof(buf), msg, argc, argv);
-	trdptf("%s]\n", buf);
-	out_logfile_print(buf, false);
-	out_logfile_print("]", true);
-#endif
-}
-
-} // End of namespace TADS2
-} // End of namespace TADS
-} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/ler.h b/engines/glk/tads/tads2/ler.h
deleted file mode 100644
index 57e3e63c2c..0000000000
--- a/engines/glk/tads/tads2/ler.h
+++ /dev/null
@@ -1,617 +0,0 @@
-/* ScummVM - Graphic Adventure Engine
- *
- * ScummVM is the legal property of its developers, whose names
- * are too numerous to list here. Please refer to the COPYRIGHT
- * file distributed with this source distribution.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
-
-#ifndef GLK_TADS_TADS2_LER
-#define GLK_TADS_TADS2_LER
-
-#include "common/scummsys.h"
-#include "common/stream.h"
-#include "common/algorithm.h"
-
-namespace Glk {
-namespace TADS {
-namespace TADS2 {
-
-// maximum length of a facility identifier
-#define ERRFACMAX    6
-
-enum ErrorCode {
-	/* memory/cache manager errors */
-	ERR_NOMEM    =  1,                                     /* out of memory */
-	ERR_FSEEK    =  2,                             /* error seeking in file */
-	ERR_FREAD    =  3,                           /* error reading from file */
-	ERR_NOPAGE   =  4,                                /* no more page slots */
-	ERR_REALCK   =  5,          /* attempting to reallocate a locked object */
-	ERR_SWAPBIG  =  6,    /* swapfile limit reached - out of virtual memory */
-	ERR_FWRITE   =  7,                                /* error writing file */
-	ERR_SWAPPG   =  8,                    /* exceeded swap page table limit */
-	ERR_CLIUSE   =  9,     /* requested client object number already in use */
-	ERR_CLIFULL  = 10,                      /* client mapping table is full */
-	ERR_NOMEM1   = 11,   /* swapping/garbage collection failed to find enuf */
-	ERR_NOMEM2   = 12,            /* no memory to resize (expand) an object */
-	ERR_OPSWAP   = 13,                          /* unable to open swap file */
-	ERR_NOHDR    = 14,                     /* can't get a new object header */
-	ERR_NOLOAD   = 15,   /* mcm cannot find object to load (internal error) */
-	ERR_LCKFRE   = 16,     /* attempting to free a locked object (internal) */
-	ERR_INVOBJ   = 17,                                    /* invalid object */
-	ERR_BIGOBJ   = 18,  /* object too big - exceeds memory allocation limit */
-
-	/* lexical analysis errors */
-	ERR_INVTOK   = 100,                                    /* invalid token */
-	ERR_STREOF   = 101,                /* end of file while scanning string */
-	ERR_TRUNC    = 102,                      /* symbol too long - truncated */
-	ERR_NOLCLSY  = 103,                   /* no space in local symbol table */
-	ERR_PRPDIR   = 104,               /* invalid preprocessor (#) directive */
-	ERR_INCNOFN  = 105,                /* no filename in #include directive */
-	ERR_INCSYN   = 106,                          /* invalid #include syntax */
-	ERR_INCSEAR  = 107,                         /* can't find included file */
-	ERR_INCMTCH  = 108,       /* no matching delimiter in #include filename */
-	ERR_MANYSYM  = 109,                    /* out of space for symbol table */
-	ERR_LONGLIN  = 110,                                    /* line too long */
-	ERR_INCRPT   = 111,           /* header file already included - ignored */
-	ERR_PRAGMA   = 112,                         /* unknown pragma (ignored) */
-	ERR_BADPELSE = 113,                                 /* unexpected #else */
-	ERR_BADENDIF = 114,                                /* unexpected #endif */
-	ERR_BADELIF  = 115,                                 /* unexpected #elif */
-	ERR_MANYPIF  = 116,                             /* #if nesting too deep */
-	ERR_DEFREDEF = 117,                           /* symbol already defined */
-	ERR_PUNDEF   = 118,                        /* #undef symbol not defined */
-	ERR_NOENDIF  = 119,                                   /* missing #endif */
-	ERR_MACNEST  = 120,                         /* macros nested too deeply */
-	ERR_BADISDEF = 121,          /* invalid argument for defined() operator */
-	ERR_PIF_NA   = 122,                           /* #if is not implemented */
-	ERR_PELIF_NA = 123,                         /* #elif is not implemented */
-	ERR_P_ERROR  = 124,                              /* error directive: %s */
-	ERR_LONG_FILE_MACRO = 125,               /* __FILE__ expansion too long */
-	ERR_LONG_LINE_MACRO = 126,               /* __LINE__ expansion too long */
-
-	/* undo errors */
-	ERR_UNDOVF   = 200,                /* operation is too big for undo log */
-	ERR_NOUNDO   = 201,                         /* no more undo information */
-	ERR_ICUNDO   = 202,          /* incomplete undo (no previous savepoint) */
-
-	/* parser errors */
-	ERR_REQTOK   = 300,    /* expected token (arg 1) - found something else */
-	ERR_REQSYM   = 301,                                  /* expected symbol */
-	ERR_REQPRP   = 302,                         /* expected a property name */
-	ERR_REQOPN   = 303,                                 /* expected operand */
-	ERR_REQARG   = 304,       /* expected comma or closing paren (arg list) */
-	ERR_NONODE   = 305,                      /* no space for new parse node */
-	ERR_REQOBJ   = 306,                             /* epxected object name */
-	ERR_REQEXT   = 307,           /* redefining symbol as external function */
-	ERR_REQFCN   = 308,                    /* redefining symbol as function */
-	ERR_NOCLASS  = 309,  /* can't use CLASS with function/external function */
-	ERR_REQUNO   = 310,                          /* required unary operator */
-	ERR_REQBIN   = 311,                         /* required binary operator */
-	ERR_INVBIN   = 312,                          /* invalid binary operator */
-	ERR_INVASI   = 313,                               /* invalid assignment */
-	ERR_REQVAR   = 314,                           /* required variable name */
-	ERR_LCLSYN   = 315,        /* required comma or semicolon in local list */
-	ERR_REQRBR   = 316,   /* required right brace (eof before end of group) */
-	ERR_BADBRK   = 317,                          /* 'break' without 'while' */
-	ERR_BADCNT   = 318,                       /* 'continue' without 'while' */
-	ERR_BADELS   = 319,                              /* 'else' without 'if' */
-	ERR_WEQASI   = 320, /* warning: possible use of '=' where ':=' intended */
-	ERR_EOF      = 321,                           /* unexpected end of file */
-	ERR_SYNTAX   = 322,                             /* general syntax error */
-	ERR_INVOP    = 323,                             /* invalid operand type */
-	ERR_NOMEMLC  = 324,             /* no memory for new local symbol table */
-	ERR_NOMEMAR  = 325,              /* no memory for argument symbol table */
-	ERR_FREDEF   = 326,   /* redefining a function which is already defined */
-	ERR_NOSW     = 327,      /* 'case' or 'default' and not in switch block */
-	ERR_SWRQCN   = 328,           /* constant required in switch case value */
-	ERR_REQLBL   = 329,                        /* label required for 'goto' */
-	ERR_NOGOTO   = 330,                       /* 'goto' label never defined */
-	ERR_MANYSC   = 331,                 /* too many superclasses for object */
-	ERR_OREDEF   = 332,                      /* redefining symbol as object */
-	ERR_PREDEF   = 333,               /* property being redefined in object */
-	ERR_BADPVL   = 334,                           /* invalid property value */
-	ERR_BADVOC   = 335,                    /* bad vocabulary property value */
-	ERR_BADTPL   = 336,       /* bad template property value (need sstring) */
-	ERR_LONGTPL  = 337,             /* template base property name too long */
-	ERR_MANYTPL  = 338,     /* too many templates (internal compiler limit) */
-	ERR_BADCMPD  = 339,   /* bad value for compound word (sstring required) */
-	ERR_BADFMT   = 340,     /* bad value for format string (sstring needed) */
-	ERR_BADSYN   = 341,     /* invalid value for synonym (sstring required) */
-	ERR_UNDFSYM  = 342,                                 /* undefined symbol */
-	ERR_BADSPEC  = 343,                                 /* bad special word */
-	ERR_NOSELF   = 344,                 /* "self" not valid in this context */
-	ERR_STREND   = 345,            /* warning: possible unterminated string */
-	ERR_MODRPLX  = 346,    /* modify/replace not allowed with external func */
-	ERR_MODFCN   = 347,                 /* modify not allowed with function */
-	ERR_MODFWD   = 348,     /* modify/replace not allowed with forward func */
-	ERR_MODOBJ   = 349,    /* modify can only be used with a defined object */
-	ERR_RPLSPEC  = 350,                 /* warning - replacing specialWords */
-	ERR_SPECNIL  = 351,        /* nil only allowed with modify specialWords */
-	ERR_BADLCL   = 353,   /* 'local' statement must precede executable code */
-	ERR_IMPPROP  = 354,          /* implied verifier '%s' is not a property */
-	ERR_BADTPLF  = 355,                    /* invalid command template flag */
-	ERR_NOTPLFLG  = 356,      /* flags are not allowed with old file format */
-	ERR_AMBIGBIN  = 357,          /* warning: operator '%s' could be binary */
-	ERR_PIA       = 358,          /* warning: possibly incorrect assignment */
-	ERR_BADSPECEXPR = 359,                /* invalid speculation evaluation */
-
-	/* code generation errors */
-	ERR_OBJOVF   = 400,     /* object cannot grow any bigger - code too big */
-	ERR_NOLBL    = 401,                  /* no more temporary labels/fixups */
-	ERR_LBNOSET  = 402,                 /* (internal error) label never set */
-	ERR_INVLSTE  = 403,                /* invalid datatype for list element */
-	ERR_MANYDBG  = 404,  /* too many debugger line records (internal limit) */
-
-	/* vocabulary setup errors */
-	ERR_VOCINUS  = 450,            /* vocabulary being redefined for object */
-	ERR_VOCMNPG  = 451,          /* too many vocwdef pages (internal limit) */
-	ERR_VOCREVB  = 452,                             /* redefining same verb */
-	ERR_VOCREVB2 = 453,             /* redefining same verb - two arguments */
-
-	/* set-up errors */
-	ERR_LOCNOBJ  = 500,           /* location of object %s is not an object */
-	ERR_CNTNLST  = 501,                /* contents of object %s is not list */
-	ERR_SUPOVF   = 502,           /* overflow trying to build contents list */
-	ERR_RQOBJNF  = 503,                     /* required object %s not found */
-	ERR_WRNONF   = 504,                    /* warning - object %s not found */
-	ERR_MANYBIF  = 505,     /* too many built-in functions (internal error) */
-
-	/* fio errors */
-	ERR_OPWGAM    = 600,                 /* unable to open game for writing */
-	ERR_WRTGAM    = 601,                      /* error writing to game file */
-	ERR_FIOMSC    = 602,             /* too many sc's for writing in fiowrt */
-	ERR_UNDEFF    = 603,                              /* undefined function */
-	ERR_UNDEFO    = 604,                                /* undefined object */
-	ERR_UNDEF     = 605,                         /* undefined symbols found */
-	ERR_OPRGAM    = 606,                 /* unable to open game for reading */
-	ERR_RDGAM     = 607,                         /* error reading game file */
-	ERR_BADHDR    = 608,    /* file has invalid header - not TADS game file */
-	ERR_UNKRSC    = 609,              /* unknown resource type in .gam file */
-	ERR_UNKOTYP   = 610,             /* unknown object type in OBJ resource */
-	ERR_BADVSN    = 611,    /* file saved by different incompatible version */
-	ERR_LDGAM     = 612,                  /* error loading object on demand */
-	ERR_LDBIG     = 613, /* object too big for load region (prob. internal) */
-	ERR_UNXEXT    = 614,                /* did not expect external function */
-	ERR_WRTVSN    = 615,     /* compiler cannot write the requested version */
-	ERR_VNOCTAB   = 616,        /* format version cannot be used with -ctab */
-	ERR_BADHDRRSC = 617,         /* invalid resource file header in file %s */
-	ERR_RDRSC     = 618,               /* error reading resource file "xxx" */
-
-	/* character mapping errors */
-	ERR_CHRNOFILE = 700,           /* unable to load character mapping file */
-
-	/* user interrupt */
-	ERR_USRINT    = 990,      /* user requested cancel of current operation */
-
-	/* run-time errors */
-	ERR_STKOVF    = 1001,                                 /* stack overflow */
-	ERR_HPOVF     = 1002,                                  /* heap overflow */
-	ERR_REQNUM    = 1003,                         /* numeric value required */
-	ERR_STKUND    = 1004,                                /* stack underflow */
-	ERR_REQLOG    = 1005,                         /* logical value required */
-	ERR_INVCMP    = 1006,     /* invalid datatypes for magnitude comparison */
-	ERR_REQSTR    = 1007,                          /* string value required */
-	ERR_INVADD    = 1008,             /* invalid datatypes for '+' operator */
-	ERR_INVSUB    = 1009,      /* invalid datatypes for binary '-' operator */
-	ERR_REQVOB    = 1010,                           /* require object value */
-	ERR_REQVFN    = 1011,                      /* required function pointer */
-	ERR_REQVPR    = 1012,                 /* required property number value */
-
-	/* non-error conditions:  run-time EXIT, ABORT, ASKIO, ASKDO */
-	ERR_RUNEXIT    = 1013,                     /* 'exit' statement executed */
-	ERR_RUNABRT    = 1014,                    /* 'abort' statement executed */
-	ERR_RUNASKD    = 1015,                    /* 'askdo' statement executed */
-	ERR_RUNASKI    = 1016,           /* 'askio' executed; int arg 1 is prep */
-	ERR_RUNQUIT    = 1017,                               /* 'quit' executed */
-	ERR_RUNRESTART = 1018,                              /* 'reset' executed */
-	ERR_RUNEXITOBJ = 1019,                            /* 'exitobj' executed */
-
-	ERR_REQVLS     = 1020,                             /* list value required */
-	ERR_LOWINX     = 1021,              /* index value too low (must be >= 1) */
-	ERR_HIGHINX    = 1022,  /* index value too high (must be <= length(list)) */
-	ERR_INVTBIF    = 1023,              /* invalid type for built-in function */
-	ERR_INVVBIF    = 1024,             /* invalid value for built-in function */
-	ERR_BIFARGC    = 1025,           /* wrong number of arguments to built-in */
-	ERR_ARGC       = 1026,      /* wrong number of arguments to user function */
-	ERR_FUSEVAL    = 1027,     /* string/list not allowed for fuse/daemon arg */
-	ERR_BADSETF    = 1028,      /* internal error in setfuse/setdaemon/notify */
-	ERR_MANYFUS    = 1029,                                  /* too many fuses */
-	ERR_MANYDMN    = 1030,                                /* too many daemons */
-	ERR_MANYNFY    = 1031,                              /* too many notifiers */
-	ERR_NOFUSE     = 1032,                       /* fuse not found in remfuse */
-	ERR_NODMN      = 1033,                   /* daemon not found in remdaemon */
-	ERR_NONFY      = 1034,                  /* notifier not found in unnotify */
-	ERR_BADREMF    = 1035,    /* internal error in remfuse/remdaemon/unnotify */
-	ERR_DMDLOOP    = 1036,     /* load-on-demand loop: property not being set */
-	ERR_UNDFOBJ    = 1037,             /* undefined object in vocabulary tree */
-	ERR_BIFCSTR    = 1038,            /* c-string conversion overflows buffer */
-	ERR_INVOPC     = 1039,                                  /* invalid opcode */
-	ERR_RUNNOBJ    = 1040,     /* runtime error: property taken of non-object */
-	ERR_EXTLOAD    = 1041,           /* unable to load external function "%s" */
-	ERR_EXTRUN     = 1042,          /* error executing external function "%s" */
-	ERR_CIRCSYN    = 1043,                                /* circular synonym */
-	ERR_DIVZERO    = 1044,                                  /* divide by zero */
-	ERR_BADDEL     = 1045,      /* can only delete objects created with "new" */
-	ERR_BADNEWSC   = 1046,     /* superclass for "new" cannot be a new object */
-	ERR_VOCSTK     = 1047,              /* insufficient space in parser stack */
-	ERR_BADFILE    = 1048,                             /* invalid file handle */
-
-	ERR_RUNEXITPRECMD = 1049,                       /* exited from preCommand */
-
-	/* run-time parser errors */
-	ERR_PRS_SENT_UNK    = 1200,          /* sentence structure not recognized */
-	ERR_PRS_VERDO_FAIL  = 1201,                           /* verDoVerb failed */
-	ERR_PRS_VERIO_FAIL  = 1202,                           /* verIoVerb failed */
-	ERR_PRS_NO_VERDO    = 1203,             /* no verDoVerb for direct object */
-	ERR_PRS_NO_VERIO    = 1204,             /* no verIoVerb for direct object */
-	ERR_PRS_VAL_DO_FAIL = 1205,            /* direct object validation failed */
-	ERR_PRS_VAL_IO_FAIL = 1206,          /* indirect object validation failed */
-
-	/* compiler/runtime/debugger driver errors */
-	ERR_USAGE     = 1500,                                /* invalid usage */
-	ERR_OPNINP    = 1501,                     /* error opening input file */
-	ERR_NODBG     = 1502,              /* game not compiled for debugging */
-	ERR_ERRFIL    = 1503,            /* unable to open error capture file */
-	ERR_PRSCXSIZ  = 1504,            /* parse pool + local size too large */
-	ERR_STKSIZE   = 1505,                         /* stack size too large */
-	ERR_OPNSTRFIL = 1506,            /* error opening string capture file */
-	ERR_INVCMAP   = 1507,                   /* invalid character map file */
-
-	/* debugger errors */
-	ERR_BPSYM         = 2000,                 /* symbol not found for breakpoint */
-	ERR_BPPROP        = 2002,             /* breakpoint symbol is not a property */
-	ERR_BPFUNC        = 2003,             /* breakpoint symbol is not a function */
-	ERR_BPNOPRP       = 2004,              /* property is not defined for object */
-	ERR_BPPRPNC       = 2005,                            /* property is not code */
-	ERR_BPSET         = 2006,         /* breakpoint already set at this location */
-	ERR_BPNOTLN       = 2007,     /* breakpoint is not at a line (OPCLINE instr) */
-	ERR_MANYBP        = 2008,                            /* too many breakpoints */
-	ERR_BPNSET        = 2009,            /* breakpoint to be deleted was not set */
-	ERR_DBGMNSY       = 2010,  /* too many symbols in debug expression (int lim) */
-	ERR_NOSOURC       = 2011,                   /* unable to find source file %s */
-	ERR_WTCHLCL       = 2012,        /* illegal to assign to local in watch expr */
-	ERR_INACTFR       = 2013, /* inactive frame (expression value not available) */
-	ERR_MANYWX        = 2014,                      /* too many watch expressions */
-	ERR_WXNSET        = 2015,                              /* watchpoint not set */
-	ERR_EXTRTXT       = 2016,               /* extraneous text at end of command */
-	ERR_BPOBJ         = 2017,              /* breakpoint symbol is not an object */
-	ERR_DBGINACT      = 2018,                          /* debugger is not active */
-	ERR_BPINUSE       = 2019,                      /* breakpoint is already used */
-	ERR_RTBADSPECEXPR = 2020,                  /* invalid speculative expression */
-	ERR_NEEDLIN2      = 2021,     /* -ds2 information not found - must recompile */
-
-	/* usage error messages */
-	ERR_TCUS1         = 3000,                          /* first tc usage message */
-	ERR_TCUSL         = 3024,                           /* last tc usage message */
-	ERR_TCTGUS1       = 3030,                         /* first tc toggle message */
-	ERR_TCTGUSL       = 3032,
-	ERR_TCZUS1        = 3040,            /* first tc -Z suboptions usage message */
-	ERR_TCZUSL        = 3041,
-	ERR_TC1US1        = 3050,            /* first tc -1 suboptions usage message */
-	ERR_TC1USL        = 3058,
-	ERR_TCMUS1        = 3070,            /* first tc -m suboptions usage message */
-	ERR_TCMUSL        = 3076,
-	ERR_TCVUS1        = 3080,                /* first -v suboption usage message */
-	ERR_TCVUSL        = 3082,
-	ERR_TRUSPARM      = 3099,
-	ERR_TRUS1         = 3100,                          /* first tr usage message */
-	ERR_TRUSL         = 3117,
-	ERR_TRUSFT1       = 3118,                       /* first tr "footer" message */
-	ERR_TRUSFTL       = 3119,                        /* last tr "footer" message */
-	ERR_TRSUS1        = 3150,            /* first tr -s suboptions usage message */
-	ERR_TRSUSL        = 3157,
-	ERR_TDBUSPARM     = 3199,
-	ERR_TDBUS1        = 3200,                         /* first tdb usage message */
-	ERR_TDBUSL        = 3214,                          /* last tdb usage message */
-
-	/* TR 16-bit MSDOS-specific usage messages */
-	ERR_TRUS_DOS_1   = 3300,
-	ERR_TRUS_DOS_L   = 3300,
-
-	/* TR 32-bit MSDOS console mode usage messages */
-	ERR_TRUS_DOS32_1 = 3310,
-	ERR_TRUS_DOS32_L = 3312,
-
-	/* TADS/Graphic errors */
-	ERR_GNOFIL       = 4001,                      /* can't find graphics file %s */
-	ERR_GNORM        = 4002,                               /* can't find room %s */
-	ERR_GNOOBJ       = 4003,                    /* can't find hot spot object %s */
-	ERR_GNOICN       = 4004                         /* can't find icon object %s */
-};
-
-/*
- *   Special error flag - this is returned from execmd() when preparseCmd
- *   returns a command list.  This indicates to voc1cmd that it should try
- *   the command over again, using the words in the new list.
- */
-#define ERR_PREPRSCMDREDO  30000             /* preparseCmd returned a list */
-#define ERR_PREPRSCMDCAN   30001    /* preparseCmd returned 'nil' to cancel */
-
-union erradef {
-	int   erraint;		// integer argument
-	char *errastr;		// text string argument
-};
-
-struct errdef {
-	errdef *       errprv;               // previous error frame
-	int            errcode;              // error code of exception being handled
-	char           errfac[ERRFACMAX+1];  // facility of current error
-	erradef        erraav[10];           // parameters for error
-	int            erraac;               // count of parameters in argc
-//    jmp_buf        errbuf;               // jump buffer for current error frame
-};
-
-#define ERRBUFSIZ 512
-
-class TADS2;
-
-// seek location record for an error message by number
-struct errmfdef {
-	uint  errmfnum;   // error number
-	size_t errmfseek; // seek location of this message
-};
-
-class errcxdef {
-public:
-	errdef   *errcxptr;               // current error frame
-	void     *errcxlgc;               // context for error logging callback
-	int       errcxofs;               // offset in argument buffer
-	char      errcxbuf[ERRBUFSIZ];    // space for argument strings
-	Common::SeekableReadStream *errcxfp;  // message file, if one is being used
-	errmfdef *errcxseek;              // seek locations of messages in file
-	uint      errcxsksz;              // size of errcxseek array
-	size_t    errcxbase;              // offset in physical file of logical error file
-	TADS2 *   errcxappctx;            // host application context
-public:
-	/**
-	 *   Format an error message, sprintf-style, using arguments in an
-	 *   erradef array (which is passed to the error-logging callback).
-	 *   Returns the length of the output string, even if the actual
-	 *   output string was truncated because the outbuf was too short.
-	 *   (If called with outbufl == 0, nothing will be written out, but
-	 *   the size of the buffer needed, minus the terminating null byte,
-	 *   will be computed and returned.)
-	 */
-	static int errfmt(char *outbuf, int outbufl, char *fmt, int argc, erradef *argv);
- public:
-	errcxdef() : errcxptr(nullptr), errcxlgc(nullptr), errcxofs(0),
-		errcxseek(nullptr), errcxsksz(0), errcxbase(0), errcxappctx(nullptr) {
-		Common::fill(&errcxbuf[0], &errcxbuf[ERRBUFSIZ], '\0');
-	}
-
-	/**
-	 * Error logging method
-	 */
-	void errcxlog(void *ctx0, char *fac, int err, int argc, erradef *argv);
-};
-
-// begin protected code
-#define ERRBEGIN(ctx) \
-  { \
-	errdef fr_; \
-	if ((fr_.errcode = setjmp(fr_.errbuf)) == 0) \
-	{ \
-	  fr_.errprv = (ctx)->errcxptr; \
-	  (ctx)->errcxptr = &fr_;
-
-// end protected code, begin error handler
-#define ERRCATCH(ctx, e) \
-	  assert(1==1 && (ctx)->errcxptr != fr_.errprv); \
-	  (ctx)->errcxptr = fr_.errprv; \
-	} \
-	else \
-	{ \
-	  assert(2==2 && (ctx)->errcxptr != fr_.errprv); \
-	  (e) = fr_.errcode; \
-	  (ctx)->errcxptr = fr_.errprv;
-
-// retrieve argument (int, string) in current error frame
-#define errargint(argnum) (fr_.erraav[argnum].erraint)
-#define errargstr(argnum) (fr_.erraav[argnum].errastr)
-
-
-#define ERREND(ctx) \
-	} \
-  }
-
-// end protected code, begin cleanup (no handling; just cleaning up)
-#define ERRCLEAN(ctx) \
-	  assert((ctx)->errcxptr != fr_.errprv); \
-	  (ctx)->errcxptr = fr_.errprv; \
-	} \
-	else \
-	{ \
-	  assert((ctx)->errcxptr != fr_.errprv); \
-	  (ctx)->errcxptr = fr_.errprv;
-
-#define ERRENDCLN(ctx) \
-	  errrse(ctx); \
-	} \
-  }
-
-
-
-// argument types for errors with arguments
-#define ERRTINT  erraint
-#define ERRTSTR  errastr
-
-// set argument count in error frame
-#define errargc(ctx,cnt) ((ctx)->errcxptr->erraac=(cnt))
-
-// enter string argument; returns pointer to argument used in errargv
-#ifdef ERR_NO_MACRO
-char *errstr(errcxdef *ctx, const char *str, int len);
-#else /* ERR_NO_MACRO */
-
-#define errstr(ctx,str,len) \
-  ((memcpy(&(ctx)->errcxbuf[(ctx)->errcxofs],str,(size_t)len), \
-   (ctx)->errcxofs += (len), \
-   (ctx)->errcxbuf[(ctx)->errcxofs++] = '\0'), \
-   &(ctx)->errcxbuf[(ctx)->errcxofs-(len)-1])
-
-#endif /* ERR_NO_MACRO */
-
-/* set argument in error frame argument vector */
-#define errargv(ctx,index,typ,arg) \
-  ((ctx)->errcxptr->erraav[index].typ=(arg))
-
-// signal an error with argument count already set
-#ifdef ERR_NO_MACRO
-void errsign(errcxdef *ctx, int e, char *facility);
-#else /* ERR_NO_MACRO */
-# ifdef DEBUG
-void errjmp(jmp_buf buf, int e);
-#  define errsign(ctx, e, fac) \
-   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
-	(ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
-	(ctx)->errcxofs=0, errjmp((ctx)->errcxptr->errbuf, e))
-# else /* DEBUG */
-#  define errsign(ctx, e, fac) \
-   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
-	(ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
-	(ctx)->errcxofs=0, longjmp((ctx)->errcxptr->errbuf, e))
-# endif /* DEBUG */
-#endif /* ERR_NO_MACRO */
-
-
-// signal an error with no arguments
-#ifdef ERR_NO_MACRO
-void errsigf(errcxdef *ctx, char *facility, int err);
-#else /* ERR_NO_MACRO */
-#define errsigf(ctx, fac, e) (errargc(ctx,0),errsign(ctx,e,fac))
-#endif /* ERR_NO_MACRO */
-
-// signal an error with one argument
-#define errsigf1(ctx, fac, e, typ1, arg1) \
-  (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errsign(ctx,e,fac))
-
-// signal an error with two arguments
-#define errsigf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
-  (errargv(ctx,0,typ1,arg1), errargv(ctx,1,typ2,arg2), \
-   errargc(ctx,2), errsign(ctx,e,fac))
-
-// resignal the current error - only usable within exception handlers
-#ifdef ERR_NO_MACRO
-void errrse1(errcxdef *ctx, errdef *fr);
-# define errrse(ctx) errrse1(ctx, &fr_)
-#else /* ERR_NO_MACRO */
-
-// void errrse(errcxdef *ctx);
-# define errrse(ctx) \
-  (errargc(ctx, fr_.erraac),\
-   memcpy((ctx)->errcxptr->erraav, fr_.erraav, \
-	(size_t)(fr_.erraac*sizeof(erradef))),\
-   errsign(ctx, fr_.errcode, fr_.errfac))
-
-#endif /* ERR_NO_MACRO */
-
-/**
- *   For use in an error handler (ERRCATCH..ERREND) only: Copy the
- *   parameters from the error currently being handled to the enclosing
- *   frame.  This is useful when "keeping" an error being handled - i.e.,
- *   the arguments will continue to be used outside of the
- *   ERRCATCH..ERREND code.
- */
-#define errkeepargs(ctx) errcopyargs(ctx, &fr_)
-
-/**
- *   copy the parameters for an error from another frame into the current
- *   frame - this can be used when we want to be able to display an error
- *   that occurred in an inner frame within code that is protected by a
- *   new enclosing error frame
- */
-#define errcopyargs(ctx, fr) \
-   (errargc((ctx), (fr)->erraac), \
-	memcpy((ctx)->errcxptr->erraav, (fr)->erraav, \
-		   (size_t)((fr)->erraac*sizeof(erradef))))
-
-// log error that's been caught, using arguments already caught
-#define errclog(ctx) \
- ((*(ctx)->errcxlog)((ctx)->errcxlgc,fr_.errfac,fr_.errcode,\
-  fr_.erraac,fr_.erraav))
-
-// log an error that's been set up but not signalled yet
-#define errprelog(ctx, err) \
- ((*(ctx)->errcxlog)((ctx)->errcxlgc,(ctx)->errcxptr->errfac,\
-   err,(ctx)->errcxptr->erraac,\
-   (ctx)->errcxptr->erraav))
-
-// log an error (no signalling, just reporting)
-#ifdef ERR_NO_MACRO
-void errlogn(errcxdef *ctx, int err, char *facility);
-#else /* ERR_NO_MACRO */
-
-#define errlogn(ctx,err,fac) \
- ((ctx)->errcxofs=0,\
-  (*(ctx)->errcxlog)((ctx)->errcxlgc,fac,err,(ctx)->errcxptr->erraac,\
-  (ctx)->errcxptr->erraav))
-
-#endif /* ERR_NO_MACRO */
-
-// log an error with no arguments
-#ifdef ERR_NO_MACRO
-void errlogf(errcxdef *ctx, char *facility, int err);
-#else /* ERR_NO_MACRO */
-
-// void errlogf(errcxdef *ctx, char *facility, int err);
-#define errlogf(ctx,fac,err) (errargc(ctx,0),errlogn(ctx,err,fac))
-
-#endif /* ERR_NO_MACRO */
-
-// log an error with one argument
-#define errlogf1(ctx, fac, e, typ1, arg1) \
- (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errlogn(ctx,e,fac))
-
-// log an error with two arguments
-#define errlogf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
- (errargv(ctx,0,typ1,arg1),errargv(ctx,1,typ2,arg2),\
-  errargc(ctx,2),errlogn(ctx,e,fac))
-
-/**
- * For compatility with old facility-free mechanism, signal with facility "TADS"
- */
-#define errsig(ctx, err) errsigf(ctx, "TADS", err)
-#define errsig1(c, e, t, a) errsigf1(c,"TADS",e,t,a)
-//#define errsig2(c, e, t1, a1, t2, a2) errsigf2(c,"TADS",e,t1,a1,t2,a2)
-#define errlog(c, e) errlogf(c, "TADS", e)
-#define errlog1(c, e, t, a) errlogf1(c,"TADS",e,t,a)
-#define errlog2(c, e, t1, a1, t2, a2) errlogf2(c,"TADS",e,t1,a1,t2,a2)
-
-#define errsig2(c, e, t1, a1, t2, a2) error("Error occurred")
-
-// get the text of an error
-void errmsg(errcxdef *ctx, char *outbuf, uint outbufl, uint err);
-
-// initialize error subsystem, opening error message file if necessary
-void errini(errcxdef *ctx, Common::SeekableReadStream *fp);
-
-// allocate and initialize error context, free error context
-errcxdef *lerini();
-void      lerfre(errcxdef *ctx);
-
-// error message structure - number + text
-struct errmdef {
-	uint   errmerr;		// error number
-	char  *errmtxt;     // text of error message
-};
-
-} // End of namespace TADS2
-} // End of namespace TADS
-} // End of namespace Glk
-
-#endif
diff --git a/engines/glk/tads/tads2/lib.h b/engines/glk/tads/tads2/lib.h
new file mode 100644
index 0000000000..605f072390
--- /dev/null
+++ b/engines/glk/tads/tads2/lib.h
@@ -0,0 +1,164 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_LIB
+#define GLK_TADS_TADS2_LIB
+
+#include "common/scummsys.h"
+#include "common/algorithm.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* short-hand for various types */
+
+typedef unsigned char uchar;
+typedef unsigned short ushort;
+typedef unsigned long  ulong;
+
+typedef byte  ub1;
+typedef signed char    sb1;
+typedef char           b1;
+typedef unsigned int   ub2;
+typedef signed int     sb2;
+typedef int            b2;
+typedef unsigned long  ub4;
+typedef signed long    sb4;
+typedef long           b4;
+typedef int            eword;
+typedef int32          int32_t;
+typedef uint32         uint32_t;
+
+
+/* maximum/minimum portable values for various types */
+#define UB4MAXVAL  0xffffffffUL
+#define UB2MAXVAL  0xffffU
+#define UB1MAXVAL  0xffU
+#define SB4MAXVAL  0x7fffffffL
+#define SB2MAXVAL  0x7fff
+#define SB1MAXVAL  0x7f
+#define SB4MINVAL  (-(0x7fffffff)-1)
+#define SB2MINVAL  (-(0x7fff)-1)
+#define SB1MINVAL  (-(0x7f)-1)
+
+/* clear a struture */
+#define CLRSTRUCT(x) memset(&(x), 0, (size_t)sizeof(x))
+#define CPSTRUCT(dst,src) memcpy(&(dst), &(src), (size_t)sizeof(dst))
+
+/* TRUE and FALSE */
+#define TRUE true
+#define FALSE false
+
+
+/* bitwise operations */
+#define bit(va, bt) ((va) & (bt))
+#define bis(va, bt) ((va) |= (bt))
+#define bic(va, bt) ((va) &= ~(bt))
+
+/*
+ *   noreg/NOREG - use for variables changed in error-protected code that
+ *   are used in error handling code.  Use 'noreg' on the declaration like
+ *   a storage class qualifier.  Use 'NOREG' as an argument call, passing
+ *   the addresses of all variables declared noreg.  For non-ANSI
+ *   compilers, a routine osnoreg(/o_ void *arg0, ... _o/) must be
+ *   defined.
+ */
+#ifdef OSANSI
+# define noreg volatile
+# define NOREG(arglist)
+#else /* OSANSI */
+# define noreg
+# define NOREG(arglist) osnoreg arglist ;
+#endif /* OSANSI */
+
+/* 
+ *   Linting directives.  You can define these before including this file
+ *   if you have a fussy compiler.  
+ */
+#ifdef LINT
+# ifndef NOTREACHED
+#  define NOTREACHED return
+# endif
+# ifndef NOTREACHEDV
+#  define NOTREACHEDV(t) return((t)0)
+# endif
+# ifndef VARUSED
+#  define VARUSED(v) varused(v)
+# endif
+void varused();
+#else /* LINT */
+# ifndef NOTREACHED
+#  define NOTREACHED
+# endif
+# ifndef NOTREACHEDV
+#  define NOTREACHEDV(t)
+# endif
+# ifndef VARUSED
+#  define VARUSED(v)
+# endif
+#endif /* LINT */
+
+/* conditionally compile code if debugging is enabled */
+#ifdef DEBUG
+# define IF_DEBUG(x) x
+#else /* DEBUG */
+# define IF_DEBUG(x)
+#endif /* DEBUG */
+
+#ifndef offsetof
+# define offsetof(s_name, m_name) (size_t)&(((s_name *)0)->m_name)
+#endif /* offsetof */
+
+/*
+ *   Define our own version of isspace(), so that we don't try to interpret
+ *   anything outside of the normal ASCII set as spaces. 
+ */
+#define t_isspace(c) \
+    (((unsigned char)(c)) <= 127 && isspace((unsigned char)(c)))
+
+
+/* round a size to worst-case alignment boundary */
+#define osrndsz(s) (((s)+3) & ~3)
+
+/* round a pointer to worst-case alignment boundary */
+#define osrndpt(p) ((uchar *)((((unsigned long)(p)) + 3) & ~3))
+
+/* read unaligned portable unsigned 2-byte value, returning int */
+#define osrp2(p) READ_LE_UINT16(p)
+
+/* read unaligned portable signed 2-byte value, returning int */
+#define osrp2s(p) READ_LE_INT16(p)
+
+/* write int to unaligned portable 2-byte value */
+#define oswp2(p, i) WRITE_LE_UINT16(p, i)
+#define oswp2s(p, i) WRITE_LE_INT16(p, i)
+
+/* read unaligned portable 4-byte value, returning unsigned long */
+#define osrp4(p) READ_LE_UINT32(p)
+#define osrp4s(p) READ_LE_INT32(p)
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/line_source.h b/engines/glk/tads/tads2/line_source.h
new file mode 100644
index 0000000000..a7e5454c60
--- /dev/null
+++ b/engines/glk/tads/tads2/line_source.h
@@ -0,0 +1,129 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* Line source definitions
+ *
+ * A line source is a mechanism for reading source text.  The tokenizer
+ * reads its input from a line source.  This is the basic class
+ * definition; individual line sources will define the functions and
+ * class data needed.
+ */
+
+#ifndef GLK_TADS_TADS2_LINE_SOURCE
+#define GLK_TADS_TADS2_LINE_SOURCE
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/object.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+/**
+ * Line source superclass structure
+ */
+struct lindef {
+    int   (*lingetp)(lindef *lin);                         /* get next line */
+    void  (*linclsp)(lindef *lin);                     /* close line source */
+    void  (*linppos)(lindef *lin, char *buf, uint buflen);
+            /* write printable rep of position to buf (for error reporting) */
+    void  (*linglop)(lindef *lin, uchar *buf);
+                       /* generate a line record for an OPCLINE instruction */
+    int   (*linwrtp)(lindef *lin, osfildef *fp);
+            /* write line source information to binary file; TRUE ==> error */
+    void  (*lincmpp)(lindef *lin, uchar *buf);
+          /* give location of compiled code for current line to line source */
+    void  (*linactp)(lindef *lin);                      /* activate for dbg */
+    void  (*lindisp)(lindef *lin);                           /* disactivate */
+    void  (*lintellp)(lindef *lin, uchar *pos);             /* get position */
+    void  (*linseekp)(lindef *lin, uchar *pos);                     /* seek */
+    int   (*linreadp)(lindef *lin, uchar *buf, uint siz);          /* fread */
+    void  (*linpaddp)(lindef *lin, uchar *pos, long delta);
+                                       /* add an offset to a position value */
+    int   (*linqtopp)(lindef *lin, uchar *pos);                  /* at top? */
+    int   (*lingetsp)(lindef *lin, uchar *buf, uint siz);       /* get line */
+    void  (*linnamp)(lindef *lin, char *buf);            /* get source name */
+    void  (*linfindp)(lindef *lin, char *buf, objnum *objp,
+                      uint *ofsp);              /* find nearest line record */
+    void  (*lingotop)(lindef *lin, int where);               /* seek global */
+    long  (*linofsp)(lindef *lin);            /* byte offset in line source */
+    void  (*linrenp)(lindef *lin, objnum oldnum, objnum newnum);
+                                       /* renumber an object (for "modify") */
+    void  (*lindelp)(lindef *lin, objnum objn);
+                                        /* delete an object (for "replace") */
+    ulong (*linlnump)(lindef *lin);          /* get the current line number */
+#define  LINGOTOP   OSFSK_SET                   /* go to top of line source */
+#define  LINGOEND   OSFSK_END                   /* go to end of line source */
+    lindef *linpar;                        /* parent of current line source */
+    lindef *linnxt;                       /* next line in line source chain */
+    int     linid;           /* serial number of line source (for debugger) */
+    char   *linbuf;                              /* pointer to current line */
+    ushort  linflg;                                                /* flags */
+#define  LINFEOF   0x01                    /* line source is at end of file */
+#define  LINFMORE  0x02             /* there's more to the line than linlen */
+#define  LINFDBG   0x04          /* debug record already generated for line */
+#define  LINFNOINC 0x08        /* ignore # directives from this line source */
+#define  LINFCMODE 0x10                  /* line source is parsed in C-mode */
+    ushort  linlen;                                   /* length of the line */
+    ushort  linlln;           /* length of line record generated by lingloc */
+};
+
+/**
+ *   Maximum allowed value for linlln, in bytes.  This allows subsystems
+ *   that need to maintain local copies of seek locations to know how big
+ *   an area to allocate for them.  
+ */
+#define LINLLNMAX   20
+
+/* macros to cover calls to functions */
+#define linget(lin) ((*((lindef *)(lin))->lingetp)((lindef *)(lin)))
+#define lincls(lin) ((*((lindef *)(lin))->linclsp)((lindef *)(lin)))
+#define linppos(lin, buf, buflen) \
+ ((*((lindef *)(lin))->linppos)((lindef *)(lin), buf, buflen))
+#define linglop(lin, buf) ((*((lindef *)(lin))->linglop)(lin, buf))
+#define linwrt(lin, fp) ((*((lindef *)(lin))->linwrtp)(lin, fp))
+#define lincmpinf(lin, buf) ((*((lindef *)(lin))->lincmpp)(lin, buf))
+#define linactiv(lin) ((*((lindef *)(lin))->linactp)(lin))
+#define lindisact(lin) ((*((lindef *)(lin))->lindisp)(lin))
+#define lintell(lin, pos) ((*((lindef *)(lin))->lintellp)(lin, pos))
+#define linseek(lin, pos) ((*((lindef *)(lin))->linseekp)(lin, pos))
+#define linread(lin, buf, siz) ((*((lindef *)(lin))->linreadp)(lin, buf, siz))
+#define linpadd(lin, pos, delta) \
+  ((*((lindef *)(lin))->linpaddp)(lin, pos, delta))
+#define linqtop(lin, pos) ((*((lindef *)(lin))->linqtopp)(lin, pos))
+#define lingets(lin, buf, siz) ((*((lindef *)(lin))->lingetsp)(lin, buf, siz))
+#define linnam(lin, buf) ((*((lindef *)(lin))->linnamp)(lin, buf))
+#define linlnum(lin) ((*((lindef *)(lin))->linlnump)(lin))
+#define linfind(lin, buf, objp, ofsp) \
+  ((*((lindef *)(lin))->linfindp)(lin, buf, objp, ofsp))
+#define lingoto(lin, where) ((*((lindef *)(lin))->lingotop)(lin, where))
+#define linofs(lin) ((*((lindef *)(lin))->linofsp)(lin))
+#define linrenum(lin, oldnum, newnum) \
+  ((*((lindef *)(lin))->linrenp)(lin, oldnum, newnum))
+#define lindelnum(lin, objn) ((*((lindef *)(lin))->lindelp)(lin, objn))
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/memory_cache.cpp b/engines/glk/tads/tads2/memory_cache.cpp
new file mode 100644
index 0000000000..3bab3b034b
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache.cpp
@@ -0,0 +1,31 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/memory_cache.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/memory_cache.h b/engines/glk/tads/tads2/memory_cache.h
new file mode 100644
index 0000000000..ec0383b7e1
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache.h
@@ -0,0 +1,403 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/*
+ * Memory cache manager
+ */
+
+#ifndef GLK_TADS_TADS2_MEMORY_CACHE
+#define GLK_TADS_TADS2_MEMORY_CACHE
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/memory_cache_loader.h"
+#include "glk/tads/tads2/memory_cache_swap.h"
+#include "glk/tads/osfrobtads.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* if the os layer doesn't want long mcm macros, we don't either */
+#ifdef OS_MCM_NO_MACRO
+# define MCM_NO_MACRO
+#endif
+
+/*
+ *   mcmon - cache object number.  Each object in the cache is referenced
+ *   by an object number, which is a number of this type.
+ */
+typedef ushort mcmon;
+
+/* invalid object number - used to indicate N/A or no object */
+#define MCMONINV ((mcmon)~0)
+
+/* invalid page number */
+#define MCMPINV ((uint)~0)
+
+union mcmodefloc {
+	mcsseg  mcmolocs;                            /* swap segment handle */
+	mclhd   mcmolocl;                        /* load file object handle */
+};
+
+/*
+ *   mcmodef - cache object definition.  Each cache object is managed by
+ *   this structure.  Pointers for a doubly-linked list are provided;
+ *   these are used to maintain a recent-use list for objects in memory,
+ *   and to maintain a free list for cache object entries not in use.  A
+ *   set of flag bits is provided, as is the size of the object and its
+ *   location (which is a memory pointer for objects in memory, a swap
+ *   file handle for swapped-out objects, or a load-file handle for
+ *   objects that are unloaded). 
+ */
+struct mcmodef {
+    uchar  *mcmoptr;               /* memory pointer (if object is present) */
+	mcmodefloc mcmoloc;                       /* object's external location */
+#define  mcmoswh  mcmoloc.mcmolocs
+#define  mcmoldh  mcmoloc.mcmolocl
+    mcmon   mcmonxt;                            /* next object in this list */
+    mcmon   mcmoprv;                        /* previous object in this list */
+    ushort  mcmoflg;                         /* flags for this cache object */
+#define  MCMOFDIRTY  0x01                     /* object has been written */
+#define  MCMOFNODISC 0x02       /* not in load file (can't be discarded) */
+#define  MCMOFLOCK   0x04                            /* object is locked */
+#define  MCMOFPRES   0x08                 /* object is present in memory */
+#define  MCMOFLRU    0x10                      /* object is in LRU chain */
+#define  MCMOFPAGE   0x20              /* object is a cache manager page */
+#define  MCMOFNOSWAP 0x40                /* object cannot be swapped out */
+#define  MCMOFFREE   0x80      /* entry refers to a free block of memory */
+#define  MCMOFREVRT 0x100           /* call revert callback upon loading */
+    uchar   mcmolcnt;                                         /* lock count */
+    ushort  mcmosiz;                                  /* size of the object */
+};
+
+/* heap header - allocate one of these in each heap */
+struct mcmhdef {
+    mcmhdef *mcmhnxt;                            /* next heap in this chain */
+};
+
+/* GLOBAL cache manager context:  tracks cache manager state */
+struct mcmcx1def {
+    mcmodef  **mcmcxtab;                        /* page table for the cache */
+    errcxdef  *mcmcxerr;                          /* error handling context */
+    mcmhdef   *mcmcxhpch;                             /* heap chain pointer */
+    mcscxdef   mcmcxswc;                            /* swap manager context */
+    mclcxdef   mcmcxldc;                                  /* loader context */
+    ulong      mcmcxmax; /* maximum amount of actual heap we can ever alloc */
+    mcmon      mcmcxlru;      /* least recently used object still in memory */
+    mcmon      mcmcxmru;                       /* most recently used object */
+    mcmon      mcmcxfre;                               /* head of free list */
+    mcmon      mcmcxunu;                             /* head of unused list */
+    ushort     mcmcxpage;                      /* last page table slot used */
+    ushort     mcmcxpgmx;        /* maximum number of pages we can allocate */
+    void     (*mcmcxcsw)(mcmcx1def *, mcmon, mcsseg, mcsseg);
+                         /* change swap handle in object to new swap handle */
+};
+
+/* CLIENT cache manager context: used by client to request mcm services */
+struct mcmcxdef {
+    mcmcx1def *mcmcxgl;                     /* global cache manager context */
+    uint       mcmcxflg;                                           /* flags */
+    uint       mcmcxmsz;                   /* maximum size of mapping table */
+    void     (*mcmcxldf)(void *ctx, mclhd handle, uchar *ptr,
+                         ushort siz);           /* callback to load objects */
+    void      *mcmcxldc;                       /* context for load callback */
+    void     (*mcmcxrvf)(void *ctx, mcmon objn);           /* revert object */
+    void      *mcmcxrvc;                     /* context for revert callback */
+    mcmon     *mcmcxmtb[1];                                /* mapping table */
+};
+
+/* context flags */
+#define MCMCXF_NO_PRP_DEL   0x0001  /* PRPFDEL is invalid in this game file */
+
+/* convert from a client object number to a global object number */
+/* mcmon mcmc2g(mcmcxdef *ctx, mcmon objn); */
+#define mcmc2g(ctx, objn) ((ctx)->mcmcxmtb[(objn)>>8][(objn)&255])
+
+/*
+ *   FREE LIST: this is a list, headed by context->mcmcxfre and chained
+ *   forward and back by mcmonxt and mcmoprv, consisting of free memory
+ *   blocks.  These refer to blocks in the heap that are not used by any
+ *   client objects. 
+ */
+/*
+ *   UNUSED LIST: this is a list, headed by context->mcmcxunu and chained
+ *   forward by mcmonxt (not back, because it's never necessary to take
+ *   anything out of the list except at the head, nor to search the list
+ *   backwards), of unused cache object entries.  These entries are not
+ *   associated with any client object or with any heap memory.  This list
+ *   is used to get a new cache object header, and deleted cache objects
+ *   are placed onto this list.  
+ */
+/*
+ *   LRU LIST: this is a list of in-memory blocks in ascending order of
+ *   recency of use by the client.  Each time a client unlocks a block,
+ *   the block is moved to the most recent position in the list (the end
+ *   of the list).  To make it fast to add a new object, we keep a pointer
+ *   to the end of the list as well as to the beginning.  The start of the
+ *   list is at context->mcmcxlru, and is the least recently unlocked
+ *   block still in memory.  The end of the list is at context->mcmcxmru,
+ *   and is the most recently unlocked block.  
+ */
+
+/*
+ *   initialize the cache manager, returning a context for cache manager
+ *   operations; a null pointer is returned if insufficient heap memory is
+ *   available for initialization.  The 'max' argument specifies the
+ *   maximum amount of actual low-level heap memory that the cache manager
+ *   can ever allocate on behalf of this context (of course, it can
+ *   overcommit the heap through swapping).  If 'max' is less than the
+ *   size of a single heap allocation, it is adjusted upwards to that
+ *   minimum.  
+ */
+mcmcx1def *mcmini(ulong max, uint pages, ulong swapsize,
+                  osfildef *swapfp, char *swapfilename, errcxdef *errctx);
+
+/* terminate the cache manager - frees the structure and all cache memory */
+void mcmterm(mcmcx1def *ctx);
+
+/* allocate a client context */
+mcmcxdef *mcmcini(mcmcx1def *globalctx, uint pages,
+                  void (*loadfn)(void *, mclhd, uchar *, ushort),
+                  void *loadctx,
+                  void (*revertfn)(void *, mcmon), void *revertctx);
+
+/* terminate a client context - frees the structure memory */
+void mcmcterm(mcmcxdef *ctx);
+
+
+/*
+ *   Lock a cache object, bringing it into memory if necessary.  Returns
+ *   a pointer to the memory containing the object.  A null pointer is
+ *   returned in case of error.  The object remains fixed in memory at the
+ *   returned location until unlocked.  Locks are stacked; that is, if
+ *   an object is locked twice in succession, it needs to be unlocked
+ *   twice in succession before it is actually unlocked.
+ */
+#ifdef MCM_NO_MACRO
+uchar *mcmlck(mcmcxdef *ctx, mcmon objnum);
+#else /* MCM_NO_MACRO */
+
+/* uchar *mcmlck(mcmcxdef *ctx, mcmon objnum); */
+#define mcmlck(ctx,num) \
+ ((mcmobje(ctx,num)->mcmoflg & MCMOFPRES ) ? \
+ ((mcmobje(ctx,num)->mcmoflg|=MCMOFLOCK), \
+  ++(mcmobje(ctx,num)->mcmolcnt), mcmobje(ctx,num)->mcmoptr) \
+ : mcmload(ctx,num))
+
+#endif /* MCM_NO_MACRO */
+
+/*
+ *   Unlock a cache object, allowing it to be moved and swapped.
+ *   Unlocking an object moves it to the end (i.e., most recently used)
+ *   position on the LRU chain, making it the least favorable to swap out
+ *   or discard.  This happens at unlock time (rather than lock time)
+ *   because presumably the client has been using the object the entire
+ *   time it was locked. For this reason, and to keep memory unfragmented
+ *   as much as possible, objects should not be kept locked except when
+ *   actually in use.  Note that locks nest; if an object is locked three
+ *   times without an intervening unlock, it must be unlocked three times
+ *   in a row.  An object can be unlocked even if it's not locked; doing
+ *   so has no effect.
+ */
+#ifdef MCM_NO_MACRO
+void mcmunlck(mcmcxdef *ctx, mcmon objnum);
+#else /* MCM_NO_MACRO */
+
+/* void mcmunlck(mcmcxdef *ctx, mcmon objnum); */
+#define mcmunlck(ctx,obj) \
+ ((mcmobje(ctx,obj)->mcmoflg & MCMOFLOCK) ? \
+  (--(mcmobje(ctx,obj)->mcmolcnt) ? (void)0 : \
+  ((mcmobje(ctx,obj)->mcmoflg&=(~MCMOFLOCK)), \
+    mcmuse((ctx)->mcmcxgl,mcmc2g(ctx,obj)))) : (void)0)
+
+#endif /* MCM_NO_MACRO */
+
+/*
+ *   Allocate a new cache object.  The new object is locked upon return.
+ *   A pointer to the memory for the new object is returned, and
+ *   the object number is returned at *nump.  A null pointer is returned
+ *   if the object cannot be allocated.
+ */
+/* uchar *mcmalo(mcmcxdef *ctx, ushort siz, mcmon *nump); */
+#define mcmalo(ctx, siz, nump) mcmalo0(ctx, siz, nump, MCMONINV, FALSE)
+
+/*
+ *   Reserve space for an object, giving it a particular client object
+ *   number.  This doesn't actually allocate any space for the object, but
+ *   just sets it up so that it can be loaded by the client when it's
+ *   needed.  
+ */
+void mcmrsrv(mcmcxdef *ctx, ushort siz, mcmon clinum, mclhd loadhd);
+
+/*
+ *   Allocate a new cache object, and associate it with a particular
+ *   client object number.  An error is signalled if the client object
+ *   number is already in use.
+ */
+/* uchar *mcmalonum(mcmcxdef *ctx, ushort siz, mcmon num); */
+#define mcmalonum(ctx, siz, num) mcmalo0(ctx, siz, (mcmon *)0, num, FALSE)
+
+/*
+ *   Reallocate an existing object.  The object's size is increased
+ *   or reduced according to newsize.  The object is locked if it is
+ *   not already, and the address of the object's memory is returned.
+ *   Note that the object can move when reallocated, even if it was
+ *   locked before the call.
+ */
+uchar *mcmrealo(mcmcxdef *ctx, mcmon objnum, ushort newsize);
+
+/*
+ *   Touch a cache object (rendering it dirty).  When an object is
+ *   written, the client must touch it to ensure that the version in
+ *   memory is not discarded.  The cache manager attempts to optimize
+ *   activity by not writing objects that can be reconstructed from the
+ *   load or swap file.  Touching the object informs the cache manager
+ *   that the object is different from any version it has in a swap or
+ *   load file.  
+ */
+/* void mcmtch(mcmcxdef *ctx, mcmon objnum); */
+#define mcmtch(ctx,obj) \
+  (mcmobje(ctx,obj)->mcmoflg |= MCMOFDIRTY)
+/* was: (mcmobje(ctx,obj)->mcmoflg |= (MCMOFDIRTY | MCMOFNODISC)) */
+
+/* get size of a cache manager object - object need not be locked */
+/* ushort mcmobjsiz(mcmcxdef *ctx, mcmon objn); */
+#define mcmobjsiz(ctx, objn) (mcmobje(ctx, objn)->mcmosiz)
+
+/* determine if object has ever been touched */
+/* int mcmobjdirty(mcmcxdef *ctx, mcmon objn); */
+#define mcmobjdirty(ctx, objn) \
+ (mcmobje(ctx, objn)->mcmoflg & (MCMOFDIRTY | MCMOFNODISC))
+
+/* get object's memory pointer - object must be locked for valid result */
+/* uchar *mcmobjptr(mcmcxdef *ctx, mcmon objn); */
+#define mcmobjptr(ctx, objn) (mcmobje(ctx, objn)->mcmoptr)
+
+/*
+ *   Free an object.  The memory occupied by the object is discarded, and
+ *   the object may no longer be referenced.  
+ */
+void mcmfre(mcmcxdef *ctx, mcmon obj);
+
+/*
+ *   "Revert" an object - convert it back to original state.  This
+ *   routine just invokes a client callback to do the actual reversion
+ *   work.  The callback is called immediately if the object is already
+ *   present in memory, but is deferred until the object is loaded/swapped
+ *   in if the object is not in memory. 
+ */
+/* void mcmrevert(mcmcxdef *ctx, mcmon objn); */
+#define mcmrevert(ctx, objn) \
+ ((mcmobje(ctx, objn)->mcmoflg & MCMOFPRES) ? \
+  ((*(ctx)->mcmcxrvf)((ctx)->mcmcxrvc, objn), DISCARD 0) \
+  : DISCARD (mcmobje(ctx, objn)->mcmoflg |= MCMOFREVRT))
+
+/* get current size of object cache */
+ulong mcmcsiz(mcmcxdef *ctx);
+
+/* change an object's swap handle (used by swapper) */
+/* void mcmcsw(mcmcx1def *ctx, ushort objn, mcsseg swapn, mcsseg oldswn); */
+#define mcmcsw(ctx, objn, swapn, oldswapn) \
+   ((*(ctx)->mcmcxcsw)(ctx, objn, swapn, oldswapn))
+
+/* ------------------------------- PRIVATE ------------------------------- */
+
+/* Unlock an object by its global handle */
+#ifdef MCM_NO_MACRO
+void mcmgunlck(mcmcx1def *ctx, mcmon objnum);
+#else /* MCM_NO_MACRO */
+
+/* void mcmgunlck(mcmcx1def *ctx, mcmon objnum); */
+#define mcmgunlck(ctx,obj) \
+ ((mcmgobje(ctx,obj)->mcmoflg & MCMOFLOCK) ? \
+  (--(mcmgobje(ctx,obj)->mcmolcnt) ? (void)0 : \
+    ((mcmgobje(ctx,obj)->mcmoflg&=(~MCMOFLOCK)), mcmuse(ctx,obj))) : \
+  (void)0)
+
+#endif /* MCM_NO_MACRO */
+
+/* real memory allocator; clients use cover macros */
+uchar *mcmalo0(mcmcxdef *ctx, ushort siz, mcmon *nump, mcmon clinum,
+               int noclitrans);
+
+/* free an object by global object number */
+void mcmgfre(mcmcx1def *ctx, mcmon obj);
+
+/* "use" an object (move to most-recent position in LRU chain) */
+void mcmuse(mcmcx1def *ctx, mcmon n);
+
+/*
+ *   Load or swap in a cache object which is currently unloaded, locking
+ *   it before returning.  Returns a pointer to the memory containing
+ *   the object, or a null pointer in case of error.  The object
+ *   remains fixed in memory at the returned location until unlocked.
+ */
+uchar *mcmload(mcmcxdef *ctx, mcmon objnum);
+
+/*
+ *   Size of each chunk of memory we'll request from the heap manager.
+ *   To cut down on wasted memory from the heap manager, we'll always make
+ *   our requests in this large size, then sub-allocate out of these
+ *   chunks. 
+ */
+#define MCMCHUNK  32768
+
+/*
+ *   number of cache entries in a page - make this a power of 2 to keep
+ *   the arithmetic to find a cache object entry simple 
+ */
+#define MCMPAGECNT 256
+
+/*
+ *   size of a page, in bytes
+ */
+#define MCMPAGESIZE (MCMPAGECNT * sizeof(mcmodef))
+
+/*
+ *   When allocating memory, and we find a free block satisfying the
+ *   request, we will split the free block if doing so would result in
+ *   enough space in the second block.  MCMSPLIT specifies the minimum
+ *   size left over that will allow a split to occur.
+ */
+#define MCMSPLIT 64
+
+/* get an object cache entyr given a GLOBAL object number */
+#define mcmgobje(ctx,num) (&((ctx)->mcmcxtab[(num)>>8][(num)&255]))
+
+/* get an object cache entry given a CLIENT object number */
+/* mcmodef *mcmobje(mcmcxdef *ctx, mcmon objnum) */
+#define mcmobje(ctx,num) mcmgobje((ctx)->mcmcxgl,mcmc2g(ctx,num))
+
+/* allocate a block that will be locked for its entire lifetime */
+void *mcmptralo(mcmcxdef *ctx, ushort siz);
+
+/* free a block allocated with mcmptralo */
+void mcmptrfre(mcmcxdef *ctx, void *block);
+
+/* change an object's swap handle */
+void mcmcswf(mcmcx1def *ctx, mcmon objn, mcsseg swapn, mcsseg oldswapn);
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/memory_cache_heap.cpp b/engines/glk/tads/tads2/memory_cache_heap.cpp
new file mode 100644
index 0000000000..fae3c5e080
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_heap.cpp
@@ -0,0 +1,51 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/memory_cache_heap.h"
+#include "glk/tads/tads2/error.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* global to keep track of all allocations */
+IF_DEBUG(ulong mchtotmem;)
+
+uchar *mchalo(errcxdef *ctx, size_t siz, char *comment) {
+    uchar *ret;
+
+    VARUSED(comment);
+    IF_DEBUG(mchtotmem += siz;)
+
+    ret = (uchar *)osmalloc(siz);
+    if (ret)
+        return(ret);
+    else {
+        errsig(ctx, ERR_NOMEM);
+        NOTREACHEDV(uchar *);
+        return 0;
+    }
+}
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/memory_cache_heap.h b/engines/glk/tads/tads2/memory_cache_heap.h
new file mode 100644
index 0000000000..269cdec3ad
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_heap.h
@@ -0,0 +1,60 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/*
+ * Memory cache heap manager
+ *
+ * This is the low-level heap manager, which maintains a list of non-relocatable,
+ * non-swappable blocks of memory.  The cache manager uses the heap manager for
+ * its basic storage needs.
+ */
+
+#ifndef GLK_TADS_TADS2_MEMORY_CACHE_HEAP
+#define GLK_TADS_TADS2_MEMORY_CACHE_HEAP
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error_handling.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/**
+ *   Allocate a block of memory; returns pointer to the block.
+ *   An out-of-memory error is signalled if insufficient memory
+ *   is available.  The comment is for debugging purposes only.
+ */
+uchar *mchalo(errcxdef *ctx, size_t siz, char *comment);
+
+/* allocate a structure */
+#define MCHNEW(errctx, typ, comment) \
+ ((typ *)mchalo(errctx, sizeof(typ), comment))
+
+/* free a block of memory */
+/* void mchfre(uchar *ptr); */
+#define mchfre(ptr) (osfree(ptr))
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/memory_cache_loader.cpp b/engines/glk/tads/tads2/memory_cache_loader.cpp
new file mode 100644
index 0000000000..f403299167
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_loader.cpp
@@ -0,0 +1,31 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/memory_cache_loader.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/memory_cache_loader.h b/engines/glk/tads/tads2/memory_cache_loader.h
new file mode 100644
index 0000000000..c7ec22db57
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_loader.h
@@ -0,0 +1,57 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/*
+ * Memory cache swap manager
+ *
+ * The cache swap manager provides swap file services to the memory
+ * cache manager.  The cache manager calls the swap manager to write
+ * objects to the swap file and read in previously swapped-out objects.
+ */
+
+#ifndef GLK_TADS_TADS2_MEMORY_CACHE_LOADER
+#define GLK_TADS_TADS2_MEMORY_CACHE_LOADER
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error_handling.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/**
+ * Loader context
+ */
+struct mclcxdef {
+    errcxdef *mclcxerr;			/* error handling context */
+};
+
+/**
+ * Loader handle
+ */
+typedef ulong mclhd;			/* essentially a seek address */
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/memory_cache_swap.cpp b/engines/glk/tads/tads2/memory_cache_swap.cpp
new file mode 100644
index 0000000000..114a7258e9
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_swap.cpp
@@ -0,0 +1,31 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/memory_cache_swap.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/memory_cache_swap.h b/engines/glk/tads/tads2/memory_cache_swap.h
new file mode 100644
index 0000000000..f1b9849aec
--- /dev/null
+++ b/engines/glk/tads/tads2/memory_cache_swap.h
@@ -0,0 +1,122 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/*
+ * Memory cache swap manager
+ *
+ * The cache swap manager provides swap file services to the memory
+ * cache manager.  The cache manager calls the swap manager to write
+ * objects to the swap file and read in previously swapped-out objects.
+ */
+
+#ifndef GLK_TADS_TADS2_MEMORY_CACHE_SWAP
+#define GLK_TADS_TADS2_MEMORY_CACHE_SWAP
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error_handling.h"
+#include "glk/tads/osfrobtads.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* Forward declarations */
+struct mcmcx1def;
+
+/**
+ * swap segment descriptor
+ */
+struct mcsdsdef {
+    ulong    mcsdsptr;                         /* seek pointer in swap file */
+    ushort   mcsdssiz;                         /* size of this swap segment */
+    ushort   mcsdsosz;                 /* size of object written to segment */
+    uint     mcsdsobj;                                  /* client object ID */
+    ushort   mcsdsflg;                                             /* flags */
+#define      MCSDSFINUSE   0x01                        /* segment is in use */
+};
+
+/**
+ * mcsseg - swap segment handle.  All swap-file segments are addressed
+ * through this handle type.  
+ */
+typedef ushort mcsseg;
+
+/**
+ * Swap manager context
+ */
+struct mcscxdef {
+    osfildef   *mcscxfp;                                /* swap file handle */
+    char       *mcscxfname;                            /* name of swap file */
+    errcxdef   *mcscxerr;                         /* error handling context */
+    ulong       mcscxtop;              /* top of swap file allocated so far */
+    ulong       mcscxmax;        /* maximum size of swap file we're allowed */
+    mcsdsdef  **mcscxtab;                     /* swap descriptor page table */
+    mcsseg      mcscxmsg;               /* maximum segment allocated so far */
+    mcmcx1def *mcscxmem;                   /* memory manager context */
+};
+
+#define MCSSEGINV ((mcsseg)~0)      /* invalid segment ID - error indicator */
+
+/* initialize swapper - returns 0 for success, other for error */
+void mcsini(struct mcscxdef *ctx, struct mcmcx1def *gmemctx, ulong maxsiz,
+            osfildef *fp, char *swapfilename, struct errcxdef *errctx);
+
+/* close swapper (release memory areas) */
+void mcsclose(struct mcscxdef *ctx);
+
+/**
+ *   Swap an object out.  The caller specifies the location and size of
+ *   the object, as well as a unique handle (arbitrary, up to the caller;
+ *   the only requirement is that it be unique among all caller objects
+ *   and always the same for a particular caller's object) and the
+ *   previous swap handle if the object ever had one.  If the object is
+ *   not dirty (it hasn't been written since being swapped in), and the
+ *   swap manager hasn't reused the swap slot, the swap manager doesn't
+ *   need to write the memory, since it already has a copy on disk;
+ *   instead, it can just mark the slot as back in use.  If the caller
+ *   doesn't wish to take advantage of this optimization, always pass in
+ *   dirty == TRUE, which will force a write regardless of the object ID.
+ */
+mcsseg mcsout(struct mcscxdef *ctx, uint objid, uchar *objptr,
+              ushort objsize, mcsseg oldswapseg, int dirty);
+            
+/* Swap an object in */
+void mcsin(struct mcscxdef *ctx, mcsseg swapseg, uchar *objptr, ushort size);
+
+
+/* number of page pointers in page table (max number of pages) */
+#define MCSPAGETAB 256
+
+/* number of swap descriptors in a page */
+#define MCSPAGECNT 256
+
+/* find swap descriptor corresponding to swap segment number */
+#define mcsdsc(ctx,seg) (&(ctx)->mcscxtab[(seg)>>8][(seg)&255])
+
+/* write out a swap segment */
+void mcswrt(mcscxdef *ctx, mcsdsdef *desc, uchar *buf, ushort bufl);
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/object.cpp b/engines/glk/tads/tads2/object.cpp
new file mode 100644
index 0000000000..2ba1161d86
--- /dev/null
+++ b/engines/glk/tads/tads2/object.cpp
@@ -0,0 +1,35 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/object.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/object.h b/engines/glk/tads/tads2/object.h
new file mode 100644
index 0000000000..5e2499ccc2
--- /dev/null
+++ b/engines/glk/tads/tads2/object.h
@@ -0,0 +1,396 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_OBJECT
+#define GLK_TADS_TADS2_OBJECT
+
+#include "glk/tads/tads.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/memory_cache.h"
+#include "glk/tads/tads2/property.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/**
+ * object number
+ */
+typedef ushort objnum;
+
+/**
+ * For non-class objects, we'll leave some space free in the object so
+ * that a few properties can be added without having to resize the
+ * object.  Class objects will probably never have anything added, so
+ * there's no need for extra space.  
+ */
+#define OBJEXTRA 64
+
+#   define   OBJFCLS   0x01                            /* object is a class */
+
+/**
+ * The object structure is actually laid out portably, using unaligned
+ * 2-byte arrays, stored least significant byte first, for each ushort
+ * (including the objnum array for the superclasses).  The actual
+ * entries are at these offsets on all machines: 
+ *
+ *      objws      0
+ *      objflg     2
+ *      objnsc     4
+ *      objnprop   6
+ *      objfree    8
+ *      objrst     10
+ *      objstat    12
+ *      objsc[0]   14
+ *      objsc[1]   16
+ *      etc
+ *      
+ * If the OBJFINDEX flag is set, the object has a property index.
+ * The index occurs after the last superclass (so it's where the
+ * property data would go if there were no index), and the property
+ * data follows.  Each index entry consists of a pair of two-byte
+ * entries:  the first is the property number, and the second is
+ * its offset within the object.  For performance reasons, an index
+ * is only built on a class object -- whenever a property is changed
+ * within an object, the entire index must be rebuilt, because the
+ * locations of many properties within the object can be changed by
+ * a single property change in the object.  The index is ordered by
+ * property number, so it can be searched using a binary search.
+ * Furthermore, "ignored" properties are excluded from the index;
+ * only the active instance of a particular property is stored.
+ * The index must be maintained by all routines that can change
+ * property information:  setp, delp, revert, etc.
+ * 
+ * Preceding the index table is a two-byte entry that gives the
+ * offset of the properties.  Since the properties immediately
+ * follow the index, this can be used to deduce how large a space
+ * is available for the index itself.
+ */
+typedef uchar objdef;
+#define OBJDEFSIZ 14   /* "sizeof(objdef)" - size of object header w/o sc's */
+
+/* object flags */
+#define OBJFCLASS  1                                   /* object is a class */
+#define OBJFINDEX  2                         /* object has a property index */
+#define OBJFMOD    4      /* object has been modified by a newer definition */
+
+/* undo context */
+struct objucxdef {
+    mcmcxdef *objucxmem;                           /* cache manager context */
+    errcxdef *objucxerr;                                   /* error context */
+    ushort    objucxsiz;                         /* size of the undo buffer */
+    ushort    objucxhead;                  /* head (position of next write) */
+    ushort    objucxtail;               /* tail (position of oldest record) */
+    ushort    objucxprv;                           /* previous head pointer */
+    ushort    objucxtop;                      /* highest head value written */
+    void    (*objucxcun)(void *ctx, uchar *data);
+                                              /* apply a client undo record */
+    ushort  (*objucxcsz)(void *ctx, uchar *data);
+                                        /* get size of a client undo record */
+    void     *objucxccx;                             /* client undo context */
+    uchar     objucxbuf[1];                                  /* undo buffer */
+};
+
+/*
+ *   Undo records are kept in a circular buffer allocated as part of an
+ *   undo context.  Offsets within the buffer are kept for the head, tail,
+ *   and previous head records.  The head always points to the byte at
+ *   which the next undo record will be written.  The previous head points
+ *   to the most recently written undo record; it contains a back link to
+ *   the undo record before that, and so forth back through the entire
+ *   chain.  (These reverse links are necessary because undo records vary
+ *   in size depending on the data contained within.)  The tail points to
+ *   the oldest undo record that's still in the buffer.  Conceptually, the
+ *   head is always "above" the tail in the buffer; since the buffer is
+ *   circular, the tail may have a higher address, but this just means
+ *   that the buffer wraps around at the top.  When the head bumps into
+ *   the tail (i.e., the head address is physically below or equal to the
+ *   tail address, and the head is then advanced so that its address
+ *   becomes higher than the tail's), the tail is advanced by discarding
+ *   as many of the least recent undo records as necessary to make room
+ *   for the new head position.  When the head and the previous head point
+ *   to the same place, we have no undo records in the buffer.  
+ */
+/**
+ *   The first byte of an undo record specifies what action is to be
+ *   undone.  If a property was added, it is undone merely by deleting the
+ *   property.  If a property was changed, it is undone by setting the
+ *   property back to its old value.  An additional special flag indicates
+ *   a "savepoint."  Normally, all changes back to a savepoint will be
+ *   undone.  
+ */
+#define OBJUADD    1             /* a property was added (undo by deleting) */
+#define OBJUCHG    2   /* a property was changed (change back to old value) */
+#define OBJUSAV    3          /* savepoint marker (no property information) */
+#define OBJUOVR    4     /* override original property (set orig to IGNORE) */
+#define OBJUCLI    5                /* client undo record (any client data) */
+
+/*
+ *   After the control byte (OBJUxxx), the object number, property
+ *   number, datatype, and data value will follow; some or all of these
+ *   may be omitted, depending on the control byte. 
+ */
+
+/* get object flags */
+#define objflg(o) ((ushort)osrp2(((char *)(o)) + 2))
+
+/* get object flags */
+#define objsflg(o, val) oswp2(((char *)(o)) + 2, val)
+
+/* given an object pointer, get a pointer to the first prpdef */
+/* prpdef *objprp(objdef *objptr); */
+#define objprp(o) ((prpdef *)(objsc(o) + 2*objnsc(o)))
+
+/* given an object pointer, get number of properties in the prpdef */
+/* int objnprop(objdef *objptr); */
+#define objnprop(o) ((ushort)osrp2(((char *)(o)) + 6))
+
+/* set number of properties */
+/* void objsnp(objdef *objptr, int newnum); */
+#define objsnp(o,n) oswp2(((char *)(o)) + 6, n)
+
+/* given an object pointer, get offset of free space */
+/* int objfree(objdef *objptr); */
+#define objfree(o) ((ushort)osrp2(((char *)(o)) + 8))
+
+/* set free space pointer */
+/* void objsfree(objdef *objptr, int newfree); */
+#define objsfree(o,n) oswp2(((char *)(o)) + 8, n)
+
+/* get number of static properties */
+/* ushort objstat(objdef *objptr); */
+#define objstat(o) ((ushort)osrp2(((char *)(o)) + 10))
+
+/* set number of static properties */
+/* void objsetst(objdef *objptr, int newstat); */
+#define objsetst(o,n) oswp2(((char *)(o)) + 10, n)
+
+/* get reset size (size of static properties) */
+/* ushort objrst(objdef *objptr); */
+#define objrst(o) ((ushort)osrp2(((char *)(o)) + 12))
+
+/* set reset size */
+/* void objsetrst(objdef *objptr, uint newrst); */
+#define objsetrst(o,n) oswp2(((char *)(o)) + 12, n)
+ 
+/* given an object pointer, get first superclass pointer */
+/* uchar *objsc(objdef *objptr); */
+#define objsc(o) (((uchar *)(o)) + OBJDEFSIZ)
+
+/* given an object pointer, get number of superclasses */
+/* int objnsc(objdef *objptr); */
+#define objnsc(o) ((ushort)osrp2(((char *)(o)) + 4))
+
+/* set number of superclasses */
+/* void objsnsc(objdef *objptr, int num); */
+#define objsnsc(o,n) oswp2(((char *)(o)) + 4, n)
+
+/* given a prpdef, get the next prpdef */
+/* prpdef *objpnxt(prpdef *p); */
+#define objpnxt(p) \
+ ((prpdef *)(((uchar *)(p)) + PRPHDRSIZ + prpsize(p)))
+
+/* get pointer to free prpdef */
+/* prpdef *objpfre(objdef *objptr); */
+#define objpfre(o) ((prpdef *)(((uchar *)(o)) + objfree(o)))
+
+/* given a prpdef and an object pointer, compute the prpdef offset */
+/* uint objpofs(objdef *objptr, prpdef *propptr); */
+#define objpofs(o,p) ((uint)((p) ? (((uchar *)(p)) - ((uchar *)(o))) : 0))
+
+/* given an object pointer and a property offset, get prpdef pointer */
+/* prpdef *objofsp(objdef *objptr, uint propofs); */
+#define objofsp(o,ofs) ((prpdef *)((ofs) ? (((uchar *)(o)) + (ofs)) : 0))
+
+/*
+ *   Get the first superclass of an object.  If it doesn't have any
+ *   superclasses, return invalid.
+ */
+objnum objget1sc(mcmcxdef *ctx, objnum objn);
+
+/*
+ *   Get an object's property WITHOUT INHERITANCE.  If the object has the
+ *   indicated property set, the byte OFFSET of the prpdef within the
+ *   object is returned.  The offset will remain valid until any type of
+ *   operation that sets a property in the object (such as objdelp,
+ *   objsetp, or an undo operation).  An offset of zero means that the
+ *   property was not set in the object.
+ */
+uint objgetp(mcmcxdef *ctx, objnum objn, prpnum prop,
+             dattyp *typptr);
+
+/*
+ *   Get the *ending* offset of the given property's value, without any
+ *   inheritance.  Returns the byte offset one past the end of the
+ *   property's data.  
+ */
+uint objgetp_end(mcmcxdef *ctx, objnum objn, prpnum prop);
+
+/*
+ *   Get a property of an object, either from the object or from a
+ *   superclass (inherited).  If the inh flag is TRUE, we do not look
+ *   at all in the object itself, but restrict our search to inherited
+ *   properties only.  We return the byte OFFSET of the prpdef within
+ *   the object in which the prpdef is found; the superclass object
+ *   itself is NOT locked upon return, but we will NOT unlock the
+ *   object passed in.  If the offset is zero, the property was not
+ *   found.  The offset returned is valid until any operation that
+ *   sets a property in the object (such as objdelp, objsetp, or an
+ *   undo operation).
+ */
+uint objgetap(mcmcxdef *ctx, noreg objnum objn, prpnum prop,
+              objnum *orn, int inh);
+
+/*
+ *   expand an object by a requested amount, returning a pointer to the
+ *   object's new location if it must be moved.  The object will be
+ *   unlocked and relocked by this call.  On return, the actual amount
+ *   of space ADDED to the object will be returned.
+ */
+objdef *objexp(mcmcxdef *ctx, objnum obj, ushort *siz);
+
+/*
+ *   Set an object's property, deleting the original value of the
+ *   property if it existed.  If an undo context is provided, write an
+ *   undo record for the change; if the undo context pointer is null, no
+ *   undo information is retained. 
+ */
+void objsetp(mcmcxdef *ctx, objnum obj, prpnum prop,
+             dattyp typ, void *val, objucxdef *undoctx);
+
+/* 
+ *   Delete a property.  If mark_only is true, we'll only mark the
+ *   property as deleted without actually reclaiming its space; this is
+ *   necessary when removing a code property (type DAT_CODE) any time
+ *   other code properties may follow, because p-code is not entirely
+ *   self-relative and thus can't always be relocated within an object. 
+ */
+void objdelp(mcmcxdef *mctx, objnum objn, prpnum prop, int mark_only);
+
+/*
+ *   Set up for emitting code into an object.  Writes a property header
+ *   of type 'code', and returns the offset of the next free byte in the
+ *   object.  Call objendemt when done.  The datatype argument is
+ *   provided so that list generation can be done through the same
+ *   mechanism, since parser lists must be converted to run-time
+ *   lists via the code generator.
+ */
+uint objemt(mcmcxdef *ctx, objnum objn, prpnum prop, dattyp typ);
+
+/* done emitting code into property, finish setting object info */
+void objendemt(mcmcxdef *ctx, objnum objn, prpnum prop, uint endofs);
+
+/*
+ *   Determine if undo records should be kept.  Undo records should be
+ *   kept only if a savepoint is present in the undo log.  If no savepoint
+ *   is present, adding undo records would be useless, since it will not
+ *   be possible to apply the undo information. 
+ */
+int objuok(objucxdef *undoctx);
+
+/*
+ *   Reserve space in an undo buffer, deleting old records as needed.
+ *   Returns a pointer to the reserved space. 
+ */
+uchar *objures(objucxdef *undoctx, uchar cmd, ushort siz);
+
+/* advance the tail pointer in an undo buffer over the record it points to */
+void objutadv(objucxdef *undoctx);
+
+/* apply one undo record, and remove it from undo list */
+void obj1undo(mcmcxdef *mctx, objucxdef *undoctx);
+
+/*
+ *   Undo back to the most recent savepoint.  If there is no savepoint in
+ *   the undo list, NOTHING will be undone.  This prevents reaching an
+ *   inconsistent state in which some, but not all, of the operations
+ *   between two savepoints are undone: either all operations between two
+ *   savepoints will be undone, or none will. 
+ */
+void objundo(mcmcxdef *mctx, objucxdef *undoctx);
+
+/* set an undo savepoint */
+void objusav(objucxdef *undoctx);
+
+/* initialize undo context */
+objucxdef *objuini(mcmcxdef *memctx, ushort undosiz,
+                   void (*undocb)(void *ctx, uchar *data),
+                   ushort (*sizecb)(void *ctx, uchar *data),
+                   void *callctx);
+
+/* free the undo context - releases memory allocated by objuini() */
+void objuterm(objucxdef *undoctx);
+
+/* discard all undo context (for times such as restarting) */
+void objulose(objucxdef *undoctx);
+
+/*
+ *   Allocate and initialize a new object.  The caller specifies the
+ *   number of superclasses to be allocated, and the amount of space (in
+ *   bytes) for the object's property data.  The caller must fill in the
+ *   superclass array.  Upon return, the object is allocated and locked,
+ *   and is initialized with no properties.  A pointer to the object's
+ *   memory is returned, and *objnptr receives the object number.
+ */
+objdef *objnew(mcmcxdef *mctx, int sccnt, ushort propspace,
+               objnum *objnptr, int classflg);
+            
+/* initialize an already allocated object */
+void objini(mcmcxdef *mctx, int sccnt, objnum objn, int classflg);
+
+/*
+ *   Add space for additional superclasses to an object.  The object can
+ *   already have some properties set (if it doesn't, it can just be
+ *   reinitialized).
+ */
+void objaddsc(mcmcxdef *mctx, int sccnt, objnum objn);
+
+/*
+ *   Delete an object's properties and superclasses.  The 'mindel'
+ *   parameter specifies the minimum property number to be deleted.
+ *   Properties below this are considered "system" properties that are not
+ *   to be deleted.  This could be used by a development environment to
+ *   store the source for an object as a special system property in the
+ *   object; when the object is recompiled, all of the object's properties
+ *   and superclasses must be deleted except the source property, which is
+ *   retained even after recompilation. 
+ */
+void objclr(mcmcxdef *mctx, objnum objn, prpnum mindel);
+
+/* Build or rebuild an object's property index */
+void objindx(mcmcxdef *mctx, objnum objn);
+
+/* set up just-compiled object: mark static part and original properties */
+void objcomp(mcmcxdef *mctx, objnum objn, int for_debug);
+
+/* revert an object to original post-compilation state */
+void objrevert(void *mctx, mcmon objn);
+
+/* reset 'ignore' flags for a newly reconstructed object */
+void objsetign(mcmcxdef *mctx, objnum objn);
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/opcode_defs.h b/engines/glk/tads/tads2/opcode_defs.h
new file mode 100644
index 0000000000..32519ae8f7
--- /dev/null
+++ b/engines/glk/tads/tads2/opcode_defs.h
@@ -0,0 +1,218 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_OPCODE_DEFS
+#define GLK_TADS_TADS2_OPCODE_DEFS
+
+/*
+ * Opcode definitions
+ *
+ * Lifted largely from the old TADS, since the basic run - time interpreter's
+ * operation is essentially the same.
+ */
+
+#include "glk/tads/tads.h"
+#include "glk/tads/tads2/data.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+#define OPCPUSHNUM  1       /* push a constant numeric value */
+#define OPCPUSHOBJ  2       /* push an object */
+#define OPCNEG      3       /* unary negation */
+#define OPCNOT      4       /* logical negation */
+#define OPCADD      5       /* addition/list concatenation */
+#define OPCSUB      6       /* subtraction/list difference */
+#define OPCMUL      7       /* multiplication */
+#define OPCDIV      8       /* division */
+#define OPCAND      9       /* logical AND */
+#define OPCOR       10      /* logical OR */
+#define OPCEQ       11      /* equality */
+#define OPCNE       12      /* inequality */
+#define OPCGT       13      /* greater than */
+#define OPCGE       14      /* greater or equal */
+#define OPCLT       15      /* less than */
+#define OPCLE       16      /* less or equal */
+#define OPCCALL     17      /* call a function */
+#define OPCGETP     18      /* get property */
+#define OPCGETPDATA 19      /* get a property, allowing only data values */
+#define OPCGETLCL   20      /* get a local variable's value */
+#define OPCPTRGETPDATA 21   /* get property via pointer; only allow data */   
+#define OPCRETURN   22      /* return without a value */
+#define OPCRETVAL   23      /* return a value */
+#define OPCENTER    24      /* enter a function */
+#define OPCDISCARD  25      /* discard top of stack */
+#define OPCJMP      26      /* unconditional jump */
+#define OPCJF       27      /* jump if false */
+#define OPCPUSHSELF 28      /* push current object */
+#define OPCSAY      29      /* implicit printout for doublequote strings */
+#define OPCBUILTIN  30      /* call a built-in function */
+#define OPCPUSHSTR  31      /* push a string */
+#define OPCPUSHLST  32      /* push a list */
+#define OPCPUSHNIL  33      /* push the NIL value */
+#define OPCPUSHTRUE 34      /* push the TRUE value */
+#define OPCPUSHFN   35      /* push the address of a function */
+#define OPCGETPSELFDATA 36  /* push property of self; only allow data */
+
+#define OPCPTRCALL  38          /* call function pointed to by top of stack */
+#define OPCPTRINH   39          /* inherit pointer to property (stack=prop) */
+#define OPCPTRGETP  40          /* get property by pointer (stack=obj,prop) */
+
+#define OPCPASS     41      /* pass to inherited handler */
+#define OPCEXIT     42      /* exit turn, but continue with fuses/daemons */
+#define OPCABORT    43      /* abort turn, skipping fuses/daemons */
+#define OPCASKDO    44      /* ask for a direct object */
+#define OPCASKIO    45      /* ask for indirect object and set preposition */
+
+/* explicit superclass inheritance opcodes */
+#define OPCEXPINH   46      /* "inherited <superclass>.<property>" */
+#define OPCEXPINHPTR 47     /* "inherited <superclass>.<prop-pointer>" */
+
+/*
+ *   Special opcodes for peephole optimization.  These are essentially
+ *   pairs of operations that occur frequently so have been collapsed into
+ *   a single instruction.
+ */
+#define OPCCALLD    48      /* call function and discard value */
+#define OPCGETPD    49      /* evaluate property and discard any value */
+#define OPCBUILTIND 50      /* call built-in function and discard value */
+
+#define OPCJE       51      /* jump if equal */
+#define OPCJNE      52      /* jump if not equal */
+#define OPCJGT      53      /* jump if greater than */
+#define OPCJGE      54      /* jump if greater or equal */
+#define OPCJLT      55      /* jump if less than */
+#define OPCJLE      56      /* jump if less or equal */
+#define OPCJNAND    57      /* jump if not AND */
+#define OPCJNOR     58      /* jump if not OR */
+#define OPCJT       59      /* jump if true */
+
+#define OPCGETPSELF 60      /* get property of the 'self' object */
+#define OPCGETPSLFD 61      /* get property of 'self' and discard result */
+#define OPCGETPOBJ  62      /* get property of a given object */
+                            /*  note: differs from GETP in that object is */
+                            /*  encoded into the instruction */
+#define OPCGETPOBJD 63      /* get property of an object and discard result */
+#define OPCINDEX    64      /* get an indexed entry from a list */
+
+#define OPCPUSHPN   67      /* push a property number */
+
+#define OPCJST      68      /* jump and save top-of-stack if true */
+#define OPCJSF      69      /* jump and save top-of-stack if false */
+#define OPCJMPD     70      /* discard stack and then jump unconditionally */
+
+#define OPCINHERIT  71      /* inherit a property from superclass */
+#define OPCCALLEXT  72      /* call external function */
+#define OPCDBGRET   73      /* return to debugger (no stack frame leaving) */
+
+#define OPCCONS     74      /* construct list from top two stack elements */
+#define OPCSWITCH   75      /* switch statement */
+
+#define OPCARGC     76      /* get argument count */
+#define OPCCHKARGC  77      /* check actual arguments against formal count */
+
+#define OPCLINE     78      /* line record */
+#define OPCFRAME    79      /* local variable frame record */
+#define OPCBP       80      /* breakpoint - replaces an OPCLINE instruction */
+#define OPCGETDBLCL 81                                /* get debugger local */
+#define OPCGETPPTRSELF 82                 /* get property pointer from self */
+#define OPCMOD      83                                            /* modulo */
+#define OPCBAND     84                                        /* binary AND */
+#define OPCBOR      85                                         /* binary OR */
+#define OPCXOR      86                                        /* binary XOR */
+#define OPCBNOT     87                                   /* binary negation */
+#define OPCSHL      88                                    /* bit shift left */
+#define OPCSHR      89                                   /* bit shift right */
+
+#define OPCNEW      90                                 /* create new object */
+#define OPCDELETE   91                                     /* delete object */
+
+
+/* ----- opcodes 192 and above are reserved for assignment operations ----- */
+
+/*
+ASSIGNMENT OPERATIONS
+    When (opcode & 0xc0 == 0xc0), we have an assignment operation.
+    (Note that this means that opcodes from 0xc0 up are all reserved
+    for assignment operations.)  The low six bits of the opcode
+    specify exactly what kind of operation is to be performed:
+    
+    bits 0-1:  specifies destination type:
+               00    2-byte operand is local number
+               01    2-byte operand is property to set in obj at tos
+               10    tos is index, [sp-1] is list to be indexed and set
+               11    tos is property pointer, [sp-1] is object
+    
+    bits 2-4:  specifies assignment operation:
+               000   := (direct assignment)
+               001   += (add tos to destination)
+               010   -= (subtract tos from destination)
+               011   *= (multiply destination by tos)
+               100   /= (divide destination by tos)
+               101   ++ (increment tos)
+               110   -- (decrement tos)
+               111   *reserved*
+               
+    bit 5:     specifies what to do with value computed by assignment
+               0     leave on stack (implies pre increment/decrement)
+               1     discard (implies post increment/decrement)
+*/
+#define OPCASI_MASK      0xc0                     /* assignment instruction */
+
+#define OPCASIDEST_MASK  0x03              /* mask to get destination field */
+#define OPCASILCL        0x00                          /* assign to a local */
+#define OPCASIPRP        0x01               /* assign to an object.property */
+#define OPCASIIND        0x02             /* assign to an element of a list */
+#define OPCASIPRPPTR     0x03                /* assign property via pointer */
+
+#define OPCASITYP_MASK   0x1c          /* mask to get assignment type field */
+#define OPCASIDIR        0x00                          /* direct assignment */
+#define OPCASIADD        0x04                             /* assign and add */
+#define OPCASISUB        0x08                        /* assign and subtract */
+#define OPCASIMUL        0x0c                        /* assign and multiply */
+#define OPCASIDIV        0x10                          /* assign and divide */
+#define OPCASIINC        0x14                                  /* increment */
+#define OPCASIDEC        0x18                                  /* decrement */
+#define OPCASIEXT        0x1c                     /* other - extension flag */
+
+/* extended assignment flags - next byte when OPCASIEXT is used */
+#define OPCASIMOD        1                             /* modulo and assign */
+#define OPCASIBAND       2                         /* binary AND and assign */
+#define OPCASIBOR        3                          /* binary OR and assign */
+#define OPCASIXOR        4                         /* binary XOR and assign */
+#define OPCASISHL        5                         /* shift left and assign */
+#define OPCASISHR        6                        /* shift right and assign */
+
+
+#define OPCASIPRE_MASK   0x20                    /* mask for pre/post field */
+#define OPCASIPOST       0x00                       /* increment after push */
+#define OPCASIPRE        0x20                      /* increment before push */
+
+/* some composite opcodes for convenience */
+#define OPCSETLCL (OPCASI_MASK | OPCASILCL | OPCASIDIR)
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/os.cpp b/engines/glk/tads/tads2/os.cpp
index 15a291a87b..e51a4d938e 100644
--- a/engines/glk/tads/tads2/os.cpp
+++ b/engines/glk/tads/tads2/os.cpp
@@ -26,6 +26,7 @@ namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
+#if 0
 OS::OS(OSystem *syst, const GlkGameDescription &gameDesc) : TADS(syst, gameDesc),
 		status_mode(0) {
 	Common::fill(&status_left[0], &status_left[OSS_STATUS_STRING_LEN], '\0');
@@ -345,6 +346,7 @@ int OS::oss_getc_from_window(winid_t win) {
 	buffered_char = oss_convert_keystroke_to_tads(ev.val1);
 	return 0;
 }
+#endif
 
 } // End of namespace TADS2
 } // End of namespace TADS
diff --git a/engines/glk/tads/tads2/os.h b/engines/glk/tads/tads2/os.h
index 45ab804f95..5dcc83c935 100644
--- a/engines/glk/tads/tads2/os.h
+++ b/engines/glk/tads/tads2/os.h
@@ -20,218 +20,5136 @@
  *
  */
 
+/* Portable interfaces to OS-specific functions
+ *
+ * This file defines interfaces to certain functions that must be called
+ * from portable code, but which must have system-specific implementations.
+ */
+
 #ifndef GLK_TADS_TADS2_OS
 #define GLK_TADS_TADS2_OS
 
-#include "glk/tads/tads.h"
-#include "glk/tads/tads2/types.h"
+#include "common/system.h"
+#include "glk/tads/osfrobtads.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/appctx.h"
 
 namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
-/**
- * Operating system compatibility layer
- */
-class OS : public TADS {
-protected:
-	char status_left[OSS_STATUS_STRING_LEN];
-	char status_right[OSS_STATUS_STRING_LEN];
-	int status_mode;
-protected:
-	/**
-	 * Constructor
-	 */
-	OS(OSystem *syst, const GlkGameDescription &gameDesc);
-
-	/**
-	 * Terminates the game
-	 */
-	void os_terminate(int rc);
-
-	/**
-	 * \defgroup Type Conversions
-	 * @{
-	 */
-
-	/**
-	 * Change a TADS prompt type (OS_AFP_*) into a Glk prompt type.
-	 */
-	uint oss_convert_prompt_type(int type);
-	
-	/**
-	 * Change a TADS file type (OSFT*) into a Glk file type.
-	 */
-	uint oss_convert_file_type(int type);
-
-	/**
-	 * Change a fileref ID (frefid_t) to a special string and put it in the
-	 * buffer which is passed to it. The string is given by
-	 *   OSS_FILEREF_STRING_PREFIX + 'nnnnn' + OSS_FILEREF_STRING_SUFFIX
-	 * where 'nnnnn' is the frefid_t pointer converted into a string of decimal
-	 * numbers. This is only really practical for 32-bit pointers; if we use
-	 * 64-bit pointers I'll have to start using a hash table or use hex
-	 * numbers.
-	 */
-	uint oss_convert_fileref_to_string(frefid_t file_to_convert, char *buffer, int buf_len);
-
-	/**
-	 * Turn a filename or a special fileref string into an actual fileref.
-	 * Notice that, since Glk doesn't know paths, we take this opportunity to
-	 * call oss_check_path, which should do the OS-dependent path changing
-	 * in the event that the filename contains path information
-	 */
-	frefid_t oss_convert_string_to_fileref(char *buffer, uint usage);
-
-	/**
-	 * Tell us if the passed string is a hashed fileref or not
-	 */
-	bool oss_is_string_a_fileref(char *buffer);
-
-	/**
-	 * Change a Glk key into a TADS one, using the CMD_xxx codes
-	 */
-	unsigned char oss_convert_keystroke_to_tads(uint key);
-
-	/**@}*/
-
-	/**
-	 * \defgroup Directory/File methods
-	 * @{
-	 */
-
-	/**
-	 * If a filename contains path information, change dirs to that path.
-	 * Returns true if the path was fiddled with
-	 */
-	bool oss_check_path(char *filename);
-
-	/**
-	 * In case we changed directories in oss_check_path, change back to the
-	 * original executable directory
-	 */
-	void oss_revert_path();
-
-	/**
-	 * Open a stream, given a string, usage, and a filemode. tadsusage is the
-	 * TADS filemode (OSFT*); tbusage is either fileusage_TextMode or
-	 * fileusage_BinaryMode (from Glk).
-	 */
-	osfildef *oss_open_stream(char *buffer, uint tadsusage, uint tbusage,
-		uint fmode, uint rock);
-
-	/**
-	 * Get a pointer to the root name portion of a filename.  This is the part
-	 * of the filename after any path or directory prefix.  For example, on
-	 * Unix, given the string "/home/mjr/deep.gam", this function should return
-	 * a pointer to the 'd' in "deep.gam".  If the filename doesn't appear to
-	 * have a path prefix, it should simply return the argument unchanged.
-	 */
-	const char *os_get_root_name(const char *buf) const { return buf; }
-
-	/**
-	 * Open a file for access
-	 */
-	osfildef *osfoprb(const char *fname, uint typ = 0);
-
-	/**
-	 * Receive notification that a character mapping file has been loaded.  We
-	 * don't need to do anything with this information, since we we're relying
-	 * on the Glk layer and ScummVM backend to handle all that
-	 */
-	void os_advise_load_charmap(const char *id, const char *ldesc, const char *sysinfo) {
-		// No implementation needed
-	}
-
-	/**
-	 * Generate a filename for a character mapping table.  On Windows, the
-	 * filename is always simply "win" plus the internal ID plus ".tcp".
-	 */
-	void os_gen_charmap_filename(char *filename, const char *internal_id,
-		const char *argv0);
-
-	/**@}*/
-
-	/**
-	 * \defgroup The main text area print routines
-	 * @{
-	 */
-
-	/**
-	 * Process hilighting codes while printing a string
-	 */
-	void oss_put_string_with_hilite(winid_t win, const char *str, size_t len);
-
-	/**
-	 * Status line handling
-	 */
-	void oss_draw_status_line();
-
-	void oss_change_status_string(char *dest, const char *src, size_t len);
-	void oss_change_status_left(const char *str, size_t len);
-	void oss_change_status_right(const char *str);
-	int os_get_status() const { return status_mode; }
-
-	/**
-	 * Flush the output
-	 */
-	void os_flush();
-
-	/**
-	 * Print a null terminated string
-	 */
-	void os_printz(const char *str) { os_print(str, strlen(str)); }
-
-	/**
-	 * Print a string
-	 */
-	void os_print(const char *str, size_t len);
-
-	/**@}*/
-
-	/**
-	 * \defgroup Memory routines
-	 * @{
-	 */
-
-	/**
-	 * Compare two strings
-	 */
-	int memicmp(const char *s1, const char *s2, int len);
-
-	/**@}*/
-
-	/**
-	 * \defgroup Input routines
-	 * @{
-	 */
-
-	/**
-	 * Wait for a key to be hit
-	 */
-	void os_waitc(void) { os_getc(); }
-
-	/**
-	 * Get a character from the keyboard. For extended characters, return 0,
-	 * then return the extended key at the next call to this function
-	 */
-	int os_getc() {
-		return oss_getc_from_window(story_win);
-	}
-
-	/**
-	 * Accept a keystroke in the passed window
-	 */
-	int oss_getc_from_window(winid_t win);
-
-
-	/**
-	 * Print a message (with os_print) and wait for a key
-	 */
-	void os_expause();
-
-	/**@}*/
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   A note on character sets:
+ *   
+ *   Except where noted, all character strings passed to and from the
+ *   osxxx functions defined herein use the local operating system
+ *   representation.  On a Windows machine localized to Eastern Europe,
+ *   for example, the character strings passed to and from the osxxx
+ *   functions would use single-byte characters in the Windows code page
+ *   1250 representation.
+ *   
+ *   Callers that use multiple character sets must implement mappings to
+ *   and from the local character set when calling the osxxx functions.
+ *   The osxxx implementations are thus free to ignore any issues related
+ *   to character set conversion or mapping.
+ *   
+ *   The osxxx implementations are specifically not permitted to use
+ *   double-byte Unicode as the native character set, nor any other
+ *   character set where a null byte could appear as part of a non-null
+ *   character.  In particular, callers may assume that null-terminated
+ *   strings passed to and from the osxxx functions contain no embedded
+ *   null bytes.  Multi-byte character sets (i.e., character sets with
+ *   mixed single-byte and double-byte characters) may be used as long as
+ *   a null byte is never part of any multi-byte character, since this
+ *   would guarantee that a null byte could always be taken as a null
+ *   character without knowledge of the encoding or context.  
+ */
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   "Far" Pointers.  Most platforms can ignore this.  For platforms with
+ *   mixed-mode addressing models, where pointers of different sizes can
+ *   be used within a single program and hence some pointers require
+ *   qualification to indicate that they use a non-default addressing
+ *   model, the keyword OSFAR should be defined to the appropriate
+ *   compiler-specific extension keyword.
+ *   
+ *   If you don't know what I'm talking about here, you should just ignore
+ *   it, because your platform probably doesn't have anything this
+ *   sinister.  As of this writing, this applies only to MS-DOS, and then
+ *   only to 16-bit implementations that must interact with other 16-bit
+ *   programs via dynamic linking or other mechanisms.  
+ */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   ANSI C99 exact-size integer types.
+ *   
+ *   C99 defines a set of integer types with exact bit sizes, named intXX_t
+ *   for a signed integer with XX bits, and uintXX_t for unsigned.  XX can be
+ *   8, 16, 32, or 64.  TADS uses the 16- and 32-bit sizes, so each platform
+ *   is responsible for defining the following types:
+ *   
+ *.    int16_t   - a signed integer type storing EXACTLY 16 bits
+ *.    uint16_t  - an unsigned integer type storing EXACTLY 16 bits
+ *.    int32_t   - a signed integer type storing EXACTLY 32 bits
+ *.    uint32_t  - an unsigned integer type storing EXACTLY 32 bits
+ *   
+ *   Many modern compilers provide definitions for these types via the
+ *   standard header stdint.h.  Where stdint.h is provided, the platform code
+ *   can merely #include <stdint.h>.
+ *   
+ *   For compilers where stdint.h isn't available, you must provide suitable
+ *   typedefs.  Note that the types must be defined with the exact bit sizes
+ *   specified; it's not sufficient to use a bigger type, because we depend
+ *   in some cases on overflow and sign extension behavior at the specific
+ *   bit size.
+ */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Thread-local storage (TLS).
+ *   
+ *   When TADS is compiled with threading support, it requires some variables
+ *   to be "thread-local".  This means that the variables have global scope
+ *   (so they're not stored in "auto" variables on the stack), but each
+ *   thread has a private copy of each such variable.
+ *   
+ *   Nearly all systems that support threads also support thread-local
+ *   storage.  Like threading support itself, though, TLS support is at
+ *   present implemented only in non-portable OS APIs rather than standard C
+ *   language features.  TLS is a requirement if TADS is compiled with
+ *   threading, but it's not needed for non-threaded builds.  TADS only
+ *   requires threading at present (version 3.1) for its network features;
+ *   since these features are optional, systems that don't have threading and
+ *   TLS support will simply need to disable the network features, which will
+ *   allow all of the threading and TLS definitions in osifc to be omitted.
+ *   
+ *   There appear to be two common styles of TLS programming models.  The
+ *   first provides non-standard compiler syntax for declarative creation of
+ *   thread-local variables.  The Microsoft (on Windows) and Gnu compilers
+ *   (on Linux and Unix) do this: they provide custom storage class modifiers
+ *   for declaring thread locals (__declspec(thread) for MSVC, __thread for
+ *   gcc).  Compilers that support declarative thread locals handle the
+ *   implementation details through code generation, so the program merely
+ *   needs to add the special TLS storage class qualifier to an otherwise
+ *   ordinary global variable declaration, and then can access the thread
+ *   local as though it were an ordinary global.
+ *   
+ *   The second programming model is via explicit OS API calls to create,
+ *   initialize, and access thread locals.  pthreads provides such an API, as
+ *   does Win32.  In fact, when you use the declarative syntax with MSVC or
+ *   gcc, the compiler generates the appropriate API calls, but the details
+ *   are transparent to the program; in contrast, when using pthreads
+ *   directly, the program must actively call the relevant APIs.
+ *   
+ *   It's probably the case that every system that has compiler-level support
+ *   for declarative thread local creation also has procedural APIs, so the
+ *   simplest way to abstract the platform differences would be to do
+ *   everything in terms of APIs.  However, it seems likely that compilers
+ *   with declarative syntax might be able to generate more efficient code,
+ *   since optimizers always benefit from declarative information.  So we'd
+ *   like to use declarative syntax whenever it's available, but fall back on
+ *   explicit API calls when it's not.  So our programming model is a union
+ *   of the two styles:
+ *   
+ *   1. For each thread local, declare the thread local:
+ *.      OS_DECL_TLS(char *, my_local);
+ *   
+ *   2. At main program startup (for the main thread only), initialize each
+ *   thread local:
+ *.      os_tls_create(my_local);
+ *   
+ *   3. Never get or set the value of a thread local directly; instead, use
+ *   the get/set functions:
+ *.      char *x = os_tls_get(char *, my_local);
+ *.      os_tls_set(my_local, "hello");
+ *   
+ *   One key feature of this implementation is that each thread local is
+ *   stored as a (void *) value.  We do it this way to allow a simple direct
+ *   mapping to the pthreads APIs, since that's going to be the most common
+ *   non-declarative implementation.  This means that a thread local variable
+ *   can contain any pointer type, but *only* a pointer type.  The standard
+ *   pattern for dealing with anything more ocmplex is the same as in
+ *   pthreads: gather up the data into a structure, malloc() an instance of
+ *   that structure at entry to each thread (including the main thread), and
+ *   os_tls_set() the variable to contain a pointer to that structure.  From
+ *   then on, use os_tls_set(my_struct *, my_local)->member to access the
+ *   member variables in the structure.  And finally, each thread must delete
+ *   the structure at thread exit.
+ */
+
+/*   
+ *   
+ *   Declare a thread local.
+ *   
+ *   - For compilers that support declarative TLS variables, the local OS
+ *   headers should use the compiler support by #defining OS_DECL_TLS to the
+ *   appropriate local declarative keyword.
+ *   
+ *   - For systems without declarative TLS support but with TLS APIs, the
+ *   global declared by this macro actually stores the slot ID (what pthreads
+ *   calls the "key") for the variable.  This macro should therefore expand
+ *   to a declaration of the appropriate API type for a slot ID; for example,
+ *   on pthreads, #define OS_DECL_TLS(t, v) pthread_key_t v.
+ *   
+ *   - For builds with no thread support, simply #define this to declare the
+ *   variable as an ordinary global: #define OS_DECL_TLS(t, v) t v.
+ */
+/* #define OS_DECL_TLS(typ, varname)  __thread typ varname */
+
+/*
+ *   For API-based systems without declarative support in the compiler, the
+ *   main program startup code must explicitly create a slot for each thread-
+ *   local variable by calling os_tls_create().  The API returns a slot ID,
+ *   which is shared among threads and therefore can be stored in an ordinary
+ *   global variable.  OS_DECL_TLS will have declared the global variable
+ *   name in this case as an ordinary global of the slot ID type.  The
+ *   os_tls_create() macro should therefore expand to a call to the slot
+ *   creation API, storing the new slot ID in the global.
+ *   
+ *   Correspondingly, before the main thread exits, it should delete each
+ *   slot it created, b calling os_tls_delete().
+ *   
+ *   For declarative systems, there's no action required here, so these
+ *   macros can be defined to empty.
+ */
+/* #define os_tls_create(varname)  pthread_key_create(&varname, NULL) */
+/* #define os_tls_delete(varname)  pthread_key_delete(varname) */
+
+
+/*
+ *   On API-based systems, each access to get or set the thread local
+ *   requires an API call, using the slot ID stored in the actual global to
+ *   get the per-thread instance of the variable's storage.
+ *.    #define os_tls_get(typ, varname) ((typ)pthread_getspecific(varname))
+ *.    #define os_tls_set(varname, val) pthread_setspecific(varname, val)
+ *   
+ *   On declarative systems, the global variable itself is the thread local,
+ *   so get/set can be implemented as direct access to the variable.
+ *.    #define os_tls_get(typ, varname) varname
+ *.    #define os_tls_set(varname, val) varname = (val)
+ */
+
+/*
+ *   Common TLS definitions - declarative thread locals
+ *   
+ *   For systems with declarative TLS support in the compiler, the OS header
+ *   can #define OS_DECLARATIVE_TLS to pick up suitable definitions for the
+ *   os_tls_xxx() macros.  The OS header must separately define OS_DECL_TLS
+ *   as appropriate for the local system.
+ */
+#ifdef OS_DECLARATIVE_TLS
+#define os_tls_create(varname)
+#define os_tls_delete(varname)
+#define os_tls_get(typ, varname) varname
+#define os_tls_set(varname, val) varname = (val)
+#endif
+
+/*
+ *   Common TLS definitions - pthreads
+ *   
+ *   For pthreads systems without declarative TLS support in the compiler,
+ *   the OS header can simply #define OS_PTHREAD_TLS to pick up the standard
+ *   definitions below. 
+ */
+#ifdef OS_PTHREAD_TLS
+#include <pthread.h>
+#define OS_DECL_TLS(typ, varname) pthread_key_t varname
+#define os_tls_create(varname) pthread_key_create(&varname, NULL)
+#define os_tls_delete(varname) pthread_key_delete(varname)
+#define os_tls_get(typ, varname) ((typ)pthread_getspecific(varname))
+#define os_tls_set(varname, val) pthread_setspecific(varname, val)
+#endif
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   <time.h> definitions.
+ *   
+ *   os_time() should act like Unix time(), returning the number of seconds
+ *   elapsed since January 1, 1970 at midnight UTC.
+ *   
+ *   The original Unix <time.h> package defined time_t as a 32-bit signed
+ *   int, and many subsequent C compilers on other platforms followed suit.
+ *   A signed 32-bit time_t has the well-known year-2038 problem; some later
+ *   C compilers tried to improve matters by using an unsigned 32-bit time_t
+ *   instead, but for many purposes this is even worse since it can't
+ *   represent any date before 1/1/1970.  *Most* modern compilers solve the
+ *   problem once and for all (for 300 billion years in either direction of
+ *   1/1/1970, anyway - enough to represent literally all of eternity in most
+ *   current cosmological models) by defining time_t as a signed 64-bit int.
+ *   But some compilers stubbornly stick to the old 32-bit time_t even in
+ *   newer versions, for the sake of compatibility with older code that might
+ *   be lax about mixing time_t's with ordinary int's.  E.g., MSVC2003 does
+ *   this.  Fortunately, some of these compilers (such as MSVC2003 again)
+ *   also define a parallel, transitional set of 64-bit time functions that
+ *   you can use by replacing all references to the standard time_t and
+ *   related names with the corresponding 64-bit names.
+ *   
+ *   We'd really like to use a 64-bit time_t wherever we can - the TADS
+ *   release cycle can be a bit slow, and we don't want 2038 to sneak up on
+ *   us and catch us unawares.  So for those compilers that offer a choice of
+ *   32 or 64 bits, we'd like to select the 64 bit version.  To facilitate
+ *   this, we define covers here for the time.h types and functions that we
+ *   use.  On platforms where the regular time_t is already 64 bits, or where
+ *   there's no 64-bit option at all, you can simply do nothing - the
+ *   defaults defined here use the standard time_t typedef and functions, so
+ *   that's what you'll get if you don't define these in the OS-specific
+ *   headers for your platform.  For compilers that provide both a 32-bit
+ *   time_t and a 64-bit other_time_t, the OS headers should #define these
+ *   macros in terms of those compiler-specific 64-bit names.
+ */
+#ifndef os_time_t
+# define os_time_t        TimeDate
+# define os_gmtime(t)     gmtime(t)
+# define os_localtime(t)  localtime(t)
+# define os_time(t)       time(t)
+#endif
+
+/*
+ *   Initialize the time zone.  This routine is meant to take care of any
+ *   work that needs to be done prior to calling localtime() and other
+ *   time-zone-dependent routines in the run-time library.  For DOS and
+ *   Windows, we need to call the run-time library routine tzset() to set up
+ *   the time zone from the environment; most systems shouldn't need to do
+ *   anything in this routine.  It's sufficient to call this once during the
+ *   process lifetime, since it's meant to perform static initialization that
+ *   lasts as long as the process is running.
+ */
+#ifndef os_tzset
+void os_tzset(void);
+#endif
+
+/*
+ *   Higher-precision time.  This retrieves the same time information as
+ *   os_time() (i.e., the elapsed time since the standard Unix Epoch, January
+ *   1, 1970 at midnight UTC), but retrieves it with the highest precision
+ *   available on the local system, up to nanosecond precision.  If less
+ *   precision is available, that's fine; just return the time to the best
+ *   precision available, but expressed in terms of the number of
+ *   nanoseconds.  For example, if you can retrieve milliseconds, you can
+ *   convert that to nanoseconds by multiplying by 1,000,000.
+ *   
+ *   On return, fills in '*seconds' with the number of whole seconds since
+ *   the Epoch, and fills in '*nanoseconds' with the fractional portion,
+ *   expressed in nanosceconds.  Note that '*nanoseconds' is merely the
+ *   fractional portion of the time, so 0 <= *nanoseconds < 1000000000.
+ */
+void os_time_ns(os_time_t *seconds, long *nanoseconds);
+
+/*
+ *   Get the local time zone name, as a location name in the IANA zoneinfo
+ *   database.  For example, locations using US Pacific Time should return
+ *   "America/Los_Angeles".
+ *   
+ *   Returns true if successful, false if not.  If the local operating system
+ *   doesn't have a way to obtain this information, or if it's not available
+ *   in the local machine's configuration, this returns false.
+ *   
+ *   The zoneinfo database is also known as the Olson or TZ (timezone)
+ *   database; it's widely used on Unix systems as the definitive source of
+ *   local time zone settings.  See http://www.iana.org/time-zones for more
+ *   information.
+ *   
+ *   On many Unix systems, the TZ environment variable contains the zoneinfo
+ *   zone name when its first character is ':'.  Windows uses a proprietary
+ *   list of time zone names that can be mapped to zoneinfo names via a
+ *   hand-coded list (such a list is maintained in the Unicode CLDR; our
+ *   Windows implementation uses the CLDR list to generate the mapping).
+ *   MacOS X uses zoneinfo keys directly; /etc/localtime is a link to the
+ *   zoneinfo file for the local zone as set via the system preferences.
+ *   
+ *   os_tzset() must be invoked at some point before this routine is called.
+ */
+int os_get_zoneinfo_key(char *buf, size_t buflen);
+
+/*
+ *   Get a description of the local time zone.  Fills in '*info' with the
+ *   available information.  Returns true on success, false on failure.
+ *   
+ *   See osstzprs.h/.c for a portable implementation of a parser for
+ *   POSIX-style TZ strings.  That can serve as a full implementation of this
+ *   function for systems that use the POSIX TZ environment variable syntax
+ *   to specify the timezone.  (That routine simply parses a string from any
+ *   source, so it can be used to parse the TZ syntax even on systems where
+ *   the string comes from somewhere other than the TZ environment variable.)
+ *   
+ *   os_tzset() must be invoked at some point before this routine is called.
+ *   
+ *   The following two structures are used for the return information:
+ *   
+ *   os_tzrule_t - Timezone Rule structure.  This describes a rule for an
+ *   annual transition between daylight savings time and standard time in a
+ *   time zone.  Most timezones that have recurring standard/daylight changes
+ *   require two of these rules, one for switching to daylight time in the
+ *   spring and one for switching to standard time in the fall.
+ *   
+ *   os_tzinfo_t - Timezone Information structure.  This describes a
+ *   timezone's clock settings, name(s), and rules for recurring annual
+ *   changes between standard time and daylight time, if applicable.
+ */
+struct os_tzrule_t
+{
+    /* 
+     *   Day of year, 1-365, NEVER counting Feb 29; set to 0 if not used.
+     *   Corresponds to the "J" format in Unix TZ strings.  (Called "Julian
+     *   day" in the POSIX docs, thus the "J", even though it's a bit of a
+     *   misnomer.)(Because of the invariance of the mapping from J-number to
+     *   date, this is just an obtuse way of specifying a month/day date.
+     *   But even so, we'll let the OS layer relay this back to us in
+     *   J-number format and count on the portable caller to work out the
+     *   date, rather than foisting that work on each platform
+     *   implementation.)
+     */
+    int jday;
+
+    /*
+     *   Day of year, 1-366, counting Feb 29 on leap years; set to 0 if not
+     *   used; ignored if 'jday' is nonzero.  This corresponds to the Julian
+     *   day sans "J" in TZ strings (almost - that TZ format uses 0-365 as
+     *   its range, so bump it up by one when parsing a TZ string).  This
+     *   format is even more obtuse than the J-day format, in that it doesn't
+     *   even have an invariant month/day mapping (not after day 59, anyway -
+     *   day 60 is either February 29 or March 1, depending on the leapness
+     *   of the year, and every day after that is similarly conditional).  As
+     *   far as I can tell, no one uses this option, so I'm not sure why it
+     *   exists.  The zoneinfo source format doesn't have a way to represent
+     *   it, which says to me that no one has ever used it in a statutory DST
+     *   start/end date definition in the whole history of time zones around
+     *   the world, since the whole history of time zones around the world is
+     *   exactly what the zoneinfo database captures in exhaustive and
+     *   painstaking detail.  If anyone had ever used it in defining a time
+     *   zone, zoneinfo would have an option for it.  My guess is that it's a
+     *   fossilized bug from some early C RTL that's been retained out of an
+     *   abundance of caution vis-a-vis compatibility, and was entirely
+     *   replaced in practice by the J-number format as soon as someone
+     *   noticed the fiddly leap year behavior.  But for the sake of
+     *   completeness...
+     */
+    int yday;
+    
+    /* 
+     *   The month (1-12), week of the month, and day of the week (1-7 for
+     *   Sunday to Saturday).  Week 1 is the first week in which 'day'
+     *   occurs, week 2 is the second, etc.; week 5 is the last occurrence of
+     *   'day' in the month.  These fields are used for "second Sunday in
+     *   March" types of rules.  Set these to zero if they're not used;
+     *   they're ignored in any case if 'jday' or 'yday' are non-zero.
+     */
+    int month;
+    int week;
+    int day;
+
+    /* time of day, in seconds after midnight (e.g., 2AM is 120 == 2*60*60) */
+    int time;
+};
+struct os_tzinfo_t
+{
+    /*
+     *   The local offset from GMT, in seconds, for standard time and
+     *   daylight time in this zone.  These values are positive for zones
+     *   east of GMT and negative for zones west: New York standard time
+     *   (EST) is 5 hours west of GMT, so its offset is -5*60*60.
+     *   
+     *   Set both of these fields (if possible) regardless of whether
+     *   standard or daylight time is currently in effect in the zone.  The
+     *   caller will select which offset to use based on the start/end rules,
+     *   or based on the 'is_dst' flag if no rules are available.
+     *   
+     *   If it's only possible to determine the current wall clock offset, be
+     *   it standard or daylight time, and it's not possible to determine the
+     *   time difference between the two, simply set both of these to the
+     *   current offset.  This information isn't available from the standard
+     *   C library, and many OS APIs also lack it.  
+     */
+    int32_t std_ofs;
+    int32_t dst_ofs;
+
+    /*
+     *   The abbreviations for the local zone's standard time and daylight
+     *   time, respectively, when displaying date/time values.  E.g., "EST"
+     *   and "EDT" for US Eastern Time.  If the zone doesn't observe daylight
+     *   time (it's on standard time year round), set dst_abbr to an empty
+     *   string.
+     *   
+     *   As with std_ofs and dst_ofs, you can set both of these to the same
+     *   string if it's only possible to determine the one that's currently
+     *   in effect.
+     */
+    char std_abbr[16];
+    char dst_abbr[16];
+
+    /*
+     *   The ongoing rules for switching between daylight and standard time
+     *   in this zone, if available.  'dst_start' is the date when daylight
+     *   savings starts, 'dst_end' is the date when standard time resumes.
+     *   Set all fields to 0 if the start/stop dates aren't available, or the
+     *   zone is on standard time year round.
+     */
+    struct os_tzrule_t dst_start;
+    struct os_tzrule_t dst_end;
+
+    /* 
+     *   True -> the zone is CURRENTLY on daylight savings time; false means
+     *   it's currently on standard time.
+     *   
+     *   This is only used if the start/end rules aren't specified.  In the
+     *   absence of start/end rules, there's no way to know when the current
+     *   standard/daylight phase ends, so we'll have to assume that the
+     *   current mode is in effect permanently.  In this case, the caller
+     *   will use only be able to use the offset and abbreviation for the
+     *   current mode and will have to ignore the other one.
+     */
+    int is_dst;
 };
+int os_get_timezone_info(struct os_tzinfo_t *info);
+
+
+/*
+ *   Get the current system high-precision timer.  This function returns a
+ *   value giving the wall-clock ("real") time in milliseconds, relative to
+ *   any arbitrary zero point.  It doesn't matter what this value is relative
+ *   to -- the only important thing is that the values returned by two
+ *   different calls should differ by the number of actual milliseconds that
+ *   have elapsed between the two calls.  This might be the number of
+ *   milliseconds since the computer was booted, since the current user
+ *   logged in, since midnight of the previous night, since the program
+ *   started running, since 1-1-1970, etc - it doesn't matter what the epoch
+ *   is, so the implementation can use whatever's convenient on the local
+ *   system.
+ *   
+ *   True millisecond precision isn't required.  Each implementation should
+ *   simply use the best precision available on the system.  If your system
+ *   doesn't have any kind of high-precision clock, you can simply use the
+ *   time() function and multiply the result by 1000 (but see the note below
+ *   about exceeding 32-bit precision).
+ *   
+ *   However, it *is* required that the return value be in *units* of
+ *   milliseconds, even if your system clock doesn't have that much
+ *   precision; so on a system that uses its own internal clock units, this
+ *   routine must multiply the clock units by the appropriate factor to yield
+ *   milliseconds for the return value.
+ *   
+ *   It is also required that the values returned by this function be
+ *   monotonically increasing.  In other words, each subsequent call must
+ *   return a value that is equal to or greater than the value returned from
+ *   the last call.  On some systems, you must be careful of two special
+ *   situations.
+ *   
+ *   First, the system clock may "roll over" to zero at some point; for
+ *   example, on some systems, the internal clock is reset to zero at
+ *   midnight every night.  If this happens, you should make sure that you
+ *   apply a bias after a roll-over to make sure that the value returned from
+ *   this return continues to increase despite the reset of the system clock.
+ *   
+ *   Second, a 32-bit signed number can only hold about twenty-three days
+ *   worth of milliseconds.  While it seems unlikely that a TADS game would
+ *   run for 23 days without a break, it's certainly reasonable to expect
+ *   that the computer itself may run this long without being rebooted.  So,
+ *   if your system uses some large type (a 64-bit number, for example) for
+ *   its high-precision timer, you may want to store a zero point the very
+ *   first time this function is called, and then always subtract this zero
+ *   point from the large value returned by the system clock.  If you're
+ *   using time(0)*1000, you should use this technique, since the result of
+ *   time(0)*1000 will almost certainly not fit in 32 bits in most cases.  
+ */
+long os_get_sys_clock_ms(void);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Hardware Configuration.  Define the following functions appropriately
+ *   for your hardware.  For efficiency, these functions should be defined
+ *   as macros if possible.
+ *   
+ *   Note that these hardware definitions are independent of the OS, at
+ *   least to the extent that your OS can run on multiple types of
+ *   hardware.  So, rather than combining these definitions into your
+ *   osxxx.h header file, we recommend that you put these definitions in a
+ *   separate h_yyy.h header file, which can be configured into os.h with
+ *   an appropriate "_M_yyy" preprocessor symbol.  Refer to os.h for
+ *   details of configuring the hardware include file.  
+ */
+
+/* 
+ *   Round a size up to worst-case alignment boundary.  For example, on a
+ *   platform where the largest type must be aligned on a 4-byte boundary,
+ *   this should round the value up to the next higher mutliple of 4 and
+ *   return the result.  
+ */
+/* size_t osrndsz(size_t siz); */
+
+/* 
+ *   Round a pointer up to worst-case alignment boundary. 
+ */
+/* void *osrndpt(void *ptr); */
+
+/* 
+ *   Read an unaligned portable unsigned 2-byte value, returning an int
+ *   value.  The portable representation has the least significant byte
+ *   first, so the value 0x1234 is represented as the byte 0x34, followed
+ *   by the byte 0x12.
+ *   
+ *   The source value must be treated as unsigned, but the result is
+ *   signed.  This is significant on 32- and 64-bit platforms, because it
+ *   means that the source value should never be sign-extended to 32-bits.
+ *   For example, if the source value is 0xffff, the result is 65535, not
+ *   -1.  
+ */
+/* int osrp2(unsigned char *p); */
+
+/* 
+ *   Read an unaligned portable signed 2-byte value, returning int.  This
+ *   differs from osrp2() in that this function treats the source value as
+ *   signed, and returns a signed result; hence, on 32- and 64-bit
+ *   platforms, the result must be sign-extended to the int size.  For
+ *   example, if the source value is 0xffff, the result is -1.  
+ */
+/* int osrp2s(unsigned char *p); */
+
+/* 
+ *   Write unsigned int to unaligned portable 2-byte value.  The portable
+ *   representation stores the low-order byte first in memory, so
+ *   oswp2(0x1234) should result in storing a byte value 0x34 in the first
+ *   byte, and 0x12 in the second byte.  
+ */
+/* void oswp2(unsigned char *p, unsigned int i); */
+
+/*
+ *   Write signed int to unaligned portable 2-byte value.  Negative values
+ *   must be stored in two's complement notation.  E.g., -1 is stored as
+ *   FF.FF, -32768 is stored as 00.80 (little-endian).  
+ *   
+ *   Virtually all modern hardware uses two's complement notation as the
+ *   native representation, which makes this routine a trivial synonym of
+ *   osrp2() (i.e., #define oswp2s(p,i) oswp2(p,i)).  We distinguish the
+ *   signed version on the extremely off chance that TADS is ever ported to
+ *   wacky hardware with a different representation for negative integers
+ *   (one's complement, sign bit, etc).  
+ */
+/* void oswp2s(unsigned char *p, int i); */
+
+/* 
+ *   Read an unaligned unsigned portable 4-byte value, returning long.  The
+ *   underlying value should be considered signed, and the result is signed.
+ *   The portable representation stores the bytes starting with the least
+ *   significant: the value 0x12345678 is stored with 0x78 in the first byte,
+ *   0x56 in the second byte, 0x34 in the third byte, and 0x12 in the fourth
+ *   byte.
+ */
+/* unsigned long osrp4(unsigned char *p); */
+
+/*
+ *   Read an unaligned signed portable 4-byte value, returning long. 
+ */
+/* long osrp4s(unsigned char *p); */
+
+/* 
+ *   Write an unsigned long to an unaligned portable 4-byte value.  The
+ *   portable representation stores the low-order byte first in memory, so
+ *   0x12345678 is written to memory as 0x78, 0x56, 0x34, 0x12.  
+ */
+/* void oswp4(unsigned char *p, unsigned long l); */
+
+/*
+ *   Write a signed long, using little-endian byte order and two's complement
+ *   notation for negative numbers.  This is a trivial synonym for oswp4()
+ *   for all platforms with native two's complement arithmetic (which is
+ *   virtually all modern platforms).  See oswp2s() for more discussion.
+ */
+/* void oswp4s(unsigned char *p, long l); */
+
+/*
+ *   For convenience and readability, the 1-byte integer (signed and
+ *   unsigned) equivalents of the above.
+ */
+#define osrp1(p) (*(unsigned char *)(p))
+#define osrp1s(p) (*(signed char *)(p))
+#define oswp1(p, b) (*(unsigned char *)(p) = (b))
+#define oswp1s(p, b) (*(signed char *)(p) = (b))
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   varargs va_copy() extension.
+ *   
+ *   On some compilers, va_list is a reference type.  This means that if a
+ *   va_list value is passed to a function that uses va_arg() to step through
+ *   the referenced arguments, the caller's copy of the va_list might be
+ *   updated on return.  This is problematic in cases where the caller needs
+ *   to use the va_list again in another function call, since the va_list is
+ *   no longer pointing to the first argument for the second call.  C99 has a
+ *   solution in the form of the va_copy() macro.  Unfortunately, this isn't
+ *   typically available in pre-C99 compilers, and isn't standard in *any*
+ *   C++ version.  We thus virtualize it here in a macro.
+ *   
+ *   os_va_copy() has identical semantics to C99 va_copy().  A matching call
+ *   to os_va_copy_end() must be made for each call to os_va_copy() before
+ *   the calling function returns; this has identical semantics to C99
+ *   va_end().
+ *   
+ *   Because our semantics are identical to the C99 version, we provide a
+ *   default definition here for compilers that define va_copy().  Platform
+ *   headers must provide suitable definitions only if their compilers don't
+ *   have va_copy().  We also provide a definition for GCC compilers that
+ *   define the private __va_copy macro, which also has the same semantics.
+ */
+#ifdef va_copy
+# define os_va_copy(dst, src) va_copy(dst, src)
+# define os_va_copy_end(dst)  va_end(dst)
+#else
+# if defined(__GNUC__) && defined(__va_copy)
+#  define os_va_copy(dst, src) __va_copy(dst, src)
+#  define os_va_copy_end(dst)  va_end(dst)
+# endif
+#endif
+
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Platform Identifiers.  You must define the following macros in your
+ *   osxxx.h header file:
+ *   
+ *   OS_SYSTEM_NAME - a string giving the system identifier.  This string
+ *   must contain only characters that are valid in a TADS identifier:
+ *   letters, numbers, and underscores; and must start with a letter or
+ *   underscore.  For example, on MS-DOS, this string is "MSDOS".
+ *   
+ *   OS_SYSTEM_LDESC - a string giving the system descriptive name.  This
+ *   is used in messages displayed to the user.  For example, on MS-DOS,
+ *   this string is "MS-DOS".  
+ */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Message Linking Configuration.  You should #define ERR_LINK_MESSAGES
+ *   in your osxxx.h header file if you want error messages linked into
+ *   the application.  Leave this symbol undefined if you want an external
+ *   message file. 
+ */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Program Exit Codes.  These values are used for the argument to exit()
+ *   to conform to local conventions.  Define the following values in your
+ *   OS-specific header:
+ *   
+ *   OSEXSUCC - successful completion.  Usually defined to 0.
+ *.  OSEXFAIL - failure.  Usually defined to 1.  
+ */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Basic memory management interface.  These functions are merely
+ *   documented here, but no prototypes are defined, because most
+ *   platforms #define macros for these functions and types, mapping them
+ *   to malloc or other system interfaces.  
+ */
+
+/*
+ *   Theoretical maximum osmalloc() size.  This may be less than the
+ *   capacity of the argument to osmalloc() on some systems.  For example,
+ *   on segmented architectures (such as 16-bit x86), memory is divided into
+ *   segments, so a single memory allocation can allocate only a subset of
+ *   the total addressable memory in the system.  This value thus specifies
+ *   the maximum amount of memory that can be allocated in one chunk.
+ *   
+ *   Note that this is an architectural maximum for the hardware and
+ *   operating system.  It doesn't have anything to do with the total amount
+ *   of memory actually available at run-time.
+ *   
+ *   #define OSMALMAX to a constant long value with theoretical maximum
+ *   osmalloc() argument value.  For a platform with a flat (unsegmented)
+ *   32-bit memory space, this is usually 0xffffffff; for 16-bit platforms,
+ *   this is usually 0xffff.  
+ */
+/* #define OSMALMAX 0xffffffff */
+
+/*   
+ *   Allocate a block of memory of the given size in bytes.  The actual
+ *   allocation may be larger, but may be no smaller.  The block returned
+ *   should be worst-case aligned (i.e., suitably aligned for any type).
+ *   Return null if the given amount of memory is not available.  
+ */
+/* void *osmalloc(size_t siz); */
+
+/*
+ *   Free memory previously allocated with osmalloc().  
+ */
+/* void osfree(void *block); */
+
+/* 
+ *   Reallocate memory previously allocated with osmalloc() or
+ *   osrealloc(), changing the block's size to the given number of bytes.
+ *   If necessary, a new block at a different address can be allocated, in
+ *   which case the data from the original block is copied (the lesser of
+ *   the old block size and the new size is copied) to the new block, and
+ *   the original block is freed.  If the new size is less than the old
+ *   size, this need not do anything at all, since the returned block can
+ *   be larger than the new requested size.  If the block cannot be
+ *   enlarged to the requested size, return null.  
+ */
+/* void *osrealloc(void *block, size_t siz); */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Basic file I/O interface.  These functions are merely documented here,
+ *   but no prototypes are defined, because most platforms #define macros for
+ *   these functions and types, mapping them to stdio or other system I/O
+ *   interfaces.  
+ *   
+ *   When writing a file, writes might or might not be buffered in
+ *   application memory; this is up to the OS implementation, which can
+ *   perform buffering according to local conventions and what's most
+ *   efficient.  However, it shouldn't make any difference to the caller
+ *   whether writes are buffered or not - the OS implementation must take
+ *   care that any buffering is invisible to the app.  (Porters: note that
+ *   the basic C stdio package has the proper behavior here, so you'll get
+ *   the correct semantics if you use a simple stdio implementation.)
+ *   
+ *   Write buffering might be visible to *other* apps, though.  In
+ *   particular, another process might not see data written to a file (with
+ *   osfwb(), os_fprint(), etc) immediately, since the write functions might
+ *   hold the written bytes in an internal memory buffer rather than sending
+ *   them to the OS.  Any internal buffers are guaranteed to be flushed to
+ *   the OS upon calling osfcls() or osfflush().  Note that it's never
+ *   *necessary* to call osfflush(), because buffered data will always be
+ *   flushed on closing the file with osfcls().  However, if you want other
+ *   apps to be able to see updates immediately, you can use osfflush() to
+ *   ensure that buffers are flushed to a file before you close it.
+ *   
+ *   You can also use osfflush() to check for buffered write errors.  When
+ *   you use osfwb() or other write functions to write data, they will return
+ *   a success indication even if the data was only copied into a buffer.
+ *   This means that a write that appeared to succeed might actually fail
+ *   later, when the buffer is flushed.  The only way to know for sure is to
+ *   explicitly flush buffers using osfflush(), and check the result code.
+ *   If the original write function and a subsequent osfflush() *both* return
+ *   success indications, then the write has definitely succeeded.  
+ */
+
+
+/*
+ *   Define the following values in your OS header to indicate local
+ *   file/path syntax conventions:
+ *   
+ *   OSFNMAX - integer indicating maximum length of a filename
+ *   
+ *   OSPATHCHAR - character giving the normal path separator character
+ *.  OSPATHALT - string giving other path separator characters
+ *.  OSPATHURL - string giving path separator characters for URL conversions
+ *.  OSPATHSEP - directory separator for PATH-style environment variables
+ *.  OSPATHPWD - string giving the special path representing the current
+ *.              working directory; for Unix or Windows, this is "."
+ *   
+ *   OSPATHURL is a little different: this specifies the characters that
+ *   should be converted to URL-style separators when converting a path from
+ *   local notation to URL notation.  This is usually the same as the union
+ *   of OSPATHCHAR and OSPATHALT, but need not be; for example, on DOS, the
+ *   colon (':') is a path separator for most purposes, but is NOT a path
+ *   character for URL conversions.
+ */
+
+/*
+ *   Define the type osfildef as the appropriate file handle structure for
+ *   your osfxxx functions.  This type is always used as a pointer, but
+ *   the value is always obtained from an osfopxxx call, and is never
+ *   synthesized by portable code, so you can use essentially any type
+ *   here that you want.
+ *   
+ *   For platforms that use C stdio functions to implement the osfxxx
+ *   functions, osfildef can simply be defined as FILE.
+ */
+/* typedef FILE osfildef; */
+
+
+/*
+ *   File types.
+ *   
+ *   These are symbols of the form OSFTxxxx defining various content types,
+ *   somewhat aking to MIME types.  These were mainly designed for the old
+ *   Mac OS (versions up to OS 9), where the file system stored a type tag
+ *   with each file's metadata.  The type tags were used for things like
+ *   filtering file selector dialogs and setting file-to-app associations in
+ *   the desktop shell.
+ *   
+ *   Our OSFTxxx symbols are abstract file types that we define, for types
+ *   used within the TADS family of applications.  They give us a common,
+ *   cross-platform reference point for each type we use.  Each port where
+ *   file types are meaningful then maps our abstract type IDs to the
+ *   corresponding port-specific type IDs.  In practice, this has never been
+ *   used anywhere other than the old Mac OS ports; in fact, it's not even
+ *   used in the modern Mac OS (OS X and later), since Apple decided to stop
+ *   fighting the tide and start using filename suffixes for this sort of
+ *   tagging, like everyone else always has.
+ *   
+ *   For the list of file types, see osifctyp.h 
+ */
+
+
+/*
+ *   Local newline convention.
+ *   
+ *   Because of the pernicious NIH ("Not Invented Here") cultures of the
+ *   major technology vendors, basically every platform out there has its own
+ *   unique way of expressing newlines in text files.  Unix uses LF (ASCII
+ *   10); Mac uses CR (ASCII 13); DOS and Windows use CR-LF pairs.  In the
+ *   past there were heaven-only-knows how many other conventions in use, but
+ *   fortunately these three have the market pretty well locked up at this
+ *   point.  But we do still have to worry about these three.
+ *   
+ *   Our strategy on input is to be open to just about anything whenever
+ *   possible.  So, when we're reading something that we believe to be a text
+ *   file, we'll treat all of these as line endings: CR, LF, CR-LF, and
+ *   LF-CR.  It's pretty safe to do this; if we have a CR and LF occurring
+ *   adjacently, it's almost certain that they're intended to be taken
+ *   together as a single newline sequence.  Likewise, if there's a lone CR
+ *   or LF, it's rare for it to mean anything other than a newline.
+ *   
+ *   On output, though, we can't be as loose.  The problem is that other
+ *   applications on our big three platforms *don't* tend to aim for the same
+ *   flexibility we do on input: other apps usually expect exactly the local
+ *   conventions on input, and don't always work well if they don't get it.
+ *   So it's important that when we're writing a text file, we write newlines
+ *   in the local convention.  This means that we sometimes need to know what
+ *   the local convention actually is.  That's where this definition comes
+ *   in.
+ *   
+ *   Each port must define OS_NEWLINE_SEQ as an ASCII string giving the local
+ *   newline sequence to write on output.  For example, DOS defines it as
+ *   "\r\n" (CR-LF).  Always define it as a STRING (not a character
+ *   constant), even if it's only one character long.
+ *   
+ *   (Note that some compilers use wacky mappings for \r and \n.  Some older
+ *   Mac compilers, for example, defined \n as CR and \r as LF, because of
+ *   the Mac convention where newline is represented as CR in a text file.
+ *   If there's any such variability on your platform, you can always use the
+ *   octal codes to be unambiguous: \012 for LF and \015 for CR.)  
+ */
+/* #define OS_NEWLINE_SEQ  "\r\n" */
+
+
+
+/* 
+ *   Open text file for reading.  This opens the file with read-only access;
+ *   we're not allowed to write to the file using this handle.  Returns NULL
+ *   on error.
+ *   
+ *   A text file differs from a binary file in that some systems perform
+ *   translations to map between C conventions and local file system
+ *   conventions; for example, on DOS, the stdio library maps the DOS CR-LF
+ *   newline convention to the C-style '\n' newline format.  On many systems
+ *   (Unix, for example), there is no distinction between text and binary
+ *   files.
+ *   
+ *   On systems that support file sharing and locking, this should open the
+ *   file in "shared read" mode - this means that other processes are allowed
+ *   to simultaneously read from the file, but no other processs should be
+ *   allowed to write to the file as long as we have it open.  If another
+ *   process already has the file open with write access, this routine should
+ *   return failure, since we can't take away the write privileges the other
+ *   process already has and thus we can't guarantee that other processes
+ *   won't write to the file while we have it open.  
+ */
+/* osfildef *osfoprt(const char *fname, os_filetype_t typ); */
+
+/*
+ *   Open a text file for "volatile" reading: we open the file with read-only
+ *   access, and we explicitly accept instability in the file's contents due
+ *   to other processes simultaneously writing to the file.  On systems that
+ *   support file sharing and locking, the file should be opened in "deny
+ *   none" mode, meaning that other processes can simultaneously open the
+ *   file for reading and/or writing even while have the file open.  
+ */
+/* osfildef *osfoprtv(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open text file for writing; returns NULL on error.  If the file already
+ *   exists, this truncates the file to zero length, deleting any existing
+ *   contents.
+ */
+/* osfildef *osfopwt(const char *fname, os_filetype_t typ); */
+
+/*
+ *   Open text file for reading and writing, keeping the file's existing
+ *   contents if the file already exists or creating a new file if no such
+ *   file exists.  Returns NULL on error. 
+ */
+/* osfildef *osfoprwt(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open text file for reading/writing.  If the file already exists,
+ *   truncate the existing contents to zero length.  Create a new file if it
+ *   doesn't already exist.  Return null on error.  
+ */
+/* osfildef *osfoprwtt(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open binary file for writing; returns NULL on error.  If the file
+ *   exists, this truncates the existing contents to zero length.
+ */
+/* osfildef *osfopwb(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open source file for reading - use the appropriate text or binary
+ *   mode.  
+ */
+/* osfildef *osfoprs(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open binary file for reading; returns NULL on error.  
+ */
+/* osfildef *osfoprb(const char *fname, os_filetype_t typ); */
+
+/*
+ *   Open binary file for 'volatile' reading; returns NULL on error.
+ *   ("Volatile" means that we'll accept writes from other processes while
+ *   reading, so the file should be opened in "deny none" mode or the
+ *   equivalent, to the extent that the local system supports file sharing
+ *   modes.)  
+ */
+/* osfildef *osfoprbv(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open binary file for random-access reading/writing.  If the file already
+ *   exists, keep the existing contents; if the file doesn't already exist,
+ *   create a new empty file.
+ *   
+ *   The caller is allowed to perform any mixture of read and write
+ *   operations on the returned file handle, and can seek around in the file
+ *   to read and write at random locations.
+ *   
+ *   If the local file system supports file sharing or locking controls, this
+ *   should generally open the file in something equivalent to "exclusive
+ *   write, shared read" mode ("deny write" in DENY terms), so that other
+ *   processes can't modify the file at the same time we're modifying it (but
+ *   it doesn't bother us to have other processes reading from the file while
+ *   we're working on it, as long as they don't mind that we could change
+ *   things on the fly).  It's not absolutely necessary to assert these
+ *   locking semantics, but if there's an option to do so this is preferred.
+ *   Stricter semantics (such as "exclusive" or "deny all" mode) are better
+ *   than less strict semantics.  Less strict semantics are dicey, because in
+ *   that case the caller has no way of knowing that another process could be
+ *   modifying the file at the same time, and no way (through osifc) of
+ *   coordinating that activity.  If less strict semantics are implemented,
+ *   the caller will basically be relying on luck to avoid corruptions due to
+ *   writing by other processes.
+ *   
+ *   Return null on error.  
+ */
+/* osfildef *osfoprwb(const char *fname, os_filetype_t typ); */
+
+/* 
+ *   Open binary file for random-access reading/writing.  If the file already
+ *   exists, truncate the existing contents (i.e., delete the contents of the
+ *   file, resetting it to a zero-length file).  Create a new file if it
+ *   doesn't already exist.  The caller is allowed to perform any mixture of
+ *   read and write operations on the returned handle, and can seek around in
+ *   the file to read and write at random locations.
+ *   
+ *   The same comments regarding sharing/locking modes for osfoprwb() apply
+ *   here as well.
+ *   
+ *   Return null on error.  
+ */
+/* osfildef *osfoprwtb(const char *fname, os_filetype_t typ); */
+
+/*
+ *   Duplicate a file handle.  Returns a new osfildef* handle that accesses
+ *   the same open file as an existing osfildef* handle.  The new handle is
+ *   independent of the original handle, with its own seek position,
+ *   buffering, etc.  The new handle and the original handle must each be
+ *   closed separately when the caller is done with them (closing one doesn't
+ *   close the other).  The effect should be roughly the same as the Unix
+ *   dup() function.
+ *   
+ *   On success, returns a new, non-null osfildef* handle duplicating the
+ *   original handle.  Returns null on failure.
+ *   
+ *   'mode' is a simplified stdio fopen() mode string.  The first
+ *   character(s) indicate the access type: "r" for read access, "w" for
+ *   write access, or "r+" for read/write access.  Note that "w+" mode is
+ *   specifically not defined, since the fopen() handling of "w+" is to
+ *   truncate any existing file contents, which is not desirable when
+ *   duplicating a handle.  The access type can optionally be followed by "t"
+ *   for text mode, "s" for source file mode, or "b" for binary mode, with
+ *   the same meanings as for the various osfop*() functions.  The default is
+ *   't' for text mode if none of these are specified.
+ *   
+ *   If the osfop*() functions are implemented in terms of stdio FILE*
+ *   objects, this can be implemented as fdopen(dup(fileno(orig)), mode), or
+ *   using equivalents if the local stdio library uses different names for
+ *   these functions.  Note that "s" (source file format) isn't a stdio mode,
+ *   so implementations must translate it to the appropriate "t" or "b" mode.
+ *   (For that matter, "t" and "b" modes aren't universally supported either,
+ *   so some implementations may have to translate these, or more likely
+ *   simply remove them, as most platforms don't distinguish text and binary
+ *   modes anyway.)
+ */
+osfildef *osfdup(osfildef *orig, const char *mode);
+
+/* 
+ *   Set a file's type information.  This is primarily for implementations on
+ *   Mac OS 9 and earlier, where the file system keeps file-type metadata
+ *   separate from the filename.  On such systems, this can be used to set
+ *   the type metadata after a file is created.  The system should map the
+ *   os_filetype_t values to the actual metadata values on the local system.
+ *   On most systems, there's no such thing as file-type metadata, in which
+ *   case this function should simply be stubbed out with an empty function.
+ */
+void os_settype(const char *f, os_filetype_t typ);
+
+/* open the error message file for reading */
+osfildef *oserrop(const char *arg0);
+
+/* 
+ *   Get a line of text from a text file.  Uses fgets semantics.  
+ */
+/* char *osfgets(char *buf, size_t len, osfildef *fp); */
+
+/* 
+ *   Write a line of text to a text file.  Uses fputs semantics.  
+ */
+/* void osfputs(const char *buf, osfildef *fp); */
+
+/*
+ *   Write to a text file.  os_fprintz() takes a null-terminated string,
+ *   while os_fprint() takes an explicit separate length argument that might
+ *   not end with a null terminator.  
+ */
+void os_fprintz(osfildef *fp, const char *str);
+void os_fprint(osfildef *fp, const char *str, size_t len);
+
+/* 
+ *   Write bytes to file.  Return 0 on success, non-zero on error.
+ */
+/* int osfwb(osfildef *fp, const void *buf, int bufl); */
+
+/*
+ *   Flush buffered writes to a file.  This ensures that any bytes written to
+ *   the file (with osfwb(), os_fprint(), etc) are actually sent out to the
+ *   operating system, rather than being buffered in application memory for
+ *   later writing.
+ *   
+ *   Note that this routine only guarantees that we write through to the
+ *   operating system.  This does *not* guarantee that the data will actually
+ *   be committed to the underlying physical storage device.  Such a
+ *   guarantee is hard to come by in general, since most modern systems use
+ *   multiple levels of software and hardware buffering - the OS might buffer
+ *   some data in system memory, and the physical disk drive might itself
+ *   buffer data in its own internal cache.  This routine thus isn't good
+ *   enough, for example, to protect transactional data that needs to survive
+ *   a power failure or a serious system crash.  What this routine *does*
+ *   ensure is that buffered data are written through to the OS; in
+ *   particular, this ensures that another process that's reading from the
+ *   same file will see all updates we've made up to this point.
+ *   
+ *   Returns 0 on success, non-zero on error.  Errors can occur for any
+ *   reason that they'd occur on an ordinary write - a full disk, a hardware
+ *   failure, etc.  
+ */
+/* int osfflush(osfildef *fp); */
+
+/* 
+ *   Read a character from a file.  Provides the same semantics as fgetc().
+ */
+/* int osfgetc(osfildef *fp); */
+
+/* 
+ *   Read bytes from file.  Return 0 on success, non-zero on error.  
+ */
+/* int osfrb(osfildef *fp, void *buf, int bufl); */
+
+/* 
+ *   Read bytes from file and return the number of bytes read.  0
+ *   indicates that no bytes could be read. 
+ */
+/* size_t osfrbc(osfildef *fp, void *buf, size_t bufl); */
+
+/* 
+ *   Get the current seek location in the file.  The first byte of the
+ *   file has seek position 0.  
+ */
+/* long osfpos(osfildef *fp); */
+
+/* 
+ *   Seek to a location in the file.  The first byte of the file has seek
+ *   position 0.  Returns zero on success, non-zero on error.
+ *   
+ *   The following constants must be defined in your OS-specific header;
+ *   these values are used for the "mode" parameter to indicate where to
+ *   seek in the file:
+ *   
+ *   OSFSK_SET - set position relative to the start of the file
+ *.  OSFSK_CUR - set position relative to the current file position
+ *.  OSFSK_END - set position relative to the end of the file 
+ */
+/* int osfseek(osfildef *fp, long pos, int mode); */
+
+/* 
+ *   Close a file.
+ *   
+ *   If the OS implementation uses buffered writes, this routine guarantees
+ *   that any buffered data are flushed to the underlying file.  So, it's not
+ *   necessary to call osfflush() before calling this routine.  However,
+ *   since this function doesn't return any error indication, a caller could
+ *   use osfflush() first to check for errors on any final buffered writes.  
+ */
+/* void osfcls(osfildef *fp); */
+
+/* 
+ *   Delete a file.  Returns zero on success, non-zero on error. 
+ */
+/* int osfdel(const char *fname); */
+
+/*
+ *   Rename/move a file.  This should apply the usual C rename() behavior.
+ *   Renames the old file to the new name, which may be in a new directory
+ *   location if supported on the local system; moves across devices,
+ *   volumes, file systems, etc may or may not be supported according to the
+ *   local system's rules.  If the new file already exists, results are
+ *   undefined.  Returns true on success, false on failure.
+ */
+/* int os_rename_file(const char *oldname, const char *newname); */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   File "stat()" information - mode, size, time stamps 
+ */
+
+/* 
+ *   Test access to a file - i.e., determine if the file exists.  Returns
+ *   zero if the file exists, non-zero if not.  (The semantics may seem
+ *   backwards, but this is consistent with the conventions used by most of
+ *   the other osfxxx calls: zero indicates success, non-zero indicates an
+ *   error.  If the file exists, "accessing" it was successful, so osfacc
+ *   returns zero; if the file doesn't exist, accessing it gets an error,
+ *   hence a non-zero return code.)  
+ */
+/* int osfacc(const char *fname) */
+
+/*
+ *   Get a file's mode and attribute flags.  This retrieves information on
+ *   the given file equivalent to the st_mode member of the 'struct stat'
+ *   data returned by the Unix stat() family of functions, as well as some
+ *   extra system-specific attributes.  On success, fills in *mode (if mode
+ *   is non-null) with the mode information as a bitwise combination of
+ *   OSFMODE_xxx values, fills in *attr (if attr is non-null) with a
+ *   combination of OSFATTR_xxx attribute flags, and returns true; on
+ *   failure, simply returns false.  Failure can occur if the file doesn't
+ *   exist, can't be accessed due to permissions, etc.
+ *   
+ *   Note that 'mode' and/or 'attr' can be null if the caller doesn't need
+ *   that information.  Implementations must check these parameters for null
+ *   pointers and skip returning the corresponding information if null.
+ *   
+ *   If the file in 'fname' is a symbolic link, the behavior depends upon
+ *   'follow_links'.  If 'follow_links' is true, the function should resolve
+ *   the link reference (and if that points to another link, the function
+ *   resolves that link as well, and so on) and return information on the
+ *   object the link points to.  Otherwise, the function returns information
+ *   on the link itself.  This only applies for symbolic links (not for hard
+ *   links), and only if the underlying OS and file system support this
+ *   distinction; if the OS transparently resolves links and doesn't allow
+ *   retrieving information about the link itself, 'follow_links' can be
+ *   ignored.  Likewise, hard links (on systems that support them) are
+ *   generally indistinguishable from regular files, so this function isn't
+ *   expected to do anything special with them.
+ *   
+ *   The '*mode' value returned is a bitwise combination of OSFMODE_xxx flag.
+ *   Many of the flags are mutually exclusive; for example, "file" and
+ *   "directory" should never be combined.  It's also possible for '*mode' to
+ *   be zero for a valid file; this means that the file is of some special
+ *   type on the local system that doesn't fit any of the OSFMODE_xxx types.
+ *   (If any ports do encounter such cases, we can add OSFMODE_xxx types to
+ *   accommodate new types.  The list below isn't meant to be final; it's
+ *   just what we've encountered so far on the platforms where TADS has
+ *   already been ported.)
+ *   
+ *   The OSFMODE_xxx values are left for the OS to define so that they can be
+ *   mapped directly to the OS API's equivalent constants, if desired.  This
+ *   makes the routine easy to write, since you can simply set *mode directly
+ *   to the mode information the OS returns from its stat() or equivalent.
+ *   However, note that these MUST be defined as bit flags - that is, each
+ *   value must be exactly a power of 2.  Windows and Unix-like systems
+ *   follow this practice, as do most "stat()" functions in C run-time
+ *   libraries, so this usually works automatically if you map these
+ *   constants to OS or C library values.  However, if a port defines its own
+ *   values for these, take care that they're all powers of 2.
+ *   
+ *   Obviously, a given OS might not have all of the file types listed here.
+ *   If any OSFMODE_xxx values aren't applicable on the local OS, you can
+ *   simply define them as zero since they'll never be returned.
+ *   
+ *   Notes on attribute flags:
+ *   
+ *   OSFATTR_HIDDEN means that the file is conventionally hidden by default
+ *   in user interface views or listings, but is still fully accessible to
+ *   the user.  Hidden files are also usually excluded by default from
+ *   wildcard patterns in commands ("rm *.*").  On Unix, a hidden file is one
+ *   whose name starts with "."; on Windows, it's a file with the HIDDEN bit
+ *   in its file attributes.  On systems where this concept exists, the user
+ *   can still manipulate these files as normal by naming them explicitly,
+ *   and can typically make them appear in UI views or directory listings via
+ *   a preference setting or command flag (e.g., "ls -a" on Unix).  The
+ *   "hidden" flag is explicitly NOT a security or permissions mechanism, and
+ *   it doesn't protect the file against intentional access by a user; it's
+ *   merely a convenience designed to reduce clutter by excluding files
+ *   maintained by the OS or by an application (such as preference files,
+ *   indices, caches, etc) from casual folder browsing, where a user is
+ *   typically only concerned with her own document files.  On systems where
+ *   there's no such naming convention or attribute metadata, this flag will
+ *   never appear.
+ *   
+ *   OSFATTR_SYSTEM is similar to 'hidden', but means that the file is
+ *   specially marked as an operating system file.  This is mostly a
+ *   DOS/Windows concept, where it corresponds to the SYSTEM bit in the file
+ *   attributes; this flag will probably never appear on other systems.  The
+ *   distinction between 'system' and 'hidden' is somewhat murky even on
+ *   Windows; most 'system' file are also marked as 'hidden', and in
+ *   practical terms in the user interface, 'system' files are treated the
+ *   same as 'hidden'.
+ *   
+ *   OSFATTR_READ means that the file is readable by this process.
+ *   
+ *   OSFATTR_WRITE means that the file is writable by this process.
+ */
+/* int osfmode(const char *fname, int follow_links, */
+/*             unsigned long *mode, unsigned long *attr); */
+
+/* file mode/type constants */
+/* #define OSFMODE_FILE    - regular file */
+/* #define OSFMODE_DIR     - directory */
+/* #define OSFMODE_BLK     - block-mode device */
+/* #define OSFMODE_CHAR    - character-mode device */
+/* #define OSFMODE_PIPE    - pipe/FIFO/other character-oriented IPC */
+/* #define OSFMODE_SOCKET  - network socket */
+/* #define OSFMODE_LINK    - symbolic link */
+
+/* file attribute constants */
+/* #define OSFATTR_HIDDEN  - hidden file */
+/* #define OSFATTR_SYSTEM  - system file */
+/* #define OSFATTR_READ    - the file is readable by this process */
+/* #define OSFATTR_WRITE   - the file is writable by this process */
+
+struct os_file_stat_t {
+    /* 
+     *   Size of the file, in bytes.  For platforms lacking 64-bit types, we
+     *   split this into high and low 32-bit portions.  Platforms where the
+     *   native stat() or equivalent only returns a 32-bit file size can
+     *   simply set sizehi to zero, since sizelo can hold the entire size
+     *   value.
+     */
+    uint32_t sizelo;
+    uint32_t sizehi;
+
+    /* 
+     *   Creation time, modification time, and last access time.  If the file
+     *   system doesn't keep information on one or more of these, use
+     *   (os_time_t)0 to indicate that the timestamp isn't available.  It's
+     *   fine to return any subset of these.  Per the standard C stat(),
+     *   these should be expressed as seconds after the Unix Epoch.
+     */
+    os_time_t cre_time;
+    os_time_t mod_time;
+    os_time_t acc_time;
+
+    /* file mode, using the same flags as returned from osfmode() */
+    unsigned long mode;
+
+    /* file attributes, using the same flags as returned from osfmode() */
+    unsigned long attrs;
+};
+
+
+/*
+ *   Get stat() information.  This fills in the portable os_file_stat
+ *   structure with the requested file information.  Returns true on success,
+ *   false on failure (file not found, permissions error, etc).
+ *   
+ *   'follow_links' has the same meaning as for osfmode().
+ */
+int os_file_stat(const char *fname, int follow_links, os_file_stat_t *s);
+
+/*
+ *   Manually resolve a symbolic link.  If the local OS and file system
+ *   support symbolic links, and the given filename is a symbolic link (in
+ *   which case osfmode(fname, FALSE, &m, &a) will set OSFMODE_LINK in the
+ *   mode bits), this fills in 'target' with the name of the link target
+ *   (i.e., the object that the link in 'fname' points to).  This should
+ *   return a fully qualified file system path.  Returns true on success,
+ *   false on failure.
+ *   
+ *   This should only resolve a single level of indirection.  If the link
+ *   target of 'fname' is itself a link to a second target, this should only
+ *   resolve the single reference from 'fname' to its direct direct.  Callers
+ *   that wish to resolve the final target of a chain of link references must
+ *   iterate until the returned path doesn't refer to a link.
+ */
+int os_resolve_symlink(const char *fname, char *target, size_t target_size);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Get a list of root directories.  If 'buf' is non-null, fills in 'buf'
+ *   with a list of strings giving the root directories for the local,
+ *   file-oriented devices on the system.  The strings are each null
+ *   terminated and are arranged consecutively in the buffer, with an extra
+ *   null terminator after the last string to mark the end of the list.
+ *   
+ *   The return value is the length of the buffer required to hold the
+ *   results.  If the caller's buffer is null or is too short, the routine
+ *   should return the full length required, and leaves the contents of the
+ *   buffer undefined; the caller shouldn't expect any contents to be filled
+ *   in if the return value is greater than buflen.  Both 'buflen' and the
+ *   return value include the null terminators, including the extra null
+ *   terminator at the end of the list.  If an error occurs, or the system
+ *   has no concept of a root directory, returns zero.
+ *   
+ *   Each result string should be expressed using the syntax for the root
+ *   directory on a device.  For example, on Windows, "C:\" represents the
+ *   root directory on the C: drive.
+ *   
+ *   "Local" means a device is mounted locally, as opposed to being merely
+ *   visible on the network via some remote node syntax; e.g., on Windows
+ *   this wouldn't include any UNC-style \\SERVER\SHARE names, and on VMS it
+ *   excludes any SERVER:: nodes.  It's up to each system how to treat
+ *   virtual local devices, i.e., those that look synctactically like local
+ *   devices but are actually mounted network devices, such as Windows mapped
+ *   network drives; we recommend including them if it would take extra work
+ *   to filter them out, and excluding them if it would take extra work to
+ *   include them.  "File-oriented" means that the returned devices are
+ *   accessed via file systems, not as character devices or raw block
+ *   devices; so this would exclude /dev/xxx devices on Unix and things like
+ *   CON: and LPT1: on Windows.
+ *   
+ *   Examples ("." represents a null byte):
+ *   
+ *   Windows: C:\.D:\.E:\..
+ *   
+ *   Unix example: /..
+ */
+size_t os_get_root_dirs(char *buf, size_t buflen);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Open a directory.  This begins an enumeration of a directory's contents.
+ *   'dirname' is a relative or absolute path to a directory.  On success,
+ *   returns true, and 'handle' is set to a port-defined handle value that's
+ *   used in subsequent calls to os_read_dir() and os_close_dir().  Returns
+ *   false on failure.
+ *   
+ *   If the routine succeeds, the caller must eventually call os_close_dir()
+ *   to release the resources associated with the handle.
+ */
+/* typedef <local system type> osdirhdl_t; */
+int os_open_dir(const char *dirname, /*OUT*/osdirhdl_t *handle);
+
+/*
+ *   Read the next file in a directory.  'handle' is a handle value obtained
+ *   from a call to os_open_dir().  On success, returns true and fills in
+ *   'fname' with the next filename; the handle is also internally updated so
+ *   that the next call to this function will retrieve the next file, and so
+ *   on until all files have been retrieved.  If an error occurs, or there
+ *   are no more files in the directory, returns false.
+ *   
+ *   The filename returned is the root filename only, without the path.  The
+ *   caller can build the full path by calling os_build_full_path() or
+ *   os_combine_paths() with the original directory name and the returned
+ *   filename as parameters.
+ *   
+ *   This routine lists all objects in the directory that are visible to the
+ *   corresponding native API, and is non-recursive.  The listing should thus
+ *   include subdirectory objects, but not the contents of subdirectories.
+ *   Implementations are encouraged to simply return all objects returned
+ *   from the corresponding native directory scan API; there's no need to do
+ *   any filtering, except perhaps in cases where it's difficult or
+ *   impossible to represent an object in terms of the osifc APIs (e.g., it
+ *   might be reasonable to exclude files without names).  System relative
+ *   links, such as the Unix/DOS "." and "..", specifically should be
+ *   included in the listing.  For unusual objects that don't fit into the
+ *   os_file_stat() taxonomy or that otherwise might create confusion for a
+ *   caller, err on the side of full disclosure (i.e., just return everything
+ *   unfiltered); if necessary, we can extend the os_file_stat() taxonomy or
+ *   add new osifc APIs to create a portable abstraction to handle whatever
+ *   is unusual or potentially confusing about the native object.  For
+ *   example, Unix implementations should feel free to return symbolic link
+ *   objects, including dangling links, since we have the portable
+ *   os_resolve_symlink() that lets the caller examine the meaning of the
+ *   link object.
+ */
+int os_read_dir(osdirhdl_t handle, char *fname, size_t fname_size);
+
+/*
+ *   Close a directory handle.  This releases the resources associated with a
+ *   directory search started with os_open_dir().  Every successful call to
+ *   os_open_dir() must have a matching call to os_close_dir().  As usual for
+ *   open/close protocols, the handle is invalid after calling this function,
+ *   so no more calls to os_read_dir() may be made with the handle.
+ */
+void os_close_dir(osdirhdl_t handle);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   NB - this routine is DEPRECATED as of TADS 2.5.16/3.1.1.  Callers should
+ *   use os_open_dir(), os_read_dir(), os_close_dir() instead.
+ *   
+ *   Find the first file matching a given pattern.  The returned context
+ *   pointer is a pointer to whatever system-dependent context structure is
+ *   needed to continue the search with the next file, and is opaque to the
+ *   caller.  The caller must pass the context pointer to the next-file
+ *   routine.  The caller can optionally cancel a search by calling the
+ *   close-search routine with the context pointer.  If the return value is
+ *   null, it indicates that no matching files were found.  If a file was
+ *   found, outbuf will be filled in with its name, and isdir will be set to
+ *   true if the match is a directory, false if it's a file.  If pattern is
+ *   null, all files in the given directory should be returned; otherwise,
+ *   pattern is a string containing '*' and '?' as wildcard characters, but
+ *   not containing any directory separators, and all files in the given
+ *   directory matching the pattern should be returned.
+ *   
+ *   Important: because this routine may allocate memory for the returned
+ *   context structure, the caller must either call os_find_next_file until
+ *   that routine returns null, or call os_find_close() to cancel the search,
+ *   to ensure that the os code has a chance to release the allocated memory.
+ *   
+ *   'outbuf' should be set on output to the name of the matching file,
+ *   without any path information.
+ *   
+ *   'outpathbuf' should be set on output to full path of the matching file.
+ *   If possible, 'outpathbuf' should use the same relative or absolute
+ *   notation that the search criteria used on input.  For example, if dir =
+ *   "resfiles", and the file found is "MyPic.jpg", outpathbuf should be set
+ *   to "resfiles/MyPic.jpg" (or appropriate syntax for the local platform).
+ *   Similarly, if dir = "/home/tads/resfiles", outpath buf should be
+ *   "/home/tads/resfiles/MyPic.jpg".  The result should always conform to
+ *   correct local conventions, which may require some amount of manipulation
+ *   of the filename; for example, on the Mac, if dir = "resfiles", the
+ *   result should be ":resfiles:MyPic.jpg" (note the added leading colon) to
+ *   conform to Macintosh relative path notation.
+ *   
+ *   Note that 'outpathbuf' may be null, in which case the caller is not
+ *   interested in the full path information.  
+ */
+/*   
+ *   Note the following possible ways this function may be called:
+ *   
+ *   dir = "", pattern = filename - in this case, pattern is the name of a
+ *   file or directory in the current directory.  filename *might* be a
+ *   relative path specified by the user (on a command line, for example);
+ *   for instance, on Unix, it could be something like "resfiles/jpegs".
+ *   
+ *   dir = path, pattern = filname - same as above, but this time the
+ *   filename or directory pattern is relative to the given path, rather
+ *   than to the current directory.  For example, we could have dir =
+ *   "/games/mygame" and pattern = "resfiles/jpegs".
+ *   
+ *   dir = path, pattern = 0 (NULL) - this should search for all files in
+ *   the given path.  The path might be absolute or it might be relative.
+ *   
+ *   dir = path, pattern = "*" - this should have the same result as when
+ *   pattern = 0.
+ *   
+ *   dir = path, pattern = "*.ext" - this should search for all files in
+ *   the given path whose names end with ".ext".
+ *   
+ *   dir = path, pattern = "abc*" - this should search for all files in
+ *   the given path whose names start with "abc".
+ *   
+ *   All of these combinations are possible because callers, for
+ *   portability, must generally not manipulate filenames directly;
+ *   instead, callers obtain paths and search strings from external
+ *   sources, such as from the user, and present them to this routine with
+ *   minimal manipulation.  
+ */
+void *os_find_first_file(const char *dir,
+                         char *outbuf, size_t outbufsiz, int *isdir,
+                         char *outpathbuf, size_t outpathbufsiz);
+
+/*
+ *   Implementation notes for porting os_find_first_file:
+ *   
+ *   The algorithm for this routine should go something like this:
+ *   
+ *   - If 'path' is null, create a variable real_path and initialize it
+ *   with the current directory.  Otherwise, copy path to real_path.
+ *   
+ *   - If 'pattern' contains any directory separators ("/" on Unix, for
+ *   example), change real_path so that it reflects the additional leading
+ *   subdirectories in the path in 'pattern', and remove the leading path
+ *   information from 'pattern'.  For example, on Unix, if real_path
+ *   starts out as "./subdir", and pattern is "resfiles/jpegs", change
+ *   real_path to "./subdir/resfiles", and change pattern to "jpegs".
+ *   Take care to add and remove path separators as needed to keep the
+ *   path strings well-formed.
+ *   
+ *   - Begin a search using appropriate OS API's for all files in
+ *   real_path.
+ *   
+ *   - Check each file found.  Skip any files that don't match 'pattern',
+ *   treating "*" as a wildcard that matches any string of zero or more
+ *   characters, and "?" as a wildcard that matches any single character
+ *   (or matches nothing at the end of a string).  For example:
+ *   
+ *.  "*" matches anything
+ *.  "abc?" matches "abc", "abcd", "abce", "abcf", but not "abcde"
+ *.  "abc???" matches "abc", "abcd", "abcde", "abcdef", but not "abcdefg"
+ *.  "?xyz" matches "wxyz", "axyz", but not "xyz" or "abcxyz"
+ *   
+ *   - Return the first file that matches, if any, by filling in 'outbuf'
+ *   and 'isdir' with appropriate information.  Before returning, allocate
+ *   a context structure (which is entirely for your own use, and opaque
+ *   to the caller) and fill it in with the information necessary for
+ *   os_find_next_file to get the next matching file.  If no file matches,
+ *   return null.  
+ */
+
+
+/*
+ *   Find the next matching file, continuing a search started with
+ *   os_find_first_file().  Returns null if no more files were found, in
+ *   which case the search will have been automatically closed (i.e.,
+ *   there's no need to call os_find_close() after this routine returns
+ *   null).  Returns a non-null context pointer, which is to be passed to
+ *   this function again to get the next file, if a file was found.
+ *   
+ *   'outbuf' and 'outpathbuf' are filled in with the filename (without
+ *   path) and full path (relative or absolute, as appropriate),
+ *   respectively, in the same manner as they do for os_find_first_file().
+ *   
+ *   Implementation note: if os_find_first_file() allocated memory for the
+ *   search context, this routine must free the memory if it returs null,
+ *   because this indicates that the search is finished and the caller
+ *   need not call os_find_close().  
+ */
+void *os_find_next_file(void *ctx, char *outbuf, size_t outbufsiz,
+                        int *isdir, char *outpathbuf, size_t outpathbufsiz);
+
+/*
+ *   Cancel a search.  The context pointer returned by the last call to
+ *   os_find_first_file() or os_find_next_file() is the parameter.  There
+ *   is no need to call this function if find-first or find-next returned
+ *   null, since they will have automatically closed the search.
+ *   
+ *   Implementation note: if os_find_first_file() allocated memory for the
+ *   search context, this routine should release the memory.  
+ */
+void os_find_close(void *ctx);
+
+/*
+ *   Special filename classification 
+ */
+enum os_specfile_t
+{
+    /* not a special file */
+    OS_SPECFILE_NONE,
+
+    /* 
+     *   current directory link - this is a file like the "." file on Unix
+     *   or DOS, which is a special link that simply refers to itself 
+     */
+    OS_SPECFILE_SELF,
+
+    /* 
+     *   parent directory link - this is a file like the ".." file on Unix
+     *   or DOS, which is a special link that refers to the parent
+     *   directory 
+     */
+    OS_SPECFILE_PARENT
+};
+
+/*
+ *   Determine if the given filename refers to a special file.  Returns the
+ *   appropriate enum value if so, or OS_SPECFILE_NONE if not.  The given
+ *   filename must be a root name - it must not contain a path prefix.  The
+ *   purpose here is to classify the results from os_find_first_file() and
+ *   os_find_next_file() to identify the special relative links, so callers
+ *   can avoid infinite recursion when traversing a directory tree.
+ */
+enum os_specfile_t os_is_special_file(const char *fname);
+
+/* ------------------------------------------------------------------------ */
+/* 
+ *   Convert string to all-lowercase. 
+ */
+char *os_strlwr(char *s);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Character classifications for quote characters.  os_squote() returns
+ *   true if its argument is any type of single-quote character;
+ *   os_dquote() returns true if its argument is any type of double-quote
+ *   character; and os_qmatch(a, b) returns true if a and b are matching
+ *   open- and close-quote characters.
+ *   
+ *   These functions allow systems with extended character codes with
+ *   weird quote characters (such as the Mac) to match the weird
+ *   characters, so that users can use the extended quotes in input.
+ *   
+ *   These are usually implemented as macros.  The most common
+ *   implementation simply returns true for the standard ASCII quote
+ *   characters:
+ *   
+ *   #define os_squote(c) ((c) == '\'')
+ *.  #define os_dquote(c) ((c) == '"')
+ *.  #define os_qmatch(a, b) ((a) == (b))
+ *   
+ *   These functions take int arguments to allow for the possibility of
+ *   Unicode input.  
+ */
+/* int os_squote(int c); */
+/* int os_dquote(int c); */
+/* int os_qmatch(int a, int b); */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Special file and directory locations
+ */
+
+/*
+ *   Get the full filename (including directory path) to the executable
+ *   file, given the argv[0] parameter passed into the main program.  This
+ *   fills in the buffer with a null-terminated string that can be used in
+ *   osfoprb(), for example, to open the executable file.
+ *   
+ *   Returns non-zero on success.  If it's not possible to determine the
+ *   name of the executable file, returns zero.
+ *   
+ *   Some operating systems might not provide access to the executable file
+ *   information, so non-trivial implementation of this routine is optional;
+ *   if the necessary information is not available, simply implement this to
+ *   return zero.  If the information is not available, callers should offer
+ *   gracefully degraded functionality if possible.  
+ */
+int os_get_exe_filename(char *buf, size_t buflen, const char *argv0);
+
+/*
+ *   Get a special directory path.  Returns the selected path, in a format
+ *   suitable for use with os_build_full_path().  The main program's argv[0]
+ *   parameter is provided so that the system code can choose to make the
+ *   special paths relative to the program install directory, but this is
+ *   entirely up to the system implementation, so the argv[0] parameter can
+ *   be ignored if it is not needed.
+ *   
+ *   The 'id' parameter selects which special path is requested; this is one
+ *   of the constants defined below.  If the id is not understood, there is
+ *   no way of signalling an error to the caller; this routine can fail with
+ *   an assert() in such cases, because it indicates that the OS layer code
+ *   is out of date with respect to the calling code.
+ *   
+ *   This routine can be implemented using one of the strategies below, or a
+ *   combination of these.  These are merely suggestions, though, and systems
+ *   are free to ignore these and implement this routine using whatever
+ *   scheme is the best fit to local conventions.
+ *   
+ *   - Relative to argv[0].  Some systems use this approach because it keeps
+ *   all of the TADS files together in a single install directory tree, and
+ *   doesn't require any extra configuration information to find the install
+ *   directory.  Since we base the path name on the executable that's
+ *   actually running, we don't need any environment variables or parameter
+ *   files or registry entries to know where to look for related files.
+ *   
+ *   - Environment variables or local equivalent.  On some systems, it is
+ *   conventional to set some form of global system parameter (environment
+ *   variables on Unix, for example) for this sort of install configuration
+ *   data.  In these cases, this routine can look up the appropriate
+ *   configuration variables in the system environment.
+ *   
+ *   - Hard-coded paths.  Some systems have universal conventions for the
+ *   installation configuration of compiler-like tools, so the paths to our
+ *   component files can be hard-coded based on these conventions.
+ *   
+ *   - Hard-coded default paths with environment variable overrides.  Let the
+ *   user set environment variables if they want, but use the standard system
+ *   paths as hard-coded defaults if the variables aren't set.  This is often
+ *   the best choice; users who expect the standard system conventions won't
+ *   have to fuss with any manual settings or even be aware of them, while
+ *   users who need custom settings aren't stuck with the defaults.
+ */
+void os_get_special_path(char *buf, size_t buflen,
+                         const char *argv0, int id);
+
+/* 
+ *   TADS 3 system resource path.  This path is used to load system
+ *   resources, such as character mapping files and error message files.  
+ */
+#define OS_GSP_T3_RES       1
+
+/* 
+ *   TADS 3 compiler - system headers.  This is the #include path for the
+ *   header files included with the compiler. 
+ */
+#define OS_GSP_T3_INC       2
+
+/*
+ *   TADS 3 compiler - system library source code.  This is the path to the
+ *   library source files that the compiler includes in every compilation by
+ *   default (such as _main.t). 
+ */
+#define OS_GSP_T3_LIB       3
+
+/*
+ *   TADS 3 compiler - user library path list.  This is a list of directory
+ *   paths, separated by the OSPATHSEP character, that should be searched for
+ *   user library files.  The TADS 3 compiler uses this as an additional set
+ *   of locations to search after the list of "-Fs" options and before the
+ *   OS_GSP_T3_LIB directory.
+ *   
+ *   This path list is intended for the user's use, so no default value is
+ *   needed.  The value should be user-configurable using local conventions;
+ *   on Unix, for example, this might be handled with an environment
+ *   variable.  
+ */
+#define OS_GSP_T3_USER_LIBS 4
+
+/*
+ *   TADS 3 interpreter - application data path.  This is the directory where
+ *   we should store things like option settings: data that we want to store
+ *   in a file, global to all games.  Depending on local system conventions,
+ *   this can be a global shared directory for all users, or can be a
+ *   user-specific directory. 
+ */
+#define OS_GSP_T3_APP_DATA 5
+
+/*
+ *   TADS 3 interpreter - system configuration files.  This is used for files
+ *   that affect all games, and generally all users on the system, so it
+ *   should be in a central location.  On Windows, for example, we simply
+ *   store these files in the install directory containing the intepreter
+ *   binary.  
+ */
+#define OS_GSP_T3_SYSCONFIG  6
+
+/*
+ *   System log files.  This is the directory for system-level status, debug,
+ *   and error logging files.  (Note that we're NOT talking about in-game
+ *   transcript logging per the SCRIPT command.  SCRIPT logs are usually sent
+ *   to files selected by the user via a save-file dialog, so these don't
+ *   need a special location.)
+ */
+#define OS_GSP_LOGFILE  7
+
+
+/* 
+ *   Seek to the resource file embedded in the current executable file,
+ *   given the main program's argv[0].
+ *   
+ *   On platforms where the executable file format allows additional
+ *   information to be attached to an executable, this function can be used
+ *   to find the extra information within the executable.
+ *   
+ *   The 'typ' argument gives a resource type to find.  This is an arbitrary
+ *   string that the caller uses to identify what type of object to find.
+ *   The "TGAM" type, for example, is used by convention to indicate a TADS
+ *   compiled GAM file.  
+ */
+osfildef *os_exeseek(const char *argv0, const char *typ);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Load a string resource.  Given a string ID number, load the string
+ *   into the given buffer.
+ *   
+ *   Returns zero on success, non-zero if an error occurs (for example,
+ *   the buffer is too small, or the requested resource isn't present).
+ *   
+ *   Whenever possible, implementations should use an operating system
+ *   mechanism for loading the string from a user-modifiable resource
+ *   store; this will make localization of these strings easier, since the
+ *   resource store can be modified without the need to recompile the
+ *   application.  For example, on the Macintosh, the normal system string
+ *   resource mechanism should be used to load the string from the
+ *   application's resource fork.
+ *   
+ *   When no operating system mechanism exists, the resources can be
+ *   stored as an array of strings in a static variable; this isn't ideal,
+ *   because it makes it much more difficult to localize the application.
+ *   
+ *   Resource ID's are application-defined.  For example, for TADS 2,
+ *   "res.h" defines the resource ID's.  
+ */
+int os_get_str_rsc(int id, char *buf, size_t buflen);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Look for a file in the "standard locations": current directory, program
+ *   directory, PATH-like environment variables, etc.  The actual standard
+ *   locations are specific to each platform; the implementation is free to
+ *   use whatever conventions are appropriate to the local system.  On
+ *   systems that have something like Unix environment variables, it might be
+ *   desirable to define a TADS-specific variable (TADSPATH, for example)
+ *   that provides a list of directories to search for TADS-related files.
+ *   
+ *   On return, fill in 'buf' with the full filename of the located copy of
+ *   the file (if a copy was indeed found), in a format suitable for use with
+ *   the osfopxxx() functions; in other words, after this function returns,
+ *   the caller should be able to pass the contents of 'buf' to an osfopxxx()
+ *   function to open the located file.
+ *   
+ *   Returns true (non-zero) if a copy of the file was located, false (zero)
+ *   if the file could not be found in any of the standard locations.  
+ */
+int os_locate(const char *fname, int flen, const char *arg0,
+              char *buf, size_t bufsiz);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Create and open a temporary file.  The file must be opened to allow
+ *   both reading and writing, and must be in "binary" mode rather than
+ *   "text" mode, if the system makes such a distinction.  Returns null on
+ *   failure.
+ *   
+ *   If 'fname' is non-null, then this routine should create and open a file
+ *   with the given name.  When 'fname' is non-null, this routine does NOT
+ *   need to store anything in 'buf'.  Note that the routine shouldn't try
+ *   to put the file in a special directory or anything like that; just open
+ *   the file with the name exactly as given.
+ *   
+ *   If 'fname' is null, this routine must choose a file name and fill in
+ *   'buf' with the chosen name; if possible, the file should be in the
+ *   conventional location for temporary files on this system, and should be
+ *   unique (i.e., it shouldn't be the same as any existing file).  The
+ *   filename stored in 'buf' is opaque to the caller, and cannot be used by
+ *   the caller except to pass to osfdel_temp().  On some systems, it may
+ *   not be possible to determine the actual filename of a temporary file;
+ *   in such cases, the implementation may simply store an empty string in
+ *   the buffer.  (The only way the filename would be unavailable is if the
+ *   implementation uses a system API that creates a temporary file, and
+ *   that API doesn't return the name of the created temporary file.  In
+ *   such cases, we don't need the name; the only reason we need the name is
+ *   so we can pass it to osfdel_temp() later, but since the system is going
+ *   to delete the file automatically, osfdel_temp() doesn't need to do
+ *   anything and thus doesn't need the name.)
+ *   
+ *   After the caller is done with the file, it should close the file (using
+ *   osfcls() as normal), then the caller MUST call osfdel_temp() to delete
+ *   the temporary file.
+ *   
+ *   This interface is intended to take advantage of systems that have
+ *   automatic support for temporary files, while allowing implementation on
+ *   systems that don't have any special temp file support.  On systems that
+ *   do have automatic delete-on-close support, this routine should use that
+ *   system-level support, because it helps ensure that temp files will be
+ *   deleted even if the caller fails to call osfdel_temp() due to a
+ *   programming error or due to a process or system crash.  On systems that
+ *   don't have any automatic delete-on-close support, this routine can
+ *   simply use the same underlying system API that osfoprwbt() normally
+ *   uses (although this routine must also generate a name for the temp file
+ *   when the caller doesn't supply one).
+ *   
+ *   This routine can be implemented using ANSI library functions as
+ *   follows: if 'fname' is non-null, return fopen(fname,"w+b"); otherwise,
+ *   set buf[0] to '\0' and return tmpfile().  
+ */
+osfildef *os_create_tempfile(const char *fname, char *buf);
+
+/*
+ *   Delete a temporary file - this is used to delete a file created with
+ *   os_create_tempfile().  For most platforms, this can simply be defined
+ *   the same way as osfdel().  For platforms where the operating system or
+ *   file manager will automatically delete a file opened as a temporary
+ *   file, this routine should do nothing at all, since the system will take
+ *   care of deleting the temp file.
+ *   
+ *   Callers are REQUIRED to call this routine after closing a file opened
+ *   with os_create_tempfile().  When os_create_tempfile() is called with a
+ *   non-null 'fname' argument, the same value should be passed as 'fname' to
+ *   this function.  When os_create_tempfile() is called with a null 'fname'
+ *   argument, then the buffer passed in the 'buf' argument to
+ *   os_create_tempfile() must be passed as the 'fname' argument here.  In
+ *   other words, if the caller explicitly names the temporary file to be
+ *   opened in os_create_tempfile(), then that same filename must be passed
+ *   here to delete the named file; if the caller lets os_create_tempfile()
+ *   generate a filename, then the generated filename must be passed to this
+ *   routine.
+ *   
+ *   If os_create_tempfile() is implemented using ANSI library functions as
+ *   described above, then this routine can also be implemented with ANSI
+ *   library calls as follows: if 'fname' is non-null and fname[0] != '\0',
+ *   then call remove(fname); otherwise do nothing.  
+ */
+int osfdel_temp(const char *fname);
+
+/*
+ *   Get the temporary file path.  This should fill in the buffer with a
+ *   path prefix (suitable for strcat'ing a filename onto) for a good
+ *   directory for a temporary file, such as the swap file.  
+ */
+void os_get_tmp_path(char *buf);
+
+/* 
+ *   Generate a name for a temporary file.  This constructs a random file
+ *   path in the system temp directory that isn't already used by an existing
+ *   file.
+ *   
+ *   On systems with long filenames, this can be implemented by selecting a
+ *   GUID-strength random name (such as 32 random hex digits) with a decent
+ *   random number generator.  That's long enough that the odds of a
+ *   collision are essentially zero.  On systems that only support short
+ *   filenames, the odds of a collision are non-zero, so the routine should
+ *   actually check that the chosen filename doesn't exist.
+ *   
+ *   Optionally, before returning, this routine *may* create (and close) an
+ *   empty placeholder file to "reserve" the chosen filename.  This isn't
+ *   required, and on systems with long filenames it's usually not necessary
+ *   because of the negligible chance of a collision.  On systems with short
+ *   filenames, a placeholder can be useful to prevent a subsequent call to
+ *   this routine, or a separate process, from using the same filename before
+ *   the caller has had a chance to use the returned name to create the
+ *   actual temp file.
+ *   
+ *   Returns true on success, false on failure.  This can fail if there's no
+ *   system temporary directory defined, or the temp directory is so full of
+ *   other files that we can't find an unused filename.  
+ */
+int os_gen_temp_filename(char *buf, size_t buflen);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Basic directory/folder management routines
+ */
+
+/*
+ *   Switch to a new working directory.
+ *   
+ *   This is meant to behave similarly to the Unix concept of a working
+ *   directory, in that it sets the base directory assumed for subsequent
+ *   file operations (e.g., the osfopxx() functions, osfdel(), etc - anything
+ *   that takes a filename or directory name as an argument).  The working
+ *   directory applies to filenames specified with relative paths in the
+ *   local system notation.  File operations on filenames specified with
+ *   absolute paths, of course, ignore the working directory.
+ */
+void os_set_pwd(const char *dir);
+
+/*
+ *   Switch the working directory to the directory containing the given
+ *   file.  Generally, this routine should only need to parse the filename
+ *   enough to determine the part that's the directory path, then use
+ *   os_set_pwd() to switch to that directory.  
+ */
+void os_set_pwd_file(const char *filename);
+
+/*
+ *   Create a directory.  This creates a new directory/folder with the given
+ *   name, which may be given as a relative or absolute path.  Returns true
+ *   on success, false on failure.
+ *   
+ *   If 'create_parents' is true, and the directory has mulitiple path
+ *   elements, this routine should create each enclosing parent that doesn't
+ *   already exist.  For example, if the path is specified as "a/b/c", and
+ *   there exists a folder "a" in the working directory, but "a" is empty,
+ *   this should first create "b" and then create "c".  If an error occurs
+ *   creating any parent, the routine should simply stop and return failure.
+ *   (Optionally, the routine may attempt to behave atomically by undoing any
+ *   parent folder creations it accomplished before failing on a nested
+ *   folder, but this isn't required.  To reduce the chances of a failure
+ *   midway through the operation, the routine might want to scan the
+ *   filename before starting to ensure that it contains only valid
+ *   characters, since an invalid character is the most likely reason for a
+ *   failure part of the way through.)
+ *   
+ *   We recommend making the routine flexible in terms of the notation it
+ *   accepts; e.g., on Unix, "/dir/sub/folder" and "/dir/sub/folder/" should
+ *   be considered equivalent.
+ */
+int os_mkdir(const char *dir, int create_parents);
+
+/*
+ *   Remove a directory.  Returns true on success, false on failure.
+ *   
+ *   If the directory isn't already empty, this routine fails.  That is, the
+ *   routine does NOT recursively delete the contents of a non-empty
+ *   directory.  It's up to the caller to delete any contents before removing
+ *   the directory, if that's the caller's intention.  (Note to implementors:
+ *   most native OS APIs to remove directories fail by default if the
+ *   directory isn't empty, so it's usually safe to implement this simply by
+ *   calling the native API.  However, if your system's version of this API
+ *   can remove a non-empty directory, you MUST add an extra test before
+ *   removing the directory to ensure it's empty, and return failure if it's
+ *   not.  For the purposes of this test, "empty" should of course ignore any
+ *   special objects that are automatically or implicitly present in all
+ *   directories, such as the Unix "." and ".." relative links.)
+ */
+int os_rmdir(const char *dir);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Filename manipulation routines
+ */
+
+/* apply a default extension to a filename, if it doesn't already have one */
+void os_defext(char *fname, const char *ext);
+
+/* unconditionally add an extention to a filename */
+void os_addext(char *fname, const char *ext);
+
+/* remove the extension from a filename */
+void os_remext(char *fname);
+
+/*
+ *   Compare two file names/paths for syntactic equivalence.  Returns true if
+ *   the names are equivalent names according to the local file system's
+ *   syntax conventions, false if not.  This does a syntax-only comparison of
+ *   the paths, without looking anything up in the file system.  This means
+ *   that a false return doesn't guarantee that the paths don't point to the
+ *   same file.
+ *   
+ *   This routine DOES make the following equivalences:
+ *   
+ *   - if the local file system is insensitive to case, the names are
+ *   compared ignoring case
+ *   
+ *   - meaningless path separator difference are ignored: on Unix, "a/b" ==
+ *   "a//b" == "a/b/"; on Windows, "a/b" == "a\\b"
+ *   
+ *   - relative links that are strictly structural or syntactic are applied;
+ *   for example, on Unix or Windows, "a/./b" == "a/b" = "a/b/c/..".  This
+ *   only applies for special relative links that can be resolved without
+ *   looking anything up in the file system.
+ *   
+ *   This DOES NOT do the following:
+ *   
+ *   - it doesn't apply working directories/volums to relative paths
+ *   
+ *   - it doesn't follow symbolic links in the file system
+ */
+int os_file_names_equal(const char *a, const char *b);
+
+/*
+ *   Get a pointer to the root name portion of a filename.  This is the part
+ *   of the filename after any path or directory prefix.  For example, on
+ *   Unix, given the string "/home/mjr/deep.gam", this function should return
+ *   a pointer to the 'd' in "deep.gam".  If the filename doesn't appear to
+ *   have a path prefix, it should simply return the argument unchanged.
+ *   
+ *   IMPORTANT: the returned pointer MUST point into the original 'buf'
+ *   string, and the contents of that buffer must NOT be modified.  The
+ *   return value must point into the same buffer because there are no
+ *   allowances for the alternatives.  In particular, (a) you can't return a
+ *   pointer to newly allocated memory, because callers won't free it, so
+ *   doing so would cause a memory leak; and (b) you can't return a pointer
+ *   to an internal static buffer, because callers might call this function
+ *   more than once and still rely on a value returned on an older call,
+ *   which would be invalid if a static buffer could be overwritten on each
+ *   call.  For these reasons, it's required that the return value point to a
+ *   position within the original string passed in 'buf'.  
+ */
+char *os_get_root_name(const char *buf);
+
+/*
+ *   Determine whether a filename specifies an absolute or relative path.
+ *   This is used to analyze filenames provided by the user (for example,
+ *   in a #include directive, or on a command line) to determine if the
+ *   filename can be considered relative or absolute.  This can be used,
+ *   for example, to determine whether to search a directory path for a
+ *   file; if a given filename is absolute, a path search makes no sense.
+ *   A filename that doesn't specify an absolute path can be combined with
+ *   a path using os_build_full_path().
+ *   
+ *   Returns true if the filename specifies an absolute path, false if
+ *   not.  
+ */
+int os_is_file_absolute(const char *fname);
+
+/*
+ *   Extract the path from a filename.  Fills in pathbuf with the path
+ *   portion of the filename.  If the filename has no path, the pathbuf
+ *   should be set appropriately for the current directory (on Unix or DOS,
+ *   for example, it can be set to an empty string).
+ *   
+ *   The result can end with a path separator character or not, depending on
+ *   local OS conventions.  Paths extracted with this function can only be
+ *   used with os_build_full_path(), so the conventions should match that
+ *   function's.
+ *   
+ *   Unix examples:
+ *   
+ *.   /home/mjr/deep.gam -> /home/mjr
+ *.   games/deep.gam -> games
+ *.   deep.gam -> [empty string]
+ *   
+ *   Mac examples:
+ *   
+ *    :home:mjr:deep.gam -> :home:mjr
+ *.   Hard Disk:games:deep.gam -> Hard Disk:games
+ *.   Hard Disk:deep.gam -> Hard Disk:
+ *.   deep.gam -> [empty string]
+ *   
+ *   VMS examples:
+ *
+ *.   SYS$DISK:[mjr.games]deep.gam -> SYS$DISK:[mjr.games]
+ *.   SYS$DISK:[mjr.games] -> SYS$DISK:[mjr]
+ *.   deep.gam -> [empty string]
+ *   
+ *   Note in the last example that we've retained the trailing colon in the
+ *   path, whereas we didn't in the others; although the others could also
+ *   retain the trailing colon, it's required only for the last case.  The
+ *   last case requires the colon because it would otherwise be impossible to
+ *   determine whether "Hard Disk" was a local subdirectory or a volume name.
+ *   
+ */
+void os_get_path_name(char *pathbuf, size_t pathbuflen, const char *fname);
+
+/*
+ *   Build a full path name, given a path and a filename.  The path may have
+ *   been specified by the user, or may have been extracted from another file
+ *   via os_get_path_name().  This routine must take care to add path
+ *   separators as needed, but also must take care not to add too many path
+ *   separators.
+ *   
+ *   This routine should reformat the path into canonical format to the
+ *   extent possible purely through syntactic analysis.  For example, special
+ *   relative links, such as Unix "." and "..", should be resolved; for
+ *   example, combining "a/./b/c" with ".." on Unix should yield "a/b".
+ *   However, symbolic links that require looking up names in the file system
+ *   should NOT be resolved.  We don't want to perform any actual file system
+ *   lookups because might want to construct hypothetical paths that don't
+ *   necessarily relate to files on the local system.
+ *   
+ *   Note that relative path names may require special care on some
+ *   platforms.  In particular, if the source path is relative, the result
+ *   should also be relative.  For example, on the Macintosh, a path of
+ *   "games" and a filename "deep.gam" should yield ":games:deep.gam" - note
+ *   the addition of the leading colon to make the result path relative.
+ *   
+ *   Note also that the 'filename' argument is not only allowed to be an
+ *   ordinary file, possibly qualified with a relative path, but is also
+ *   allowed to be a subdirectory.  The result in this case should be a path
+ *   that can be used as the 'path' argument to a subsequent call to
+ *   os_build_full_path; this allows a path to be built in multiple steps by
+ *   descending into subdirectories one at a time.
+ *   
+ *   Unix examples:
+ *   
+ *.   /home/mjr + deep.gam -> /home/mjr/deep.gam"
+ *.   /home/mjr + .. -> /home
+ *.   /home/mjr + ../deep.gam -> /home/deep.gam
+ *.   /home/mjr/ + deep.gam -> /home/mjr/deep.gam"
+ *.   games + deep.gam -> games/deep.gam"
+ *.   games/ + deep.gam -> games/deep.gam"
+ *.   /home/mjr + games/deep.gam -> /home/mjr/games/deep.gam"
+ *.   games + scifi/deep.gam -> games/scifi/deep.gam"
+ *.   /home/mjr + games -> /home/mjr/games"
+ *   
+ *   Mac examples:
+ *   
+ *.   Hard Disk: + deep.gam -> Hard Disk:deep.gam
+ *.   :games: + deep.gam -> :games:deep.gam
+ *.   :games:deep + ::test.gam -> :games:test.gam
+ *.   games + deep.gam -> :games:deep.gam
+ *.   Hard Disk: + :games:deep.gam -> Hard Disk:games:deep.gam
+ *.   games + :scifi:deep.gam -> :games:scifi:deep.gam
+ *.   Hard Disk: + games -> Hard Disk:games
+ *.   Hard Disk:games + scifi -> Hard Disk:games:scifi
+ *.   Hard Disk:games:scifi + deep.gam -> Hard Disk:games:scifi:deep.gam
+ *.   Hard Disk:games + :scifi:deep.gam -> Hard Disk:games:scifi:deep.gam
+ *   
+ *   VMS examples:
+ *   
+ *.   [home.mjr] + deep.gam -> [home.mjr]deep.gam
+ *.   [home.mjr] + [-]deep.gam -> [home]deep.gam
+ *.   mjr.dir + deep.gam -> [.mjr]deep.gam
+ *.   [home]mjr.dir + deep.gam -> [home.mjr]deep.gam
+ *.   [home] + [.mjr]deep.gam -> [home.mjr]deep.gam
+ */
+void os_build_full_path(char *fullpathbuf, size_t fullpathbuflen,
+                        const char *path, const char *filename);
+
+/*
+ *   Combine a path and a filename to form a full path to the file.  This is
+ *   *almost* the same as os_build_full_path(), but if the 'filename' element
+ *   is a special relative link, such as Unix '.' or '..', this preserves
+ *   that special link in the final name.
+ *   
+ *   Unix examples:
+ *   
+ *.    /home/mjr + deep.gam -> /home/mjr/deep.gam
+ *.    /home/mjr + . -> /home/mjr/.
+ *.    /home/mjr + .. -> /home/mjr/..
+ *   
+ *   Mac examples:
+ *   
+ *.    Hard Disk:games + deep.gam -> HardDisk:games:deep.gam
+ *.    Hard Disk:games + :: -> HardDisk:games::
+ *   
+ *   VMS exmaples:
+ *   
+ *.    [home.mjr] + deep.gam -> [home.mjr]deep.gam
+ *.    [home.mjr] + [-] -> [home.mjr.-]
+ */
+void os_combine_paths(char *fullpathbuf, size_t pathbuflen,
+                      const char *path, const char *filename);
+
+
+/*
+ *   Get the absolute, fully qualified filename for a file.  This fills in
+ *   'result_buf' with the absolute path to the given file, taking into
+ *   account the current working directory and any other implied environment
+ *   information that affects the way the file system would resolve the given
+ *   file name to a specific file on disk if we opened the file now using
+ *   this name.
+ *   
+ *   The returned path should be in absolute path form, meaning that it's
+ *   independent of the current working directory or any other environment
+ *   settings.  That is, this path should still refer to the same file even
+ *   if the working directory changes.
+ *   
+ *   Note that it's valid to get the absolute path for a file that doesn't
+ *   exist, or for a path with directory components that don't exist.  For
+ *   example, a caller might generate the absolute path for a file that it's
+ *   about to create, or a hypothetical filename for path comparison
+ *   purposes.  The function should succeed even if the file or any path
+ *   components don't exist.  If the file is in relative format, and any path
+ *   elements don't exist but are syntactically well-formed, the result
+ *   should be the path obtained from syntactically combining the working
+ *   directory with the relative path.
+ *   
+ *   On many systems, a given file might be reachable through more than one
+ *   absolute path.  For example, on Unix it might be possible to reach a
+ *   file through symbolic links to the file itself or to parent directories,
+ *   or hard links to the file.  It's up to the implementation to determine
+ *   which path to use in such cases.
+ *   
+ *   On success, returns true.  If it's not possible to resolve the file name
+ *   to an absolute path, the routine copies the original filename to the
+ *   result buffer exactly as given, and returns false.  
+ */
+int os_get_abs_filename(char *result_buf, size_t result_buf_size,
+                        const char *filename);
+
+/*
+ *   Get the relative version of the given filename path 'filename', relative
+ *   to the given base directory 'basepath'.  Both paths must be given in
+ *   absolute format.
+ *   
+ *   Returns true on success, false if it's not possible to rewrite the path
+ *   in relative terms.  For example, on Windows, it's not possible to
+ *   express a path on the "D:" drive as relative to a base path on the "C:"
+ *   drive, since each drive letter has an independent root folder; there's
+ *   no namespace entity enclosing a drive letter's root folder.  On
+ *   Unix-like systems where the entire namespace has a single hierarchical
+ *   root, it should always be possible to express any path relative to any
+ *   other.
+ *   
+ *   The result should be a relative path that can be combined with
+ *   'basepath' using os_build_full_path() to reconstruct a path that
+ *   identifies the same file as the original 'filename' (it's not important
+ *   that this procedure would result in the identical string - it just has
+ *   to point to the same file).  If it's not possible to express the
+ *   filename relative to the base path, fill in 'result_buf' with the
+ *   original filename and return false.
+ *   
+ *   Windows examples:
+ *   
+ *.    c:\mjr\games | c:\mjr\games\deep.gam  -> deep.gam
+ *.    c:\mjr\games | c:\mjr\games\tads\deep.gam  -> tads\deep.gam
+ *.    c:\mjr\games | c:\mjr\tads\deep.gam  -> ..\tads\deep.gam
+ *.    c:\mjr\games | d:\deep.gam  ->  d:\deep.gam (and return false)
+ *   
+ *   Mac OS examples:
+ *   
+ *.    Mac HD:mjr:games | Mac HD:mjr:games:deep.gam -> deep.gam
+ *.    Mac HD:mjr:games | Mac HD:mjr:games:tads:deep.gam -> :tads:deep.gam
+ *.    Mac HD:mjr:games | Ext Disk:deep.gam -> Ext Disk:deep.gam (return false)
+ *   
+ *   VMS examples:
+ *   
+ *.    SYS$:[mjr.games] | SYS$:[mjr.games]deep.gam -> deep.gam
+ *.    SYS$:[mjr.games] | SYS$:[mjr.games.tads]deep.gam -> [.tads]deep.gam
+ *.    SYS$:[mjr.games] | SYS$:[mjr.tads]deep.gam -> [-.tads]deep.gam
+ *.    SYS$:[mjr.games] | DISK$:[mjr]deep.gam -> DISK$[mjr]deep.gam (ret false)
+ */
+int os_get_rel_path(char *result_buf, size_t result_buf_size,
+                    const char *basepath, const char *filename);
+
+/*
+ *   Determine if the given file is in the given directory.  Returns true if
+ *   so, false if not.  'filename' is a relative or absolute file name;
+ *   'path' is a relative or absolute directory path, such as one returned
+ *   from os_get_path_name().
+ *   
+ *   If 'include_subdirs' is true, the function returns true if the file is
+ *   either directly in the directory 'path', OR it's in any subdirectory of
+ *   'path'.  If 'include_subdirs' is false, the function returns true only
+ *   if the file is directly in the given directory.
+ *   
+ *   If 'match_self' is true, the function returns true if 'filename' and
+ *   'path' are the same directory; otherwise it returns false in this case.
+ *   
+ *   This routine is allowed to return "false negatives" - that is, it can
+ *   claim that the file isn't in the given directory even when it actually
+ *   is.  The reason is that it's not always possible to determine for sure
+ *   that there's not some way for a given file path to end up in the given
+ *   directory.  In contrast, a positive return must be reliable.
+ *   
+ *   If possible, this routine should fully resolve the names through the
+ *   file system to determine the path relationship, rather than merely
+ *   analyzing the text superficially.  This can be important because many
+ *   systems have multiple ways to reach a given file, such as via symbolic
+ *   links on Unix; analyzing the syntax alone wouldn't reveal these multiple
+ *   pathways.
+ *   
+ *   SECURITY NOTE: If possible, implementations should fully resolve all
+ *   symbolic links, relative paths (e.g., Unix ".."), etc, before rendering
+ *   judgment.  One important application for this routine is to determine if
+ *   a file is in a sandbox directory, to enforce security restrictions that
+ *   prevent a program from accessing files outside of a designated folder.
+ *   If the implementation fails to resolve symbolic links or relative paths,
+ *   a malicious program or user could bypass the security restriction by,
+ *   for example, creating a symbolic link within the sandbox directory that
+ *   points to the root folder.  Implementations can avoid this loophole by
+ *   converting the file and directory names to absolute paths and resolving
+ *   all symbolic links and relative notation before comparing the paths.
+ */
+int os_is_file_in_dir(const char *filename, const char *path,
+                      int include_subdirs, int match_self);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Convert an OS filename path to URL-style format.  This isn't a true URL
+ *   conversion; rather, it simply expresses a filename in Unix-style
+ *   notation, as a series of path elements separated by '/' characters.
+ *   Unlike true URLs, we don't use % encoding or a scheme prefix (file://,
+ *   etc).
+ *   
+ *   The result path never ends in a trailing '/', unless the entire result
+ *   path is "/".  This is for consistency; even if the source path ends with
+ *   a local path separator, the result doesn't.
+ *   
+ *   If the local file system syntax uses '/' characters as ordinary filename
+ *   characters, these must be replaced with some other suitable character in
+ *   the result, since otherwise they'd be taken as path separators when the
+ *   URL is parsed.  If possible, the substitution should be reversible with
+ *   respect to os_cvt_dir_url(), so that the same URL read back in on this
+ *   same platform will produce the same original filename.  One particular
+ *   suggestion is that if the local system uses '/' to delimit what would be
+ *   a filename extension on other platforms, replace '/' with '.', since
+ *   this will provide reversibility as well as a good mapping if the URL is
+ *   read back in on another platform.
+ *   
+ *   The local equivalents of "." and "..", if they exist, are converted to
+ *   "." and ".." in the URL notation.
+ *   
+ *   Examples:
+ *   
+ *.   Windows: images\rooms\startroom.jpg -> images/rooms/startroom.jpg
+ *.   Windows: ..\startroom.jpg -> ../startroom.jpg
+ *.   Mac:     :images:rooms:startroom.jpg -> images/rooms/startroom.jpg
+ *.   Mac:     ::startroom.jpg -> ../startroom.jpg
+ *.   VMS:     [.images.rooms]startroom.jpg -> images/rooms/startroom.jpg
+ *.   VMS:     [-.images]startroom.jpg -> ../images/startroom.jpg
+ *.   Unix:    images/rooms/startroom.jpg -> images/rooms/startroom.jpg
+ *.   Unix:    ../images/startroom.jpg -> ../images/startroom.jpg
+ *   
+ *   If the local name is an absolute path in the local file system (e.g.,
+ *   Unix /file, Windows C:\file), translate as follows.  If the local
+ *   operating system uses a volume or device designator (Windows C:, VMS
+ *   SYS$DISK:, etc), make the first element of the path the exact local
+ *   syntax for the device designator: /C:/ on Windows, /SYS$DISK:/ on VMS,
+ *   etc.  Include the local syntax for the device prefix.  For a system like
+ *   Unix with a unified file system root ("/"), simply start with the root
+ *   directory.  Examples:
+ *   
+ *.    Windows:  C:\games\deep.gam         -> /C:/games/deep.gam
+ *.    Windows:  C:games\deep.gam          -> /C:./games/deep.gam
+ *.    Windows:  \\SERVER\DISK\games\deep.gam -> /\\SERVER/DISK/games/deep.gam
+ *.    Mac OS 9: Hard Disk:games:deep.gam  -> /Hard Disk:/games/deep.gam
+ *.    VMS:      SYS$DISK:[games]deep.gam  -> /SYS$DISK:/games/deep.gam
+ *.    Unix:     /games/deep.gam           -> /games/deep.gam
+ *   
+ *   Rationale: it's effectively impossible to create a truly portable
+ *   representation of an absolute path.  Operating systems are too different
+ *   in the way they represent root paths, and even if that were solvable, a
+ *   root path is essentially unusable across machines anyway because it
+ *   creates a dependency on the contents of a particular machine's disk.  So
+ *   if we're called upon to translate an absolute path, we can forget about
+ *   trying to be truly portable and instead focus on round-trip fidelity -
+ *   i.e., making sure that applying os_cvt_url_dir() to our result recovers
+ *   the exact original path, assuming it's done on the same operating
+ *   system.  The approach outlined above should achieve round-trip fidelity
+ *   when a local path is converted to a URL and back on the same machine,
+ *   since the local URL-to-path converter should recognize its own special
+ *   type of local absolute path prefix.  It also produces reasonable results
+ *   on other platforms - see the os_cvt_url_dir() comments below for
+ *   examples of the decoding results for absolute paths moved to new
+ *   platforms.  The result when a device-rooted absolute path is encoded on
+ *   one machine and then decoded on another will generally be a local path
+ *   with a root on the default device/volume and an outermost directory with
+ *   a name based on the original machine's device/volume name.  This
+ *   obviously won't reproduce the exact original path, but since that's
+ *   impossible anyway, this is probably as good an approximation as we can
+ *   create.
+ *   
+ *   Character sets: the input could be in local or UTF-8 character sets.
+ *   The implementation shouldn't care, though - just treat bytes in the
+ *   range 0-127 as plain ASCII, and everything else as opaque.  I.e., do not
+ *   quote or otherwise modify characters outside the 0-127 range.  
+ */
+void os_cvt_dir_url(char *result_buf, size_t result_buf_size,
+                    const char *src_path);
+
+/*
+ *   Convert a URL-style path into a filename path expressed in the local
+ *   file system's syntax.  Fills in result_buf with a file path, constructed
+ *   using the local file system syntax, that corresponds to the path in
+ *   src_url expressed in URL-style syntax.  Examples:
+ *   
+ *   images/rooms/startroom.jpg -> 
+ *.   Windows   -> images\rooms\startroom.jpg
+ *.   Mac OS 9  -> :images:rooms:startroom.jpg
+ *.   VMS       -> [.images.rooms]startroom.jpg
+ *   
+ *   The source format isn't a true URL; it's simply a series of path
+ *   elements separated by '/' characters.  Unlike true URLs, our input
+ *   format doesn't use % encoding and doesn't have a scheme (file://, etc).
+ *   (Any % in the source is treated as an ordinary character and left as-is,
+ *   even if it looks like a %XX sequence.  Anything that looks like a scheme
+ *   prefix is left as-is, with any // treated as path separators.
+ *   
+ *   images/file%20name.jpg ->
+ *.   Windows   -> images\file%20name.jpg
+ *   
+ *   file://images/file.jpg ->
+ *.   Windows   -> file_\\images\file.jpg
+ *   
+ *   Any characters in the path that are invalid in the local file system
+ *   naming rules are converted to "_", unless "_" is itself invalid, in
+ *   which case they're converted to "X".  One exception is that if '/' is a
+ *   valid local filename character (rather than a path separator as it is on
+ *   Unix and Windows), it can be used as the replacement for the character
+ *   that os_cvt_dir_url uses as its replacement for '/', so that this
+ *   substitution is reversible when a URL is generated and then read back in
+ *   on this same platform.
+ *   
+ *   images/file:name.jpg ->
+ *.   Windows   -> images\file_name.jpg
+ *.   Mac OS 9  -> :images:file_name.jpg
+ *.   Unix      -> images/file:name.jpg
+ *   
+ *   The path elements "." and ".." are specifically defined as having their
+ *   Unix meanings: "." is an alias for the preceding path element, or the
+ *   working directory if it's the first element, and ".." is an alias for
+ *   the parent of the preceding element.  When these appear as path
+ *   elements, this routine translates them to the appropriate local
+ *   conventions.  "." may be translated simply by removing it from the path,
+ *   since it reiterates the previous path element.  ".." may be translated
+ *   by removing the previous element - HOWEVER, if ".." appears as the first
+ *   element, it has to be retained and translated to the equivalent local
+ *   notation, since it will have to be applied later, when the result_buf
+ *   path is actually used to open a file, at which point it will combined
+ *   with the working directory or another base path.
+ *   
+ *.  /images/../file.jpg -> [Windows] file.jpg
+ *.  ../images/file.jpg ->
+ *.   Windows  -> ..\images\file.jpg
+ *.   Mac OS 9 -> ::images:file.jpg
+ *.   VMS      -> [-.images]file.jpg
+ *   
+ *   If the URL path is absolute (starts with a '/'), the routine inspects
+ *   the path to see if it was created by the same OS, according to the local
+ *   rules for converting absolute paths in os_cvt_dir_url() (see).  If so,
+ *   we reverse the encoding done there.  If it doesn't appear that the name
+ *   was created by the same operating system - that is, if reversing the
+ *   encoding doesn't produce a valid local filename - then we create a local
+ *   absolute path as follows.  If the local system uses device/volume
+ *   designators, we start with the current working device/volume or some
+ *   other suitable default volume.  We then add the first element of the
+ *   path, if any, as the root directory name, applying the usual "_" or "X"
+ *   substitution for any characters that aren't allowed in local names.  The
+ *   rest of the path is handled in the usual fashion.
+ *   
+ *.  /images/file.jpg ->
+ *.    Windows -> \images\file.jpg
+ *.    Unix    -> /images/file.jpg
+ *   
+ *.  /c:/images/file.jpg ->
+ *.    Windows -> c:\images\file.jpg
+ *.    Unix    -> /c:/images/file.jpg
+ *.    VMS     -> SYS$DISK:[c__.images]file.jpg
+ *   
+ *.  /Hard Disk:/images/file.jpg ->
+ *.    Windows -> \Hard Disk_\images\file.jpg
+ *.    Unix    -> SYS$DISK:[Hard_Disk_.images]file.jpg
+ *   
+ *   Note how the device/volume prefix becomes the top-level directory when
+ *   moving a path across machines.  It's simply not possible to reconstruct
+ *   the exact original path in such cases, since device/volume syntax rules
+ *   have little in common across systems.  But this seems like a good
+ *   approximation in that (a) it produces a valid local path, and (b) it
+ *   gives the user a reasonable basis for creating a set of folders to mimic
+ *   the original source system, if they want to use that approach to port
+ *   the data rather than just changing the paths internally in the source
+ *   material.
+ *   
+ *   Character sets: use the same rules as for os_cvt_dir_url().  
+ */
+void os_cvt_url_dir(char *result_buf, size_t result_buf_size,
+                    const char *src_url);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Get a suitable seed for a random number generator; should use the system
+ *   clock or some other source of an unpredictable and changing seed value.
+ */
+void os_rand(long *val);
+
+/*
+ *   Generate random bytes for use in seeding a PRNG (pseudo-random number
+ *   generator).  This is an extended version of os_rand() for PRNGs that use
+ *   large seed vectors containing many bytes, rather than the simple 32-bit
+ *   seed that os_rand() assumes.
+ *   
+ *   As with os_rand(), this function isn't meant to be used directly as a
+ *   random number source for ongoing use - instead, this is intended mostly
+ *   for seeding a PRNG, which will then be used as the primary source of
+ *   random numbers.  The big problem with using this routine directly as a
+ *   randomness source is that some implementations might rely heavily on
+ *   environmental randomness, such as the real-time clock or OS usage
+ *   statistics.  Such sources tend to provide reasonable entropy from one
+ *   run to the next, but not within a single session, as the underlying data
+ *   sources don't change rapidly enough.
+ *   
+ *   Ideally, this routine should generate *truly* random bytes obtained from
+ *   hardware sources.  Not all systems can provide that, though, so true
+ *   randomness isn't guaranteed.  Here are the suggested implementation
+ *   options, in descending order of desirability:
+ *   
+ *   1.  Use a hardware source of true randomness, such as a /dev/rand type
+ *   of device.  However, note that this call should return reasonably
+ *   quickly, so always use a non-blocking source.  Some Unix /dev/rand
+ *   devices, for example, can block indefinitely to allow sufficient entropy
+ *   to accumulate.
+ *   
+ *   2. Use a cryptographic random number source provided by the OS.  Some
+ *   systems provide this as an API service.  If going this route, be sure
+ *   that the OS generator is itself "seeded" with some kind of true
+ *   randomness source, as it defeats the whole purpose if you always return
+ *   a fixed pseudo-random sequence each time the program runs.
+ *   
+ *   3. Use whatever true random sources are available locally to seed a
+ *   software pseudo-random number generator, then generate bytes from your
+ *   PRNG.  Some commonly available sources of true randomness are a
+ *   high-resolution timer, the system clock, the current process ID,
+ *   logged-in user ID, environment variables, uninitialized pages of memory,
+ *   the IP address; each of these sources might give you a few bits of
+ *   entropy at best, so the best bet is to use an ensemble.  You could, for
+ *   example, concatenate a bunch of this type of information together and
+ *   calculate an MD5 or SHA1 hash to mix the bits more thoroughly.  For the
+ *   PRNG, use a cryptographic generator.  (You could use the ISAAC generator
+ *   from TADS 3, as that's a crypto PRNG, but it's probably better to use a
+ *   different generator here since TADS 3 is going to turn around and use
+ *   this function's output to seed ISAAC - seeding one ISAAC instance with
+ *   another ISAAC's output seems likely to magnify any weaknesses in the
+ *   ISAAC algorithm.)  Note that this option is basically the DIY version of
+ *   option 2.  Option 2 is better because the OS probably has access to
+ *   better sources of true randomness than an application does.  
+ */
+void os_gen_rand_bytes(unsigned char *buf, size_t len);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Display routines.
+ *   
+ *   Our display model is a simple stdio-style character stream.
+ *   
+ *   In addition, we provide an optional "status line," which is a
+ *   non-scrolling area where a line of text can be displayed.  If the status
+ *   line is supported, text should only be displayed in this area when
+ *   os_status() is used to enter status-line mode (mode 1); while in status
+ *   line mode, text is written to the status line area, otherwise (mode 0)
+ *   it's written to the normal main text area.  The status line is normally
+ *   shown in a different color to set it off from the rest of the text.
+ *   
+ *   The OS layer can provide its own formatting (word wrapping in
+ *   particular) if it wants, in which case it should also provide pagination
+ *   using os_more_prompt().  
+ */
+
+/*
+ *   OS_MAXWIDTH - the maximum width of a line of text.  Most platforms use
+ *   135 for this, but you can use more or less as appropriate.  If you use
+ *   OS-level line wrapping, then the true width of a text line is
+ *   irrelevant, and the portable code will use this merely for setting its
+ *   internal buffer sizes.
+ *   
+ *   This must be defined in the os_xxx.h header file for each platform.
+ */
+/*#define OS_MAXWIDTH 135 - example only: define for real in os_xxx.h header*/
+
+/*
+ *   Print a string on the console.  These routines come in two varieties:
+ *   
+ *   os_printz - write a NULL-TERMINATED string
+ *.  os_print - write a COUNTED-LENGTH string, which may not end with a null
+ *   
+ *   These two routines are identical except that os_printz() takes a string
+ *   which is terminated by a null byte, and os_print() instead takes an
+ *   explicit length, and a string that may not end with a null byte.
+ *   
+ *   os_printz(str) may be implemented as simply os_print(str, strlen(str)).
+ *   
+ *   The string is written in one of three ways, depending on the status mode
+ *   set by os_status():
+ *   
+ *   status mode == 0 -> write to main text window
+ *.  status mode == 1 -> write to status line
+ *.  anything else -> do not display the text at all
+ *   
+ *   Implementations are free to omit any status line support, in which case
+ *   they should simply suppress all output when the status mode is anything
+ *   other than zero.
+ *   
+ *   The following special characters must be recognized in the displayed
+ *   text:
+ *   
+ *   '\n' - newline: end the current line and move the cursor to the start of
+ *   the next line.  If the status line is supported, and the current status
+ *   mode is 1 (i.e., displaying in the status line), then two special rules
+ *   apply to newline handling: newlines preceding any other text should be
+ *   ignored, and a newline following any other text should set the status
+ *   mode to 2, so that all subsequent output is suppressed until the status
+ *   mode is changed with an explicit call by the client program to
+ *   os_status().
+ *   
+ *   '\r' - carriage return: end the current line and move the cursor back to
+ *   the beginning of the current line.  Subsequent output is expected to
+ *   overwrite the text previously on this same line.  The implementation
+ *   may, if desired, IMMEDIATELY clear the previous text when the '\r' is
+ *   written, rather than waiting for subsequent text to be displayed.
+ *   
+ *   All other characters may be assumed to be ordinary printing characters.
+ *   The routine need not check for any other special characters.
+ *   
+ */
+void os_printz(const char *str);
+void os_print(const char *str, size_t len);
+
+/*
+ *   Print to the debugger console.  These routines are for interactive
+ *   debugger builds only: they display the given text to a separate window
+ *   within the debugger UI (separate from the main game command window)
+ *   where the debugger displays status information specific to the debugging
+ *   session (such as compiler/build output, breakpoint status messages,
+ *   etc).  For example, TADS Workbench on Windows displays these messages in
+ *   its "Debug Log" window.
+ *   
+ *   These routines only need to be implemented for interactive debugger
+ *   builds, such as TADS Workbench on Windows.  These can be omitted for
+ *   regular interpreter builds.  
+ */
+void os_dbg_printf(const char *fmt, ...);
+void os_dbg_vprintf(const char *fmt, va_list args);
+
+/*
+ *   Allocating sprintf and vsprintf.  These work like the regular C library
+ *   sprintf and vsprintf funtions, but they allocate a return buffer that's
+ *   big enough to hold the result, rather than formatting into a caller's
+ *   buffer.  This protects against buffer overruns and ensures that the
+ *   result isn't truncated.
+ *   
+ *   On return, '*bufptr' is filled in with a pointer to a buffer allocated
+ *   with osmalloc().  This buffer contains the formatted string result.  The
+ *   caller is responsible for freeing the buffer by calling osfree().
+ *   *bufptr can be null on return if an error occurs.
+ *   
+ *   The return value is the number of bytes written to the allocated buffer,
+ *   not including the null terminator.  If an error occurs, the return value
+ *   is -1 and *bufptr is undefined.
+ *   
+ *   Many modern C libraries provide equivalents of these, usually called
+ *   asprintf() and vasprintf(), respectively.  
+ */
+/* int os_asprintf(char **bufptr, const char *fmt, ...); */
+int os_vasprintf(char **bufptr, const char *fmt, va_list ap);
+
+
+/* 
+ *   Set the status line mode.  There are three possible settings:
+ *   
+ *   0 -> main text mode.  In this mode, all subsequent text written with
+ *   os_print() and os_printz() is to be displayed to the main text area.
+ *   This is the normal mode that should be in effect initially.  This mode
+ *   stays in effect until an explicit call to os_status().
+ *   
+ *   1 -> statusline mode.  In this mode, text written with os_print() and
+ *   os_printz() is written to the status line, which is usually rendered as
+ *   a one-line area across the top of the terminal screen or application
+ *   window.  In statusline mode, leading newlines ('\n' characters) are to
+ *   be ignored, and any newline following any other character must change
+ *   the mode to 2, as though os_status(2) had been called.
+ *   
+ *   2 -> suppress mode.  In this mode, all text written with os_print() and
+ *   os_printz() must simply be ignored, and not displayed at all.  This mode
+ *   stays in effect until an explicit call to os_status().  
+ */
+void os_status(int stat);
+
+/* get the status line mode */
+int os_get_status();
+
+/* 
+ *   Set the score value.  This displays the given score and turn counts on
+ *   the status line.  In most cases, these values are displayed at the right
+ *   edge of the status line, in the format "score/turns", but the format is
+ *   up to the implementation to determine.  In most cases, this can simply
+ *   be implemented as follows:
+ *   
+ *.  void os_score(int score, int turncount)
+ *.  {
+ *.     char buf[40];
+ *.     sprintf(buf, "%d/%d", score, turncount);
+ *.     os_strsc(buf);
+ *.  }
+ */
+void os_score(int score, int turncount);
+
+/* display a string in the score area in the status line */
+void os_strsc(const char *p);
+
+/* clear the screen */
+void oscls(void);
+
+/* redraw the screen */
+void os_redraw(void);
+
+/* flush any buffered display output */
+void os_flush(void);
+
+/*
+ *   Update the display - process any pending drawing immediately.  This
+ *   only needs to be implemented for operating systems that use
+ *   event-driven drawing based on window invalidations; the Windows and
+ *   Macintosh GUI's both use this method for drawing window contents.
+ *   
+ *   The purpose of this routine is to refresh the display prior to a
+ *   potentially long-running computation, to avoid the appearance that the
+ *   application is frozen during the computation delay.
+ *   
+ *   Platforms that don't need to process events in the main thread in order
+ *   to draw their window contents do not need to do anything here.  In
+ *   particular, text-mode implementations generally don't need to implement
+ *   this routine.
+ *   
+ *   This routine doesn't absolutely need a non-empty implementation on any
+ *   platform, but it will provide better visual feedback if implemented for
+ *   those platforms that do use event-driven drawing.  
+ */
+void os_update_display();
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Set text attributes.  Text subsequently displayed through os_print() and
+ *   os_printz() are to be displayed with the given attributes.
+ *   
+ *   'attr' is a (bitwise-OR'd) combination of OS_ATTR_xxx values.  A value
+ *   of zero indicates normal text, with no extra attributes.  
+ */
+void os_set_text_attr(int attr);
+
+/* attribute code: bold-face */
+#define OS_ATTR_BOLD     0x0001
+
+/* attribute code: italic */
+#define OS_ATTR_ITALIC   0x0002
+
+/*
+ *   Abstract attribute codes.  Each platform can choose a custom rendering
+ *   for these by #defining them before this point, in the OS-specific header
+ *   (osdos.h, osmac.h, etc).  We provide *default* definitions in case the
+ *   platform doesn't define these.
+ *   
+ *   For compatibility with past versions, we treat HILITE, EM, and BOLD as
+ *   equivalent.  Platforms that can display multiple kinds of text
+ *   attributes (boldface and italic, say) should feel free to use more
+ *   conventional HTML mappings, such as EM->italic and STRONG->bold.  
+ */
+
+/* 
+ *   "Highlighted" text, as appropriate to the local platform.  On most
+ *   text-mode platforms, the only kind of rendering variation possible is a
+ *   brighter or intensified color.  If actual bold-face is available, that
+ *   can be used instead.  This is the attribute used for text enclosed in a
+ *   TADS2 "\( \)" sequence.  
+ */
+#ifndef OS_ATTR_HILITE
+# define OS_ATTR_HILITE  OS_ATTR_BOLD
+#endif
+
+/* HTML <em> attribute - by default, map this to bold-face */
+#ifndef OS_ATTR_EM
+# define OS_ATTR_EM      OS_ATTR_BOLD
+#endif
+
+/* HTML <strong> attribute - by default, this has no effect */
+#ifndef OS_ATTR_STRONG
+# define OS_ATTR_STRONG  0
+#endif
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Colors.
+ *   
+ *   There are two ways of encoding a color.  First, a specific color can be
+ *   specified as an RGB (red-green-blue) value, with discreet levels for
+ *   each component's intensity, ranging from 0 to 255.  Second, a color can
+ *   be "parameterized," which doesn't specify a color in absolute terms but
+ *   rather specified one of a number of pre-defined *types* of colors;
+ *   these pre-defined types can be chosen by the OS implementation, or, on
+ *   some systems, selected by the user via a preferences mechanism.
+ *   
+ *   The os_color_t type encodes a color in 32 bits.  The high-order 8 bits
+ *   of a color value give the parameterized color identifier, or are set to
+ *   zero to indicate an RGB color.  An RGB color is encoded in the
+ *   low-order 24 bits, via the following formula:
+ *   
+ *   (R << 16) + (G << 8) + B
+ *   
+ *   R specifies the intensity of the red component of the color, G green,
+ *   and B blue.  Each of R, G, and B must be in the range 0-255.  
+ */
+typedef unsigned long os_color_t;
+
+/* encode an R, G, B triplet into an os_color_t value */
+#define os_rgb_color(r, g, b) (((r) << 16) + ((g) << 8) + (b))
+
+/* 
+ *   Determine if a color is given as an RGB value or as a parameterized
+ *   color value.  Returns true if the color is given as a parameterized
+ *   color (one of the OS_COLOR_xxx values), false if it's given as an
+ *   absolute RGB value.  
+ */
+#define os_color_is_param(color) (((color) & 0xFF000000) != 0)
+
+/* get the red/green/blue components of an os_color_t value */
+#define os_color_get_r(color) ((int)(((color) >> 16) & 0xFF))
+#define os_color_get_g(color) ((int)(((color) >> 8) & 0xFF))
+#define os_color_get_b(color) ((int)((color) & 0xFF))
+
+/*
+ *   Parameterized color codes.  These are os_color_t values that indicate
+ *   colors by type, rather than by absolute RGB values.  
+ */
+
+/* 
+ *   "transparent" - applicable to backgrounds only, this specifies that the
+ *   current screen background color should be used 
+ */
+#define OS_COLOR_P_TRANSPARENT ((os_color_t)0x01000000)
+
+/* "normal text" color (as set via user preferences, if applicable) */
+#define OS_COLOR_P_TEXT        ((os_color_t)0x02000000)
+
+/* normal text background color (from user preferences) */
+#define OS_COLOR_P_TEXTBG      ((os_color_t)0x03000000)
+
+/* "status line" text color (as set via user preferences, if applicable) */
+#define OS_COLOR_P_STATUSLINE  ((os_color_t)0x04000000)
+
+/* status line background color (from user preferences) */
+#define OS_COLOR_P_STATUSBG    ((os_color_t)0x05000000)
+
+/* input text color (as set via user preferences, if applicable) */
+#define OS_COLOR_P_INPUT       ((os_color_t)0x06000000)
+
+/*
+ *   Set the text foreground and background colors.  This sets the text
+ *   color for subsequent os_printf() and os_vprintf() calls.
+ *   
+ *   The background color can be OS_COLOR_TRANSPARENT, in which case the
+ *   background color is "inherited" from the current screen background.
+ *   Note that if the platform is capable of keeping old text for
+ *   "scrollback," then the transparency should be a permanent attribute of
+ *   the character - in other words, it should not be mapped to the current
+ *   screen color in the scrollback buffer, because doing so would keep the
+ *   current screen color even if the screen color changes in the future. 
+ *   
+ *   Text color support is optional.  If the platform doesn't support text
+ *   colors, this can simply do nothing.  If the platform supports text
+ *   colors, but the requested color or attributes cannot be displayed, the
+ *   implementation should use the best available approximation.  
+ */
+void os_set_text_color(os_color_t fg, os_color_t bg);
+
+/*
+ *   Set the screen background color.  This sets the text color for the
+ *   background of the screen.  If possible, this should immediately redraw
+ *   the main text area with this background color.  The color is given as an
+ *   OS_COLOR_xxx value.
+ *   
+ *   If the platform is capable of redisplaying the existing text, then any
+ *   existing text that was originally displayed with 'transparent'
+ *   background color should be redisplayed with the new screen background
+ *   color.  In other words, the 'transparent' background color of previously
+ *   drawn text should be a permanent attribute of the character - the color
+ *   should not be mapped on display to the then-current background color,
+ *   because doing so would lose the transparency and thus retain the old
+ *   screen color on a screen color change.  
+ */
+void os_set_screen_color(os_color_t color);
+
+
+/* ------------------------------------------------------------------------ */
+/* 
+ *   os_plain() - Use plain ascii mode for the display.  If possible and
+ *   necessary, turn off any text formatting effects, such as cursor
+ *   positioning, highlighting, or coloring.  If this routine is called,
+ *   the terminal should be treated as a simple text stream; users might
+ *   wish to use this mode for things like text-to-speech converters.
+ *   
+ *   Purely graphical implementations that cannot offer a textual mode
+ *   (such as Mac OS or Windows) can ignore this setting.
+ *   
+ *   If this routine is to be called, it must be called BEFORE os_init().
+ *   The implementation should set a flag so that os_init() will know to
+ *   set up the terminal for plain text output.  
+ */
+#ifndef os_plain
+/* 
+ *   some platforms (e.g. Mac OS) define this to be a null macro, so don't
+ *   define a prototype in those cases 
+ */
+void os_plain(void);
+#endif
+
+/*
+ *   Set the game title.  The output layer calls this routine when a game
+ *   sets its title (via an HTML <title> tag, for example).  If it's
+ *   convenient to do so, the OS layer can use this string to set a window
+ *   caption, or whatever else makes sense on each system.  Most
+ *   character-mode implementations will provide an empty implementation,
+ *   since there's not usually any standard way to show the current
+ *   application title on a character-mode display.  
+ */
+void os_set_title(const char *title);
+
+/*
+ *   Show the system-specific MORE prompt, and wait for the user to respond.
+ *   Before returning, remove the MORE prompt from the screen.
+ *   
+ *   This routine is only used and only needs to be implemented when the OS
+ *   layer takes responsibility for pagination; this will be the case on
+ *   most systems that use proportionally-spaced (variable-pitch) fonts or
+ *   variable-sized windows, since on such platforms the OS layer must do
+ *   most of the formatting work, leaving the standard output layer unable
+ *   to guess where pagination should occur.
+ *   
+ *   If the portable output formatter handles the MORE prompt, which is the
+ *   usual case for character-mode or terminal-style implementations, this
+ *   routine is not used and you don't need to provide an implementation.
+ *   Note that HTML TADS provides an implementation of this routine, because
+ *   the HTML renderer handles line breaking and thus must handle
+ *   pagination.  
+ */
+void os_more_prompt();
+
+/*
+ *   Interpreter Class Configuration.
+ *   
+ *   If this is a TEXT-ONLY interpreter: DO NOT define USE_HTML.
+ *   
+ *   If this is a MULTIMEDIA (HTML TADS) intepreter: #define USE_HTML
+ *   
+ *   (This really should be called something like OS_USE_HTML - the USE_ name
+ *   is for historical reasons.  This purpose of this macro is to configure
+ *   the tads 2 VM-level output formatter's line breaking and MORE mode
+ *   behavior.  In HTML mode, the VM-level formatter knows that it's feeding
+ *   its output to a page layout engine, so the VM-level output is just a
+ *   text stream.  In plain-text mode, the VM formatter *is* the page layout
+ *   engine, so it needs to do all of the word wrapping and MORE prompting
+ *   itself.  The tads 3 output layer does NOT use this macro for its
+ *   equivalent configuration, but instead has different .cpp files for the
+ *   different modes, and you simply link in the one for the configuration
+ *   you want.)  
+ */
+/* #define USE_HTML */
+
+
+/*
+ *   Enter HTML mode.  This is only used when the run-time is compiled
+ *   with the USE_HTML flag defined.  This call instructs the renderer
+ *   that HTML sequences should be parsed; until this call is made, the
+ *   renderer should not interpret output as HTML.  Non-HTML
+ *   implementations do not need to define this routine, since the
+ *   run-time will not call it if USE_HTML is not defined.  
+ */
+void os_start_html(void);
+
+/* exit HTML mode */
+void os_end_html(void);
+
+/*
+ *   Global variables with the height and width (in character cells - rows
+ *   and columns) of the main text display area into which os_printf
+ *   displays.  The height and width are given in text lines and character
+ *   columns, respectively.  The portable code can use these values to
+ *   format text for display via os_printf(); for example, the caller can
+ *   use the width to determine where to put line breaks.
+ *   
+ *   These values are only needed for systems where os_printf() doesn't
+ *   perform its own word-wrap formatting.  On systems such as the Mac,
+ *   where os_printf() performs word wrapping, these sizes aren't really
+ *   important because the portable code doesn't need to perform any real
+ *   formatting.
+ *   
+ *   These variables reflect the size of the "main text area," which is the
+ *   area of the screen excluding the status line and any "banner" windows
+ *   (as created with the os_banner_xxx() interfaces).
+ *   
+ *   The OS code must initialize these variables during start-up, and must
+ *   adjust them whenever the display size is changed by user action or
+ *   other external events (for example, if we're running inside a terminal
+ *   window, and the user resizes the window, the OS code must recalculate
+ *   the layout and adjust these accordingly).  
+ */
+extern int G_os_pagelength;
+extern int G_os_linewidth;
+
+/*
+ *   Global flag that tells the output formatter whether to count lines
+ *   that it's displaying against the total on the screen so far.  If this
+ *   variable is true, lines are counted, and the screen is paused with a
+ *   [More] message when it's full.  When not in MORE mode, lines aren't
+ *   counted.  This variable should be set to false when displaying text
+ *   that doesn't count against the current page, such as status line
+ *   information.
+ *   
+ *   This flag should not be modified by OS code.  Instead, the output
+ *   formatter will set this flag according to its current state; the OS
+ *   code can use this flag to determine whether or not to display a MORE
+ *   prompt during os_printf()-type operations.  Note that this flag is
+ *   normally interesting to the OS code only when the OS code itself is
+ *   handling the MORE prompt.  
+ */
+extern int G_os_moremode;
+
+/*
+ *   Global buffer containing the name of the byte-code file (the "game
+ *   file") loaded into the VM.  This is used only where applicable, which
+ *   generally means in TADS Interpreter builds.  In other application
+ *   builds, this is simply left empty.  The application is responsible for
+ *   setting this during start-up (or wherever else the byte-code filename
+ *   becomes known or changes).  
+ */
+extern char G_os_gamename[OSFNMAX];
+
+/*
+ *   Set non-stop mode.  This tells the OS layer that it should disable any
+ *   MORE prompting it would normally do.
+ *   
+ *   This routine is needed only when the OS layer handles MORE prompting; on
+ *   character-mode platforms, where the prompting is handled in the portable
+ *   console layer, this can be a dummy implementation.  
+ */
+void os_nonstop_mode(int flag);
+
+/* 
+ *   Update progress display with current info, if appropriate.  This can
+ *   be used to provide a status display during compilation.  Most
+ *   command-line implementations will just ignore this notification; this
+ *   can be used for GUI compiler implementations to provide regular
+ *   display updates during compilation to show the progress so far.  
+ */
+/* void os_progress(const char *fname, unsigned long linenum); */
+
+/* 
+ *   Set busy cursor.  If 'flag' is true, provide a visual representation
+ *   that the system or application is busy doing work.  If 'flag' is
+ *   false, remove any visual "busy" indication and show normal status.
+ *   
+ *   We provide a prototype here if your osxxx.h header file does not
+ *   #define a macro for os_csr_busy.  On many systems, this function has
+ *   no effect at all, so the osxxx.h header file simply #define's it to
+ *   do an empty macro.  
+ */
+#ifndef os_csr_busy
+void os_csr_busy(int flag);
+#endif
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   User Input Routines
+ */
+
+/*
+ *   Ask the user for a filename, using a system-dependent dialog or other
+ *   mechanism.  Returns one of the OS_AFE_xxx status codes (see below).
+ *   
+ *   prompt_type is the type of prompt to provide -- this is one of the
+ *   OS_AFP_xxx codes (see below).  The OS implementation doesn't need to
+ *   pay any attention to this parameter, but it can be used if desired to
+ *   determine the type of dialog to present if the system provides
+ *   different types of dialogs for different types of operations.
+ *   
+ *   file_type is one of the OSFTxxx codes for system file type.  The OS
+ *   implementation is free to ignore this information, but can use it to
+ *   filter the list of files displayed if desired; this can also be used
+ *   to apply a default suffix on systems that use suffixes to indicate
+ *   file type.  If OSFTUNK is specified, it means that no filtering
+ *   should be performed, and no default suffix should be applied.  
+ */
+int os_askfile(const char *prompt, char *fname_buf, int fname_buf_len,
+               int prompt_type, os_filetype_t file_type);
+
+/* 
+ *   os_askfile status codes 
+ */
+
+/* success */
+#define OS_AFE_SUCCESS  0 
+
+/* 
+ *   Generic failure - this is largely provided for compatibility with
+ *   past versions, in which only zero and non-zero error codes were
+ *   meaningful; since TRUE is defined as 1 on most platforms, we assume
+ *   that 1 is probably the generic non-zero error code that most OS
+ *   implementations have traditionally used.  In addition, this can be
+ *   used to indicate any other error for which there is no more specific
+ *   error code.  
+ */
+#define OS_AFE_FAILURE  1
+
+/* user cancelled */
+#define OS_AFE_CANCEL   2
+
+/* 
+ *   os_askfile prompt types
+ *   
+ *   Important note: do not change these values when porting TADS.  These
+ *   values can be used by games, so they must be the same on all
+ *   platforms.  
+ */
+#define OS_AFP_OPEN    1     /* choose an existing file to open for reading */
+#define OS_AFP_SAVE    2          /* choose a filename for saving to a file */
+
+
+/* 
+ *   Read a string of input.  Fills in the buffer with a null-terminated
+ *   string containing a line of text read from the standard input.  The
+ *   returned string should NOT contain a trailing newline sequence.  On
+ *   success, returns 'buf'; on failure, including end of file, returns a
+ *   null pointer.  
+ */
+unsigned char *os_gets(unsigned char *buf, size_t bufl);
+
+/*
+ *   Read a string of input with an optional timeout.  This behaves like
+ *   os_gets(), in that it allows the user to edit a line of text (ideally
+ *   using the same editing keys that os_gets() does), showing the line of
+ *   text under construction during editing.  This routine differs from
+ *   os_gets() in that it returns if the given timeout interval expires
+ *   before the user presses Return (or the local equivalent).
+ *   
+ *   If the user presses Return before the timeout expires, we store the
+ *   command line in the given buffer, just as os_gets() would, and we return
+ *   OS_EVT_LINE.  We also update the display in the same manner that
+ *   os_gets() would, by moving the cursor to a new line and scrolling the
+ *   displayed text as needed.
+ *   
+ *   If a timeout occurs before the user presses Return, we store the command
+ *   line so far in the given buffer, statically store the cursor position,
+ *   insert mode, buffer text, and anything else relevant to the editing
+ *   state, and we return OS_EVT_TIMEOUT.
+ *   
+ *   If the implementation does not support the timeout operation, this
+ *   routine should simply return OS_EVT_NOTIMEOUT immediately when called;
+ *   the routine should not allow the user to perform any editing if the
+ *   timeout is not supported.  Callers must use the ordinary os_gets()
+ *   routine, which has no timeout capabilities, if the timeout is not
+ *   supported.
+ *   
+ *   When we return OS_EVT_TIMEOUT, the caller is responsible for doing one
+ *   of two things.
+ *   
+ *   The first possibility is that the caller performs some work that doesn't
+ *   require any display operations (in other words, the caller doesn't
+ *   invoke os_printf, os_getc, or anything else that would update the
+ *   display), and then calls os_gets_timeout() again.  In this case, we will
+ *   use the editing state that we statically stored before we returned
+ *   OS_EVT_TIMEOUT to continue editing where we left off.  This allows the
+ *   caller to perform some computation in the middle of user command editing
+ *   without interrupting the user - the extra computation is transparent to
+ *   the user, because we act as though we were still in the midst of the
+ *   original editing.
+ *   
+ *   The second possibility is that the caller wants to update the display.
+ *   In this case, the caller must call os_gets_cancel() BEFORE making any
+ *   display changes.  Then, the caller must do any post-input work of its
+ *   own, such as updating the display mode (for example, closing HTML font
+ *   tags that were opened at the start of the input).  The caller is now
+ *   free to do any display work it wants.
+ *   
+ *   If we have information stored from a previous call that was interrupted
+ *   by a timeout, and os_gets_cancel(TRUE) was never called, we will resume
+ *   editing where we left off when the cancelled call returned; this means
+ *   that we'll restore the cursor position, insertion state, and anything
+ *   else relevant.  Note that if os_gets_cancel(FALSE) was called, we must
+ *   re-display the command line under construction, but if os_gets_cancel()
+ *   was never called, we will not have to make any changes to the display at
+ *   all.
+ *   
+ *   Note that when resuming an interrupted editing session (interrupted via
+ *   os_gets_cancel()), the caller must re-display the prompt prior to
+ *   invoking this routine.
+ *   
+ *   Note that we can return OS_EVT_EOF in addition to the other codes
+ *   mentioned above.  OS_EVT_EOF indicates that an error occurred reading,
+ *   which usually indicates that the application is being terminated or that
+ *   some hardware error occurred reading the keyboard.  
+ *   
+ *   If 'use_timeout' is false, the timeout should be ignored.  Without a
+ *   timeout, the function behaves the same as os_gets(), except that it will
+ *   resume editing of a previously-interrupted command line if appropriate.
+ *   (This difference is why the timeout is optional: a caller might not need
+ *   a timeout, but might still want to resume a previous input that did time
+ *   out, in which case the caller would invoke this routine with
+ *   use_timeout==FALSE.  The regular os_gets() would not satisfy this need,
+ *   because it cannot resume an interrupted input.)
+ *   
+ *   Note that a zero timeout has the same meaning as for os_get_event(): if
+ *   input is available IMMEDIATELY, return the input, otherwise return
+ *   immediately with the OS_EVT_TIMEOUT result code.  
+ */
+int os_gets_timeout(unsigned char *buf, size_t bufl,
+                    unsigned long timeout_in_milliseconds, int use_timeout);
+
+/*
+ *   Cancel an interrupted editing session.  This MUST be called if any
+ *   output is to be displayed after a call to os_gets_timeout() returns
+ *   OS_EVT_TIMEOUT.
+ *   
+ *   'reset' indicates whether or not we will forget the input state saved
+ *   by os_gets_timeout() when it last returned.  If 'reset' is true, we'll
+ *   clear the input state, so that the next call to os_gets_timeout() will
+ *   start with an empty input buffer.  If 'reset' is false, we will retain
+ *   the previous input state, if any; this means that the next call to
+ *   os_gets_timeout() will re-display the same input buffer that was under
+ *   construction when it last returned.
+ *   
+ *   This routine need not be called if os_gets_timeout() is to be called
+ *   again with no other output operations between the previous
+ *   os_gets_timeout() call and the next one.
+ *   
+ *   Note that this routine needs only a trivial implementation when
+ *   os_gets_timeout() is not supported (i.e., the function always returns
+ *   OS_EVT_NOTIMEOUT).  
+ */
+void os_gets_cancel(int reset);
+
+/* 
+ *   Read a character from the keyboard.  For extended keystrokes, this
+ *   function returns zero, and then returns the CMD_xxx code for the
+ *   extended keystroke on the next call.  For example, if the user presses
+ *   the up-arrow key, the first call to os_getc() should return 0, and the
+ *   next call should return CMD_UP.  Refer to the CMD_xxx codes below.
+ *   
+ *   os_getc() should return a high-level, translated command code for
+ *   command editing.  This means that, where a functional interpretation of
+ *   a key and the raw key-cap interpretation both exist as CMD_xxx codes,
+ *   the functional interpretation should be returned.  For example, on Unix,
+ *   Ctrl-E is conventionally used in command editing to move to the end of
+ *   the line, following Emacs key bindings.  Hence, os_getc() should return
+ *   CMD_END for this keystroke, rather than a single 0x05 character (ASCII
+ *   Ctrl-E), because CMD_END is the high-level command code for the
+ *   operation.
+ *   
+ *   The translation ability of this function allows for system-dependent key
+ *   mappings to functional meanings.  
+ */
+int os_getc(void);
+
+/*
+ *   Read a character from the keyboard, following the same protocol as
+ *   os_getc() for CMD_xxx codes (i.e., when an extended keystroke is
+ *   encountered, os_getc_raw() returns zero, then returns the CMD_xxx code
+ *   on the subsequent call).
+ *   
+ *   This function differs from os_getc() in that this function returns the
+ *   low-level, untranslated key code whenever possible.  This means that,
+ *   when a functional interpretation of a key and the raw key-cap
+ *   interpretation both exist as CMD_xxx codes, this function returns the
+ *   key-cap interpretation.  For the Unix Ctrl-E example in the comments
+ *   describing os_getc() above, this function should return 5 (the ASCII
+ *   code for Ctrl-E), because the ASCII control character interpretation is
+ *   the low-level key code.
+ *   
+ *   This function should return all control keys using their ASCII control
+ *   codes, whenever possible.  Similarly, this function should return ASCII
+ *   27 for the Escape key, if possible.  
+ *   
+ *   For keys for which there is no portable ASCII representation, this
+ *   should return the CMD_xxx sequence.  So, this function acts exactly the
+ *   same as os_getc() for arrow keys, function keys, and other special keys
+ *   that have no ASCII representation.  This function returns a
+ *   non-translated version ONLY when an ASCII representation exists - in
+ *   practice, this means that this function and os_getc() vary only for CTRL
+ *   keys and Escape.  
+ */
+int os_getc_raw(void);
+
+
+/* wait for a character to become available from the keyboard */
+void os_waitc(void);
+
+/*
+ *   Constants for os_getc() when returning commands.  When used for
+ *   command line editing, special keys (arrows, END, etc.)  should cause
+ *   os_getc() to return 0, and return the appropriate CMD_ value on the
+ *   NEXT call.  Hence, os_getc() must keep the appropriate information
+ *   around statically for the next call when a command key is issued.
+ *   
+ *   The comments indicate which CMD_xxx codes are "translated" codes and
+ *   which are "raw"; the difference is that, when a particular keystroke
+ *   could be interpreted as two different CMD_xxx codes, one translated
+ *   and the other raw, os_getc() should always return the translated
+ *   version of the key, and os_getc_raw() should return the raw version.
+ */
+#define CMD_UP    1                        /* move up/up arrow (translated) */
+#define CMD_DOWN  2                    /* move down/down arrow (translated) */
+#define CMD_RIGHT 3                  /* move right/right arrow (translated) */
+#define CMD_LEFT  4                    /* move left/left arrow (translated) */
+#define CMD_END   5              /* move cursor to end of line (translated) */
+#define CMD_HOME  6            /* move cursor to start of line (translated) */
+#define CMD_DEOL  7                   /* delete to end of line (translated) */
+#define CMD_KILL  8                      /* delete entire line (translated) */
+#define CMD_DEL   9                /* delete current character (translated) */
+#define CMD_SCR   10                 /* toggle scrollback mode (translated) */
+#define CMD_PGUP  11                                /* page up (translated) */
+#define CMD_PGDN  12                              /* page down (translated) */
+#define CMD_TOP   13                            /* top of file (translated) */
+#define CMD_BOT   14                         /* bottom of file (translated) */
+#define CMD_F1    15                               /* function key F1 (raw) */
+#define CMD_F2    16                               /* function key F2 (raw) */
+#define CMD_F3    17                               /* function key F3 (raw) */
+#define CMD_F4    18                               /* function key F4 (raw) */
+#define CMD_F5    19                               /* function key F5 (raw) */
+#define CMD_F6    20                               /* function key F6 (raw) */
+#define CMD_F7    21                               /* function key F7 (raw) */
+#define CMD_F8    22                               /* function key F8 (raw) */
+#define CMD_F9    23                               /* function key F9 (raw) */
+#define CMD_F10   24                              /* function key F10 (raw) */
+#define CMD_CHOME 25                                  /* control-home (raw) */
+#define CMD_TAB   26                                    /* tab (translated) */
+#define CMD_SF2   27                                      /* shift-F2 (raw) */
+/* not used (obsolete) - 28 */
+#define CMD_WORD_LEFT  29      /* word left (ctrl-left on dos) (translated) */
+#define CMD_WORD_RIGHT 30    /* word right (ctrl-right on dos) (translated) */
+#define CMD_WORDKILL 31                   /* delete word right (translated) */
+#define CMD_EOF   32                                   /* end-of-file (raw) */
+#define CMD_BREAK 33     /* break (Ctrl-C or local equivalent) (translated) */
+#define CMD_INS   34                                    /* insert key (raw) */
+
+
+/*
+ *   ALT-keys - add alphabetical code to CMD_ALT: ALT-A == CMD_ALT + 0,
+ *   ALT-B == CMD_ALT + 1, ALT-C == CMD_ALT + 2, etc
+ *   
+ *   These keys are all raw (untranslated).  
+ */
+#define CMD_ALT   128                                  /* start of ALT keys */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Event information structure for os_get_event.  The appropriate union
+ *   member should be filled in, depending on the type of event that
+ *   occurs. 
+ */
+union os_event_info_t
+{
+    /* 
+     *   OS_EVT_KEY - this returns the one or two characters of the
+     *   keystroke.  If the key is an extended key, so that os_getc() would
+     *   return a two-character sequence for the keystroke, the first
+     *   character should be zero and the second the extended key code.
+     *   Otherwise, the first character should simply be the ASCII key code.
+     *   
+     *   The key code here is the "raw" keycode, equivalent to the codes
+     *   returned by os_getc_raw().  Note in particular that this means that
+     *   CTRL and Escape keys are presented as one-byte ASCII control
+     *   characters, not as two-byte CMD_xxx sequences.  
+     *   
+     *   For multi-byte character sets (Shift-JIS, for example), note that
+     *   os_get_event() must NOT return a complete two-byte character here.
+     *   The two bytes here are exclusively used to represent special
+     *   CMD_xxx keys (such as arrow keys and function keys).  For a
+     *   keystroke that is represented in a multi-byte character set using
+     *   more than one byte, os_get_event() must return a series of events.
+     *   Return an ordinary OS_EVT_KEY for the first byte of the sequence,
+     *   putting the byte in key[0]; then, return the second byte as a
+     *   separate OS_EVT_KEY as the next event; and so on for any additional
+     *   bytes.  This will allow callers that are not multibyte-aware to
+     *   treat multi-byte characters as though they were sequences of
+     *   one-byte characters.  
+     */
+    int key[2];
+
+    /*
+     *   OS_EVT_HREF - this returns the text of the HREF as a
+     *   null-terminated string.  
+     */
+    char href[256];
+
+    /* command ID (for OS_EVT_COMMAND) */
+    int cmd_id;
+};
+typedef union os_event_info_t os_event_info_t;
+
+/*
+ *   Event types for os_get_event 
+ */
+
+/* invalid/no event */
+#define OS_EVT_NONE      0x0000
+
+/* OS_EVT_KEY - user typed a key on the keyboard */
+#define OS_EVT_KEY       0x0001
+
+/* OS_EVT_TIMEOUT - no event occurred before the timeout elapsed */
+#define OS_EVT_TIMEOUT   0x0002
+
+/* 
+ *   OS_EVT_HREF - user clicked on a <A HREF> link.  This only applies to
+ *   the HTML-enabled run-time. 
+ */
+#define OS_EVT_HREF      0x0003
+
+/* 
+ *   OS_EVT_NOTIMEOUT - caller requested a timeout, but timeout is not
+ *   supported by this version of the run-time 
+ */
+#define OS_EVT_NOTIMEOUT 0x0004
+
+/*
+ *   OS_EVT_EOF - an error occurred reading the event.  This generally
+ *   means that the application is quitting or we can no longer read from
+ *   the keyboard or terminal. 
+ */
+#define OS_EVT_EOF       0x0005
+
+/* 
+ *   OS_EVT_LINE - user entered a line of text on the keyboard.  This event
+ *   is not returned from os_get_event(), but rather from os_gets_timeout().
+ */
+#define OS_EVT_LINE      0x0006
+
+
+/*
+ *   Get an input event.  The event types are shown above.  If use_timeout is
+ *   false, this routine should simply wait until one of the events it
+ *   recognizes occurs, then return the appropriate information on the event.
+ *   If use_timeout is true, this routine should return OS_EVT_TIMEOUT after
+ *   the given number of milliseconds elapses if no event occurs first.
+ *   
+ *   This function is not obligated to obey the timeout.  If a timeout is
+ *   specified and it is not possible to obey the timeout, the function
+ *   should simply return OS_EVT_NOTIMEOUT.  The trivial implementation thus
+ *   checks for a timeout, returns an error if specified, and otherwise
+ *   simply waits for the user to press a key.
+ *   
+ *   A timeout value of 0 does *not* mean that there's no timeout (i.e., it
+ *   doesn't mean we should wait indefinitely) - that's specified by passing
+ *   FALSE for use_timeout.  A zero timeout also doesn't meant that the
+ *   function should unconditionally return OS_EVT_TIMEOUT.  Instead, a zero
+ *   timeout specifically means that IF an event is available IMMEDIATELY,
+ *   without blocking the thread, we should return that event; otherwise we
+ *   should immediately return a timeout event.  
+ */
+int os_get_event(unsigned long timeout_in_milliseconds, int use_timeout,
+                 os_event_info_t *info);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Extended os_get_event() codes.
+ *   
+ *   THESE ARE NOT USED in the basic osifc implementation - these are only
+ *   used if the interpreter supports the "extended" interface defined in
+ *   osifcext.h.  
+ */
+
+/*
+ *   System menu command event.  Some interpreters (such as HTML TADS for
+ *   Windows) provide menu commands for common system-level game verbs -
+ *   SAVE, RESTORE, UNDO, QUIT.  By default, these commands are returned as
+ *   literal command strings ("save", "restore", etc) via os_gets(), as
+ *   though the user had typed the commands at the keyboard.  The extended OS
+ *   interface allows the program to receive these commands via
+ *   os_get_event().  When a command is enabled for os_get_event() via the
+ *   extended OS interface, and the player selects the command via a menu (or
+ *   toolbar button, etc) during a call to os_get_event(), os_get_event()
+ *   returns this event code, with the menu ID stored in the cmd_id field of
+ *   the event structure.  
+ */
+#define OS_EVT_COMMAND   0x0100
+
+/* command IDs for OS_EVT_COMMAND */
+#define OS_CMD_NONE      0x0000     /* invalid command ID, for internal use */
+#define OS_CMD_SAVE      0x0001                                /* save game */
+#define OS_CMD_RESTORE   0x0002                             /* restore game */
+#define OS_CMD_UNDO      0x0003                           /* undo last turn */
+#define OS_CMD_QUIT      0x0004                                /* quit game */
+#define OS_CMD_CLOSE     0x0005                    /* close the game window */
+#define OS_CMD_HELP      0x0006                           /* show game help */
+
+/* highest command ID used in this version of the interface */
+#define OS_CMD_LAST      0x0006
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Ask for input through a dialog.
+ *   
+ *   'prompt' is a text string to display as a prompting message.  For
+ *   graphical systems, this message should be displayed in the dialog;
+ *   for text systems, this should be displayed on the terminal after a
+ *   newline.
+ *   
+ *   'standard_button_set' is one of the OS_INDLG_xxx values defined
+ *   below, or zero.  If this value is zero, no standard button set is to
+ *   be used; the custom set of buttons defined in 'buttons' is to be used
+ *   instead.  If this value is non-zero, the appropriate set of standard
+ *   buttons, with labels translated to the local language if possible, is
+ *   to be used.
+ *   
+ *   'buttons' is an array of strings to use as button labels.
+ *   'button_count' gives the number of entries in the 'buttons' array.
+ *   'buttons' and 'button_count' are ignored if 'standard_button_set' is
+ *   non-zero, since a standard set of buttons is used instead.  If
+ *   'buttons' and 'button_count' are to be used, each entry contains the
+ *   label of a button to show.  
+ */
+/*   
+ *   An ampersand ('&') character in a label string indicates that the
+ *   next character after the '&' is to be used as the short-cut key for
+ *   the button, if supported.  The '&' should NOT be displayed in the
+ *   string; instead, the character should be highlighted according to
+ *   local system conventions.  On Windows, for example, the short-cut
+ *   character should be shown underlined; on a text display, the response
+ *   might be shown with the short-cut character enclosed in parentheses.
+ *   If there is no local convention for displaying a short-cut character,
+ *   then the '&' should simply be removed from the displayed text.  
+ *   
+ *   The short-cut key specified by each '&' character should be used in
+ *   processing responses.  If the user presses the key corresponding to a
+ *   button's short-cut, the effect should be the same as if the user
+ *   clicked the button with the mouse.  If local system conventions don't
+ *   allow for short-cut keys, any short-cut keys can be ignored.
+ *   
+ *   'default_index' is the 1-based index of the button to use as the
+ *   default.  If this value is zero, there is no default response.  If
+ *   the user performs the appropriate system-specific action to select
+ *   the default response for the dialog, this is the response that is to
+ *   be selected.  On Windows, for example, pressing the "Return" key
+ *   should select this item.
+ *   
+ *   'cancel_index' is the 1-based index of the button to use as the
+ *   cancel response.  If this value is zero, there is no cancel response.
+ *   This is the response to be used if the user cancels the dialog using
+ *   the appropriate system-specific action.  On Windows, for example,
+ *   pressing the "Escape" key should select this item.  
+ */
+/*
+ *   icon_id is one of the OS_INDLG_ICON_xxx values defined below.  If
+ *   possible, an appropriate icon should be displayed in the dialog.
+ *   This can be ignored in text mode, and also in GUI mode if there is no
+ *   appropriate system icon.
+ *   
+ *   The return value is the 1-based index of the response selected.  If
+ *   an error occurs, return 0.  
+ */
+int os_input_dialog(int icon_id, const char *prompt, int standard_button_set,
+                    const char **buttons, int button_count,
+                    int default_index, int cancel_index);
+
+/*
+ *   Standard button set ID's 
+ */
+
+/* OK */
+#define OS_INDLG_OK            1
+
+/* OK, Cancel */
+#define OS_INDLG_OKCANCEL      2
+
+/* Yes, No */
+#define OS_INDLG_YESNO         3
+
+/* Yes, No, Cancel */
+#define OS_INDLG_YESNOCANCEL   4
+
+/*
+ *   Dialog icons 
+ */
+
+/* no icon */
+#define OS_INDLG_ICON_NONE     0
+
+/* warning */
+#define OS_INDLG_ICON_WARNING  1
+
+/* information */
+#define OS_INDLG_ICON_INFO     2
+
+/* question */
+#define OS_INDLG_ICON_QUESTION 3
+
+/* error */
+#define OS_INDLG_ICON_ERROR    4
+
+
+
+/* ------------------------------------------------------------------------ */
+/* 
+ *   OS main entrypoint 
+ */
+int os0main(int oargc, char **oargv,
+            int (*mainfn)(int, char **, char *), 
+            const char *before, const char *config);
+
+/* 
+ *   new-style OS main entrypoint - takes an application container context 
+ */
+int os0main2(int oargc, char **oargv,
+             int (*mainfn)(int, char **, struct appctxdef *, char *),
+             const char *before, const char *config,
+             struct appctxdef *appctx);
+
+/*
+ *   OBSOLETE - Get filename from startup parameter, if possible; returns
+ *   true and fills in the buffer with the parameter filename on success,
+ *   false if no parameter file could be found.
+ *   
+ *   (This was used until TADS 2.2.5 for the benefit of the Mac interpreter,
+ *   and interpreters on systems with similar desktop shells, to allow the
+ *   user to launch the terp by double-clicking on a saved game file.  The
+ *   terp would read the launch parameters, discover that a saved game had
+ *   been used to invoke it, and would then stash away the saved game info
+ *   for later retrieval from this function.  This functionality was replaced
+ *   in 2.2.5 with a command-line parameter: the terp now uses the desktop
+ *   launch data to synthesize a suitable argv[] vectro to pass to os0main()
+ *   or os0main2().  This function should now simply be stubbed out - it
+ *   should simply return FALSE.)  
+ */
+int os_paramfile(char *buf);
+
+/* 
+ *   Initialize.  This should be called during program startup to
+ *   initialize the OS layer and check OS-specific command-line arguments.
+ *   
+ *   If 'prompt' and 'buf' are non-null, and there are no arguments on the
+ *   given command line, the OS code can use the prompt to ask the user to
+ *   supply a filename, then store the filename in 'buf' and set up
+ *   argc/argv to give a one-argument command string.  (This mechanism for
+ *   prompting for a filename is obsolescent, and is retained for
+ *   compatibility with a small number of existing implementations only;
+ *   new implementations should ignore this mechanism and leave the
+ *   argc/argv values unchanged.)  
+ */
+int os_init(int *argc, char *argv[], const char *prompt,
+            char *buf, int bufsiz);
+
+/*
+ *   Termination functions.  There are three main termination functions,
+ *   described individually below; here's a brief overview of the
+ *   relationship among the functions.  The important thing to realize is
+ *   that these functions have completely independent purposes; they should
+ *   never call one another, and they should never do any of the work that's
+ *   intended for the others.
+ *   
+ *   os_uninit() is meant to undo the effects of os_init().  On many
+ *   systems, os_init() has some global effect, such as setting the terminal
+ *   to some special input or output mode.  os_uninit's purpose is to undo
+ *   these global effects, returning the terminal mode (and whatever else)
+ *   to the conditions they were in at program startup.  Portable callers
+ *   are meant to call this routine at some point before terminating if they
+ *   ever called os_init().  Note that this routine DOES NOT terminate the
+ *   program - it should simply undo anything that os_init() did and return,
+ *   to let the caller do any additional termination work of its own.
+ *   
+ *   os_expause() optionally pauses before termination, to allow the user to
+ *   acknowledge any text the program displays just before exiting.  This
+ *   doesn't have to do anything at all, but it's useful on systems where
+ *   program termination will do something drastic like close the window:
+ *   without a pause, the user wouldn't have a chance to read any text the
+ *   program displayed after the last interactive input, because the window
+ *   would abruptly disappear moments after the text was displayed.  For
+ *   systems where termination doesn't have such drastic effects, there's no
+ *   need to do anything in this routine.  Because it's up to this routine
+ *   whether or not to pause, this routine must display a prompt if it's
+ *   going to pause for user input - the portable caller obviously can't do
+ *   so, because the caller doesn't know if the routine is going to pause or
+ *   not (so if the caller displayed a prompt assuming the routine would
+ *   pause, the prompt would show up even on systems where there actually is
+ *   no pause, which would be confusing).  This routine DOES NOT terminate
+ *   the program; it simply pauses if necessary to allow the user to
+ *   acknowledge the last bit of text the program displayed, then returns to
+ *   allow the caller to carry on with its own termination work.
+ *   
+ *   os_term() is meant to perform the same function as the C standard
+ *   library routine exit(): this actually terminates the program, exiting
+ *   to the operating system.  This routine is not meant to return to its
+ *   caller, because it's supposed to exit the program directly.  For many
+ *   systems, this routine can simply call exit(); the portable code calls
+ *   this routine instead of calling exit() directly, because some systems
+ *   have their own OS-specific way of terminating rather than using exit().
+ *   This routine MUST NOT undo the effects of os_init(), because callers
+ *   might not have ever called os_init(); callers are required to call
+ *   os_uninit() if they ever called os_init(), before calling os_term(), so
+ *   this routine can simply assume that any global modes set by os_init()
+ *   have already been undone by the time this is called.  
+ */
+
+/*
+ *   Uninitialize.  This is called prior to progam termination to reverse
+ *   the effect of any changes made in os_init().  For example, if
+ *   os_init() put the terminal in raw mode, this should restore the
+ *   previous terminal mode.  This routine should not terminate the
+ *   program (so don't call exit() here) - the caller might have more
+ *   processing to perform after this routine returns.  
+ */
+void os_uninit(void);
+
+/* 
+ *   Pause prior to exit, if desired.  This is meant to be called by
+ *   portable code just before the program is to be terminated; it can be
+ *   implemented to show a prompt and wait for user acknowledgment before
+ *   proceeding.  This is useful for implementations that are using
+ *   something like a character-mode terminal window running on a graphical
+ *   operating system: this gives the implementation a chance to pause
+ *   before exiting, so that the window doesn't just disappear
+ *   unceremoniously.
+ *   
+ *   This is allowed to do nothing at all.  For regular character-mode
+ *   systems, this routine usually doesn't do anything, because when the
+ *   program exits, the terminal will simply return to the OS command
+ *   prompt; none of the text displayed just before the program exited will
+ *   be lost, so there's no need for any interactive pause.  Likewise, for
+ *   graphical systems where the window will remain open, even after the
+ *   program exits, until the user explicitly closes the window, there's no
+ *   need to do anything here.
+ *   
+ *   If this is implemented to pause, then this routine MUST show some kind
+ *   of prompt to let the user know we're waiting.  In the simple case of a
+ *   text-mode terminal window on a graphical OS, this should simply print
+ *   out some prompt text ("Press a key to exit...") and then wait for the
+ *   user to acknowledge the prompt (by pressing a key, for example).  For
+ *   graphical systems, the prompt could be placed in the window's title
+ *   bar, or status-bar, or wherever is appropriate for the OS.  
+ */
+void os_expause(void);
+
+/* 
+ *   Terminate.  This should exit the program with the given exit status.
+ *   In general, this should be equivalent to the standard C library
+ *   exit() function, but we define this interface to allow the OS code to
+ *   do any necessary pre-termination cleanup.  
+ */
+void os_term(int status);
+
+/* 
+ *   Install/uninstall the break handler.  If possible, the OS code should
+ *   set (if 'install' is true) or clear (if 'install' is false) a signal
+ *   handler for keyboard break signals (control-C, etc, depending on
+ *   local convention).  The OS code should set its own handler routine,
+ *   which should note that a break occurred with an internal flag; the
+ *   portable code uses os_break() from time to time to poll this flag.  
+ */
+void os_instbrk(int install);
+
+/*
+ *   Check for user break ("control-C", etc) - returns true if a break is
+ *   pending, false if not.  If this returns true, it should "consume" the
+ *   pending break (probably by simply clearing the OS code's internal
+ *   break-pending flag).  
+ */
+int os_break(void);
+
+/*
+ *   Sleep for a given interval.  This should simply pause for the given
+ *   number of milliseconds, then return.  On multi-tasking systems, this
+ *   should use a system API to suspend the current process for the desired
+ *   delay; on single-tasking systems, this can simply sit in a wait loop
+ *   until the desired interval has elapsed.  
+ */
+void os_sleep_ms(long delay_in_milliseconds);
+
+/*
+ *   Yield CPU; returns TRUE if user requested an interrupt (a "control-C"
+ *   type of operation to abort the entire program), FALSE to continue.
+ *   Portable code should call this routine from time to time during lengthy
+ *   computations that don't involve any UI operations; if practical, this
+ *   routine should be invoked roughly every 10 to 100 milliseconds.
+ *   
+ *   The purpose of this routine is to support "cooperative multitasking"
+ *   systems, such as pre-X MacOS, where it's necessary for each running
+ *   program to call the operating system explicitly in order to yield the
+ *   CPU from time to time to other concurrently running programs.  On
+ *   cooperative multitasking systems, a program can only lose control of
+ *   the CPU by making specific system calls, usually related to GUI events;
+ *   a program can never lose control of the CPU asynchronously.  So, a
+ *   program that performs lengthy computations without any UI interaction
+ *   can cause the rest of the system to freeze up until the computations
+ *   are finished; but if a compute-intensive program explicitly yields the
+ *   CPU from time to time, it allows other programs to remain responsive.
+ *   Yielding the CPU at least every 100 milliseconds or so will generally
+ *   allow the UI to remain responsive; yielding more frequently than every
+ *   10 ms or so will probably start adding noticeable overhead.
+ *   
+ *   On single-tasking systems (such as MS-DOS), there's only one program
+ *   running at a time, so there's no need to yield the CPU; on virtually
+ *   every modern system, the OS automatically schedules CPU time without
+ *   the running programs having any say in the matter, so again there's no
+ *   need for a program to yield the CPU.  For systems where this routine
+ *   isn't needed, the system header should simply #define os_yield to
+ *   something like "((void)0)" - this will allow the compiler to completely
+ *   ignore calls to this routine for systems where they aren't needed.
+ *   
+ *   Note that this routine is NOT meant to provide scheduling hinting to
+ *   modern systems with true multitasking, so a trivial implementation is
+ *   fine for any modern system.  
+ */
+#ifndef os_yield
+int os_yield(void);
+#endif
+
+/*
+ *   Set the default saved-game extension.  This routine will NOT be called
+ *   when we're using the standard saved game extension; this routine will be
+ *   invoked only if we're running as a stand-alone game, and the game author
+ *   specified a non-standard saved-game extension when creating the
+ *   stand-alone game.
+ *   
+ *   This routine is not required if the system does not use the standard,
+ *   semi-portable os0.c implementation.  Even if the system uses the
+ *   standard os0.c implementation, it can provide an empty routine here if
+ *   the system code doesn't need to do anything special with this
+ *   information.
+ *   
+ *   The extension is specified as a null-terminated string.  The extension
+ *   does NOT include the leading period.  
+ */
+void os_set_save_ext(const char *ext);
+
+/* 
+ *   Get the saved game extension previously set with os_set_save_ext().
+ *   Returns null if no custom extension has been set.
+ */
+const char *os_get_save_ext();
+
+
+/* ------------------------------------------------------------------------*/
+/*
+ *   Translate a character from the HTML 4 Unicode character set to the
+ *   current character set used for display.  Takes an HTML 4 character
+ *   code and returns the appropriate local character code.
+ *   
+ *   The result buffer should be filled in with a null-terminated string
+ *   that should be used to represent the character.  Multi-character
+ *   results are possible, which may be useful for certain approximations
+ *   (such as using "(c)" for the copyright symbol).
+ *   
+ *   Note that we only define this prototype if this symbol isn't already
+ *   defined as a macro, which may be the case on some platforms.
+ *   Alternatively, if the function is already defined (for example, as an
+ *   inline function), the defining code can define OS_XLAT_HTML4_DEFINED,
+ *   in which case we'll also omit this prototype.
+ *   
+ *   Important: this routine provides the *default* mapping that is used
+ *   when no external character mapping file is present, and for any named
+ *   entities not defined in the mapping file.  Any entities in the
+ *   mapping file, if used, will override this routine.
+ *   
+ *   A trivial implementation of this routine (that simply returns a
+ *   one-character result consisting of the original input character,
+ *   truncated to eight bits if necessary) can be used if you want to
+ *   require an external mapping file to be used for any game that
+ *   includes HTML character entities.  The DOS version implements this
+ *   routine so that games will still look reasonable when played with no
+ *   mapping file present, but other systems are not required to do this.  
+ */
+#ifndef os_xlat_html4
+# ifndef OS_XLAT_HTML4_DEFINED
+void os_xlat_html4(unsigned int html4_char,
+                   char *result, size_t result_buf_len);
+# endif
+#endif
+
+/*
+ *   Generate a filename for a character-set mapping file.  This function
+ *   should determine the current native character set in use, if
+ *   possible, then generate a filename, according to system-specific
+ *   conventions, that we should attempt to load to get a mapping between
+ *   the current native character set and the internal character set
+ *   identified by 'internal_id'.
+ *   
+ *   The internal character set ID is a string of up to 4 characters.
+ *   
+ *   On DOS, the native character set is a DOS code page.  DOS code pages
+ *   are identified by 3- or 4-digit identifiers; for example, code page
+ *   437 is the default US ASCII DOS code page.  We generate the
+ *   character-set mapping filename by appending the internal character
+ *   set identifier to the DOS code page number, then appending ".TCP" to
+ *   the result.  So, to map between ISO Latin-1 (internal ID = "La1") and
+ *   DOS code page 437, we would generate the filename "437La1.TCP".
+ *   
+ *   Note that this function should do only two things.  First, determine
+ *   the current native character set that's in use.  Second, generate a
+ *   filename based on the current native code page and the internal ID.
+ *   This function is NOT responsible for figuring out the mapping or
+ *   anything like that -- it's simply where we generate the correct
+ *   filename based on local convention.
+ *   
+ *   'filename' is a buffer of at least OSFNMAX characters.
+ *   
+ *   'argv0' is the executable filename from the original command line.
+ *   This parameter is provided so that the system code can look for
+ *   mapping files in the original TADS executables directory, if desired.
+ */
+void os_gen_charmap_filename(char *filename, char *internal_id,
+                             char *argv0);
+
+/*
+ *   Receive notification that a character mapping file has been loaded.
+ *   The caller doesn't require this routine to do anything at all; this
+ *   is purely for the system-dependent code's use so that it can take
+ *   care of any initialization that it must do after the caller has
+ *   loaded a charater mapping file.  'id' is the character set ID, and
+ *   'ldesc' is the display name of the character set.  'sysinfo' is the
+ *   extra system information string that is stored in the mapping file;
+ *   the interpretation of this information is up to this routine.
+ *   
+ *   For reference, the Windows version uses the extra information as a
+ *   code page identifier, and chooses its default font character set to
+ *   match the code page.  On DOS, the run-time requires the player to
+ *   activate an appropriate code page using a DOS command (MODE CON CP
+ *   SELECT) prior to starting the run-time, so this routine doesn't do
+ *   anything at all on DOS. 
+ */
+void os_advise_load_charmap(const char *id, const char *ldesc, const char *sysinfo);
+
+/*
+ *   Generate the name of the character set mapping table for Unicode
+ *   characters to and from the given local character set.  Fills in the
+ *   buffer with the implementation-dependent name of the desired
+ *   character set map.  See below for the character set ID codes.
+ *   
+ *   For example, on Windows, the implementation would obtain the
+ *   appropriate active code page (which is simply a Windows character set
+ *   identifier number) from the operating system, and build the name of
+ *   the Unicode mapping file for that code page, such as "CP1252".  On
+ *   Macintosh, the implementation would look up the current script system
+ *   and return the name of the Unicode mapping for that script system,
+ *   such as "ROMAN" or "CENTEURO".
+ *   
+ *   If it is not possible to determine the specific character set that is
+ *   in use, this function should return "asc7dflt" (ASCII 7-bit default)
+ *   as the character set identifier on an ASCII system, or an appropriate
+ *   base character set name on a non-ASCII system.  "asc7dflt" is the
+ *   generic character set mapping for plain ASCII characters.
+ *   
+ *   The given buffer must be at least 32 bytes long; the implementation
+ *   must limit the result it stores to 32 bytes.  (We use a fixed-size
+ *   buffer in this interface for simplicity, and because there seems no
+ *   need for greater flexibility in the interface; a character set name
+ *   doesn't carry very much information so shouldn't need to be very
+ *   long.  Note that this function doesn't generate a filename, but
+ *   simply a mapping name; in practice, a map name will be used to
+ *   construct a mapping file name.)
+ *   
+ *   Because this function obtains the Unicode mapping name, there is no
+ *   need to specify the internal character set to be used: the internal
+ *   character set is Unicode.  
+ */
+/*
+ *   Implementation note: when porting this routine, the convention that
+ *   you use to name your mapping files is up to you.  You should simply
+ *   choose a convention for this implementation, and then use the same
+ *   convention for packaging the mapping files for your OS release.  In
+ *   most cases, the best convention is to use the names that the Unicode
+ *   consortium uses in their published cross-mapping listings, since
+ *   these listings can be used as the basis of the mapping files that you
+ *   include with your release.  For example, on Windows, the convention
+ *   is to use the code page number to construct the map name, as in
+ *   CP1252 or CP1250.  
+ */
+void os_get_charmap(char *mapname, int charmap_id);
+
+/*
+ *   Character map for the display (i.e., for the user interface).  This
+ *   is the character set which is used for input read from the keyboard,
+ *   and for output displayed on the monitor or terminal.  
+ */
+#define OS_CHARMAP_DISPLAY     1
+
+/* 
+ *   Character map for mapping filename strings.  This should identify the
+ *   character set currently in use on the local system for filenames
+ *   (i.e., for strings identifying objects in the local file system),
+ *   providing a suitable name for use in opening a mapping file.
+ *   
+ *   On many platforms, the entire system uses only one character set at
+ *   the OS level, so the file system character set is the same as the
+ *   display character set.  Some systems define a particular character
+ *   set for file system use, though, because different users might be
+ *   running applications on terminals that display different character
+ *   sets.  
+ */
+#define OS_CHARMAP_FILENAME    2
+
+/*
+ *   Default character map for file contents.  On most systems, this will
+ *   be the same as display.  On some systems, it won't be possible to
+ *   know in general what character set files use; in fact, this isn't
+ *   possible anywhere, since a file might have been copied without
+ *   translation from a different type of computer using a different
+ *   character set.  So, this isn't meant to provide a reliable choice of
+ *   character set for any arbitrary file; it's simply meant to be a good
+ *   guess that most files on this system are likely to use.  
+ */
+#define OS_CHARMAP_FILECONTENTS  3
+
+/*
+ *   Default character map for the command line.  This is the maping we use
+ *   to interpret command line arguments passed to our main() or equivalent.
+ *   On most systems, this will be the same as the display character set.
+ */
+#define OS_CHARMAP_CMDLINE     4
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   External Banner Interface.  This interface provides the ability to
+ *   divide the display window into multiple sub-windows, each with its own
+ *   independent contents.
+ *   
+ *   To determine where a new banner is displayed, we look at the banners as
+ *   a tree, rooted at the "main window," the special banner that the system
+ *   automatically creates initially for the main game text.  We start by
+ *   allocating the entire display (or the entire application window, if
+ *   we're running on a GUI system) to the main window.  We then traverse
+ *   the tree, starting with the root window's children.  For each child
+ *   window, we allocate space for the child out of the parent window's
+ *   area, according to the child's alignment and size settings, and deduct
+ *   this space from the parent window's size.  We then lay out the children
+ *   of the child.
+ *   
+ *   For each banner window, we take its requested space out of the parent
+ *   window's area by starting at the edge of the parent window rectangle as
+ *   indicated by the banner's alignment, and taking the requested `width
+ *   (for a left/right banner) or height (for a top/bottom banner), limiting
+ *   to the available width/height in the parent window's space.  Give the
+ *   banner the full extent of the parent's space in its other dimension (so
+ *   a left/right banner gets the full height of the parent space, and a
+ *   top/bottom banner gets the full width).
+ *   
+ *   Note that the layout proceeds exclusively down the tree (i.e., from the
+ *   root to children to grandchildren, and so on).  It *appears* that a
+ *   child affects its parent, because of the deduction step: a child
+ *   acquires screen space by carving out a chunk of its parent.  The right
+ *   way to think about this, though, is that the parent's full area is the
+ *   union of the parent window and all of its children; when viewed this
+ *   way, the parent's full area is fully determined the instant the parent
+ *   is laid out, and never changes as its children are laid out.  Note in
+ *   particular that a child can never make a parent larger; the only thing
+ *   a child can do to a parent is carve out a chunk of the parent for
+ *   itself, which doesn't affect the boundaries of the union of the parent
+ *   plus its children.
+ *   
+ *   Note also that if the banner has a border, and the implementation
+ *   actually draws borders, the border must be drawn for the *full* area of
+ *   the banner, as defined above.  For example, suppose we have two
+ *   borders: banner A is a child of the main window, is top-aligned, and
+ *   has a border.  Banner B is a child of banner A, right-aligned, with no
+ *   border.  Obviously, without considering banner B, banner A's space runs
+ *   across the entire width of the main window, so its border (at the
+ *   bottom of its area) runs across the entire width of the main window.
+ *   Banner B carves out some space from A's right side for itself, so
+ *   banner A's actual on-screen area runs from the left edge of the main
+ *   window to banner B's left edge.  However, even though banner A itself
+ *   no longer runs the full width of the main window, banner A's *full*
+ *   area - that is, the union of banner A's on-screen area and all of its
+ *   children's full areas - does still run the entire width of the main
+ *   window, hence banner A's border must still run the full width of the
+ *   main window.  The simple way of looking at this is that a banner's
+ *   border is always to be drawn exactly the same way, regardless of
+ *   whether or not the banner has children - simply draw the banner as it
+ *   would be drawn if the banner had no children.
+ *   
+ *   Each time a banner is added or removed, we must recalculate the layout
+ *   of the remaining banners and main text area.  The os_banner_xxx()
+ *   implementation is responsible for this layout refiguring.
+ *   
+ *   The entire external banner window interface is optional, although the
+ *   functions must at least be defined as dummies to avoid linker errors
+ *   when building.  If a platform doesn't implement this feature,
+ *   os_banner_create() should simply return null, and the other routines
+ *   can do nothing.  
+ */
+
+/* 
+ *   Create a banner window.  'info' gives the desired parameters for the new
+ *   banner.
+ *   
+ *   Note that certain requested parameter settings might or might not be
+ *   respected, depending on the capabilities of the platform and user
+ *   preferences.  os_banner_getinfo() can be used after creation to
+ *   determine which parameter settings are actually used in the new banner.
+ *   
+ *   'parent' gives the parent of this banner; this is the banner handle of
+ *   another banner window, or null.  If 'parent' is null, then the new
+ *   banner is a child of the main window, which the system creates
+ *   automatically at startup and which contains the main input/output
+ *   transcript.  The new banner's on-screen area is carved out of the
+ *   parent's space, according to the alignment and size settings of the new
+ *   window, so this determines how the window is laid out on the screen.
+ *   
+ *   'where' is OS_BANNER_FIRST to make the new window the first child of its
+ *   parent; OS_BANNER_LAST to make it the last child of its parent;
+ *   OS_BANNER_BEFORE to insert it immediately before the existing banner
+ *   identified by handle in 'other'; or OS_BANNER_AFTER to insert
+ *   immediately after 'other'.  When BEFORE or AFTER is used, 'other' must
+ *   be another child of the same parent; if it is not, the routine should
+ *   act as though 'where' were given as OS_BANNER_LAST.
+ *   
+ *   'other' is a banner handle for an existing banner window.  This is used
+ *   to specify the relative position among children of the new banner's
+ *   parent, if 'where' is either OS_BANNER_BEFORE or OS_BANNER_AFTER.  If
+ *   'where' is OS_BANNER_FIRST or OS_BANNER_LAST, 'other' is ignored.
+ *   
+ *   'wintype' is the type of the window.  This is one of the
+ *   OS_BANNER_TYPE_xxx codes indicating what kind of window is desired.
+ *   
+ *   'align' is the banner's alignment, given as an OS_BANNER_ALIGN_xxx
+ *   value.  Top/bottom banners are horizontal: they run across the full
+ *   width of the existing main text area.  Left/right banners are vertical:
+ *   they run down the full height of the existing main text area.
+ *   
+ *   'siz' is the requested size of the new banner.  The meaning of 'siz'
+ *   depends on the value of 'siz_units', which can be OS_BANNER_SIZE_PCT to
+ *   set the size as a percentage of the REMAINING space, or
+ *   OS_BANNER_SIZE_ABS to set an absolute size in the "natural" units of the
+ *   window.  The natural units vary by window type: for text and text grid
+ *   windows, this is in rows/columns of '0' characters in the default font
+ *   for the window.  Note that when OS_BANNER_SIZE_ABS is used in a text or
+ *   text grid window, the OS implementation MUST add the space needed for
+ *   margins and borders when determining the actual pixel size of the
+ *   window; in other words, the window should be large enough that it can
+ *   actually display the given number or rows or columns.
+ *   
+ *   The size is interpreted as a width or height according to the window's
+ *   orientation.  For a TOP or BOTTOM banner, the size is the height; for a
+ *   LEFT or RIGHT banner, the size is the width.  A banner has only one
+ *   dimension's size given, since the other dimension's size is determined
+ *   automatically by the layout rules.
+ *   
+ *   Note that the window's size can be changed later using
+ *   banner_size_to_contents() or banner_set_size().
+ *   
+ *   'style' is a combination of OS_BANNER_STYLE_xxx flags - see below.  The
+ *   style flags give the REQUESTED style for the banner, which might or
+ *   might not be respected, depending on the platform's capabilities, user
+ *   preferences, and other factors.  os_banner_getinfo() can be used to
+ *   determine which style flags are actually used.
+ *   
+ *   Returns the "handle" to the new banner window, which is an opaque value
+ *   that is used in subsequent os_banner_xxx calls to operate on the window.
+ *   Returns null if the window cannot be created.  An implementation is not
+ *   required to support this functionality at all, and can subset it if it
+ *   does support it (for example, an implementation could support only
+ *   top/bottom-aligned banners, but not left/right-aligned), so callers must
+ *   be prepared for this routine to return null.  
+ */
+void *os_banner_create(void *parent, int where, void *other, int wintype,
+                       int align, int siz, int siz_units,
+                       unsigned long style);
+
+
+/*
+ *   insertion positions 
+ */
+#define OS_BANNER_FIRST   1
+#define OS_BANNER_LAST    2
+#define OS_BANNER_BEFORE  3
+#define OS_BANNER_AFTER   4
+
+/*
+ *   banner types 
+ */
+
+/* 
+ *   Normal text stream window.  This is a text stream that behaves
+ *   essentially like the main text window: text is displayed to this
+ *   through os_banner_disp(), always in a stream-like fashion by adding new
+ *   text to the end of any exiting text.
+ *   
+ *   Systems that use proportional fonts should usually simply use the same
+ *   font they use by default in the main text window.  However, note that
+ *   the OS_BANNER_STYLE_TAB_ALIGN style flag might imply that a fixed-pitch
+ *   font should be used even when proportional fonts are available, because
+ *   a fixed-pitch font will allow the calling code to rely on using spaces
+ *   to align text within the window.  
+ */
+#define OS_BANNER_TYPE_TEXT       1
+
+/* 
+ *   "Text grid" window.  This type of window is similar to an normal text
+ *   window (OS_BANNER_TYPE_TEXT), but is guaranteed to arrange its text in
+ *   a regular grid of character cells, all of the same size.  This means
+ *   that the output position can be moved to an arbitrary point within the
+ *   window at any time, so the calling program can precisely control the
+ *   layout of the text in the window.
+ *   
+ *   Because the output position can be moved to arbitrary positions in the
+ *   window, it is possible to overwrite text previously displayed.  When
+ *   this happens, the old text is completely obliterated by the new text,
+ *   leaving no trace of the overwritten text.
+ *   
+ *   In order to guarantee that character cells are all the same size, this
+ *   type of window does not allow any text attributes.  The implementation
+ *   should simply ignore any attempts to change text attributes in this
+ *   type of window.  However, colors can be used to the same degree they
+ *   can be used in an ordinary text window.
+ *   
+ *   To guarantee the regular spacing of character cells, all
+ *   implementations must use fixed-pitch fonts for these windows.  This
+ *   applies even to platforms where proportional fonts are available.  
+ */
+#define OS_BANNER_TYPE_TEXTGRID   2
+
+
+/* 
+ *   banner alignment types 
+ */
+#define OS_BANNER_ALIGN_TOP       0
+#define OS_BANNER_ALIGN_BOTTOM    1
+#define OS_BANNER_ALIGN_LEFT      2
+#define OS_BANNER_ALIGN_RIGHT     3
+
+/*
+ *   size units 
+ */
+#define OS_BANNER_SIZE_PCT  1
+#define OS_BANNER_SIZE_ABS  2
+
+
+/* 
+ *   banner style flags 
+ */
+
+/* 
+ *   The banner has a visible border; this indicates that a line is to be
+ *   drawn to separate the banner from the adjacent window or windows
+ *   "inside" the banner.  So, a top-aligned banner will have its border
+ *   drawn along its bottom edge; a left-aligned banner will show a border
+ *   along its right edge; and so forth.
+ *   
+ *   Note that character-mode platforms generally do NOT respect the border
+ *   style, since doing so takes up too much screen space.  
+ */
+#define OS_BANNER_STYLE_BORDER     0x00000001
+
+/*
+ *   The banner has a vertical/horizontal scrollbar.  Character-mode
+ *   platforms generally do not support scrollbars.  
+ */
+#define OS_BANNER_STYLE_VSCROLL    0x00000002
+#define OS_BANNER_STYLE_HSCROLL    0x00000004
+
+/* 
+ *   Automatically scroll the banner vertically/horizontally whenever new
+ *   text is displayed in the window.  In other words, whenever
+ *   os_banner_disp() is called, scroll the window so that the text that the
+ *   new cursor position after the new text is displayed is visible in the
+ *   window.
+ *   
+ *   Note that this style is independent of the presence of scrollbars.
+ *   Even if there are no scrollbars, we can still scroll the window's
+ *   contents programmatically.
+ *   
+ *   Implementations can, if desired, keep an internal buffer of the
+ *   window's contents, so that the contents can be recalled via the
+ *   scrollbars if the text displayed in the banner exceeds the space
+ *   available in the banner's window on the screen.  If the implementation
+ *   does keep such a buffer, we recommend the following method for managing
+ *   this buffer.  If the AUTO_VSCROLL flag is not set, then the banner's
+ *   contents should be truncated at the bottom when the contents overflow
+ *   the buffer; that is, once the banner's internal buffer is full, any new
+ *   text that the calling program attempts to add to the banner should
+ *   simply be discarded.  If the AUTO_VSCROLL flag is set, then the OLDEST
+ *   text should be discarded instead, so that the most recent text is
+ *   always retained.  
+ */
+#define OS_BANNER_STYLE_AUTO_VSCROLL 0x00000008
+#define OS_BANNER_STYLE_AUTO_HSCROLL 0x00000010
+
+/*
+ *   Tab-based alignment is required/supported.  On creation, this is a hint
+ *   to the implementation that is sometimes necessary to determine what
+ *   kind of font to use in the new window, for non-HTML platforms.  If this
+ *   flag is set on creation, the caller is indicating that it wants to use
+ *   <TAB> tags to align text in the window.
+ *   
+ *   Character-mode implementations that use a single font with fixed pitch
+ *   can simply ignore this.  These implementations ALWAYS have a working
+ *   <TAB> capability, because the portable output formatter provides <TAB>
+ *   interpretation for a fixed-pitch window.
+ *   
+ *   Full HTML TADS implementations can also ignore this.  HTML TADS
+ *   implementations always have full <TAB> support via the HTML
+ *   parser/renderer.
+ *   
+ *   Text-only implementations on GUI platforms (i.e., implementations that
+ *   are not based on the HTML parser/renderer engine in HTML TADS, but
+ *   which run on GUI platforms with proportionally-spaced text) should use
+ *   this flag to determine the font to display.  If this flag is NOT set,
+ *   then the caller doesn't care about <TAB>, and the implementation is
+ *   free to use a proportionally-spaced font in the window if desired.
+ *   
+ *   When retrieving information on an existing banner, this flag indicates
+ *   that <TAB> alignment is actually supported on the window.  
+ */
+#define OS_BANNER_STYLE_TAB_ALIGN 0x00000020
+
+/*
+ *   Use "MORE" mode in this window.  By default, a banner window should
+ *   happily allow text to overflow the vertical limits of the window; the
+ *   only special thing that should happen on overflow is that the window
+ *   should be srolled down to show the latest text, if the auto-vscroll
+ *   style is set.  With this flag, though, a banner window acts just like
+ *   the main text window: when the window fills up vertically, we show a
+ *   MORE prompt (using appropriate system conventions), and wait for the
+ *   user to indicate that they're ready to see more text.  On most systems,
+ *   the user acknowledges a MORE prompt by pressing a key or scrolling with
+ *   the mouse, but it's up to the system implementor to decide what's
+ *   appropriate for the system.
+ *   
+ *   Note that MORE mode in ANY banner window should generally override all
+ *   other user input focus.  In other words, if the game in the main window
+ *   would like to read a keystroke from the user, but one of the banner
+ *   windows is pausing with a MORE prompt, any keyboard input should be
+ *   directed to the banner paused at the MORE prompt, not to the main
+ *   window; the main window should not receive any key events until the MORE
+ *   prompt has been removed.
+ *   
+ *   This style requires the auto-vscroll style.  Implementations should
+ *   assume auto-vscroll when this style is set.  This style can be ignored
+ *   with text grid windows.  
+ */
+#define OS_BANNER_STYLE_MOREMODE  0x00000040
+
+/*
+ *   This banner is a horizontal/vertical "strut" for sizing purposes.  This
+ *   means that the banner's content size is taken into account when figuring
+ *   the content size of its *parent* banner.  If the banner has the same
+ *   orientation as the parent, its content size is added to its parent's
+ *   internal content size to determine the parent's overall content size.
+ *   If the banner's orientation is orthogonal to the parent's, then the
+ *   parent's overall content size is the larger of the parent's internal
+ *   content size and this banner's content size.  
+ */
+#define OS_BANNER_STYLE_HSTRUT    0x00000080
+#define OS_BANNER_STYLE_VSTRUT    0x00000100
+
+
+/* 
+ *   Delete a banner.  This removes the banner from the display, which
+ *   requires recalculating the entire screen's layout to reallocate this
+ *   banner's space to other windows.  When this routine returns, the banner
+ *   handle is invalid and can no longer be used in any os_banner_xxx
+ *   function calls.  
+ *   
+ *   If the banner has children, the children will no longer be displayed,
+ *   but will remain valid in memory until deleted.  A child window's
+ *   display area always comes out of its parent's space, so once the parent
+ *   is gone, a child has no way to acquire any display space; resizing the
+ *   child won't help, since it simply has no way to obtain any screen space
+ *   once its parent has been deleted.  Even though the window's children
+ *   will become invisible, their banner handles will remain valid; the
+ *   caller is responsible for explicitly deleting the children even after
+ *   deleting their parent.  
+ */
+void os_banner_delete(void *banner_handle);
+
+/*
+ *   "Orphan" a banner.  This tells the osifc implementation that the caller
+ *   wishes to sever all of its ties with the banner (as part of program
+ *   termination, for example), but that the calling program does not
+ *   actually require that the banner's on-screen display be immediately
+ *   removed.
+ *   
+ *   The osifc implementation can do one of two things:
+ *   
+ *   1.  Simply call os_banner_delete().  If the osifc implementation
+ *   doesn't want to do anything extra with the banner, it can simply delete
+ *   the banner, since the caller has no more use for it.
+ *   
+ *   2.  Take ownership of the banner.  If the osifc implementation wishes
+ *   to continue displaying the final screen configuration after a program
+ *   has terminated, it can simply take over the banner and leave it on the
+ *   screen.  The osifc subsystem must eventually delete the banner itself
+ *   if it takes this routine; for example, if the osifc subsystem allows
+ *   another client program to be loaded into the same window after a
+ *   previous program has terminated, it would want to delete any orphaned
+ *   banners from the previous program when loading a new program.  
+ */
+void os_banner_orphan(void *banner_handle);
+
+/*
+ *   Banner information structure.  This is filled in by the system-specific
+ *   implementation in os_banner_getinfo().  
+ */
+struct os_banner_info_t
+{
+    /* alignment */
+    int align;
+
+    /* style flags - these indicate the style flags actually in use */
+    unsigned long style;
+
+    /* 
+     *   Actual on-screen size of the banner, in rows and columns.  If the
+     *   banner is displayed in a proportional font or can display multiple
+     *   fonts of different sizes, this is approximated by the number of "0"
+     *   characters in the window's default font that will fit in the
+     *   window's display area.  
+     */
+    int rows;
+    int columns;
+
+    /*
+     *   Actual on-screen size of the banner in pixels.  This is meaningful
+     *   only for full HTML interpreter; for text-only interpreters, these
+     *   are always set to zero.
+     *   
+     *   Note that even if we're running on a GUI operating system, these
+     *   aren't meaningful unless this is a full HTML interpreter.  Text-only
+     *   interpreters should always set these to zero, even on GUI OS's.  
+     */
+    int pix_width;
+    int pix_height;
+
+    /* 
+     *   OS line wrapping flag.  If this is set, the window uses OS-level
+     *   line wrapping because the window uses a proportional font, so the
+     *   caller does not need to (and should not) perform line breaking in
+     *   text displayed in the window.
+     *   
+     *   Note that OS line wrapping is a PERMANENT feature of the window.
+     *   Callers can note this information once and expect it to remain
+     *   fixed through the window's lifetime.  
+     */
+    int os_line_wrap;
+};
+typedef struct os_banner_info_t os_banner_info_t;
+
+/* 
+ *   Get information on the banner - fills in the information structure with
+ *   the banner's current settings.  Note that this should indicate the
+ *   ACTUAL properties of the banner, not the requested properties; this
+ *   allows callers to determine how the banner is actually displayed, which
+ *   depends upon the platform's capabilities and user preferences.
+ *   
+ *   Returns true if the information was successfully obtained, false if
+ *   not.  This can return false if the underlying OS window has already
+ *   been closed by a user action, for example.  
+ */
+int os_banner_getinfo(void *banner_handle, os_banner_info_t *info);
+
+/* 
+ *   Get the character width/height of the banner, for layout purposes.  This
+ *   gives the size of the banner in character cells.
+ *   
+ *   These are not meaningful when the underlying window uses a proportional
+ *   font or varying fonts of different sizes.  When the size of text varies
+ *   in the window, the OS layer is responsible for word-wrapping and other
+ *   layout, in which case these simply return zero.
+ *   
+ *   Note that these routines might appear to be redundant with the 'rows'
+ *   and 'columns' information returned from os_banner_getinfo(), but these
+ *   have two important distinctions.  First, these routines return only the
+ *   width and height information, so they can be implemented with less
+ *   overhead than os_banner_getinfo(); this is important because formatters
+ *   might need to call these routines frequently while formatting text.
+ *   Second, these routines are not required to return an approximation for
+ *   windows using proportional fonts, as os_banner_getinfo() does; these can
+ *   simply return zero when a proportional font is in use.  
+ */
+int os_banner_get_charwidth(void *banner_handle);
+int os_banner_get_charheight(void *banner_handle);
+
+/* clear the contents of a banner */
+void os_banner_clear(void *banner_handle);
+
+/* 
+ *   Display output on a banner.  Writes the output to the window on the
+ *   display at the current output position.
+ *   
+ *   The following special characters should be recognized and handled:
+ *   
+ *   '\n' - newline; move output position to the start of the next line.
+ *   
+ *   '\r' - move output position to start of current line; subsequent text
+ *   overwrites any text previously displayed on the current line.  It is
+ *   permissible to delete the old text immediately on seeing the '\r',
+ *   rather than waiting for additional text to actually overwrite it.
+ *   
+ *   All other characters should simply be displayed as ordinary printing
+ *   text characters.  Note that tab characters should not be passed to this
+ *   routine, but if they are, they can simply be treated as ordinary spaces
+ *   if desired.  Other control characters (backspace, escape, etc) should
+ *   never be passed to this routine; the implementation is free to ignore
+ *   any control characters not listed above.
+ *   
+ *   If any text displayed here overflows the current boundaries of the
+ *   window on the screen, the text MUST be "clipped" to the current window
+ *   boundaries; in other words, anything this routine tries to display
+ *   outside of the window's on-screen rectangle must not actually be shown
+ *   on the screen.
+ *   
+ *   Text overflowing the display boundaries MUST also be retained in an
+ *   internal buffer.  This internal buffer can be limited to the actual
+ *   maximum display size of the terminal screen or application window, if
+ *   desired.  It is necessary to retain clipped text, because this allows a
+ *   window to be expanded to the size of its contents AFTER the contents
+ *   have already been displayed.
+ *   
+ *   If the banner does its own line wrapping, it must indicate this via the
+ *   os_line_wrap flag in the os_banner_getinfo() return data.  If the
+ *   banner doesn't indicate this flag, then it must not do any line
+ *   wrapping at all, even if the caller attempts to write text beyond the
+ *   right edge of the window - any text overflowing the width of the window
+ *   must simply be clipped.
+ *   
+ *   Text grid banners must ALWAYS clip - these banners should never perform
+ *   any line wrapping.  
+ */
+void os_banner_disp(void *banner_handle, const char *txt, size_t len);
+
+/*
+ *   Set the text attributes in a banner, for subsequent text displays.
+ *   'attr' is a (bitwise-OR'd) combination of OS_ATTR_xxx values. 
+ */
+void os_banner_set_attr(void *banner_handle, int attr);
+
+/* 
+ *   Set the text color in a banner, for subsequent text displays.  The 'fg'
+ *   and 'bg' colors are given as RGB or parameterized colors; see the
+ *   definition of os_color_t for details.
+ *   
+ *   If the underlying renderer is HTML-enabled, then this should not be
+ *   used; the appropriate HTML code should simply be displayed to the
+ *   banner instead.  
+ */
+void os_banner_set_color(void *banner_handle, os_color_t fg, os_color_t bg);
+
+/* 
+ *   Set the screen color in the banner - this is analogous to the screen
+ *   color in the main text area.
+ *   
+ *   If the underlying renderer is HTML-enabled, then this should not be
+ *   used; the HTML <BODY> tag should be used instead.  
+ */
+void os_banner_set_screen_color(void *banner_handle, os_color_t color);
+
+/* flush output on a banner */
+void os_banner_flush(void *banner_handle);
+
+/*
+ *   Set the banner's size.  The size has the same meaning as in
+ *   os_banner_create().
+ *   
+ *   'is_advisory' indicates whether the sizing is required or advisory only.
+ *   If this flag is false, then the size should be set as requested.  If
+ *   this flag is true, it means that the caller intends to call
+ *   os_banner_size_to_contents() at some point, and that the size being set
+ *   now is for advisory purposes only.  Platforms that support
+ *   size-to-contents may simply ignore advisory sizing requests, although
+ *   they might want to ensure that they have sufficient off-screen buffer
+ *   space to keep track of the requested size of display, so that the
+ *   information the caller displays in preparation for calling
+ *   size-to-contents will be retained.  Platforms that do not support
+ *   size-to-contents should set the requested size even when 'is_advisory'
+ *   is true.  
+ */
+void os_banner_set_size(void *banner_handle, int siz, int siz_units,
+                        int is_advisory);
+
+/* 
+ *   Set the banner to the size of its current contents.  This can be used
+ *   to set the banner's size after some text (or other material) has been
+ *   displayed to the banner, so that the size can be set according to the
+ *   banner's actual space requirements.
+ *   
+ *   This changes the banner's "requested size" to match the current size.
+ *   Subsequent calls to os_banner_getinfo() will thus indicate a requested
+ *   size according to the size set here.  
+ */
+void os_banner_size_to_contents(void *banner_handle);
+
+/* 
+ *   Turn HTML mode on/off in the banner window.  If the underlying renderer
+ *   doesn't support HTML, these have no effect.  
+ */
+void os_banner_start_html(void *banner_handle);
+void os_banner_end_html(void *banner_handle);
+
+/*
+ *   Set the output coordinates in a text grid window.  The grid window is
+ *   arranged into character cells numbered from row zero, column zero for
+ *   the upper left cell.  This function can only be used if the window was
+ *   created with type OS_BANNER_TYPE_TEXTGRID; the request should simply be
+ *   ignored by other window types.
+ *   
+ *   Moving the output position has no immediate effect on the display, and
+ *   does not itself affect the "content size" for the purposes of
+ *   os_banner_size_to_contents().  This simply sets the coordinates where
+ *   any subsequent text is displayed.  
+ */
+void os_banner_goto(void *banner_handle, int row, int col);
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Get system information.  'code' is a SYSINFO_xxx code, which
+ *   specifies what type of information to get.  The 'param' argument's
+ *   meaning depends on which code is selected.  'result' is a pointer to
+ *   an integer that is to be filled in with the result value.  If the
+ *   code is not known, this function should return FALSE.  If the code is
+ *   known, the function should fill in *result and return TRUE.
+ */
+int os_get_sysinfo(int code, void *param, long *result);
+
+/* determine if systemInfo is supported - os_get_sysinfo never gets this */
+#define SYSINFO_SYSINFO   1
+
+/* get interpreter version number - os_get_sysinfo never gets this */
+#define SYSINFO_VERSION   2
+
+/* get operating system name - os_get_sysinfo never gets this */
+#define SYSINFO_OS_NAME   3
+
+/* 
+ *   Can the system process HTML directives?  returns 1 if so, 0 if not.
+ *   Note that if this returns false, then all of the codes below from
+ *   JPEG to LINKS are implicitly false as well, since TADS can only use
+ *   images, sounds, and links through HTML. 
+ */
+#define SYSINFO_HTML      4
+
+/* can the system display JPEG's?  1 if yes, 0 if no */
+#define SYSINFO_JPEG      5
+
+/* can the system display PNG's?  1 if yes, 0 if no */
+#define SYSINFO_PNG       6
+
+/* can the system play WAV's?  1 if yes, 0 if no */
+#define SYSINFO_WAV       7
+
+/* can the system play MIDI's?  1 if yes, 0 if no */
+#define SYSINFO_MIDI      8
+
+/* can the system play MIDI and WAV's simultaneously?  yes=1, no=0 */
+#define SYSINFO_WAV_MIDI_OVL  9
+
+/* can the system play multiple WAV's simultaneously?  yes=1, no=0 */
+#define SYSINFO_WAV_OVL   10
+
+/*
+ *   GENERAL NOTES ON PREFERENCE SETTINGS:
+ *   
+ *   Several of the selectors below refer to the preference settings.  We're
+ *   talking about user-settable options to control various aspects of the
+ *   interpreter.  The conventional GUI for this kind of thing is a dialog
+ *   box reachable through a menu command named something like "Options" or
+ *   "Preferences".  A couple of general notes about these:
+ *   
+ *   1.  The entire existence of a preferences mechanism is optional -
+ *   interpreter writers aren't required to implement anything along these
+ *   lines.  In some cases the local platforms might not have any suitable
+ *   conventions for a preferences UI (e.g., character-mode console
+ *   applications), and in other cases the terp developer might just want to
+ *   omit a prefs mechanism because of the work involved to implement it, or
+ *   to keep the UI simpler.
+ *   
+ *   2.  If a given SYSINFO_PREF_xxx selector refers to a preference item
+ *   that's not implemented in the local interpreter, the terp should simply
+ *   return a suitable default result.  For example, if the interpreter
+ *   doesn't have a preference item to allow the user to turn sounds off, the
+ *   selector SYSINFO_PREF_SOUNDS should return 1 to indicate that the user
+ *   has not in fact turned off sounds (because there's no way to do so).
+ *   
+ *   3.  The various SYSINFO_PREF_xxx selectors are purely queries - they're
+ *   NOT a mechanism for enforcing the preferences.  For example, if the
+ *   interpreter provides a "Sounds On/Off" option, it's up to the terp to
+ *   enforce it the Off setting by ignoring any sound playback requests.  The
+ *   game isn't under any obligation to query any of the preferences or to
+ *   alter its behavior based on their settings - you should expect that the
+ *   game will go on trying to play sounds even when "Sounds Off" is selected
+ *   in the preferences.  The purpose of these SYSINFO selectors is to let
+ *   the game determine the current presentation status, but *only if it
+ *   cares*.  For example, the game might determine whether or not sounds are
+ *   actually being heard just before playing a sound effect that's important
+ *   to the progress of the game, so that it can provide a visual alternative
+ *   if the effect won't be heard.  
+ */
+
+/* 
+ *   Get image preference setting - 1 = images can be displayed, 0 = images
+ *   are not being displayed because the user turned off images in the
+ *   preferences.  This is, of course, irrelevant if images can't be
+ *   displayed at all.
+ *   
+ *   See the general notes on preferences queries above.  
+ */
+#define SYSINFO_PREF_IMAGES  11
+
+/*
+ *   Get digitized sound effect (WAV) preference setting - 1 = sounds can be
+ *   played, 0 = sounds are not being played because the user turned off
+ *   sounds in the preferences.
+ *   
+ *   See the general notes on preferences queries above.  
+ */
+#define SYSINFO_PREF_SOUNDS  12
+
+/*
+ *   Get music (MIDI) preference setting - 1 = music can be played, 0 = music
+ *   is not being played because the user turned off music in the
+ *   preferences.
+ *   
+ *   See the general notes on preferences queries above.  
+ */
+#define SYSINFO_PREF_MUSIC   13
+
+/*
+ *   Get link display preference setting - 0 = links are not being displayed
+ *   because the user set a preference item that suppresses all links (which
+ *   doesn't actually hide them, but merely displays them and otherwise
+ *   treats them as ordinary text).  1 = links are to be displayed normally.
+ *   2 = links can be displayed temporarily by the user by pressing a key or
+ *   some similar action, but aren't being displayed at all times.  
+ *   
+ *   See the general note on preferences queries above.  
+ */
+#define SYSINFO_PREF_LINKS   14
+
+/* can the system play MPEG sounds of any kind? */
+#define SYSINFO_MPEG         15
+
+/* can the system play MPEG audio 2.0 layer I/II/III sounds? */
+#define SYSINFO_MPEG1        16
+#define SYSINFO_MPEG2        17
+#define SYSINFO_MPEG3        18
+
+/* 
+ *   is the system *currently* in HTML mode?  os_get_sysinfo never gets
+ *   this code, since the portable output layer keeps track of this 
+ */
+#define SYSINFO_HTML_MODE    19
+
+/* 
+ *   Does the system allow following external URL links of the various
+ *   types?  These return true if the system is capable of following these
+ *   types of hypertext links, false if not.  Note that, if the system is
+ *   capable of following these links, these should return true regardless
+ *   of any current mode settings; in particular, these should not be
+ *   sensitive to the current HTML mode or the current link display mode,
+ *   since the question is not whether a link now displayed can be
+ *   followed by the user, but rather whether the system has the
+ *   capability to follow these types of links at all.  
+ */
+#define SYSINFO_LINKS_HTTP   20
+#define SYSINFO_LINKS_FTP    21
+#define SYSINFO_LINKS_NEWS   22
+#define SYSINFO_LINKS_MAILTO 23
+#define SYSINFO_LINKS_TELNET 24
+
+/* is PNG transparency supported? */
+#define SYSINFO_PNG_TRANS    25
+
+/* is PNG alpha blending supported? */
+#define SYSINFO_PNG_ALPHA    26
+
+/* is the Ogg Vorbis audio format supported? */
+#define SYSINFO_OGG          27
+
+/* can the system display MNG's? */
+#define SYSINFO_MNG          28
+
+/* can the system display MNG's with transparency? */
+#define SYSINFO_MNG_TRANS    29
+
+/* can the system display MNG's with alpha blending? */
+#define SYSINFO_MNG_ALPHA    30
+
+/* can we display highlighted text in its own appearance? */
+#define SYSINFO_TEXT_HILITE  31
+
+/* 
+ *   Can we display text colors?  This returns a SYSINFO_TXC_xxx code
+ *   indicating the level of color support.
+ *   
+ *   The os_xxx interfaces don't presently support anything beyond the ANSI
+ *   colors; however, HTML-enabled interpreters generally support full RGB
+ *   colors, so we call this out as a separate level.  
+ */
+#define SYSINFO_TEXT_COLORS  32
+
+/* no text color support */
+#define SYSINFO_TXC_NONE      0
+
+/* parameterized color names only (OS_COLOR_P_TEXT, etc) */
+#define SYSINFO_TXC_PARAM     1
+
+/* 
+ *   we support only the basic ANSI colors, foreground control only (white,
+ *   black, blue, red, green, yellow, cyan, magenta) 
+ */
+#define SYSINFO_TXC_ANSI_FG   2
+
+/* ANSI colors, foreground and background */
+#define SYSINFO_TXC_ANSI_FGBG 3
+
+/* full RGB support */
+#define SYSINFO_TXC_RGB       4
+
+/* are the os_banner_xxx() interfaces supported? */
+#define SYSINFO_BANNERS      33
+
+/* Interpreter Class - this returns one of the SYSINFO_ICLASS_xxx codes */
+#define SYSINFO_INTERP_CLASS 34
+
+/* 
+ *   Interpreter class: Character-mode Text-Only.  Interpreters of this class
+ *   use a single, fixed-pitch font to display all text, and use the
+ *   text-only HTML subset, and cannot display graphics.
+ */
+#define SYSINFO_ICLASS_TEXT    1
+
+/* 
+ *   Interpreter class: Text-Only GUI.  Interpreters of this class are
+ *   traditional text-only interpreters running on graphical operating
+ *   systems.  These interpreters might use multiple fonts (for example, they
+ *   might display highlighted text in boldface), and might use
+ *   proportionally-spaced text for some windows.  These interpreters support
+ *   the text-only HTML subset, and cannot display graphics.
+ *   
+ *   Text-only GUI interpreters act essentially the same as character-mode
+ *   text-only interpreters, from the perspective of the client program.  
+ */
+#define SYSINFO_ICLASS_TEXTGUI 2
+
+/*
+ *   Interpreter class: HTML.  Interpreters of this class can display
+ *   graphics and sounds, can display multiple fonts and font sizes, can use
+ *   proportional fonts, and support the full HTML TADS markup language for
+ *   formatting.  
+ */
+#define SYSINFO_ICLASS_HTML    3
+
+/*
+ *   Audio fade information.
+ *   
+ *   SYSINFO_AUDIO_FADE: basic fade-in and fade-out support.  Interpreters
+ *   that don't support audio fade at all should return 0.  Interpreters that
+ *   support fades should return a bitwise OR'd combination of
+ *   SYSINFO_AUDIOFADE_xxx flags below indicating which formats can be used
+ *   with fades.
+ *   
+ *   SYSINFO_AUDIO_CROSSFADE: cross-fades are supported (i.e., simultaneous
+ *   play of overlapping tracks, one fading out while the other fades in).
+ *   If cross-fades aren't supported, return 0.  If they're supported, return
+ *   a combination of SYSINFO_AUDIOFADE_xxx flags indicating which formats
+ *   can be used with cross-fades.  
+ */
+#define SYSINFO_AUDIO_FADE       35
+#define SYSINFO_AUDIO_CROSSFADE  36
+
+/* 
+ *   Specific audio fading features.  These are bit flags that can be
+ *   combined to indicate the fading capabilities of the interpreter.  
+ */
+#define SYSINFO_AUDIOFADE_MPEG  0x0001          /* supported for MPEG audio */
+#define SYSINFO_AUDIOFADE_OGG   0x0002          /* supported for Ogg Vorbis */
+#define SYSINFO_AUDIOFADE_WAV   0x0004                 /* supported for WAV */
+#define SYSINFO_AUDIOFADE_MIDI  0x0008                /* supported for MIDI */
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Integer division operators.  For any compiler that follows ANSI C
+ *   rules, no definitions are required for these routine, since the
+ *   standard definitions below will work properly.  However, if your
+ *   compiler does not follow ANSI standards with respect to integer
+ *   division of negative numbers, you must provide implementations of
+ *   these routines that produce the correct results.
+ *   
+ *   Division must "truncate towards zero," which means that any
+ *   fractional part is dropped from the result.  If the result is
+ *   positive, the result must be the largest integer less than the
+ *   algebraic result: 11/3 yields 3.  If the result is negative, the
+ *   result must be the smallest integer less than the result: (-11)/3
+ *   yields -3.
+ *   
+ *   The remainder must obey the relationship (a/b)*b + a%b == a, for any
+ *   integers a and b (b != 0).
+ *   
+ *   If your compiler does not obey the ANSI rules for the division
+ *   operators, make the following changes in your osxxx.h file
+ *   
+ *   - define the symbol OS_NON_ANSI_DIVIDE in the osxxx.h file
+ *   
+ *   - either define your own macros for os_divide_long() and
+ *   os_remainder_long(), or put actual prototypes for these functions
+ *   into your osxxx.h file and write appropriate implementations of these
+ *   functions in one of your osxxx.c or .cpp files.
+ */
+/* long os_divide_long(long a, long b);    // returns (a/b) with ANSI rules */
+/* long os_remainder_long(long a, long b); // returns (a%b) with ANSI rules */
+
+/* standard definitions for any ANSI compiler */
+#ifndef OS_NON_ANSI_DIVIDE
+#define os_divide_long(a, b)     ((a) / (b))
+#define os_remainder_long(a, b)  ((a) % (b))
+#endif
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Special "switch" statement optimization flags.  These definitions are
+ *   OPTIONAL - if a platform doesn't provide these definitions, suitable
+ *   code that's fully portable will be used.
+ *   
+ *   On some compilers, the performance of a "switch" statement can be
+ *   improved by fully populating the switch with all possible "case"
+ *   values.  When the compiler can safely assume that every possible "case"
+ *   value is specifically called out in the switch, the compiler can
+ *   generate somewhat faster code by omitting any range check for the
+ *   controlling expression of the switch: a range check is unnecessary
+ *   because the compiler knows that the value can never be outside the
+ *   "case" table.
+ *   
+ *   This type of optimization doesn't apply to all compilers.  When a given
+ *   platform's compiler can be coerced to produce faster "switch"
+ *   statements, though, there might be some benefit in defining these
+ *   symbols according to local platform rules.
+ *   
+ *   First, #define OS_FILL_OUT_CASE_TABLES if you want this type of switch
+ *   optimization at all.  This symbol is merely a flag, so it doesn't need
+ *   a value - #defining it is enough to activate the special code.  If you
+ *   don't define this symbol, then the code that cares about this will
+ *   simply generate ordinary switches, leaving holes in the case table and
+ *   using "default:" to cover them.  If the platform's osxxx.h header does
+ *   #define OS_FILL_OUT_CASE_TABLES, then the portable code will know to
+ *   fill out case tables with all possible alternatives where it's possible
+ *   and potentially beneficial to do so.
+ *   
+ *   Second, if you #define OS_FILL_OUT_CASE_TABLES, you MUST ALSO #define
+ *   OS_IMPOSSIBLE_DEFAULT_CASE.  The value for this symbol must be some
+ *   code to insert into a "switch" statement at the point where a
+ *   "default:" case would normally go.  On some compilers, special
+ *   extensions allow the program to explicitly indicate within a switch
+ *   that all possible cases are covered, so that the compiler doesn't have
+ *   to be relied upon to infer this for itself (which would be impossible
+ *   for it to do in many cases anyway).  You can use an empty definition
+ *   for this symbol if your compiler doesn't have any special construct for
+ *   indicating a fully-populated case table.
+ *   
+ *   Note that *most* switch statements in portable code won't care one way
+ *   or the other about these definitions.  There's a time/space trade-off
+ *   in fully populating a switch's case table, so only the most
+ *   time-critical code will bother trying.  
+ */
+
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   TADS 2 swapping configuration.  Define OS_DEFAULT_SWAP_ENABLED to 0
+ *   if you want swapping turned off, 1 if you want it turned on.  If we
+ *   haven't defined a default swapping mode yet, turn swapping on by
+ *   default.  
+ */
+#ifndef OS_DEFAULT_SWAP_ENABLED
+# define OS_DEFAULT_SWAP_ENABLED   1
+#endif
+
+/*
+ *   If the system "long description" (for the banner) isn't defined, make
+ *   it the same as the platform ID string.  
+ */
+#ifndef OS_SYSTEM_LDESC
+# define OS_SYSTEM_LDESC  OS_SYSTEM_NAME
+#endif
+
+/*
+ *   TADS 2 Usage Lines
+ *   
+ *   If the "usage" lines (i.e., the descriptive lines of text describing
+ *   how to run the various programs) haven't been otherwise defined,
+ *   define defaults for them here.  Some platforms use names other than
+ *   tc, tr, and tdb for the tools (for example, on Unix they're usually
+ *   tadsc, tadsr, and tadsdb), so the usage lines should be adjusted
+ *   accordingly; simply define them earlier than this point (in this file
+ *   or in one of the files included by this file, such as osunixt.h) for
+ *   non-default text.  
+ */
+#ifndef OS_TC_USAGE
+# define OS_TC_USAGE  "usage: tc [options] file"
+#endif
+#ifndef OS_TR_USAGE
+# define OS_TR_USAGE  "usage: tr [options] file"
+#endif
+#ifndef OS_TDB_USAGE
+# define OS_TDB_USAGE  "usage: tdb [options] file"
+#endif
+
+/*
+ *   Ports can define a special TDB startup message, which is displayed
+ *   after the copyright/version banner.  If it's not defined at this
+ *   point, define it to an empty string.  
+ */
+#ifndef OS_TDB_STARTUP_MSG
+# define OS_TDB_STARTUP_MSG ""
+#endif
+
+/*
+ *   If a system patch sub-level isn't defined, define it here as zero.
+ *   The patch sub-level is used on some systems where a number of ports
+ *   are derived from a base port (for example, a large number of ports
+ *   are based on the generic Unix port).  For platforms like the Mac,
+ *   where the porting work applies only to that one platform, this
+ *   sub-level isn't meaningful.
+ */
+#ifndef OS_SYSTEM_PATCHSUBLVL
+# define OS_SYSTEM_PATCHSUBLVL  "0"
+#endif
 
 } // End of namespace TADS2
 } // End of namespace TADS
diff --git a/engines/glk/tads/tads2/post_compilation.h b/engines/glk/tads/tads2/post_compilation.h
new file mode 100644
index 0000000000..1dde838d02
--- /dev/null
+++ b/engines/glk/tads/tads2/post_compilation.h
@@ -0,0 +1,96 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* definitions for post-compilation setup
+ *
+ * Does post-compilation setup, such as setting up contents lists
+ * faster run-time performance, but run - time errors could be disastrous.
+ */
+
+#ifndef GLK_TADS_TADS2_POST_COMPILATION
+#define GLK_TADS_TADS2_POST_COMPILATION
+
+#include "glk/tads/tads2/run.h"
+#include "glk/tads/tads2/tokenizer.h"
+#include "glk/tads/tads2/vocabulary.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* setup context */
+struct supcxdef {
+    errcxdef *supcxerr;
+    mcmcxdef *supcxmem;                    /* memory manager client context */
+    voccxdef *supcxvoc;                   /* player command parsing context */
+    tokthdef *supcxtab;                           /* top-level symbol table */
+    runcxdef *supcxrun;                                /* execution context */
+    uchar    *supcxbuf;                        /* space for building a list */
+    ushort    supcxlen;                                   /* size of buffer */
+};
+
+/* set up contents list for one object for demand-on-load */
+void supcont(void *ctx, objnum obj, prpnum prp);
+
+/* set up inherited vocabulary (called before executing game) */
+void supivoc(supcxdef *ctx);
+
+/* find required objects/functions */
+void supfind(errcxdef *ctx, tokthdef *tab, voccxdef *voc,
+             objnum *preinit, int warnlevel, int casefold);
+
+/* set up reserved words */
+void suprsrv(supcxdef *sup, void (*bif[])(struct bifcxdef *, int),
+             toktdef *tab, int fncntmax, int v1compat, char *new_do,
+             int casefold);
+
+/* set up built-in functions without symbol table (for run-time) */
+void supbif(supcxdef *sup, void (*bif[])(struct bifcxdef *, int),
+            int bifsiz);
+
+/* log an undefined-object error */
+void sup_log_undefobj(mcmcxdef *mctx, errcxdef *ec, int err,
+                      char *sym_name, int sym_name_len, objnum objn);
+
+/* set up inherited vocabulary for a particular object */
+void supivoc1(supcxdef *sup, voccxdef *ctx, vocidef *v, objnum target,
+              int inh_from_obj, int flags);
+
+/* get name of an object out of symbol table */
+void supgnam(char *buf, tokthdef *tab, objnum objn);
+
+/* table of built-in functions */
+typedef struct supbidef supbidef;
+struct supbidef
+{
+    char  *supbinam;                                    /* name of function */
+    void (*supbifn)(struct bifcxdef *, int);           /* C routine to call */
+};
+
+/* external definition for special token table */
+extern tokldef supsctab[];
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/property.h b/engines/glk/tads/tads2/property.h
new file mode 100644
index 0000000000..86a4b69d67
--- /dev/null
+++ b/engines/glk/tads/tads2/property.h
@@ -0,0 +1,167 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* property definitions
+ *
+ * A property structure must be binary-portable, because properties are
+ * stored in objects, which must be binary-portable.  Hence, the internal
+ * structure of a property header is not a C structure, but a portable
+ * sequence of bytes.  Multi-byte quantities are stored in Intel format.
+ * 
+ * property number    - 2 bytes
+ * property datatype  - 1 byte
+ * property size      - 2 bytes
+ * property flags     - 1 byte
+ * 
+ * This header is followed immediately by the property value.  For
+ * convenience, a set of macros is defined to provide access to the
+ * fields of a property header.
+ */
+
+#ifndef GLK_TADS_TADS2_PROPERTY
+#define GLK_TADS_TADS2_PROPERTY
+
+#include "glk/tads/tads.h"
+#include "glk/tads/tads2/data.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/**
+ * a property number, used to look up all properties */
+typedef ushort prpnum;
+
+typedef uchar prpdef;                   /* prpdef is just an array of bytes */
+#define PRPHDRSIZ 6           /* "sizeof(prpdef)" - size of property header */
+
+/* Macros to provide access to property header entries */
+#define prpprop(p) osrp2((uchar *)(p))
+#define prptype(p) (*(((uchar *)(p)) + 2))
+#define prpsize(p) osrp2((((uchar *)(p)) + 3))
+#define prpflg(p)  (*(((uchar *)(p)) + 5))
+#define prpvalp(p) (((uchar *)(p)) + 6)
+
+#define prpsetprop(p,n) oswp2((uchar *)(p), n)
+#define prpsetsize(p,s) oswp2((((uchar *)(p)) + 3), s)
+
+/* property flag values */
+#define PRPFORG   0x01                /* property is original startup value */
+#define PRPFIGN   0x02               /* ignore this prop (has been changed) */
+#define PRPFDEL   0x04             /* property has been permanently deleted */
+
+/**
+ * Invalid property number - this number will never be used as an actual
+ * property, so it can be used to signify the lack of a valid property 
+ */
+#define PRP_INVALID     0
+
+/* certain property types are special, and are reserved here */
+#define PRP_DOACTION    1                              /* doAction property */
+
+/* vocabulary properties - keep these contiguous, and must start at 2 */
+#define PRP_VERB        2                      /* verb vocabulary property  */
+#define PRP_NOUN        3                       /* noun vocabulary property */
+#define PRP_ADJ         4                  /* adjective vocabulary property */
+#define PRP_PREP        5                /* preposition vocabulary property */
+#define PRP_ARTICLE     6                    /* article vocabulary property */
+#define PRP_PLURAL      7                     /* plural vocabulary property */
+
+/* determine if a property is a vocab property */
+/* int prpisvoc(prpnum p); */
+#define prpisvoc(p) ((p) >= PRP_VERB && (p) <= PRP_PLURAL)
+
+/* more properties... */
+#define PRP_SDESC       8
+#define PRP_THEDESC     9
+#define PRP_DODEFAULT   10
+#define PRP_IODEFAULT   11
+#define PRP_IOACTION    12
+#define PRP_LOCATION    13
+#define PRP_VALUE       14
+#define PRP_ROOMACTION  15
+#define PRP_ACTORACTION 16
+#define PRP_CONTENTS    17
+#define PRP_TPL         18           /* special built-in TEMPLATE structure */
+#define PRP_PREPDEFAULT 19
+#define PRP_VERACTOR    20
+#define PRP_VALIDDO     21
+#define PRP_VALIDIO     22
+#define PRP_LOOKAROUND  23
+#define PRP_ROOMCHECK   24
+#define PRP_STATUSLINE  25
+#define PRP_LOCOK       26
+#define PRP_ISVIS       27
+#define PRP_NOREACH     28
+#define PRP_ISHIM       29
+#define PRP_ISHER       30
+#define PRP_ACTION      31                                 /* action method */
+#define PRP_VALDOLIST   32                                   /* validDoList */
+#define PRP_VALIOLIST   33                                   /* validIoList */
+#define PRP_IOBJGEN     34                                       /* iobjGen */
+#define PRP_DOBJGEN     35                                       /* dobjGen */
+#define PRP_NILPREP     36                                       /* nilPrep */
+#define PRP_REJECTMDO   37                               /* rejectMultiDobj */
+#define PRP_MOVEINTO    38                                      /* moveInto */
+#define PRP_CONSTRUCT   39                                     /* construct */
+#define PRP_DESTRUCT    40                                      /* destruct */
+#define PRP_VALIDACTOR  41                                    /* validActor */
+#define PRP_PREFACTOR   42                                /* preferredActor */
+#define PRP_ISEQUIV     43                                  /* isEquivalent */
+#define PRP_ADESC       44
+#define PRP_MULTISDESC  45
+#define PRP_TPL2        46         /* new-style built-in TEMPLATE structure */
+#define PRP_ANYVALUE    47   /* anyvalue(n) - value to use for '#' with ANY */
+#define PRP_NEWNUMOBJ   48   /* newnumbered(n) - create new numbered object */
+#define PRP_UNKNOWN     49           /* internal property for unknown words */
+#define PRP_PARSEUNKNOWNDOBJ 50                         /* parseUnknownDobj */
+#define PRP_PARSEUNKNOWNIOBJ 51                         /* parseUnknownIobj */
+#define PRP_DOBJCHECK   52                                     /* dobjCheck */
+#define PRP_IOBJCHECK   53                                     /* iobjCheck */
+#define PRP_VERBACTION  54                                    /* verbAction */
+#define PRP_DISAMBIGDO  55                                  /* disambigDobj */
+#define PRP_DISAMBIGIO  56                                  /* disambigIobj */
+#define PRP_PREFIXDESC  57                                    /* prefixdesc */
+#define PRP_ISTHEM      58                                        /* isThem */
+
+/* properties used by TADS/Graphic */
+#define PRP_GP_PIC      100                                   /* gp_picture */
+#define PRP_GP_NAME     101                                      /* gp_name */
+#define PRP_GP_DEFVERB  102                                   /* gp_defverb */
+#define PRP_GP_ACTIVE   103                                    /* gp_active */
+#define PRP_GP_HOTLIST  104                                   /* gp_hotlist */
+#define PRP_GP_ICON     105                                      /* gp_icon */
+#define PRP_GP_DEFVERB2 106                                  /* gp_defverb2 */
+#define PRP_GP_DEFPREP  107                                   /* gp_defprep */
+#define PRP_GP_HOTID    108                                     /* gp_hotid */
+#define PRP_GP_OVERLAY  109                                   /* gp_overlay */
+#define PRP_GP_HOTX     110                                      /* gp_hotx */
+#define PRP_GP_HOTY     111                                      /* gp_hoty */
+
+/* highest reserved property number - must match last one above */
+#define PRP_LASTRSV     111
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/regex.cpp b/engines/glk/tads/tads2/regex.cpp
index a7f7d99369..5d608dfa4a 100644
--- a/engines/glk/tads/tads2/regex.cpp
+++ b/engines/glk/tads/tads2/regex.cpp
@@ -68,10 +68,8 @@ Notes
 */
 
 #include "glk/tads/tads2/regex.h"
-#include "glk/tads/tads2/ler.h"
-#include "glk/tads/tads2/os.h"
-//#include "glk/tads/tads2/std.h"
-#//include "engines/glk/tads/tads2/ler.h"
+#include "glk/tads/tads2/memory_cache_heap.h"
+#include "common/util.h"
 
 namespace Glk {
 namespace TADS {
@@ -128,1148 +126,1461 @@ enum {
 	RE_GROUP_MATCH_9      = (RE_GROUP_MATCH_0 + 9)
 };
 
-re_context::re_context(errcxdef *errctx) {
-	// save the error context
-	_errctx = errctx;
-	
-	// clear states
-	_next_state = RE_STATE_FIRST_VALID;
+/* ------------------------------------------------------------------------ */
+/*
+ *   A machine description.  Machines are fully described by their initial
+ *   and final state ID's.  
+ */
+struct re_machine {
+    /* the machine's initial state */
+    re_state_id init;
 
-	// clear groups
-	_cur_group = 0;
+    /* the machine's final state */
+    re_state_id final;
+};
 
-	// no string buffer yet
-	_strbuf = 0;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize the context.  The memory for the context structure itself
+ *   is allocated and maintained by the caller.  
+ */
+void re_init(re_context *ctx, errcxdef *errctx)
+{
+    /* save the error context */
+    ctx->errctx = errctx;
+    
+    /* no tuple array yet */
+    ctx->tuple_arr = 0;
+    ctx->tuples_alloc = 0;
+
+    /* clear states */
+    ctx->next_state = RE_STATE_FIRST_VALID;
+
+    /* clear groups */
+    ctx->cur_group = 0;
+
+    /* no string buffer yet */
+    ctx->strbuf = 0;
 }
 
-re_context::~re_context() {
-	// reset state
-	reset();
-
-	// if we allocated a string buffer, delete it
-	if (_strbuf != 0) {
-		mchfre(_strbuf);
-		_strbuf = nullptr;
-	}
+/* ------------------------------------------------------------------------ */
+/*
+ *   Reset compiler - clears states and tuples 
+ */
+static void re_reset(re_context *ctx)
+{
+    int i;
+    
+    /* delete any range tables we've allocated */
+    for (i = 0 ; i < ctx->next_state ; ++i)
+    {
+        if (ctx->tuple_arr[i].char_range != 0)
+        {
+            mchfre(ctx->tuple_arr[i].char_range);
+            ctx->tuple_arr[i].char_range = 0;
+        }
+    }
+
+    /* clear states */
+    ctx->next_state = RE_STATE_FIRST_VALID;
+
+    /* clear groups */
+    ctx->cur_group = 0;
 }
 
-void re_context::reset() {
-	int i;
-	
-	// delete any range tables we've allocated
-	for (i = 0 ; i < _next_state ; ++i) {
-		if (_tuple_arr[i].char_range != 0) {
-			mchfre(_tuple_arr[i].char_range);
-			_tuple_arr[i].char_range = 0;
-		}
-	}
-
-	// clear states
-	_next_state = RE_STATE_FIRST_VALID;
-
-	// clear groups
-	_cur_group = 0;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Delete the context - frees structures associated with the context.
+ *   Does NOT free the memory used by the context structure itself.  
+ */
+void re_delete(re_context *ctx)
+{
+    /* reset state */
+    re_reset(ctx);
+    
+    /* if we've allocated an array, delete it */
+    if (ctx->tuple_arr != 0)
+    {
+        mchfre(ctx->tuple_arr);
+        ctx->tuple_arr = 0;
+    }
+
+    /* if we allocated a string buffer, delete it */
+    if (ctx->strbuf != 0)
+    {
+        mchfre(ctx->strbuf);
+        ctx->strbuf = 0;
+    }
 }
 
-re_state_id re_context::alloc_state() {
-	// If we don't have enough room for another state, expand the array 
-	if (_next_state >= (int)_tuple_arr.size()) {
-		// bump the size by a bit
-		_tuple_arr.resize(_tuple_arr.size() + 100);
-	}
-
-	// initialize the next state
-	_tuple_arr[_next_state].next_state_1 = RE_STATE_INVALID;
-	_tuple_arr[_next_state].next_state_2 = RE_STATE_INVALID;
-	_tuple_arr[_next_state].ch = RE_EPSILON;
-	_tuple_arr[_next_state].flags = 0;
-	_tuple_arr[_next_state].char_range = 0;
-
-	// return the new state's ID
-	return _next_state++;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Allocate a new state ID 
+ */
+static re_state_id re_alloc_state(re_context *ctx)
+{
+    /*
+     *   If we don't have enough room for another state, expand the array 
+     */
+    if (ctx->next_state >= ctx->tuples_alloc)
+    {
+        uint new_alloc;
+        
+        /* bump the size by a bit */
+        new_alloc = ctx->tuples_alloc + 100;
+        
+        /* allocate or expand the array */
+        if (ctx->tuples_alloc == 0)
+        {
+            /* allocate the initial memory block */
+            ctx->tuple_arr =
+                (re_tuple *)mchalo(ctx->errctx,
+                                   (new_alloc * sizeof(re_tuple)),
+                                   "regex");
+        }
+        else
+        {
+            re_tuple *ptr;
+            
+            /* allocate a new memory block */
+            ptr = (re_tuple *)mchalo(ctx->errctx,
+                                     (new_alloc * sizeof(re_tuple)),
+                                     "regex");
+            
+            /* copy the old memory to the new memory */
+            memcpy(ptr, ctx->tuple_arr, ctx->tuples_alloc * sizeof(re_tuple));
+
+            /* free the old block */
+            mchfre(ctx->tuple_arr);
+
+            /* use the new block */
+            ctx->tuple_arr = ptr;
+        }
+
+        /* remember the new allocation size */
+        ctx->tuples_alloc = new_alloc;
+    }
+
+    /* initialize the next state */
+    ctx->tuple_arr[ctx->next_state].next_state_1 = RE_STATE_INVALID;
+    ctx->tuple_arr[ctx->next_state].next_state_2 = RE_STATE_INVALID;
+    ctx->tuple_arr[ctx->next_state].ch = RE_EPSILON;
+    ctx->tuple_arr[ctx->next_state].flags = 0;
+    ctx->tuple_arr[ctx->next_state].char_range = 0;
+
+    /* return the new state's ID */
+    return ctx->next_state++;
 }
 
-void re_context::set_trans(re_state_id id, re_state_id dest_id, char ch) {
-	re_tuple *tuple;
-	
-	/* 
-	 * get the tuple containing the transitions for this state ID - the
-	 * state ID is the index of the state's transition tuple in the array 
-	 */
-	tuple = &_tuple_arr[id];
-
-	/*
-	 * If the first state pointer hasn't been set yet, set it to the new
-	 * destination.  Otherwise, set the second state pointer.
-	 * 
-	 * Only set the character on setting the first state.  When setting
-	 * the second state, we must assume that the character for the state
-	 * has already been set, since any given state can have only one
-	 * character setting.  
-	 */
-	if (tuple->next_state_1 == RE_STATE_INVALID) {
-		/* 
-		 * set the character ID, unless the state has been marked with a
-		 * special flag which indicates that the character value has
-		 * another meaning (in particular, a group marker) 
-		 */
-		if (!(tuple->flags & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END)))
-			tuple->ch = ch;
-
-		// set the first transition
-		tuple->next_state_1 = dest_id;
-	} else {
-		// set only the second transition state - don't set the character
-		tuple->next_state_2 = dest_id;
-	}
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Set a transition from a state to a given destination state.  
+ */
+static void re_set_trans(re_context *ctx,
+                         re_state_id id, re_state_id dest_id, char ch)
+{
+    re_tuple *tuple;
+    
+    /* 
+     *   get the tuple containing the transitions for this state ID - the
+     *   state ID is the index of the state's transition tuple in the
+     *   array 
+     */
+    tuple = &ctx->tuple_arr[id];
+
+    /*
+     *   If the first state pointer hasn't been set yet, set it to the new
+     *   destination.  Otherwise, set the second state pointer.
+     *   
+     *   Only set the character on setting the first state.  When setting
+     *   the second state, we must assume that the character for the state
+     *   has already been set, since any given state can have only one
+     *   character setting.  
+     */
+    if (tuple->next_state_1 == RE_STATE_INVALID)
+    {
+        /* 
+         *   set the character ID, unless the state has been marked with a
+         *   special flag which indicates that the character value has
+         *   another meaning (in particular, a group marker) 
+         */
+        if (!(tuple->flags & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END)))
+            tuple->ch = ch;
+
+        /* set the first transition */
+        tuple->next_state_1 = dest_id;
+    }
+    else
+    {
+        /* set only the second transition state - don't set the character */
+        tuple->next_state_2 = dest_id;
+    }
 }
 
-void re_context::init_machine(re_machine *machine) {
-	machine->init = alloc_state();
-	machine->final = alloc_state();
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize a new machine, giving it an initial and final state 
+ */
+static void re_init_machine(re_context *ctx, re_machine *machine)
+{
+    machine->init = re_alloc_state(ctx);
+    machine->final = re_alloc_state(ctx);
 }
 
-void re_context::build_char(re_machine *machine, char ch) {
-	// initialize our new machine
-	init_machine(machine);
+/*
+ *   Build a character recognizer
+ */
+static void re_build_char(re_context *ctx, re_machine *machine, char ch)
+{
+    /* initialize our new machine */
+    re_init_machine(ctx, machine);
 
-	// allocate a transition tuple for the new state
-	set_trans(machine->init, machine->final, ch);
+    /* allocate a transition tuple for the new state */
+    re_set_trans(ctx, machine->init, machine->final, ch);
 }
 
-void re_context::build_char_range(re_machine *machine, unsigned char *range, int exclusion) {
-	unsigned char *range_copy;
-	
-	// initialize our new machine
-	init_machine(machine);
-
-	// allocate a transition table for the new state
-	set_trans(machine->init, machine->final, (char)(exclusion ? RE_RANGE_EXCL : RE_RANGE));
+/*
+ *   Build a character range recognizer.  'range' is a 256-bit (32-byte)
+ *   bit vector.  
+ */
+static void re_build_char_range(re_context *ctx, re_machine *machine,
+                                unsigned char *range, int exclusion)
+{
+    unsigned char *range_copy;
+    
+    /* initialize our new machine */
+    re_init_machine(ctx, machine);
+
+    /* allocate a transition table for the new state */
+    re_set_trans(ctx, machine->init, machine->final,
+                 (char)(exclusion ? RE_RANGE_EXCL : RE_RANGE));
+
+    /* allocate a copy of the range bit vector */
+    range_copy = (unsigned char *)mchalo(ctx->errctx, 32, "regex range");
+
+    /* copy the caller's range */
+    memcpy(range_copy, range, 32);
+
+    /* store it in the tuple */
+    ctx->tuple_arr[machine->init].char_range = range_copy;
+}
+                                
 
-	// allocate a copy of the range bit vector
-	range_copy = (unsigned char *)mchalo(_errctx, 32, "regex range");
+/*
+ *   Build a group recognizer.  This is almost the same as a character
+ *   recognizer, but matches a previous group rather than a literal
+ *   character. 
+ */
+static void re_build_group_matcher(re_context *ctx,
+                                   re_machine *machine, int group_num)
+{
+    /* initialize our new machine */
+    re_init_machine(ctx, machine);
+
+    /* 
+     *   Allocate a transition tuple for the new state, using the group ID
+     *   as the character code.  Store the special code for a group
+     *   recognizer rather than the normal literal character code.  
+     */
+    re_set_trans(ctx, machine->init, machine->final,
+                 (char)(group_num + RE_GROUP_MATCH_0));
+}
 
-	// copy the caller's range
-	memcpy(range_copy, range, 32);
 
-	// store it in the tuple
-	_tuple_arr[machine->init].char_range = range_copy;
+/*
+ *   Build a concatenation recognizer 
+ */
+static void re_build_concat(re_context *ctx, re_machine *new_machine,
+                            re_machine *lhs, re_machine *rhs)
+{
+    /* initialize the new machine */
+    re_init_machine(ctx, new_machine);
+
+    /* 
+     *   set up an epsilon transition from the new machine's initial state
+     *   to the first submachine's initial state 
+     */
+    re_set_trans(ctx, new_machine->init, lhs->init, RE_EPSILON);
+
+    /*
+     *   Set up an epsilon transition from the first submachine's final
+     *   state to the second submachine's initial state 
+     */
+    re_set_trans(ctx, lhs->final, rhs->init, RE_EPSILON);
+
+    /*
+     *   Set up an epsilon transition from the second submachine's final
+     *   state to our new machine's final state 
+     */
+    re_set_trans(ctx, rhs->final, new_machine->final, RE_EPSILON);
 }
 
-void re_context::build_group_matcher(re_machine *machine, int group_num) {
-	// initialize our new machine
-	init_machine(machine);
-
-	/* 
-	 * Allocate a transition tuple for the new state, using the group ID
-	 * as the character code.  Store the special code for a group
-	 * recognizer rather than the normal literal character code.  
-	 */
-	set_trans(machine->init, machine->final, (char)(group_num + RE_GROUP_MATCH_0));
+/*
+ *   Build a group machine.  sub_machine contains the machine that
+ *   expresses the group's contents; we'll fill in new_machine with a
+ *   newly-created machine that encloses and marks the group.  
+ */
+static void re_build_group(re_context *ctx, re_machine *new_machine,
+                           re_machine *sub_machine, int group_id)
+{
+    /* initialize the container machine */
+    re_init_machine(ctx, new_machine);
+
+    /* 
+     *   set up an epsilon transition from the new machine's initial state
+     *   into the initial state of the group, and another transition from
+     *   the group's final state into the container's final state 
+     */
+    re_set_trans(ctx, new_machine->init, sub_machine->init, RE_EPSILON);
+    re_set_trans(ctx, sub_machine->final, new_machine->final, RE_EPSILON);
+
+    /*
+     *   Mark the initial and final states of the group machine as being
+     *   group markers.  
+     */
+    ctx->tuple_arr[new_machine->init].flags |= RE_STATE_GROUP_BEGIN;
+    ctx->tuple_arr[new_machine->final].flags |= RE_STATE_GROUP_END;
+
+    /* store the group ID in the 'ch' member of the start and end states */
+    ctx->tuple_arr[new_machine->init].ch = group_id;
+    ctx->tuple_arr[new_machine->final].ch = group_id;
 }
 
-void re_context::build_concat(re_machine *new_machine, re_machine *lhs, re_machine *rhs) {
-	// initialize the new machine
-	init_machine(new_machine);
-
-	/* 
-	 * Set up an epsilon transition from the new machine's initial state
-	 * to the first submachine's initial state 
-	 */
-	set_trans(new_machine->init, lhs->init, RE_EPSILON);
-
-	/*
-	 * Set up an epsilon transition from the first submachine's final
-	 * state to the second submachine's initial state 
-	 */
-	set_trans(lhs->final, rhs->init, RE_EPSILON);
-
-	/*
-	 * Set up an epsilon transition from the second submachine's final
-	 * state to our new machine's final state 
-	 */
-	set_trans(rhs->final, new_machine->final, RE_EPSILON);
+/*
+ *   Build an alternation recognizer 
+ */
+static void re_build_alter(re_context *ctx, re_machine *new_machine,
+                           re_machine *lhs, re_machine *rhs)
+{
+    /* initialize the new machine */
+    re_init_machine(ctx, new_machine);
+
+    /*
+     *   Set up an epsilon transition from our new machine's initial state
+     *   to the initial state of each submachine 
+     */
+    re_set_trans(ctx, new_machine->init, lhs->init, RE_EPSILON);
+    re_set_trans(ctx, new_machine->init, rhs->init, RE_EPSILON);
+
+    /*
+     *   Set up an epsilon transition from the final state of each
+     *   submachine to our final state 
+     */
+    re_set_trans(ctx, lhs->final, new_machine->final, RE_EPSILON);
+    re_set_trans(ctx, rhs->final, new_machine->final, RE_EPSILON);
 }
 
-void re_context::build_group(re_machine *new_machine, re_machine *sub_machine, int group_id) {
-	// initialize the container machine
-	init_machine(new_machine);
-
-	/* 
-	 * set up an epsilon transition from the new machine's initial state
-	 * into the initial state of the group, and another transition from
-	 * the group's final state into the container's final state 
-	 */
-	set_trans(new_machine->init, sub_machine->init, RE_EPSILON);
-	set_trans(sub_machine->final, new_machine->final, RE_EPSILON);
-
-	// Mark the initial and final states of the group machine as being group markers
-	_tuple_arr[new_machine->init].flags |= RE_STATE_GROUP_BEGIN;
-	_tuple_arr[new_machine->final].flags |= RE_STATE_GROUP_END;
-
-	// store the group ID in the 'ch' member of the start and end states
-	_tuple_arr[new_machine->init].ch = group_id;
-	_tuple_arr[new_machine->final].ch = group_id;
+/*
+ *   Build a closure recognizer
+ */
+static void re_build_closure(re_context *ctx,
+                             re_machine *new_machine, re_machine *sub,
+                             char specifier)
+{
+    /* initialize the new machine */
+    re_init_machine(ctx, new_machine);
+
+    /* 
+     *   set up an epsilon transition from our initial state to the
+     *   submachine's initial state, and from the submachine's final state
+     *   to our final state 
+     */
+    re_set_trans(ctx, new_machine->init, sub->init, RE_EPSILON);
+    re_set_trans(ctx, sub->final, new_machine->final, RE_EPSILON);
+
+    /*
+     *   If this is an unbounded closure ('*' or '+', but not '?'), set up
+     *   the loop transition that takes us from the new machine's final
+     *   state back to its initial state.  We don't do this on the
+     *   zero-or-one closure, because we can only match the expression
+     *   once.  
+     */
+    if (specifier != '?')
+        re_set_trans(ctx, sub->final, sub->init, RE_EPSILON);
+
+    /*
+     *   If this is a zero-or-one closure or a zero-or-more closure, set
+     *   up an epsilon transition from our initial state to our final
+     *   state, since we can skip the entire subexpression.  We don't do
+     *   this on the one-or-more closure, because we can't skip the
+     *   subexpression in this case.  
+     */
+    if (specifier != '+')
+        re_set_trans(ctx, new_machine->init, new_machine->final, RE_EPSILON);
 }
 
-void re_context::build_alter(re_machine *new_machine, re_machine *lhs, re_machine *rhs) {
-	// initialize the new machine
-	init_machine(new_machine);
-
-	/*
-	 * Set up an epsilon transition from our new machine's initial state
-	 * to the initial state of each submachine 
-	 */
-	set_trans(new_machine->init, lhs->init, RE_EPSILON);
-	set_trans(new_machine->init, rhs->init, RE_EPSILON);
-
-	/*
-	 * Set up an epsilon transition from the final state of each
-	 * submachine to our final state 
-	 */
-	set_trans(lhs->final, new_machine->final, RE_EPSILON);
-	set_trans(rhs->final, new_machine->final, RE_EPSILON);
+/*
+ *   Build a null machine 
+ */
+static void re_build_null_machine(re_context *ctx, re_machine *machine)
+{
+    machine->init = machine->final = RE_STATE_INVALID;
 }
 
-void re_context::build_closure(re_machine *new_machine, re_machine *sub, char specifier) {
-	// initialize the new machine
-	init_machine(new_machine);
-
-	/* 
-	 * Set up an epsilon transition from our initial state to the submachine's initial
-	 * state, and from the submachine's final state to our final state 
-	 */
-	set_trans(new_machine->init, sub->init, RE_EPSILON);
-	set_trans(sub->final, new_machine->final, RE_EPSILON);
-
-	/*
-	 * If this is an unbounded closure ('*' or '+', but not '?'), set up
-	 * the loop transition that takes us from the new machine's final
-	 * state back to its initial state.  We don't do this on the
-	 * zero-or-one closure, because we can only match the expression
-	 * once.  
-	 */
-	if (specifier != '?')
-		set_trans(sub->final, sub->init, RE_EPSILON);
-
-	/*
-	 * If this is a zero-or-one closure or a zero-or-more closure, set
-	 * up an epsilon transition from our initial state to our final
-	 * state, since we can skip the entire subexpression.  We don't do
-	 * this on the one-or-more closure, because we can't skip the
-	 * subexpression in this case.  
-	 */
-	if (specifier != '+')
-		set_trans(new_machine->init, new_machine->final, RE_EPSILON);
+/* ------------------------------------------------------------------------ */
+/*
+ *   Determine if a machine is null 
+ */
+static int re_is_machine_null(re_context *ctx, re_machine *machine)
+{
+    return (machine->init == RE_STATE_INVALID);
 }
 
-void re_context::concat_onto(re_machine *dest, re_machine *rhs) {
-	// check for a null destination machine
-	if (dest->isNull()) {
-		/* 
-		 * the first machine is null - simply copy the second machine
-		 * onto the first unchanged 
-		 */
-		*dest = *rhs;
-	} else {
-		re_machine new_machine;
-		
-		// build the concatenated machine
-		build_concat(&new_machine, dest, rhs);
-
-		// copy the concatenated machine onto the first machine
-		*dest = new_machine;
-	}
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Concatenate the second machine onto the first machine, replacing the
+ *   first machine with the resulting machine.  If the first machine is a
+ *   null machine (created with re_build_null_machine), we'll simply copy
+ *   the second machine into the first. 
+ */
+static void re_concat_onto(re_context *ctx,
+                           re_machine *dest, re_machine *rhs)
+{
+    /* check for a null destination machine */
+    if (re_is_machine_null(ctx, dest))
+    {
+        /* 
+         *   the first machine is null - simply copy the second machine
+         *   onto the first unchanged 
+         */
+        *dest = *rhs;
+    }
+    else
+    {
+        re_machine new_machine;
+        
+        /* build the concatenated machine */
+        re_build_concat(ctx, &new_machine, dest, rhs);
+
+        /* copy the concatenated machine onto the first machine */
+        *dest = new_machine;
+    }
 }
 
-void re_context::alternate_onto(re_machine *dest, re_machine *rhs) {
-	// check to see if the first machine is null
-	if (dest->isNull()) {
-		/* 
-		 * the first machine is null - simply copy the second machine
-		 * onto the first 
-		 */
-		*dest = *rhs;
-	} else {
-		/* 
-		 * if the second machine is null, don't do anything; otherwise,
-		 * build the alternation 
-		 */
-		if (!rhs->isNull()) {
-			re_machine new_machine;
-			
-			// build the alternation
-			build_alter(&new_machine, dest, rhs);
-
-			// replace the first machine with the alternation
-			*dest = new_machine;
-		}
-	}
+/*
+ *   Alternate the second machine onto the first machine, replacing the
+ *   first machine with the resulting machine.  If the first machine is a
+ *   null machine, this simply replaces the first machine with the second
+ *   machine.  If the second machine is null, this simply leaves the first
+ *   machine unchanged. 
+ */
+static void re_alternate_onto(re_context *ctx,
+                              re_machine *dest, re_machine *rhs)
+{
+    /* check to see if the first machine is null */
+    if (re_is_machine_null(ctx, dest))
+    {
+        /* 
+         *   the first machine is null - simply copy the second machine
+         *   onto the first 
+         */
+        *dest = *rhs;
+    }
+    else
+    {
+        /* 
+         *   if the second machine is null, don't do anything; otherwise,
+         *   build the alternation 
+         */
+        if (!re_is_machine_null(ctx, rhs))
+        {
+            re_machine new_machine;
+            
+            /* build the alternation */
+            re_build_alter(ctx, &new_machine, dest, rhs);
+
+            /* replace the first machine with the alternation */
+            *dest = new_machine;
+        }
+    }
 }
 
-/**
- * Set a bit in a bit vector.
+/* ------------------------------------------------------------------------ */
+/*
+ *   Set a bit in a bit vector.
  */
 #define re_set_bit(set, bit) \
-	(((unsigned char *)(set))[(bit) >> 3] |= (1 << ((bit) & 7)))
+    (((unsigned char *)(set))[(bit) >> 3] |= (1 << ((bit) & 7)))
 
-/**
- * Test a bit in a bit vector 
+/*
+ *   Test a bit in a bit vector 
  */
 #define re_is_bit_set(set, bit) \
-	((((unsigned char *)(set))[(bit) >> 3] & (1 << ((bit) & 7))) != 0)
-
-re_status_t re_context::compile(const char *expr, size_t exprlen, re_machine *result_machine) {
-	re_machine cur_machine;
-	re_machine alter_machine;
-	re_machine new_machine;
-	size_t group_stack_level;
-	struct {
-		re_machine old_cur;
-		re_machine old_alter;
-		int group_id;
-	} group_stack[50];
-
-	// reset everything
-	reset();
-
-	// start out with no current machine and no alternate machine
-	cur_machine.build_null_machine();
-	alter_machine.build_null_machine();
-
-	// nothing on the stack yet
-	group_stack_level = 0;
-
-	// loop until we run out of expression to parse
-	for (; exprlen != 0 ; ++expr, --exprlen) {
-		switch(*expr) {
-		case '^':
-			/*
-			 * beginning of line - if we're not at the beginning of the
-			 * current expression (i.e., we already have some
-			 * concatentations accumulated), treat it as an ordinary
-			 * character 
-			 */
-			if (!cur_machine.isNull())
-				goto normal_char;
-
-			// build a new start-of-text recognizer
-			build_char(&new_machine, RE_TEXT_BEGIN);
-
-			/* 
-			 * concatenate it onto the string - note that this can't
-			 * have any postfix operators 
-			 */
-			concat_onto(&cur_machine, &new_machine);
-			break;
-
-		case '$':
-			/*
-			 * End of line specifier - if there's anything left after
-			 * the '$' other than a close parens or alternation
-			 * specifier, great it as a normal character 
-			 */
-			if (exprlen > 1
-				&& (*(expr+1) != ')' && *(expr+1) != '|'))
-				goto normal_char;
-
-			// build a new end-of-text recognizer
-			build_char(&new_machine, RE_TEXT_END);
-
-			/* 
-			 * concatenate it onto the string - note that this can't
-			 * have any postfix operators 
-			 */
-			concat_onto(&cur_machine, &new_machine);
-			break;
-			
-		case '(':
-			/* 
-			 * Add a nesting level.  Push the current machine and
-			 * alternate machines onto the group stack, and clear
-			 * everything out for the new group. 
-			 */
-			if (group_stack_level > sizeof(group_stack)/sizeof(group_stack[0])) {
-				/* we cannot proceed - return an error */
-				return RE_STATUS_GROUP_NESTING_TOO_DEEP;
-			}
-
-			// save the current state on the stack
-			group_stack[group_stack_level].old_cur = cur_machine;
-			group_stack[group_stack_level].old_alter = alter_machine;
-
-			/* 
-			 * Assign the group a group ID - groups are numbered in
-			 * order of their opening (left) parentheses, so we want to
-			 * assign a group number now.  We won't actually need to
-			 * know the group number until we get to the matching close
-			 * paren, but we need to assign it now, so store it in the
-			 * group stack. 
-			 */
-			group_stack[group_stack_level].group_id = _cur_group;
-
-			// consume the group number
-			_cur_group++;
-
-			// push the level
-			++group_stack_level;
-
-			// start the new group with empty machines
-			cur_machine.build_null_machine();
-			alter_machine.build_null_machine();
-			break;
-
-		case ')':
-			// if there's nothing on the stack, ignore this
-			if (group_stack_level == 0)
-				break;
-
-			// take a level off the stack
-			--group_stack_level;
-
-			/* 
-			 * Remove a nesting level.  If we have a pending alternate
-			 * expression, build the alternation expression.  This will
-			 * leave the entire group expression in alter_machine,
-			 * regardless of whether an alternation was in progress or
-			 * not.  
-			 */
-			alternate_onto(&alter_machine, &cur_machine);
-
-			/*
-			 * Create a group machine that encloses the group and marks
-			 * it with a group number.  We assigned the group number
-			 * when we parsed the open paren, so read that group number
-			 * from the stack.
-			 * 
-			 * Note that this will leave 'new_machine' with the entire
-			 * group machine.  
-			 */
-			build_group(&new_machine, &alter_machine,
-				group_stack[group_stack_level].group_id);
-
-			/*
-			 * Pop the stack - restore the alternation and current
-			 * machines that were in progress before the group started. 
-			 */
-			cur_machine = group_stack[group_stack_level].old_cur;
-			alter_machine = group_stack[group_stack_level].old_alter;
-
-			/*
-			 * Check the group expression (in new_machine) for postfix
-			 * expressions 
-			 */
-			goto apply_postfix;
-
-		case '|':
-			/* 
-			 * Start a new alternation.  This ends the current
-			 * alternation; if we have a previous pending alternate,
-			 * build an alternation machine out of the previous
-			 * alternate and the current machine and move that to the
-			 * alternate; otherwise, simply move the current machine to
-			 * the pending alternate. 
-			 */
-			alternate_onto(&alter_machine, &cur_machine);
-
-			/* 
-			 * the alternation starts out with a blank slate, so null
-			 * out the current machine 
-			 */
-			cur_machine.build_null_machine();
-			break;
-
-		case '%':
-			// quoted character - skip the quote mark and see what we have 
-			++expr;
-			--exprlen;
-
-			// check to see if we're at the end of the expression
-			if (exprlen == 0) {
-				/* 
-				 * end of the string - ignore it, but undo the extra
-				 * increment of the expression index so that we exit the
-				 * enclosing loop properly 
-				 */
-				--expr;
-				++exprlen;
-				break;
-			}
-
-			// see what we have
-			switch(*expr) {
-			case '1':
-			case '2':
-			case '3':
-			case '4':
-			case '5':
-			case '6':
-			case '7':
-			case '8':
-			case '9':
-				// group match - build a new literal group recognizer
-				build_group_matcher(&new_machine, (int)(*expr - '1'));
-
-				// apply any postfix expression to the group recognizer
-				goto apply_postfix;
-
-			case '<':
-				// build a beginning-of-word recognizer
-				build_char(&new_machine, RE_WORD_BEGIN);
-
-				// it can't be postfixed - just concatenate it
-				concat_onto(&cur_machine, &new_machine);
-				break;
-
-			case '>':
-				// build an end-of-word recognizer */
-				build_char(&new_machine, RE_WORD_END);
-
-				// it can't be postfixed - just concatenate it
-				concat_onto(&cur_machine, &new_machine);
-				break;
-
-			case 'w':
-				// word character
-				build_char(&new_machine, RE_WORD_CHAR);
-				goto apply_postfix;
-
-			case 'W':
-				// non-word character
-				build_char(&new_machine, RE_NON_WORD_CHAR);
-				goto apply_postfix;
-
-			case 'b':
-				// word boundary
-				build_char(&new_machine, RE_WORD_BOUNDARY);
-
-				// it can't be postfixed
-				concat_onto(&cur_machine, &new_machine);
-				break;
-
-			case 'B':
-				// not a word boundary
-				build_char(&new_machine, RE_NON_WORD_BOUNDARY);
-
-				// it can't be postfixed
-				concat_onto(&cur_machine, &new_machine);
-				break;
-
-			default:
-				// build a new literal character recognizer
-				build_char(&new_machine, *expr);
-
-				// apply any postfix expression to the character
-				goto apply_postfix;
-			}
-			break;
-
-		case '.':
-			/* 
-			 * wildcard character - build a single character recognizer
-			 * for the special wildcard symbol, then go check it for a
-			 * postfix operator 
-			 */
-			build_char(&new_machine, RE_WILDCARD);
-			goto apply_postfix;
-			break;
-
-		case '[': {
-			// range expression
-			int is_exclusive = false;
-			unsigned char set[32];
-
-			// clear out the set of characters in the range
-			memset(set, 0, sizeof(set));
-
-			// first, skip the open bracket
-			++expr;
-			--exprlen;
-
-			// check to see if starts with the exclusion character
-			if (exprlen != 0 && *expr == '^') {
-				// skip the exclusion specifier
-				++expr;
-				--exprlen;
-
-				// note it
-				is_exclusive = true;
-			}
-
-			// if the first character is a ']', include it in the range 
-			if (exprlen != 0 && *expr == ']') {
-				re_set_bit(set, (int)']');
-				++expr;
-				--exprlen;
-			}
-
-			// if the next character is a '-', include it in the range        
-			if (exprlen != 0 && *expr == '-') {
-				re_set_bit(set, (int)'-');
-				++expr;
-				--exprlen;
-			}
-
-			// scan the character set
-			while (exprlen != 0 && *expr != ']') {
-				int ch;
-
-				// note this character
-				ch = (int)(unsigned char)*expr;
-
-				// set it
-				re_set_bit(set, ch);
-
-				// skip this character of the expression
-				++expr;
-				--exprlen;
-
-				// check for a range
-				if (exprlen != 0 && *expr == '-') {
-					int ch2;
-	
-					// skip the '-'
-					++expr;
-					--exprlen;
-					if (exprlen != 0) {
-						// get the other end of the range
-						ch2 = (int)(unsigned char)*expr;
-
-						// skip the second character
-						++expr;
-						--exprlen;
-
-						// if the range is reversed, swap it
-						if (ch > ch2)
-							SWAP(ch, ch2);
-
-						// fill in the range
-						for ( ; ch <= ch2 ; ++ch)
-							re_set_bit(set, ch);
-					}
-				}
-			}
-
-			// create a character range machine
-			build_char_range(&new_machine, set, is_exclusive);
-
-			// apply any postfix operator
-			goto apply_postfix;
-			break;
-		}
-
-		default:
-		normal_char:
-			/* 
-			 * it's an ordinary character - build a single character
-			 * recognizer machine, and then concatenate it onto any
-			 * existing machine 
-			 */
-			build_char(&new_machine, *expr);
-
-		apply_postfix:
-			/*
-			 * Check for a postfix operator, and apply it to the machine
-			 * in 'new_machine' if present.  In any case, concatenate
-			 * the 'new_machine' (modified by a postix operator or not)
-			 * to the current machien.  
-			 */
-			if (exprlen > 1) {
-				switch(*(expr+1)) {
-				case '*':
-				case '+':
-				case '?':
-					/*
-					 * We have a postfix closure operator.  Build a new
-					 * closure machine out of 'new_machine'.  
-					 */
-					{
-						re_machine closure_machine;
-						
-						// move onto the closure operator
-						++expr;
-						--exprlen;
-						
-						// build the closure machine
-						build_closure(&closure_machine, &new_machine, *expr);
-						
-						// replace the original machine with the closure
-						new_machine = closure_machine;
-						
-						/* 
-						 * skip any redundant closure symbols, keeping
-						 * only the first one we saw 
-						 */
-						while (exprlen > 1 && (*(expr+1) == '?'
-											   || *(expr+1) == '+'
-											   || *(expr+1) == '*')) {
-							++expr;
-							--exprlen;
-						}
-					}
-					break;
-					
-				default:
-					/* no postfix operator */
-					break;
-				}
-			}
-
-			/*
-			 * Concatenate the new machine onto the current machine
-			 * under construction.  
-			 */
-			concat_onto(&cur_machine, &new_machine);
-			break;
-		}
-	}
-
-	// complete any pending alternation
-	alternate_onto(&alter_machine, &cur_machine);
-
-	// store the resulting machine in the caller's machine descriptor
-	*result_machine = alter_machine;
-
-	// no errors encountered
-	return RE_STATUS_SUCCESS;
+    ((((unsigned char *)(set))[(bit) >> 3] & (1 << ((bit) & 7))) != 0)
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Compile an expression 
+ */
+static re_status_t re_compile(re_context *ctx,
+                              const char *expr, size_t exprlen,
+                              re_machine *result_machine)
+{
+    re_machine cur_machine;
+    re_machine alter_machine;
+    re_machine new_machine;
+    size_t group_stack_level;
+    struct
+    {
+        re_machine old_cur;
+        re_machine old_alter;
+        int group_id;
+    } group_stack[50];
+
+    /* reset everything */
+    re_reset(ctx);
+
+    /* start out with no current machine and no alternate machine */
+    re_build_null_machine(ctx, &cur_machine);
+    re_build_null_machine(ctx, &alter_machine);
+
+    /* nothing on the stack yet */
+    group_stack_level = 0;
+
+    /* loop until we run out of expression to parse */
+    for ( ; exprlen != 0 ; ++expr, --exprlen)
+    {
+        switch(*expr)
+        {
+        case '^':
+            /*
+             *   beginning of line - if we're not at the beginning of the
+             *   current expression (i.e., we already have some
+             *   concatentations accumulated), treat it as an ordinary
+             *   character 
+             */
+            if (!re_is_machine_null(ctx, &cur_machine))
+                goto normal_char;
+
+            /* build a new start-of-text recognizer */
+            re_build_char(ctx, &new_machine, RE_TEXT_BEGIN);
+
+            /* 
+             *   concatenate it onto the string - note that this can't
+             *   have any postfix operators 
+             */
+            re_concat_onto(ctx, &cur_machine, &new_machine);
+            break;
+
+        case '$':
+            /*
+             *   End of line specifier - if there's anything left after
+             *   the '$' other than a close parens or alternation
+             *   specifier, great it as a normal character 
+             */
+            if (exprlen > 1
+                && (*(expr+1) != ')' && *(expr+1) != '|'))
+                goto normal_char;
+
+            /* build a new end-of-text recognizer */
+            re_build_char(ctx, &new_machine, RE_TEXT_END);
+
+            /* 
+             *   concatenate it onto the string - note that this can't
+             *   have any postfix operators 
+             */
+            re_concat_onto(ctx, &cur_machine, &new_machine);
+            break;
+            
+        case '(':
+            /* 
+             *   Add a nesting level.  Push the current machine and
+             *   alternate machines onto the group stack, and clear
+             *   everything out for the new group. 
+             */
+            if (group_stack_level
+                > sizeof(group_stack)/sizeof(group_stack[0]))
+            {
+                /* we cannot proceed - return an error */
+                return RE_STATUS_GROUP_NESTING_TOO_DEEP;
+            }
+
+            /* save the current state on the stack */
+            group_stack[group_stack_level].old_cur = cur_machine;
+            group_stack[group_stack_level].old_alter = alter_machine;
+
+            /* 
+             *   Assign the group a group ID - groups are numbered in
+             *   order of their opening (left) parentheses, so we want to
+             *   assign a group number now.  We won't actually need to
+             *   know the group number until we get to the matching close
+             *   paren, but we need to assign it now, so store it in the
+             *   group stack. 
+             */
+            group_stack[group_stack_level].group_id = ctx->cur_group;
+
+            /* consume the group number */
+            ctx->cur_group++;
+
+            /* push the level */
+            ++group_stack_level;
+
+            /* start the new group with empty machines */
+            re_build_null_machine(ctx, &cur_machine);
+            re_build_null_machine(ctx, &alter_machine);
+            break;
+
+        case ')':
+            /* if there's nothing on the stack, ignore this */
+            if (group_stack_level == 0)
+                break;
+
+            /* take a level off the stack */
+            --group_stack_level;
+
+            /* 
+             *   Remove a nesting level.  If we have a pending alternate
+             *   expression, build the alternation expression.  This will
+             *   leave the entire group expression in alter_machine,
+             *   regardless of whether an alternation was in progress or
+             *   not.  
+             */
+            re_alternate_onto(ctx, &alter_machine, &cur_machine);
+
+            /*
+             *   Create a group machine that encloses the group and marks
+             *   it with a group number.  We assigned the group number
+             *   when we parsed the open paren, so read that group number
+             *   from the stack.
+             *   
+             *   Note that this will leave 'new_machine' with the entire
+             *   group machine.  
+             */
+            re_build_group(ctx, &new_machine, &alter_machine,
+                           group_stack[group_stack_level].group_id);
+
+            /*
+             *   Pop the stack - restore the alternation and current
+             *   machines that were in progress before the group started. 
+             */
+            cur_machine = group_stack[group_stack_level].old_cur;
+            alter_machine = group_stack[group_stack_level].old_alter;
+
+            /*
+             *   Check the group expression (in new_machine) for postfix
+             *   expressions 
+             */
+            goto apply_postfix;
+
+        case '|':
+            /* 
+             *   Start a new alternation.  This ends the current
+             *   alternation; if we have a previous pending alternate,
+             *   build an alternation machine out of the previous
+             *   alternate and the current machine and move that to the
+             *   alternate; otherwise, simply move the current machine to
+             *   the pending alternate. 
+             */
+            re_alternate_onto(ctx, &alter_machine, &cur_machine);
+
+            /* 
+             *   the alternation starts out with a blank slate, so null
+             *   out the current machine 
+             */
+            re_build_null_machine(ctx, &cur_machine);
+            break;
+
+        case '%':
+            /* 
+             *   quoted character - skip the quote mark and see what we
+             *   have 
+             */
+            ++expr;
+            --exprlen;
+
+            /* check to see if we're at the end of the expression */
+            if (exprlen == 0)
+            {
+                /* 
+                 *   end of the string - ignore it, but undo the extra
+                 *   increment of the expression index so that we exit the
+                 *   enclosing loop properly 
+                 */
+                --expr;
+                ++exprlen;
+                break;
+            }
+
+            /* see what we have */
+            switch(*expr)
+            {
+            case '1':
+            case '2':
+            case '3':
+            case '4':
+            case '5':
+            case '6':
+            case '7':
+            case '8':
+            case '9':
+                /* group match - build a new literal group recognizer */
+                re_build_group_matcher(ctx, &new_machine, (int)(*expr - '1'));
+
+                /* apply any postfix expression to the group recognizer */
+                goto apply_postfix;
+
+            case '<':
+                /* build a beginning-of-word recognizer */
+                re_build_char(ctx, &new_machine, RE_WORD_BEGIN);
+
+                /* it can't be postfixed - just concatenate it */
+                re_concat_onto(ctx, &cur_machine, &new_machine);
+                break;
+
+            case '>':
+                /* build an end-of-word recognizer */
+                re_build_char(ctx, &new_machine, RE_WORD_END);
+
+                /* it can't be postfixed - just concatenate it */
+                re_concat_onto(ctx, &cur_machine, &new_machine);
+                break;
+
+            case 'w':
+                /* word character */
+                re_build_char(ctx, &new_machine, RE_WORD_CHAR);
+                goto apply_postfix;
+
+            case 'W':
+                /* non-word character */
+                re_build_char(ctx, &new_machine, RE_NON_WORD_CHAR);
+                goto apply_postfix;
+
+            case 'b':
+                /* word boundary */
+                re_build_char(ctx, &new_machine, RE_WORD_BOUNDARY);
+
+                /* it can't be postfixed */
+                re_concat_onto(ctx, &cur_machine, &new_machine);
+                break;
+
+            case 'B':
+                /* not a word boundary */
+                re_build_char(ctx, &new_machine, RE_NON_WORD_BOUNDARY);
+
+                /* it can't be postfixed */
+                re_concat_onto(ctx, &cur_machine, &new_machine);
+                break;
+
+            default:
+                /* build a new literal character recognizer */
+                re_build_char(ctx, &new_machine, *expr);
+
+                /* apply any postfix expression to the character */
+                goto apply_postfix;
+            }
+            break;
+
+        case '.':
+            /* 
+             *   wildcard character - build a single character recognizer
+             *   for the special wildcard symbol, then go check it for a
+             *   postfix operator 
+             */
+            re_build_char(ctx, &new_machine, RE_WILDCARD);
+            goto apply_postfix;
+            break;
+
+        case '[':
+            /* range expression */
+            {
+                int is_exclusive = FALSE;
+                unsigned char set[32];
+
+                /* clear out the set of characters in the range */
+                memset(set, 0, sizeof(set));
+
+                /* first, skip the open bracket */
+                ++expr;
+                --exprlen;
+
+                /* check to see if starts with the exclusion character */
+                if (exprlen != 0 && *expr == '^')
+                {
+                    /* skip the exclusion specifier */
+                    ++expr;
+                    --exprlen;
+
+                    /* note it */
+                    is_exclusive = TRUE;
+                }
+
+                /* 
+                 *   if the first character is a ']', include it in the
+                 *   range 
+                 */
+                if (exprlen != 0 && *expr == ']')
+                {
+                    re_set_bit(set, (int)']');
+                    ++expr;
+                    --exprlen;
+                }
+
+                /*
+                 *   if the next character is a '-', include it in the
+                 *   range 
+                 */
+                if (exprlen != 0 && *expr == '-')
+                {
+                    re_set_bit(set, (int)'-');
+                    ++expr;
+                    --exprlen;
+                }
+
+                /* scan the character set */
+                while (exprlen != 0 && *expr != ']')
+                {
+                    int ch;
+                    
+                    /* note this character */
+                    ch = (int)(unsigned char)*expr;
+
+                    /* set it */
+                    re_set_bit(set, ch);
+
+                    /* skip this character of the expression */
+                    ++expr;
+                    --exprlen;
+
+                    /* check for a range */
+                    if (exprlen != 0 && *expr == '-')
+                    {
+                        int ch2;
+                        
+                        /* skip the '-' */
+                        ++expr;
+                        --exprlen;
+                        if (exprlen != 0)
+                        {
+                            /* get the other end of the range */
+                            ch2 = (int)(unsigned char)*expr;
+
+                            /* skip the second character */
+                            ++expr;
+                            --exprlen;
+
+                            /* if the range is reversed, swap it */
+                            if (ch > ch2)
+                            {
+                                int tmp = ch;
+                                ch = ch2;
+                                ch2 = tmp;
+                            }
+
+                            /* fill in the range */
+                            for ( ; ch <= ch2 ; ++ch)
+                                re_set_bit(set, ch);
+                        }
+                    }
+                }
+
+                /* create a character range machine */
+                re_build_char_range(ctx, &new_machine, set, is_exclusive);
+
+                /* apply any postfix operator */
+                goto apply_postfix;
+            }            
+            break;
+
+        default:
+        normal_char:
+            /* 
+             *   it's an ordinary character - build a single character
+             *   recognizer machine, and then concatenate it onto any
+             *   existing machine 
+             */
+            re_build_char(ctx, &new_machine, *expr);
+
+        apply_postfix:
+            /*
+             *   Check for a postfix operator, and apply it to the machine
+             *   in 'new_machine' if present.  In any case, concatenate
+             *   the 'new_machine' (modified by a postix operator or not)
+             *   to the current machien.  
+             */
+            if (exprlen > 1)
+            {
+                switch(*(expr+1))
+                {
+                case '*':
+                case '+':
+                case '?':
+                    /*
+                     *   We have a postfix closure operator.  Build a new
+                     *   closure machine out of 'new_machine'.  
+                     */
+                    {
+                        re_machine closure_machine;
+                        
+                        /* move onto the closure operator */
+                        ++expr;
+                        --exprlen;
+                        
+                        /* build the closure machine */
+                        re_build_closure(ctx, &closure_machine,
+                                         &new_machine, *expr);
+                        
+                        /* replace the original machine with the closure */
+                        new_machine = closure_machine;
+                        
+                        /* 
+                         *   skip any redundant closure symbols, keeping
+                         *   only the first one we saw 
+                         */
+                        while (exprlen > 1 && (*(expr+1) == '?'
+                                               || *(expr+1) == '+'
+                                               || *(expr+1) == '*'))
+                        {
+                            ++expr;
+                            --exprlen;
+                        }
+                    }
+                    break;
+                    
+                default:
+                    /* no postfix operator */
+                    break;
+                }
+            }
+
+            /*
+             *   Concatenate the new machine onto the current machine
+             *   under construction.  
+             */
+            re_concat_onto(ctx, &cur_machine, &new_machine);
+            break;
+        }
+    }
+
+    /* complete any pending alternation */
+    re_alternate_onto(ctx, &alter_machine, &cur_machine);
+
+    /* store the resulting machine in the caller's machine descriptor */
+    *result_machine = alter_machine;
+
+    /* no errors encountered */
+    return RE_STATUS_SUCCESS;
 }
 
-void re_context::note_group(re_group_register *regs, re_state_id id, const char *p) {
-	int group_index;
-
-	/*
-	 * Check to see if this is a valid state and it's a group marker -
-	 * if not, there's nothing to do 
-	 */
-	if (id == RE_STATE_INVALID
-		|| !(_tuple_arr[id].flags
-			 & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END))
-		|| (group_index = (int)_tuple_arr[id].ch) >= RE_GROUP_REG_CNT)
-		return;
-
-	// It's a valid group marker - note the appropriate register value 
-	if ((_tuple_arr[id].flags & RE_STATE_GROUP_BEGIN) != 0)
-		regs[group_index].start_ofs = p;
-	else
-		regs[group_index].end_ofs = p;
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Pattern recognizer 
+ */
+
+/*
+ *   Note a group position if appropriate 
+ */
+static void re_note_group(re_context *ctx, re_group_register *regs,
+                          re_state_id id, const char *p)
+{
+    int group_index;
+
+    /*
+     *   Check to see if this is a valid state and it's a group marker -
+     *   if not, there's nothing to do 
+     */
+    if (id == RE_STATE_INVALID
+        || !(ctx->tuple_arr[id].flags
+             & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END))
+        || (group_index = (int)ctx->tuple_arr[id].ch) >= RE_GROUP_REG_CNT)
+        return;
+
+    /*
+     *   It's a valid group marker - note the appropriate register value 
+     */
+    if ((ctx->tuple_arr[id].flags & RE_STATE_GROUP_BEGIN) != 0)
+        regs[group_index].start_ofs = p;
+    else
+        regs[group_index].end_ofs = p;
 }
 
-bool re_context::is_word_char(char c) const {
-	return Common::isAlnum(c);
+/*
+ *   Determine if a character is part of a word.  We consider letters and
+ *   numbers to be word characters.  
+ */
+static int re_is_word_char(char c) {
+	return Common::isAlnum((unsigned char)c);
 }
 
-int re_context::match(const char *entire_str, const char *str, size_t origlen,
-		const re_machine *machine, re_group_register *regs) {
-	re_state_id cur_state;
-	const char *p;
-	size_t curlen;
-
-	// start at the machine's initial state
-	cur_state = machine->init;
-
-	// start at the beginning of the string
-	p = str;
-	curlen = origlen;
-
-	// note any group involved in the initial state
-	note_group(regs, cur_state, p);
-
-	/* 
-	 * if we're starting in the final state, immediately return success
-	 * with a zero-length match 
-	 */
-	if (cur_state == machine->final) {
-		// return success with a zero-length match
-		return 0;
-	}
-
-	// run the machine
-	for (;;) {
-		re_tuple *tuple;
-
-		// get the tuple for this state
-		tuple = &_tuple_arr[cur_state];
-
-		// if this is a group state, adjust the group registers
-		note_group(regs, cur_state, p);
-		
-		// see what kind of state we're in
-		if (!(tuple->flags & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END))
-			&& tuple->ch != RE_EPSILON) {
-			/*
-			 * This is a character or group recognizer state.  If we
-			 * match the character or group, continue on to the next
-			 * state; otherwise, return failure.
-			 */
-			switch(tuple->ch) {
-			case RE_GROUP_MATCH_0:
-			case RE_GROUP_MATCH_0 + 1:
-			case RE_GROUP_MATCH_0 + 2:
-			case RE_GROUP_MATCH_0 + 3:
-			case RE_GROUP_MATCH_0 + 4:
-			case RE_GROUP_MATCH_0 + 5:
-			case RE_GROUP_MATCH_0 + 6:
-			case RE_GROUP_MATCH_0 + 7:
-			case RE_GROUP_MATCH_0 + 8:
-			case RE_GROUP_MATCH_0 + 9: {
-				int group_num;
-				re_group_register *group_reg;
-				size_t reg_len;
-
-				// it's a group - get the group number
-				group_num = tuple->ch - RE_GROUP_MATCH_0;
-				group_reg = &regs[group_num];
-					
-				/* 
-				 * if this register isn't defined, there's nothing
-				 * to match, so fail 
-				 */
-				if (group_reg->start_ofs == 0 || group_reg->end_ofs == 0)
-					return -1;
-					
-				// calculate the length of the register value
-				reg_len = group_reg->end_ofs - group_reg->start_ofs;
-
-				// if we don't have enough left to match, it fails
-				if (curlen < reg_len)
-					return -1;
-
-				// if the string doesn't match exactly, we fail
-				if (memcmp(p, group_reg->start_ofs, reg_len) != 0)
-					return -1;
-					
-				/*
-				 * It matches exactly - skip the entire length of
-				 * the register in the source string 
-				 */
-				p += reg_len;
-				curlen -= reg_len;
-				break;
-			}
-
-			case RE_TEXT_BEGIN:
-				/* 
-				 * Match only the exact beginning of the string - if
-				 * we're anywhere else, this isn't a match.  If this
-				 * succeeds, we don't skip any characters.  
-				 */
-				if (p != entire_str)
-					return -1;
-				break;
-
-			case RE_TEXT_END:
-				/*
-				 * Match only the exact end of the string - if we're
-				 * anywhere else, this isn't a match.  Don't skip any
-				 * characters on success.  
-				 */
-				if (curlen != 0)
-					return -1;
-				break;
-
-			case RE_WORD_BEGIN:
-				/* 
-				 * if the previous character is a word character, we're
-				 * not at the beginning of a word 
-				 */
-				if (p != entire_str && is_word_char(*(p - 1)))
-					return -1;
-
-				/* 
-				 * if we're at the end of the string, or the current
-				 * character isn't the start of a word, we're not at the
-				 * beginning of a word 
-				 */
-				if (curlen == 0 || !is_word_char(*p))
-					return -1;
-				break;
-
-			case RE_WORD_END:
-				/*
-				 * if the current character is a word character, we're not
-				 * at the end of a word 
-				 */
-				if (curlen != 0 && is_word_char(*p))
-					return -1;
-
-				/*
-				 * if we're at the beginning of the string, or the
-				 * previous character is not a word character, we're not
-				 * at the end of a word 
-				 */
-				if (p == entire_str || !is_word_char(*(p - 1)))
-					return -1;
-				break;
-
-			case RE_WORD_CHAR:
-				/* if it's not a word character, it's a failure */
-				if (curlen == 0 || !is_word_char(*p))
-					return -1;
-
-				/* skip this character of input */
-				++p;
-				--curlen;
-				break;
-
-			case RE_NON_WORD_CHAR:
-				/* if it's a word character, it's a failure */
-				if (curlen == 0 || is_word_char(*p))
-					return -1;
-
-				/* skip the input */
-				++p;
-				--curlen;
-				break;
-
-			case RE_WORD_BOUNDARY:
-			case RE_NON_WORD_BOUNDARY:
-				{
-					int prev_is_word;
-					int next_is_word;
-					int boundary;
-
-					/*
-					 * Determine if the previous character is a word
-					 * character -- if we're at the beginning of the
-					 * string, it's obviously not, otherwise check its
-					 * classification 
-					 */
-					prev_is_word = (p != entire_str
-									&& is_word_char(*(p - 1)));
-
-					/* make the same check for the current character */
-					next_is_word = (curlen != 0
-									&& is_word_char(*p));
-
-					/*
-					 * Determine if this is a boundary - it is if the
-					 * two states are different 
-					 */
-					boundary = ((prev_is_word != 0) ^ (next_is_word != 0));
-
-					/* 
-					 * make sure it matches what was desired, and return
-					 * failure if not 
-					 */
-					if ((tuple->ch == RE_WORD_BOUNDARY && !boundary)
-						|| (tuple->ch == RE_NON_WORD_BOUNDARY && boundary))
-						return -1;
-				}
-				break;
-
-			case RE_WILDCARD:
-				// make sure we have a character to match
-				if (curlen == 0)
-					return -1;
-
-				// skip this character
-				++p;
-				--curlen;
-				break;
-
-			case RE_RANGE:
-			case RE_RANGE_EXCL: {
-				int match_val;
-
-				// make sure we have a character to match
-				if (curlen == 0)
-					return -1;
-
-				// see if we match
-				match_val = re_is_bit_set(tuple->char_range, (int)(unsigned char)*p);
-					
-				// make sure we got what we wanted
-				if ((tuple->ch == RE_RANGE && !match_val)
-					|| (tuple->ch == RE_RANGE_EXCL && match_val))
-					return -1;
-
-				// skip this character of the input
-				++p;
-				--curlen;
-				break;
-			}
-
-			default:
-				// make sure we have an exact match
-				if (curlen == 0 || tuple->ch != *p)
-					return -1;
-
-				// skip this character of the input
-				++p;
-				--curlen;
-				break;
-			}
-
-			/* 
-			 * if we got this far, we were successful - move on to the
-			 * next state 
-			 */
-			cur_state = tuple->next_state_1;
-		} else if (tuple->next_state_2 == RE_STATE_INVALID) {
-			/*
-			 * We have only one transition, so this state is entirely
-			 * deterministic.  Simply move on to the next state. 
-			 */
-			cur_state = tuple->next_state_1;
-		} else {
-			re_machine sub_machine;
-			re_group_register regs1[RE_GROUP_REG_CNT];
-			re_group_register regs2[RE_GROUP_REG_CNT];
-			int ret1;
-			int ret2;
-			
-			/*
-			 * This state has two possible transitions, and we don't
-			 * know which one to take.  So, try both, see which one
-			 * works better, and return the result.  Try the first
-			 * transition first.  Note that each separate attempt must
-			 * use a separate copy of the registers.  
-			 */
-			memcpy(regs1, regs, sizeof(regs1));
-			sub_machine.init = tuple->next_state_1;
-			sub_machine.final = machine->final;
-			ret1 = match(entire_str, p, curlen, &sub_machine, regs1);
-
-			/*
-			 * Now try the second transition 
-			 */
-			memcpy(regs2, regs, sizeof(regs2));
-			sub_machine.init = tuple->next_state_2;
-			sub_machine.final = machine->final;
-			ret2 = match(entire_str, p, curlen, &sub_machine, regs2);
-
-			/*
-			 * If they both failed, the whole thing failed.  Otherwise,
-			 * return the longer of the two, plus the length we
-			 * ourselves matched previously.  Note that we return the
-			 * register set from the winning match.  
-			 */
-			if (ret1 < 0 && ret2 < 0) {
-				// they both failed
-				return -1;
-			} else if (ret1 > ret2) {
-				// use the first register set and result length
-				memcpy(regs, regs1, sizeof(regs1));
-				return ret1 + (p - str);
-			} else {
-				// use the second register set and result length
-				memcpy(regs, regs2, sizeof(regs2));
-				return ret2 + (p - str);
-			}
-		}
-
-		// If we're in the final state, return success 
-		if (cur_state == machine->final) {
-			// finish off any group involved in the final state
-			note_group(regs, cur_state, p);
-			
-			// return the length we matched
-			return p - str;
-		}
-	}
+/*
+ *   Match a string to a compiled expression.  Returns the length of the
+ *   match if successful, or -1 if no match was found.  
+ */
+static int re_match(re_context *ctx, const char *entire_str,
+                    const char *str, size_t origlen,
+                    const re_machine *machine, re_group_register *regs)
+{
+    re_state_id cur_state;
+    const char *p;
+    size_t curlen;
+
+    /* start at the machine's initial state */
+    cur_state = machine->init;
+
+    /* start at the beginning of the string */
+    p = str;
+    curlen = origlen;
+
+    /* note any group involved in the initial state */
+    re_note_group(ctx, regs, cur_state, p);
+
+    /* 
+     *   if we're starting in the final state, immediately return success
+     *   with a zero-length match 
+     */
+    if (cur_state == machine->final)
+    {
+        /* return success with a zero-length match */
+        return 0;
+    }
+
+    /* run the machine */
+    for (;;)
+    {
+        re_tuple *tuple;
+
+        /* get the tuple for this state */
+        tuple = &ctx->tuple_arr[cur_state];
+
+        /* if this is a group state, adjust the group registers */
+        re_note_group(ctx, regs, cur_state, p);
+        
+        /* see what kind of state we're in */
+        if (!(tuple->flags & (RE_STATE_GROUP_BEGIN | RE_STATE_GROUP_END))
+            && tuple->ch != RE_EPSILON)
+        {
+            /*
+             *   This is a character or group recognizer state.  If we
+             *   match the character or group, continue on to the next
+             *   state; otherwise, return failure.
+             */
+            switch(tuple->ch)
+            {
+            case RE_GROUP_MATCH_0:
+            case RE_GROUP_MATCH_0 + 1:
+            case RE_GROUP_MATCH_0 + 2:
+            case RE_GROUP_MATCH_0 + 3:
+            case RE_GROUP_MATCH_0 + 4:
+            case RE_GROUP_MATCH_0 + 5:
+            case RE_GROUP_MATCH_0 + 6:
+            case RE_GROUP_MATCH_0 + 7:
+            case RE_GROUP_MATCH_0 + 8:
+            case RE_GROUP_MATCH_0 + 9:
+                {
+                    int group_num;
+                    re_group_register *group_reg;
+                    size_t reg_len;
+                    
+                    /* it's a group - get the group number */
+                    group_num = tuple->ch - RE_GROUP_MATCH_0;
+                    group_reg = &regs[group_num];
+                    
+                    /* 
+                     *   if this register isn't defined, there's nothing
+                     *   to match, so fail 
+                     */
+                    if (group_reg->start_ofs == 0 || group_reg->end_ofs == 0)
+                        return -1;
+                    
+                    /* calculate the length of the register value */
+                    reg_len = group_reg->end_ofs - group_reg->start_ofs;
+                    
+                    /* if we don't have enough left to match, it fails */
+                    if (curlen < reg_len)
+                        return -1;
+                    
+                    /* if the string doesn't match exactly, we fail */
+                    if (memcmp(p, group_reg->start_ofs, reg_len) != 0)
+                        return -1;
+                    
+                    /*
+                     *   It matches exactly - skip the entire length of
+                     *   the register in the source string 
+                     */
+                    p += reg_len;
+                    curlen -= reg_len;
+                }
+                break;
+
+            case RE_TEXT_BEGIN:
+                /* 
+                 *   Match only the exact beginning of the string - if
+                 *   we're anywhere else, this isn't a match.  If this
+                 *   succeeds, we don't skip any characters.  
+                 */
+                if (p != entire_str)
+                    return -1;
+                break;
+
+            case RE_TEXT_END:
+                /*
+                 *   Match only the exact end of the string - if we're
+                 *   anywhere else, this isn't a match.  Don't skip any
+                 *   characters on success.  
+                 */
+                if (curlen != 0)
+                    return -1;
+                break;
+
+            case RE_WORD_BEGIN:
+                /* 
+                 *   if the previous character is a word character, we're
+                 *   not at the beginning of a word 
+                 */
+                if (p != entire_str && re_is_word_char(*(p-1)))
+                    return -1;
+
+                /* 
+                 *   if we're at the end of the string, or the current
+                 *   character isn't the start of a word, we're not at the
+                 *   beginning of a word 
+                 */
+                if (curlen == 0 || !re_is_word_char(*p))
+                    return -1;
+                break;
+
+            case RE_WORD_END:
+                /*
+                 *   if the current character is a word character, we're not
+                 *   at the end of a word 
+                 */
+                if (curlen != 0 && re_is_word_char(*p))
+                    return -1;
+
+                /*
+                 *   if we're at the beginning of the string, or the
+                 *   previous character is not a word character, we're not
+                 *   at the end of a word 
+                 */
+                if (p == entire_str || !re_is_word_char(*(p-1)))
+                    return -1;
+                break;
+
+            case RE_WORD_CHAR:
+                /* if it's not a word character, it's a failure */
+                if (curlen == 0 || !re_is_word_char(*p))
+                    return -1;
+
+                /* skip this character of input */
+                ++p;
+                --curlen;
+                break;
+
+            case RE_NON_WORD_CHAR:
+                /* if it's a word character, it's a failure */
+                if (curlen == 0 || re_is_word_char(*p))
+                    return -1;
+
+                /* skip the input */
+                ++p;
+                --curlen;
+                break;
+
+            case RE_WORD_BOUNDARY:
+            case RE_NON_WORD_BOUNDARY:
+                {
+                    int prev_is_word;
+                    int next_is_word;
+                    int boundary;
+
+                    /*
+                     *   Determine if the previous character is a word
+                     *   character -- if we're at the beginning of the
+                     *   string, it's obviously not, otherwise check its
+                     *   classification 
+                     */
+                    prev_is_word = (p != entire_str
+                                    && re_is_word_char(*(p-1)));
+
+                    /* make the same check for the current character */
+                    next_is_word = (curlen != 0
+                                    && re_is_word_char(*p));
+
+                    /*
+                     *   Determine if this is a boundary - it is if the
+                     *   two states are different 
+                     */
+                    boundary = ((prev_is_word != 0) ^ (next_is_word != 0));
+
+                    /* 
+                     *   make sure it matches what was desired, and return
+                     *   failure if not 
+                     */
+                    if ((tuple->ch == RE_WORD_BOUNDARY && !boundary)
+                        || (tuple->ch == RE_NON_WORD_BOUNDARY && boundary))
+                        return -1;
+                }
+                break;
+
+            case RE_WILDCARD:
+                /* make sure we have a character to match */
+                if (curlen == 0)
+                    return -1;
+
+                /* skip this character */
+                ++p;
+                --curlen;
+                break;
+
+            case RE_RANGE:
+            case RE_RANGE_EXCL:
+                {
+                    int match;
+                    
+                    /* make sure we have a character to match */
+                    if (curlen == 0)
+                        return -1;
+                    
+                    /* see if we match */
+                    match = re_is_bit_set(tuple->char_range,
+                                          (int)(unsigned char)*p);
+                    
+                    /* make sure we got what we wanted */
+                    if ((tuple->ch == RE_RANGE && !match)
+                        || (tuple->ch == RE_RANGE_EXCL && match))
+                        return -1;
+
+                    /* skip this character of the input */
+                    ++p;
+                    --curlen;
+                }
+                break;
+
+            default:
+                /* make sure we have an exact match */
+                if (curlen == 0 || tuple->ch != *p)
+                    return -1;
+
+                /* skip this character of the input */
+                ++p;
+                --curlen;
+                break;
+            }
+
+            /* 
+             *   if we got this far, we were successful - move on to the
+             *   next state 
+             */
+            cur_state = tuple->next_state_1;
+        }
+        else if (tuple->next_state_2 == RE_STATE_INVALID)
+        {
+            /*
+             *   We have only one transition, so this state is entirely
+             *   deterministic.  Simply move on to the next state. 
+             */
+            cur_state = tuple->next_state_1;
+        }
+        else
+        {
+            re_machine sub_machine;
+            re_group_register regs1[RE_GROUP_REG_CNT];
+            re_group_register regs2[RE_GROUP_REG_CNT];
+            int ret1;
+            int ret2;
+            
+            /*
+             *   This state has two possible transitions, and we don't
+             *   know which one to take.  So, try both, see which one
+             *   works better, and return the result.  Try the first
+             *   transition first.  Note that each separate attempt must
+             *   use a separate copy of the registers.  
+             */
+            memcpy(regs1, regs, sizeof(regs1));
+            sub_machine.init = tuple->next_state_1;
+            sub_machine.final = machine->final;
+            ret1 = re_match(ctx, entire_str, p, curlen, &sub_machine, regs1);
+
+            /*
+             *   Now try the second transition 
+             */
+            memcpy(regs2, regs, sizeof(regs2));
+            sub_machine.init = tuple->next_state_2;
+            sub_machine.final = machine->final;
+            ret2 = re_match(ctx, entire_str, p, curlen, &sub_machine, regs2);
+
+            /*
+             *   If they both failed, the whole thing failed.  Otherwise,
+             *   return the longer of the two, plus the length we
+             *   ourselves matched previously.  Note that we return the
+             *   register set from the winning match.  
+             */
+            if (ret1 < 0 && ret2 < 0)
+            {
+                /* they both failed */
+                return -1;
+            }
+            else if (ret1 > ret2)
+            {
+                /* use the first register set and result length */
+                memcpy(regs, regs1, sizeof(regs1));
+                return ret1 + (p - str);
+            }
+            else
+            {
+                /* use the second register set and result length */
+                memcpy(regs, regs2, sizeof(regs2));
+                return ret2 + (p - str);
+            }
+        }
+
+        /*
+         *   If we're in the final state, return success 
+         */
+        if (cur_state == machine->final)
+        {
+            /* finish off any group involved in the final state */
+            re_note_group(ctx, regs, cur_state, p);
+            
+            /* return the length we matched */
+            return p - str;
+        }
+    }
 }
 
-int re_context::search(const char *str, size_t len, const re_machine *machine,
-		re_group_register *regs, int *result_len) {
-	int ofs;
-	
-	/*
-	 * Starting at the first character in the string, search for the
-	 * pattern at each subsequent character until we either find the
-	 * pattern or run out of string to test. 
-	 */
-	for (ofs = 0 ; ofs < (int)len ; ++ofs) {
-		int matchlen;
-		
-		// check for a match
-		matchlen = match(str, str + ofs, len - ofs, machine, regs);
-		if (matchlen >= 0) {
-			// we found a match here - return the length and offset
-			*result_len = matchlen;
-			return ofs;
-		}
-	}
-
-	// we didn't find a match
-	return -1;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Search for a regular expression within a string.  Returns -1 if the
+ *   string cannot be found, otherwise returns the offset from the start
+ *   of the string to be searched of the start of the first match for the
+ *   pattern.  
+ */
+static int re_search(re_context *ctx, const char *str, size_t len,
+                     const re_machine *machine, re_group_register *regs,
+                     int *result_len)
+{
+    int ofs;
+    
+    /*
+     *   Starting at the first character in the string, search for the
+     *   pattern at each subsequent character until we either find the
+     *   pattern or run out of string to test. 
+     */
+    for (ofs = 0 ; ofs < (int)len ; ++ofs)
+    {
+        int matchlen;
+        
+        /* check for a match */
+        matchlen = re_match(ctx, str, str + ofs, len - ofs,
+                            machine, regs);
+        if (matchlen >= 0)
+        {
+            /* we found a match here - return the length and offset */
+            *result_len = matchlen;
+            return ofs;
+        }
+    }
+
+    /* we didn't find a match */
+    return -1;
 }
 
-void re_context::save_search_str(const char *str, size_t len) {
-	// if the string is empty, this is easy
-	if (len == 0) {
-		// nothing to store - just save the length and return
-		_curlen = 0;
-		return;
-	}
-	
-	// if the current buffer isn't big enough, allocate a new one
-	if (_strbuf == 0 || _strbufsiz < len) {
-		/* 
-		 * free any previous buffer - its contents are no longer
-		 * important, since we're about to overwrite it with a new
-		 * string 
-		 */
-		if (_strbuf != 0)
-			mchfre(_strbuf);
-
-		/* 
-		 * allocate a new buffer; round up to the next 256-byte
-		 * increment to make sure we're not constantly reallocating to
-		 * random sizes 
-		 */
-		_strbufsiz = ((len + 255) & ~255);
-
-		// allocate it
-		_strbuf = (char *)mchalo(_errctx, _strbufsiz, "regex str");
-	}
-
-	// copy the string
-	memcpy(_strbuf, str, len);
-
-	// save the length
-	_curlen = len;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Make a copy of a search string in our private buffer.
+ */
+static void re_save_search_str(re_context *ctx, const char *str, size_t len)
+{
+    /* if the string is empty, this is easy */
+    if (len == 0)
+    {
+        /* nothing to store - just save the length and return */
+        ctx->curlen = 0;
+        return;
+    }
+    
+    /* if the current buffer isn't big enough, allocate a new one */
+    if (ctx->strbuf == 0 || ctx->strbufsiz < len)
+    {
+        /* 
+         *   free any previous buffer - its contents are no longer
+         *   important, since we're about to overwrite it with a new
+         *   string 
+         */
+        if (ctx->strbuf != 0)
+            mchfre(ctx->strbuf);
+
+        /* 
+         *   allocate a new buffer; round up to the next 256-byte
+         *   increment to make sure we're not constantly reallocating to
+         *   random sizes 
+         */
+        ctx->strbufsiz = ((len + 255) & ~255);
+
+        /* allocate it */
+        ctx->strbuf = (char *)mchalo(ctx->errctx, ctx->strbufsiz,
+                                     "regex str");
+    }
+
+    /* copy the string */
+    memcpy(ctx->strbuf, str, len);
+
+    /* save the length */
+    ctx->curlen = len;
 }
 
-int re_context::compile_and_search(const char *pattern, size_t patlen,
-		const char *searchstr, size_t searchlen, int *result_len) {
-	re_machine machine;
-	
-	// compile the expression - return failure if we get an error
-	if (compile(pattern, patlen, &machine) != RE_STATUS_SUCCESS)
-		return -1;
-
-	// save the search string in our internal buffer
-	save_search_str(searchstr, searchlen);
-
-	// clear the group registers
-	memset(_regs, 0, sizeof(_regs));
-
-	/* 
-	 * search for the pattern in our copy of the string - use the copy
-	 * so that the group registers stay valid even if the caller
-	 * deallocates the original string after we return
-	 */
-	return search(_strbuf, _curlen, &machine, _regs, result_len);
+/* ------------------------------------------------------------------------ */
+/*
+ *   Compile an expression and search for a match within the given string.
+ *   Returns the offset of the match, or -1 if no match was found.  
+ */
+int re_compile_and_search(re_context *ctx,
+                          const char *pattern, size_t patlen,
+                          const char *searchstr, size_t searchlen,
+                          int *result_len)
+{
+    re_machine machine;
+    
+    /* compile the expression - return failure if we get an error */
+    if (re_compile(ctx, pattern, patlen, &machine) != RE_STATUS_SUCCESS)
+        return -1;
+
+    /* save the search string in our internal buffer */
+    re_save_search_str(ctx, searchstr, searchlen);
+
+    /* clear the group registers */
+    memset(ctx->regs, 0, sizeof(ctx->regs));
+
+    /* 
+     *   search for the pattern in our copy of the string - use the copy
+     *   so that the group registers stay valid even if the caller
+     *   deallocates the original string after we return
+     */
+    return re_search(ctx, ctx->strbuf, ctx->curlen, &machine,
+                     ctx->regs, result_len);
 }
 
-int re_context::compile_and_match(const char *pattern, size_t patlen,
-		const char *searchstr, size_t searchlen) {
-	re_machine machine;
+/* ------------------------------------------------------------------------ */
+/*
+ *   Compile an expression and check for a match.  Returns the length of
+ *   the match if we found a match, -1 if we found no match.  This is not
+ *   a search function; we merely match the leading substring of the given
+ *   string to the given pattern.  
+ */
+int re_compile_and_match(re_context *ctx,
+                         const char *pattern, size_t patlen,
+                         const char *searchstr, size_t searchlen)
+{
+    re_machine machine;
 
-	// compile the expression - return failure if we get an error
-	if (compile(pattern, patlen, &machine) != RE_STATUS_SUCCESS)
-		return 0;
+    /* compile the expression - return failure if we get an error */
+    if (re_compile(ctx, pattern, patlen, &machine) != RE_STATUS_SUCCESS)
+        return FALSE;
 
-	// save the search string in our internal buffer
-	save_search_str(searchstr, searchlen);
+    /* save the search string in our internal buffer */
+    re_save_search_str(ctx, searchstr, searchlen);
 
-	// clear the group registers
-	memset(_regs, 0, sizeof(_regs));
+    /* clear the group registers */
+    memset(ctx->regs, 0, sizeof(ctx->regs));
 
-	// match the string
-	return match(_strbuf, _strbuf, _curlen, &machine, _regs);
+    /* match the string */
+    return re_match(ctx, ctx->strbuf, ctx->strbuf, ctx->curlen,
+                    &machine, ctx->regs);
 }
 
+
 } // End of namespace TADS2
 } // End of namespace TADS
 } // End of namespace Glk
diff --git a/engines/glk/tads/tads2/regex.h b/engines/glk/tads/tads2/regex.h
index cd975e066b..48c2dd0ad4 100644
--- a/engines/glk/tads/tads2/regex.h
+++ b/engines/glk/tads/tads2/regex.h
@@ -24,289 +24,165 @@
 #define GLK_TADS_TADS2_REGEX
 
 #include "common/array.h"
-#include "glk/tads/tads2/ler.h"
+#include "glk/tads/tads2/error_handling.h"
 
 namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
-/**
- * state ID
- */
+
+/* state ID */
 typedef int re_state_id;
 
-/**
- * invalid state ID - used to mark null machines
- */
+/* invalid state ID - used to mark null machines */
 #define RE_STATE_INVALID   ((re_state_id)-1)
 
-/**
- * first valid state ID
- */
+/* first valid state ID */
 #define RE_STATE_FIRST_VALID  ((re_state_id)0)
 
 
-/**
+/* ------------------------------------------------------------------------ */
+/*
  *   Group register structure.  Each register keeps track of the starting
- *   and ending offset of the group's text.
+ *   and ending offset of the group's text.  
  */
-struct re_group_register {
-	const char *start_ofs;
-	const char *end_ofs;
-};
+typedef struct
+{
+    const char *start_ofs;
+    const char *end_ofs;
+} re_group_register;
 
-/**
- * number of group registers we keep
- */
+/* number of group registers we keep */
 #define RE_GROUP_REG_CNT  10
 
-/**
- * Denormalized state transition tuple.  Each tuple represents the
- * complete set of transitions out of a particular state.  A particular
- * state can have one character transition, or two epsilon transitions.
- * Note that we don't need to store the state ID in the tuple, because
- * the state ID is the index of the tuple in an array of state tuples.
+
+/* ------------------------------------------------------------------------ */
+/* 
+ *   Denormalized state transition tuple.  Each tuple represents the
+ *   complete set of transitions out of a particular state.  A particular
+ *   state can have one character transition, or two epsilon transitions.
+ *   Note that we don't need to store the state ID in the tuple, because
+ *   the state ID is the index of the tuple in an array of state tuples.  
  */
-struct re_tuple {
-	// the character we must match to transition to the target state
-	char ch;
+typedef struct
+{
+    /* the character we must match to transition to the target state */
+    char ch;
 
-	// the target states
-	re_state_id next_state_1;
-	re_state_id next_state_2;
+    /* the target states */
+    re_state_id next_state_1;
+    re_state_id next_state_2;
 
-	// character range match table, if used
-	unsigned char *char_range;
+    /* character range match table, if used */
+    unsigned char *char_range;
 
-	// flags
-	byte flags;
-};
+    /* flags */
+    unsigned char flags;
+} re_tuple;
 
 
-/**
- * Tuple flags
+/*
+ *   Tuple flags 
  */
-enum {
-	// this state is the start of a group - the 'ch' value is the group ID
-	RE_STATE_GROUP_BEGIN = 0x02,
 
-	// this state is the end of a group - 'ch' is the group ID */
-	RE_STATE_GROUP_END = 0x04
-};
+/* this state is the start of a group - the 'ch' value is the group ID */
+#define RE_STATE_GROUP_BEGIN  0x02
+
+/* this state is the end of a group - 'ch' is the group ID */
+#define RE_STATE_GROUP_END    0x04
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Regular expression compilation context structure.  This tracks the
+ *   state of the compilation and stores the resources associated with the
+ *   compiled expression.  
+ */
+typedef struct
+{
+    /* error context */
+    errcxdef *errctx;
+
+    /* next available state ID */
+    re_state_id next_state;
+
+    /*
+     *   The array of transition tuples.  We'll allocate this array and
+     *   expand it as necessary.  
+     */
+    re_tuple *tuple_arr;
 
-/**
- * Status codes
+    /* number of transition tuples allocated in the array */
+    int tuples_alloc;
+
+    /* current group ID */
+    int cur_group;
+
+    /* group registers */
+    re_group_register regs[RE_GROUP_REG_CNT];
+
+    /* 
+     *   Buffer for retaining a copy of the last string we scanned.  We
+     *   retain our own copy of each string, and point the group registers
+     *   into this copy rather than the caller's original string -- this
+     *   ensures that the group registers remain valid even after the
+     *   caller has deallocated the original string.  
+     */
+    char *strbuf;
+
+    /* length of the string currently in the buffer */
+    size_t curlen;
+
+    /* size of the buffer allocated to strbuf */
+    size_t strbufsiz;
+} re_context;
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   Status codes 
  */
-typedef enum {
-	// success
-	RE_STATUS_SUCCESS = 0,
+typedef enum
+{
+    /* success */
+    RE_STATUS_SUCCESS = 0,
 
-	// compilation error - group nesting too deep
-	RE_STATUS_GROUP_NESTING_TOO_DEEP
+    /* compilation error - group nesting too deep */
+    RE_STATUS_GROUP_NESTING_TOO_DEEP
 } re_status_t;
 
 
-/**
- * Regular expression compilation.  This tracks the state of the compilation and
- * stores the resources associated with the compiled expression.
+/* ------------------------------------------------------------------------ */
+/*
+ *   Initialize the context.  The memory for the context structure itself
+ *   must be allocated and maintained by the caller. 
+ */
+void re_init(re_context *ctx, errcxdef *errctx);
+
+/*
+ *   Delete the context - frees structures associated with the context.
+ *   Does NOT free the memory used by the context structure itself.  
+ */
+void re_delete(re_context *ctx);
+
+/*
+ *   Compile an expression and search for a match within the given string.
+ *   Returns the offset of the match, or -1 if no match was found.  
+ */
+int re_compile_and_search(re_context *ctx,
+                          const char *pattern, size_t patlen,
+                          const char *searchstr, size_t searchlen,
+                          int *result_len);
+
+/*
+ *   Compile an expression and check for a match.  Returns the length of
+ *   the match if we found a match, -1 if we found no match.  This is not
+ *   a search function; we merely match the leading substring of the given
+ *   string to the given pattern.  
  */
-class re_context {
-	/**
-	 * A machine description.  Machines are fully described by their initial
-	 * and final state ID's.
-	 */
-	struct re_machine {
-		re_state_id init;		///< the machine's initial state
-		re_state_id final;		///< the machine's final state
-
-		re_machine() : init(0), final(0) {}
-
-		/**
-		 * Build a null machine
-		 */
-		void build_null_machine() {
-			init = final = RE_STATE_INVALID;
-		}
-
-		/**
-		 * Determine if a machine is null
-		 */
-		bool isNull() const {
-			return (init == RE_STATE_INVALID);
-		}
-	};
-private:
-	/**
-	 * Reset compiler - clears states and tuples
-	 */
-	void reset();
-
-	/**
-	 * Set a transition from a state to a given destination state
-	 */
-	void set_trans(re_state_id id, re_state_id dest_id, char ch);
-
-	/**
-	 * Initialize a new machine, giving it an initial and final state
-	 */
-	void init_machine(re_machine *machine);
-
-	/**
-	 * Build a character recognizer
-	 */
-	void build_char(re_machine *machine, char ch);
-
-	/**
-	 * Build a character range recognizer.  'range' is a 256-bit (32-byte) bit vector.
-	 */
-	void build_char_range(re_machine *machine, unsigned char *range, int exclusion);
-
-	/**
-	 * Build a group recognizer.  This is almost the same as a character
-	 * recognizer, but matches a previous group rather than a literal character.
-	 */
-	void build_group_matcher(re_machine *machine, int group_num);
-
-	/**
-	 *   Build a concatenation recognizer
-	 */
-	void build_concat(re_machine *new_machine, re_machine *lhs, re_machine *rhs);
-
-	/**
-	 * Build a group machine.  sub_machine contains the machine that
-	 * expresses the group's contents; we'll fill in new_machine with a
-	 * newly-created machine that encloses and marks the group.
-	 */
-	void build_group(re_machine *new_machine, re_machine *sub_machine, int group_id);
-
-	/**
-	 * Build an alternation recognizer
-	 */
-	void build_alter(re_machine *new_machine, re_machine *lhs, re_machine *rhs);
-
-	/**
-	 * Build a closure recognizer
-	 */
-	void build_closure(re_machine *new_machine, re_machine *sub, char specifier);
-
-	/**
-	 * Concatenate the second machine onto the first machine, replacing the
-	 * first machine with the resulting machine.  If the first machine is a
-	 * null machine (created with re_build_null_machine), we'll simply copy
-	 * the second machine into the first.
-	 */
-	void concat_onto(re_machine *dest, re_machine *rhs);
-
-	/**
-	 * Alternate the second machine onto the first machine, replacing the
-	 * first machine with the resulting machine.  If the first machine is a
-	 * null machine, this simply replaces the first machine with the second
-	 * machine.  If the second machine is null, this simply leaves the first
-	 * machine unchanged.
-	 */
-	void alternate_onto(re_machine *dest, re_machine *rhs);
-
-	/**
-	 * Compile an expression
-	 */
-	re_status_t compile(const char *expr, size_t exprlen, re_machine *result_machine);
-
-	/**
-	 * Note a group position if appropriate
-	 */
-	void note_group(re_group_register *regs, re_state_id id, const char *p);
-
-	/**
-	 * Determine if a character is part of a word.  We consider letters and
-	 * numbers to be word characters.
-	 */
-	bool is_word_char(char c) const;
-
-	/**
-	 * Match a string to a compiled expression.  Returns the length of the
-	 * match if successful, or -1 if no match was found.
-	 */
-	int match(const char *entire_str, const char *str, size_t origlen,
-		const re_machine *machine, re_group_register *regs);
-
-	/**
-	 * Search for a regular expression within a string.  Returns -1 if the string
-	 * cannot be found, otherwise returns the offset from the start of the string
-	 * to be searched of the start of the first match for the pattern.
-	 */
-	int search(const char *str, size_t len, const re_machine *machine,
-		re_group_register *regs, int *result_len);
-
-	/**
-	 * Make a copy of a search string in our private buffer.
-	 */
-	void save_search_str(const char *str, size_t len);
-public:
-	errcxdef *_errctx;			///< error context
-	re_state_id _next_state;	///< next available state ID
-
-	/**
-	 * The array of transition tuples.  We'll allocate this array and
-	 * expand it as necessary.
-	 */
-	Common::Array<re_tuple> _tuple_arr;
-
-	// current group ID
-	int _cur_group;
-
-	// group registers
-	re_group_register _regs[RE_GROUP_REG_CNT];
-
-	/**
-	 * Buffer for retaining a copy of the last string we scanned.  We
-	 * retain our own copy of each string, and point the group registers
-	 * into this copy rather than the caller's original string -- this
-	 * ensures that the group registers remain valid even after the
-	 * caller has deallocated the original string.
-	 */
-	char *_strbuf;
-
-	/**
-	 * length of the string currently in the buffer
-	 */
-	size_t _curlen;
-
-	/**
-	 * size of the buffer allocated to strbuf
-	 */
-	size_t _strbufsiz;
-public:
-	/**
-	 * Constructor.  The memory for the context structure itself
-	 * must be allocated and maintained by the caller.
-	 */
-	re_context(errcxdef *errctx);
-
-	/**
-	 * Destructor
-	 */
-	~re_context();
-
-	/**
-	 * Allocate a new state ID
-	 */
-	re_state_id alloc_state();
-
-	/**
-	 * Compile an expression and search for a match within the given string.
-	 * Returns the offset of the match, or -1 if no match was found.
-	 */
-	int compile_and_search(const char *pattern, size_t patlen,
-		const char *searchstr, size_t searchlen, int *result_len);
-
-	/**
-	 * Compile an expression and check for a match.  Returns the length of the match
-	 * if we found a match, -1 if we found no match.  This is not a search function;
-	 * we merely match the leading substring of the given string to the given pattern.
-	 */
-	int compile_and_match(const char *pattern, size_t patlen,
-		const char *searchstr, size_t searchlen);
-};
+int re_compile_and_match(re_context *ctx,
+                         const char *pattern, size_t patlen,
+                         const char *searchstr, size_t searchlen);
 
 } // End of namespace TADS2
 } // End of namespace TADS
diff --git a/engines/glk/tads/tads2/run.cpp b/engines/glk/tads/tads2/run.cpp
new file mode 100644
index 0000000000..5123d650fe
--- /dev/null
+++ b/engines/glk/tads/tads2/run.cpp
@@ -0,0 +1,52 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software{} you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation{} either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY{} without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program{} if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/run.h"
+#include "glk/tads/tads2/data.h"
+#include "glk/tads/tads2/vocabulary.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+int runsdef::runsiz() const {
+	switch (runstyp) {
+	case DAT_NUMBER:
+		return 4;
+	case DAT_SSTRING:
+	case DAT_LIST:
+		return osrp2(runsv.runsvstr);
+	case DAT_PROPNUM:
+	case DAT_OBJECT:
+	case DAT_FNADDR:
+		return 2;
+	default:
+		return 0;
+	}
+}
+
+/*--------------------------------------------------------------------------*/
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/run.h b/engines/glk/tads/tads2/run.h
new file mode 100644
index 0000000000..b6694bf523
--- /dev/null
+++ b/engines/glk/tads/tads2/run.h
@@ -0,0 +1,393 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+/* Definitions for code execution
+ *
+ * The preprocessor symbol RUNFAST can be defined if run - time checking
+ * of stack overflow, stack underflow, and other unusual but potentially
+ * dangerous conditions is to be turned off.This will result in somewhat
+ * faster run-time performance, but run - time errors could be disastrous.
+ */
+
+#ifndef GLK_TADS_TADS2_RUN
+#define GLK_TADS_TADS2_RUN
+
+#include "common/scummsys.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/debug.h"
+#include "glk/tads/tads2/object.h"
+#include "glk/tads/tads2/memory_cache.h"
+#include "glk/tads/tads2/memory_cache_swap.h"
+#include "glk/tads/tads2/opcode_defs.h"
+#include "glk/tads/tads2/property.h"
+#include "glk/tads/tads2/text_io.h"
+#include "glk/tads/tads2/tokenizer.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* Forward declarations */
+struct runcxdef;
+struct runufdef;
+struct voccxdef;
+
+/**
+ * Stack element - the stack is an array of these structures
+ */
+struct runsdef {
+    uchar  runstyp;                                      /* type of element */
+    union {
+        long    runsvnum;                                  /* numeric value */
+        objnum  runsvobj;                                   /* object value */
+        prpnum  runsvprp;                          /* property number value */
+        uchar  *runsvstr;                              /* string/list value */
+    }      runsv;
+
+
+	/**
+	 * Determine size of a data item
+	 */
+	int runsiz() const;
+};
+
+/**
+ * External function control structure
+ */
+struct runxdef {
+    char    runxnam[TOKNAMMAX + 1];            /* name of external function */
+    int   (*runxptr)(void *);          /* pointer to memory containing code */
+};
+
+/**
+ * External function context structure - passed to user exits
+ */
+struct runuxdef {
+    runcxdef *runuxctx;		/* run-time context */
+    runufdef *runuxvec;		/* vector of functions */
+    int runuxargc;					/* count of arguments to function */
+};
+
+/**
+ * External function callback vector
+ */
+struct runufdef {
+    int    (*runuftyp)(runuxdef *);         /* type of top of stack */
+    long   (*runufnpo)(runuxdef *);                 /* pop a number */
+    uchar *(*runufspo)(runuxdef *);                 /* pop a string */
+    void   (*runufdsc)(runuxdef *); /* discard item at top of stack */
+    void   (*runufnpu)(runuxdef *, long);          /* push a number */
+    void   (*runufspu)(runuxdef *, uchar *); /* push alloc'd string */
+    void   (*runufcspu)(runuxdef *, char *);     /* push a C-string */
+    uchar *(*runufsal)(runuxdef *, int);   /* allocate a new string */
+    void   (*runuflpu)(runuxdef *, int);/* push DAT_TRUE or DAT_NIL */
+};
+
+/**
+ * Execution context
+ */
+struct runcxdef {
+    errcxdef   *runcxerr;                       /* error management context */
+    mcmcxdef   *runcxmem;    /* cache manager context for object references */
+    runsdef    *runcxstk;                      /* base of interpreter stack */
+    runsdef    *runcxstop;                                  /* top of stack */
+    runsdef    *runcxsp;     /* current stack pointer (stack grows upwards) */
+    runsdef    *runcxbp;                                    /* base pointer */
+    uchar      *runcxheap;          /* run-time variable-length object heap */
+    uchar      *runcxhp;                            /* current heap pointer */
+    uchar      *runcxhtop;                                   /* top of heap */
+    objucxdef  *runcxundo;                                  /* undo context */
+    tiocxdef   *runcxtio;                               /* text I/O context */
+    void       *runcxbcx;        /* context for built-in callback functions */
+    void     (**runcxbi)(struct bifcxdef *ctx, int argc);
+                                                      /* built-in functions */
+    dbgcxdef *runcxdbg;                          /* debugger context */
+    voccxdef *runcxvoc;             /* player command parser context */
+    void      (*runcxdmd)(void *ctx, objnum obj, prpnum prp);
+                                         /* demand-loader callback function */
+    void       *runcxdmc;                 /* demand-loader callback context */
+    runxdef    *runcxext;                        /* external function array */
+    int         runcxexc;                    /* count of external functions */
+    uint        runcxlofs;        /* offset of last line record encountered */
+    char       *runcxgamename;                     /* name of the .GAM file */
+    char       *runcxgamepath;      /* absolute directory path of .GAM file */
+
+	/**
+	 * Execute a function, given the function object number
+	 */
+	void runfn(noreg objnum objn, int argc);
+
+	/**
+	 * Execute p-code given a pointer to the code.  p is the actual pointer
+	 * to the first byte of code to be executed. self is the object to be
+	 * used for the special 'self' pseudo-object, and target is the object
+	 * whose data are actually being executed.  targprop is the property being
+	 * executed; 0 is used for functions.
+	 */
+	void runexe(uchar *p, objnum self, objnum target,
+		prpnum targprop, int argc);
+
+	/**
+	 * Push a value onto the stack
+	 */
+	void runpush(dattyp typ, runsdef *val);
+
+	/**
+	 * Push a value onto the stack that's already in the heap
+	 */
+	void runrepush(runsdef *val);
+
+	/**
+	 * Push a number onto the stack
+	 */
+	void runpnum(long val);
+
+	/**
+	 * Push an object onto the stack
+	 */
+	void runpobj(objnum obj);
+
+	/**
+	 * push nil
+	 */
+	void runpnil(runcxdef *ctx);
+
+	/**
+	 * push a value onto the stack from a buffer (propdef, list)
+	 */
+	void runpbuf(int typ, void *val);
+
+	/**
+	 * Push a counted-length string onto the stack
+	 */
+	void runpstr(char *str, int len, int sav);
+
+	/**
+	 * Push a C-style string onto the stack, converting escape codes.  If
+	 * the character contains backslashes, newline, or tab characters, we'll
+	 * convert these characters to their escaped equivalent.
+	 */
+	void runpushcstr(char *str, size_t len, int sav);
+
+	/**
+	 * Push a property onto the stack.  codepp is a pointer to the caller's
+	 * code pointer, which will be updated if necessary; callobj and
+	 * callofsp are the object and starting offset within the object of the
+	 * code being executed by the caller, which are needed to update
+	 * *codepp.  Property 0 is used if a function is being executed.  obj
+	 * and prop are the object and property number whose value is to be
+	 * pushed.  If 'inh' is TRUE, it means that only a property inherited
+	 * by 'obj' is to be considered; this is used for "pass"/"inherited"
+	 * operations, with the current target object given as 'obj'.
+	 */
+	void runpprop(uchar *noreg *codepp, objnum callobj,
+		prpnum callprop, noreg objnum obj, prpnum prop, int inh,
+		int argc, objnum self);
+
+	/**
+	 * compare magnitudes of numbers/strings on top of stack; strcmp-like value
+	 */
+	int runmcmp(runcxdef *ctx);
+
+	/**
+	 * True if items at top of stack are equal, FALSE otherwise
+	 */
+	int runeq(runcxdef *ctx);
+
+	/**
+	 * Garbage collect heap, making sure 'siz' bytes are available afterwards
+	 */
+	void runhcmp(uint siz, uint below,
+		runsdef *val1, runsdef *val2, runsdef *val3);
+
+	/**
+	 * Find a sublist within a list, returning pointer to sublist or null
+	 */
+	uchar *runfind(uchar *list, runsdef *item);
+
+	/**
+	 * Restore code pointer from object.property + offset
+	 */
+	uchar *runcprst(uint ofs, objnum obj, prpnum prop);
+
+	/**
+	 * Add two runsdef values, returning result in *val
+	 */
+	void runadd(runsdef *val2, uint below);
+
+	/**
+	 * Subtract val2 from val, returning result in *val; return TRUE if
+	 * value changed, FALSE otherwise (this is returned when subtracting
+	 * something from a list that isn't in the list)
+	 */
+	int runsub(runsdef *val2, uint below);
+};
+
+/* top level runpprop, when caller is not executing in an object */
+/* void runppr(objnum obj, prpnum prp, int argc); */
+#define runppr(ctx, obj, prp, argc) \
+ runpprop(ctx, (uchar **)0, (objnum)0, (prpnum)0, obj, prp, FALSE, argc, obj)
+
+/* discard top element on stack */
+/* void rundisc(runcxdef *ctx); */
+#define rundisc(ctx) (runstkund(ctx), (--((ctx)->runcxsp)))
+
+/* pop the top element on the stack */
+/* void runpop(runsdef *val); */
+#define runpop(ctx, v) \
+ (runstkund(ctx), memcpy(v, (--((ctx)->runcxsp)), (size_t)sizeof(runsdef)))
+
+/* pop a numeric value, signalling an error if not a number */
+/* long runpopnum(runcxdef *ctx); */
+#define runpopnum(ctx) \
+ (runstkund(ctx), ((--((ctx)->runcxsp))->runstyp!=DAT_NUMBER ? \
+  (runsig(ctx,ERR_REQNUM), (long)0) : \
+  ((ctx)->runcxsp->runsv.runsvnum)))
+
+/* pop an object, signalling an error if not an object */
+/* objnum runpopobj(runcxdef *ctx); */
+#define runpopobj(ctx) \
+ (runstkund(ctx), ((--(ctx)->runcxsp))->runstyp!=DAT_OBJECT ? \
+  (runsig(ctx,ERR_REQVOB), (objnum)0) : \
+  ((ctx)->runcxsp->runsv.runsvobj))
+
+/* pop an object or nil - returns MCMONINV if the value is nil */
+#define runpopobjnil(ctx) \
+  (runstkund(ctx), ((--(ctx)->runcxsp))->runstyp==DAT_OBJECT ? \
+   ((ctx)->runcxsp->runsv.runsvobj) : \
+   ((ctx)->runcxsp->runstyp==DAT_NIL ? MCMONINV : \
+    (runsig(ctx,ERR_REQVOB), (objnum)0)))
+
+/* pop a list, signalling an error if not a list */
+/* uchar *runpoplst(runcxdef *ctx); */
+#define runpoplst(ctx) \
+ (runstkund(ctx), ((--(ctx)->runcxsp))->runstyp!=DAT_LIST ? \
+  (runsig(ctx,ERR_REQVLS), (uchar *)0) : \
+  (uchar *)((ctx)->runcxsp->runsv.runsvstr))
+
+/* pop a property number, signalling an error if not a property number */
+/* prpnum runpopprp(runcxdef *ctx); */
+#define runpopprp(ctx) \
+ (runstkund(ctx), ((--(ctx)->runcxsp))->runstyp!=DAT_PROPNUM ? \
+  (runsig(ctx,ERR_REQVPR), (prpnum)0) : \
+  ((ctx)->runcxsp->runsv.runsvprp))
+
+
+/* pop function pointer */
+/* objnum runpopfn(runcxdef *ctx); */
+#define runpopfn(ctx) \
+  ((objnum)(runstkund(ctx), ((--(ctx)->runcxsp))->runstyp!=DAT_FNADDR ? \
+                      (runsig(ctx,ERR_REQVFN), (objnum)0) : \
+                      ((ctx)->runcxsp->runsv.runsvobj)))
+
+/* pop a string value */
+/* char *runpopstr(runcxdef *ctx); */
+#define runpopstr(ctx) \
+ (runstkund(ctx), ((--((ctx)->runcxsp))->runstyp!=DAT_SSTRING ? \
+  (runsig(ctx,ERR_REQSTR), (uchar *)0) : \
+  ((ctx)->runcxsp->runsv.runsvstr)))
+
+
+/* pop a logical value - TRUE for DAT_TRUE, FALSE for DAT_NIL */
+/* int runpoplog(runcxdef *ctx); */
+#define runpoplog(ctx) \
+ ((--((ctx)->runcxsp))->runstyp==DAT_TRUE ? TRUE : \
+  (ctx)->runcxsp->runstyp==DAT_NIL ? FALSE : \
+  (runsig(ctx, ERR_REQLOG), 0))
+
+/* get type of top of stack */
+/* int runtostyp(runcxdef *ctx); */
+#define runtostyp(ctx) (((ctx)->runcxsp - 1)->runstyp)
+
+/* determine if top of stack is logical value (returns TRUE if so) */
+/* int runtoslog(runcxdef *ctx); */
+#define runtoslog(ctx) \
+ (runtostyp(ctx) == DAT_TRUE || runtostyp(ctx) == DAT_NIL)
+
+/* convert C logical to TADS logical (TRUE->DAT_TRUE, FALSE->DAT_NIL) */
+/* int runclog(int log); */
+#define runclog(l) ((l) ? DAT_TRUE : DAT_NIL)
+
+
+/* 
+ *   Check to ensure we have enough arguments to pass to a function or method
+ *   call - this simply ensures we have enough data in the current frame.
+ *   This is important because the called function will be able to write to
+ *   our frame.  If we don't have enough arguments, we'll push enough 'nil'
+ *   values to meet the need.  
+ */
+#define runcheckargc(ctx, nargc) \
+    while ((ctx)->runcxsp - (ctx)->runcxbp < *(nargc)) \
+        runpnil(ctx)
+
+#ifdef RUNFAST
+# define runstkovf(ctx) (DISCARD 0)
+# define runstkund(ctx) (DISCARD 0)
+#else /* RUNFAST */
+# define runstkovf(ctx) \
+ ((ctx)->runcxsp >= (ctx)->runcxstop ? (runsig(ctx, ERR_STKOVF), \
+ DISCARD 0) : DISCARD 0)
+# define runstkund(ctx) \
+ ((ctx)->runcxsp == (ctx)->runcxstk ? runsig(ctx, ERR_STKUND), \
+ DISCARD 0 : DISCARD 0)
+#endif /* RUNFAST */
+
+/* reserve space in heap, collecting garbage if necessary */
+/* void runhres(uint siz, uint below); */
+#define runhres(ctx, siz, below) \
+ ((uint)((ctx)->runcxhtop - (ctx)->runcxhp) > (uint)(siz) ? DISCARD 0 : \
+ (runhcmp(ctx, siz, below, (runsdef *)0, (runsdef *)0, (runsdef *)0),\
+  DISCARD 0))
+
+/* reserve space, with various amounts of saving */
+#define runhres1(ctx, siz, below, val1) \
+  ((uint)((ctx)->runcxhtop - (ctx)->runcxhp) > (uint)(siz) ? DISCARD 0 : \
+  (runhcmp(ctx, siz, below, val1, (runsdef *)0, (runsdef *)0), DISCARD 0))
+
+#define runhres2(ctx, siz, below, val1, val2) \
+ ((uint)((ctx)->runcxhtop - (ctx)->runcxhp) > (uint)(siz) ? DISCARD 0 : \
+ (runhcmp(ctx, siz, below, val1, val2, (runsdef *)0), DISCARD 0))
+
+#define runhres3(ctx, siz, below, val1, val2, val3) \
+ ((uint)((ctx)->runcxhtop - (ctx)->runcxhp) > (uint)(siz) ? DISCARD 0 : \
+ (runhcmp(ctx, siz, below, val1, val2, val3), DISCARD 0))
+
+
+/* leave a stack frame, removing arguments */
+/* void runleave(uint parms); */
+#define runleave(ctx, parms) \
+ (((ctx)->runcxsp = (ctx)->runcxbp), \
+  ((ctx)->runcxbp = (runsdef *)((--((ctx)->runcxsp))->runsv.runsvstr)), \
+  ((ctx)->runcxsp -= (parms)))
+
+/* reset run-time: throw away entire stack and heap */
+/* void runrst(runcxdef *ctx); */
+#define runrst(ctx) (((ctx)->runcxsp = (ctx)->runcxstk), \
+                     ((ctx)->runcxhp = (ctx)->runcxheap), \
+                     dbgrst(ctx->runcxdbg))
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/tads2.cpp b/engines/glk/tads/tads2/tads2.cpp
index a772b44aed..b391857613 100644
--- a/engines/glk/tads/tads2/tads2.cpp
+++ b/engines/glk/tads/tads2/tads2.cpp
@@ -21,13 +21,18 @@
  */
 
 #include "glk/tads/tads2/tads2.h"
+#include "glk/tads/tads2/built_in.h"
+#include "glk/tads/tads2/debug.h"
+#include "glk/tads/tads2/file_io.h"
+#include "glk/tads/tads2/post_compilation.h"
+#include "glk/tads/tads2/run.h"
+#include "glk/tads/tads2/vocabulary.h"
 
 namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
-TADS2::TADS2(OSystem *syst, const GlkGameDescription &gameDesc) : OS(syst, gameDesc) {
-	cmap_init_default();
+TADS2::TADS2(OSystem *syst, const GlkGameDescription &gameDesc) : TADS(syst, gameDesc) {
 }
 
 void TADS2::runGame() {
@@ -35,7 +40,7 @@ void TADS2::runGame() {
 	errctx.errcxlgc = &errctx;
 	errctx.errcxfp = nullptr;
 	errctx.errcxofs = 0;
-	errctx.errcxappctx = this;
+	errctx.errcxappctx = nullptr;
 
 	/* copyright-date-string */
 #ifdef T2_COPYRIGHT_NOTICE
@@ -48,13 +53,519 @@ void TADS2::runGame() {
 #endif
 
 	trdmain1(&errctx);
-
-	// pause before exiting if the OS desires it
-	os_expause();
 }
 
 void TADS2::trdmain1(errcxdef *errctx) {
+	osfildef  *swapfp = (osfildef *)0;
+	runcxdef   runctx;
+	bifcxdef   bifctx;
+	voccxdef   vocctx;
+	void(*bif[100])(bifcxdef *, int);
+	mcmcxdef  *mctx = 0;
+	mcmcx1def *globalctx = 0;
+	dbgcxdef   dbg;
+	supcxdef   supctx;
+	char      *swapname = 0;
+	char       swapbuf[OSFNMAX];
+	char     **argp;
+	char      *arg;
+	char      *infile;
+	char       infile_abs[OSFNMAX];      /* fully-qualified input file name */
+	char       infile_path[OSFNMAX];         /* absolute path to input file */
+	char      *exefile;            /* try with executable file if no infile */
+	ulong      swapsize = 0xffffffffL;        /* allow unlimited swap space */
+	int        swapena = OS_DEFAULT_SWAP_ENABLED;      /* swapping enabled? */
+	int        i;
+	int        pause = FALSE;                 /* pause after finishing game */
+	fiolcxdef  fiolctx;
+	noreg int  loadopen = FALSE;
+	char       inbuf[OSFNMAX];
+	ulong      cachelimit = 0xffffffff;
+	ushort     undosiz = TRD_UNDOSIZ;      /* default undo context size 16k */
+	objucxdef *undoptr = 0;
+	uint       flags;         /* flags used to write the file we're reading */
+	objnum     preinit;         /* preinit object, if we need to execute it */
+	uint       heapsiz = TRD_HEAPSIZ;
+	uint       stksiz = TRD_STKSIZ;
+	runsdef   *mystack;
+	uchar     *myheap;
+	extern osfildef *cmdfile;     /* hacky v1 qa interface - command log fp */
+	extern osfildef *logfp;        /* hacky v1 qa interface - output log fp */
+	int        preload = FALSE;              /* TRUE => preload all objects */
+	ulong      totsize;
+	extern voccxdef *main_voc_ctx;
+	int        safety_read, safety_write;          /* file I/O safety level */
+	char      *restore_file = 0;                    /* .SAV file to restore */
+	char      *charmap = 0;                           /* character map file */
+	int        charmap_none;       /* explicitly do not use a character set */
+	int        doublespace = TRUE;        /* formatter double-space setting */
+#ifdef TODO
+	NOREG((&loadopen))
+
+		/* initialize the output formatter */
+		out_init();
+
+	/* set safety level to 2 by default - read any/write current dir only */
+	safety_read = safety_write = 2;
+
+	/* no -ctab- yet */
+	charmap_none = FALSE;
+
+	/* parse arguments */
+	for (i = 1, argp = argv + 1; i < argc; ++argp, ++i)
+	{
+		arg = *argp;
+		if (*arg == '-')
+		{
+			switch (*(arg + 1))
+			{
+			case 'c':
+				if (!strcmp(arg + 1, "ctab"))
+				{
+					/* get the character mapping table */
+					charmap = cmdarg(ec, &argp, &i, argc, 4, trdusage);
+				}
+				else if (!strcmp(arg + 1, "ctab-"))
+				{
+					/* use the default mapping */
+					charmap_none = TRUE;
+				}
+				else
+					trdusage(ec);
+				break;
+
+			case 'r':
+				/* restore a game */
+				restore_file = cmdarg(ec, &argp, &i, argc, 1, trdusage);
+				break;
+
+			case 'i':
+				qasopn(cmdarg(ec, &argp, &i, argc, 1, trdusage), TRUE);
+				break;
+
+			case 'o':
+				cmdfile = osfopwt(cmdarg(ec, &argp, &i, argc, 1, trdusage),
+					OSFTCMD);
+				break;
+
+			case 'l':
+				logfp = osfopwt(cmdarg(ec, &argp, &i, argc, 1, trdusage),
+					OSFTCMD);
+				break;
+
+			case 'p':
+				if (!stricmp(arg, "-plain"))
+				{
+					os_plain();
+					break;
+				}
+				pause = cmdtog(ec, pause, arg, 1, trdusage);
+				break;
+
+			case 'd':
+				if (!strnicmp(arg, "-double", 7))
+				{
+					/* get the argument value */
+					doublespace = cmdtog(ec, doublespace, arg, 6, trdusage);
+
+					/* set the double-space mode in the formatter */
+					out_set_doublespace(doublespace);
+					break;
+				}
+				break;
+
+			case 's':
+			{
+				char *p;
+
+				/* get the option */
+				p = cmdarg(ec, &argp, &i, argc, 1, trdusage);
+
+				/* if they're asking for help, display detailed usage */
+				if (*p == '?')
+					trdusage_s(ec);
+
+				/* get the safety level from the argument */
+				safety_read = *p - '0';
+				safety_write = (*(p + 1) != '\0' ? *(p + 1) - '0' :
+					safety_read);
+
+				/* range-check the values */
+				if (safety_read < 0 || safety_read > 4
+					|| safety_write < 0 || safety_write > 4)
+					trdusage_s(ec);
+
+				/* tell the host system about the setting */
+				if (appctx != 0 && appctx->set_io_safety_level != 0)
+					(*appctx->set_io_safety_level)
+					(appctx->io_safety_level_ctx,
+						safety_read, safety_write);
+			}
+			break;
+
+			case 'm':
+				switch (*(arg + 2))
+				{
+				case 's':
+					stksiz = atoi(cmdarg(ec, &argp, &i, argc, 2, trdusage));
+					break;
+
+				case 'h':
+					heapsiz = atoi(cmdarg(ec, &argp, &i, argc, 2, trdusage));
+					break;
+
+				default:
+					cachelimit = atol(cmdarg(ec, &argp, &i, argc, 1,
+						trdusage));
+					break;
+				}
+				break;
+
+			case 't':
+				/* swap file options:  -tf file, -ts size, -t- (no swap) */
+				switch (*(arg + 2))
+				{
+				case 'f':
+					swapname = cmdarg(ec, &argp, &i, argc, 2, trdusage);
+					break;
+
+				case 's':
+					swapsize = atol(cmdarg(ec, &argp, &i, argc, 2, trdusage));
+					break;
+
+				case 'p':
+					preload = cmdtog(ec, preload, arg, 2, trdusage);
+					break;
+
+				default:
+					swapena = cmdtog(ec, swapena, arg, 1, trdusage);
+					break;
+				}
+				break;
+
+			case 'u':
+				undosiz = atoi(cmdarg(ec, &argp, &i, argc, 1, trdusage));
+				break;
+
+			default:
+				trdusage(ec);
+			}
+		}
+		else break;
+	}
+
+	/* presume we won't take the .gam from the application executable */
+	exefile = 0;
+
+	/* get input name argument, and make sure it's the last argument */
+	if (i == argc)
+	{
+		osfildef *fp;
+		ulong     curpos;
+		ulong     endpos;
+		int       use_exe;
+
+		/*
+		*   There's no input name argument, so we need to find the game
+		*   to play some other way.  First, check to see if we have a
+		*   game to restore, and if so whether it has the .GAM name
+		*   encoded into it.  Next, look to see if there's a game
+		*   attached to the executable file; if so, use it.  If not, see
+		*   if the host system wants to provide a name through its
+		*   callback.
+		*/
+
+		/* presume we won't find a game attached to the executable file */
+		infile = 0;
+		use_exe = FALSE;
+
+		/*
+		*   see if we have a saved game to restore, and it specifies the
+		*   GAM file that saved it
+		*/
+		if (restore_file != 0)
+		{
+			/* try getting the game name from the restore file */
+			if (fiorso_getgame(restore_file, inbuf, sizeof(inbuf)))
+			{
+				/* got it - use this file */
+				infile = inbuf;
+			}
+		}
+
+		/*
+		*   it that didn't work, try to read from os-dependent part of
+		*   program being executed
+		*/
+		if (infile == 0)
+		{
+			/* try opening the executable file */
+			exefile = (argv && argv[0] ? argv[0] : "TRX");
+			fp = os_exeseek(exefile, "TGAM");
+			if (fp != 0)
+			{
+				/* see if there's a game file attached to the executable */
+				curpos = osfpos(fp);
+				osfseek(fp, 0L, OSFSK_END);
+				endpos = osfpos(fp);
+				osfcls(fp);
+
+				/* if we found it, use it */
+				if (endpos != curpos)
+					use_exe = TRUE;
+			}
+		}
+
+		/*
+		*   if we didn't find a game in the executable, try the host
+		*   system callback
+		*/
+		if (infile == 0 && !use_exe)
+		{
+			/*
+			*   ask the host system callback what to do - if we don't
+			*   have a host system callback, or the callback
+			*/
+			if (appctx != 0 && appctx->get_game_name != 0)
+			{
+				/* call the host system callback */
+				if ((*appctx->get_game_name)(appctx->get_game_name_ctx,
+					inbuf, sizeof(inbuf)))
+				{
+					/* the host system provided a name - use it */
+					infile = inbuf;
+				}
+				else
+				{
+					/*
+					*   the host didn't provide a name - simply display a
+					*   message indicating that no game file has been
+					*   chosen, and return
+					*/
+					trdptf("\n");
+					trdptf("(No game has been selected.)\n");
+					return;
+				}
+			}
+			else
+			{
+				/*
+				*   we've run out of ways to get a filename - give the
+				*   user the usage message and quit
+				*/
+				trdusage(ec);
+			}
+		}
+	}
+	else
+	{
+		infile = *argp;
+		if (i + 1 != argc)
+			trdusage(ec);
 
+#ifndef OS_HATES_EXTENSIONS
+		/*
+		*   If original name exists, use it; otherwise, try adding .GAM.
+		*   Note that this code is ifdef'd so that platforms that don't
+		*   use filename extensions in the manner conventional for DOS
+		*   and Unix won't use this code.
+		*/
+		if (osfacc(infile))
+		{
+			strcpy(inbuf, infile);
+			os_defext(inbuf, "gam");
+			infile = inbuf;
+		}
+#endif /* !defined(OS_HATES_EXTENSIONS) */
+	}
+
+	/* open up the swap file */
+	if (swapena && swapsize)
+	{
+		swapfp = os_create_tempfile(swapname, swapbuf);
+		if (swapname == 0) swapname = swapbuf;
+		if (swapfp == 0) errsig(ec, ERR_OPSWAP);
+	}
+
+	/* load the character map */
+	if (charmap_none)
+		cmap_override();
+	else if (cmap_load(charmap))
+		errsig(ec, ERR_INVCMAP);
+
+	ERRBEGIN(ec)
+
+		/* initialize cache manager context */
+		globalctx = mcmini(cachelimit, 128, swapsize, swapfp, swapname, ec);
+	mctx = mcmcini(globalctx, 128, fioldobj, &fiolctx,
+		objrevert, (void *)0);
+	mctx->mcmcxrvc = mctx;
+
+	/* set up an undo context */
+	if (undosiz)
+		undoptr = objuini(mctx, undosiz, vocdundo, vocdusz, &vocctx);
+	else
+		undoptr = (objucxdef *)0;
+
+	/* set up vocabulary context */
+	vocini(&vocctx, ec, mctx, &runctx, undoptr, 100, 100, 200);
+
+	/*
+	*   save a pointer to the voc context globally, so that certain
+	*   external routines (such as Unix-style signal handlers) can reach
+	*   it
+	*/
+	main_voc_ctx = &vocctx;
+
+	/* allocate stack and heap */
+	totsize = (ulong)stksiz * (ulong)sizeof(runsdef);
+	if (totsize != (size_t)totsize)
+		errsig1(ec, ERR_STKSIZE, ERRTINT, (uint)(65535 / sizeof(runsdef)));
+	mystack = (runsdef *)mchalo(ec, (size_t)totsize, "runtime stack");
+	myheap = mchalo(ec, heapsiz, "runtime heap");
+
+	/* get the absolute path for the input file */
+	if (infile != 0)
+		os_get_abs_filename(infile_abs, sizeof(infile_abs), infile);
+	else if (exefile != 0)
+		os_get_abs_filename(infile_abs, sizeof(infile_abs), exefile);
+	else
+		infile_abs[0] = '\0';
+	os_get_path_name(infile_path, sizeof(infile_path), infile_abs);
+
+	/* set up execution context */
+	runctx.runcxerr = ec;
+	runctx.runcxmem = mctx;
+	runctx.runcxstk = mystack;
+	runctx.runcxstop = &mystack[stksiz];
+	runctx.runcxsp = mystack;
+	runctx.runcxbp = mystack;
+	runctx.runcxheap = myheap;
+	runctx.runcxhp = myheap;
+	runctx.runcxhtop = &myheap[heapsiz];
+	runctx.runcxundo = undoptr;
+	runctx.runcxbcx = &bifctx;
+	runctx.runcxbi = bif;
+	runctx.runcxtio = (tiocxdef *)0;
+	runctx.runcxdbg = &dbg;
+	runctx.runcxvoc = &vocctx;
+	runctx.runcxdmd = supcont;
+	runctx.runcxdmc = &supctx;
+	runctx.runcxext = 0;
+	runctx.runcxgamename = infile;
+	runctx.runcxgamepath = infile_path;
+
+	/* set up setup context */
+	supctx.supcxerr = ec;
+	supctx.supcxmem = mctx;
+	supctx.supcxtab = (tokthdef *)0;
+	supctx.supcxbuf = (uchar *)0;
+	supctx.supcxlen = 0;
+	supctx.supcxvoc = &vocctx;
+	supctx.supcxrun = &runctx;
+
+	/* set up debug context */
+	dbg.dbgcxtio = (tiocxdef *)0;
+	dbg.dbgcxmem = mctx;
+	dbg.dbgcxerr = ec;
+	dbg.dbgcxtab = (tokthdef *)0;
+	dbg.dbgcxfcn = 0;
+	dbg.dbgcxdep = 0;
+	dbg.dbgcxflg = 0;
+	dbg.dbgcxlin = (lindef *)0;                      /* no line sources yet */
+
+													 /* set up built-in function context */
+	CLRSTRUCT(bifctx);
+	bifctx.bifcxerr = ec;
+	bifctx.bifcxrun = &runctx;
+	bifctx.bifcxtio = (tiocxdef *)0;
+	bifctx.bifcxrnd = 0;
+	bifctx.bifcxrndset = FALSE;
+	bifctx.bifcxappctx = appctx;
+	bifctx.bifcxsafetyr = safety_read;
+	bifctx.bifcxsafetyw = safety_write;
+	bifctx.bifcxsavext = save_ext;
+
+	/* initialize the regular expression parser context */
+	re_init(&bifctx.bifcxregex, ec);
+
+	/* add the built-in functions, keywords, etc */
+	supbif(&supctx, bif, (int)(sizeof(bif) / sizeof(bif[0])));
+
+	/* set up status line hack */
+	runistat(&vocctx, &runctx, (tiocxdef *)0);
+
+	/* turn on the "busy" cursor before loading */
+	os_csr_busy(TRUE);
+
+	/* read the game from the binary file */
+	fiord(mctx, &vocctx, (struct tokcxdef *)0,
+		infile, exefile, &fiolctx, &preinit, &flags,
+		(struct tokpdef *)0, (uchar **)0, (uint *)0, (uint *)0,
+		(preload ? 2 : 0), appctx, argv[0]);
+	loadopen = TRUE;
+
+	/* turn off the "busy" cursor */
+	os_csr_busy(FALSE);
+
+	/* play the game */
+	plygo(&runctx, &vocctx, (tiocxdef *)0, preinit, restore_file);
+
+	/* close load file */
+	fiorcls(&fiolctx);
+
+	if (pause)
+	{
+		trdptf("[press a key to exit]");
+		os_waitc();
+		trdptf("\n");
+	}
+
+	/* close and delete swapfile, if one was opened */
+	trd_close_swapfile(&runctx);
+
+	/* make sure the script file is closed, if we have one */
+	qasclose();
+
+	ERRCLEAN(ec)
+		/* close and delete swapfile, if one was opened */
+		trd_close_swapfile(&runctx);
+
+	/* close the load file if one was opened */
+	if (loadopen)
+		fiorcls(&fiolctx);
+
+	/* vocctx is going out of scope - forget the global reference to it */
+	main_voc_ctx = 0;
+
+	/* delete the voc context */
+	vocterm(&vocctx);
+
+	/* delete the undo context */
+	if (undoptr != 0)
+		objuterm(undoptr);
+
+	/* release the object cache structures */
+	if (mctx != 0)
+		mcmcterm(mctx);
+	if (globalctx != 0)
+		mcmterm(globalctx);
+	ERRENDCLN(ec)
+
+		/* vocctx is going out of scope - forget the global reference to it */
+		main_voc_ctx = 0;
+
+	/* delete the voc contxt */
+	vocterm(&vocctx);
+
+	/* delete the undo context */
+	if (undoptr != 0)
+		objuterm(undoptr);
+
+	/* release the object cache structures */
+	mcmcterm(mctx);
+	mcmterm(globalctx);
+#endif
 }
 
 void TADS2::trdptf(const char *fmt, ...) {
diff --git a/engines/glk/tads/tads2/tads2.h b/engines/glk/tads/tads2/tads2.h
index 2472929840..0ea1662b00 100644
--- a/engines/glk/tads/tads2/tads2.h
+++ b/engines/glk/tads/tads2/tads2.h
@@ -23,38 +23,35 @@
 #ifndef GLK_TADS_TADS2
 #define GLK_TADS_TADS2
 
-#include "glk/tads/tads2/os.h"
-#include "glk/tads/tads2/ler.h"
+#include "glk/tads/tads.h"
+#include "glk/tads/tads2/error_handling.h"
+#include "glk/tads/tads2/appctx.h"
 
 namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
-/**
- * map a native character (read externally) into an internal character
+/*
+ *   Run-time version number 
  */
-#define cmap_n2i(c) (G_cmap_input[(unsigned char)(c)])
+#define  TADS_RUNTIME_VERSION   "2.5.17"
 
-/**
- * map an internal character into a native character (for display)
- */
-#define cmap_i2n(c) (G_cmap_output[(unsigned char)(c)])
-
-/**
- * the full name (for display purposes) of the loaded character set
- */
-#define CMAP_LDESC_MAX_LEN  40
-
-/**
- * Maximum expansion for an HTML entity mapping 
- */
-#define CMAP_MAX_ENTITY_EXPANSION  50
+# define TRD_HEAPSIZ  4096
+# define TRD_STKSIZ   200
+# define TRD_UNDOSIZ  (16 * 1024)
+# define TDD_HEAPSIZ  4096
+# define TDD_STKSIZ   200
+# define TDD_UNDOSIZ  (16 * 1024)
+# define TDD_POOLSIZ  (2 * 1024)
+# define TDD_LCLSIZ   0
 
+# define ERR_TRUS_OS_FIRST    100
+# define ERR_TRUS_OS_LAST      99
 
 /**
  * TADS 2 game interpreter
  */
-class TADS2 : public OS {
+class TADS2 : public TADS {
 private:
 	// STUBS
 	void os_printz(const Common::String &s) {}
@@ -62,41 +59,6 @@ private:
 		const char *expansion, size_t expansion_len) {}
 private:
 	/**
-	 * \defgroup cmap
-	 * @{
-	 */
-
-	/**
-	 * flag: true -> a character set has been explicitly loaded, so we
-	 * should ignore any game character set setting 
-	 */
-	bool S_cmap_loaded;
-
-	/**
-	 * input-mapping table - for native character 'n', cmap_input[n] yields
-	 * the internal character code 
-	 */
-	unsigned char G_cmap_input[256];
-
-	/**
-	 * output-mapping table - for internal character 'n', cmap_output[n]
-	 * yields the output character code 
-	 */
-	unsigned char G_cmap_output[256];
-
-	/**
-	 * the ID of the loaded character set
-	 */
-	char G_cmap_id[5];
-
-	/**
-	 * the full name (for display purposes) of the loaded character set
-	 */
-	char G_cmap_ldesc[CMAP_LDESC_MAX_LEN + 1];
-
-	/**@}*/
-private:
-	/**
 	 * \defgroup trd
 	 * @{
 	 */
@@ -109,55 +71,6 @@ private:
 	void trdptf(const char *fmt, ...);
 
 	/**@}*/
-
-	/**
-	 * \defgroup cmap
-	 * @{
-	 */
-
-	/**
-	 * Initialize the default character mappings.  If no mapping file is to
-	 * be read, this function will establish identify mappings that leave
-	 * characters untranslated. 
-	 */
-	void cmap_init_default();
-
-	/**
-	 * Load a character map file.  Returns zero on success, non-zero on
-	 * failure.  If filename is null, we'll use the default mapping.
-	 */
-	int cmap_load(const char *filename);
-
-	/**
-	 * Turn off character translation.  This overrides any game character
-	 * set that we find and simply uses the default translation. 
-	 */
-	void cmap_override(void);
-
-	/**
-	 * Set the game's internal character set.  This should be called when a
-	 * game is loaded, and the game specifies an internal character set.  If
-	 * there is no character map file explicitly loaded, we will attempt to
-	 * load a character mapping file that maps this character set to the
-	 * current native character set.  Signals an error on failure.  This
-	 * routine will succeed (without doing anything) if a character set has
-	 * already been explicitly loaded, since an explicitly-loaded character
-	 * set overrides the automatic character set selection that we attempt
-	 * when loading a game.
-	 * 
-	 * argv0 must be provided so that we know where to look for our mapping
-	 * file on systems where mapping files are stored in the same directory
-	 * as the TADS executables.  
-	 */
-	void cmap_set_game_charset(errcxdef *errctx, const char *internal_id,
-		const char *internal_ldesc, const char *argv0);
-
-	/**
-	 * Internal routine to load a character map from a file 
-	 */
-	int cmap_load_internal(const char *filename);
-
-	/**@}*/
 public:
 	/**
 	 * Constructor
@@ -175,7 +88,7 @@ public:
 	virtual InterpreterType getInterpreterType() const override { return INTERPRETER_TADS2; }
 };
 
-typedef TADS2 appctxdef;
+//typedef TADS2 appctxdef;
 
 } // End of namespace TADS2
 } // End of namespace TADS
diff --git a/engines/glk/tads/tads2/tads2_cmap.cpp b/engines/glk/tads/tads2/tads2_cmap.cpp
deleted file mode 100644
index 68945f7336..0000000000
--- a/engines/glk/tads/tads2/tads2_cmap.cpp
+++ /dev/null
@@ -1,268 +0,0 @@
-/* ScummVM - Graphic Adventure Engine
- *
- * ScummVM is the legal property of its developers, whose names
- * are too numerous to list here. Please refer to the COPYRIGHT
- * file distributed with this source distribution.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
-
-#include "glk/tads/tads2/tads2.h"
-#include "glk/tads/tads2/types.h"
-
-namespace Glk {
-namespace TADS {
-namespace TADS2 {
-
-/**
- * Signatures for character map files.  The signature is stored at the
- * beginning of the file.
- */
-// single-byte character map version 1.0.0
-#define CMAP_SIG_S100  "TADS2 charmap S100\n\r\01a"
-
-void TADS2::cmap_init_default() {
-	size_t i;
-
-	// initialize the input table
-	for (i = 0 ; i < sizeof(G_cmap_input)/sizeof(G_cmap_input[0]) ; ++i)
-		G_cmap_input[i] = (unsigned char)i;
-
-	// initialize the output table
-	for (i = 0 ; i < sizeof(G_cmap_output)/sizeof(G_cmap_output[0]) ; ++i)
-		G_cmap_output[i] = (unsigned char)i;
-
-	// we have a null ID
-	memset(G_cmap_id, 0, sizeof(G_cmap_id));
-
-	// indicate that it's the default
-	strcpy(G_cmap_ldesc, "(native/no mapping)");
-
-	// note that we have no character set loaded
-	S_cmap_loaded = false;
-}
-
-int TADS2::cmap_load_internal(const char *filename) {
-	osfildef *fp;
-	static char sig1[] = CMAP_SIG_S100;
-	char buf[256];
-	uchar lenbuf[2];
-	size_t len;
-	int sysblk;
-
-	// if there's no mapping file, use the default mapping
-	if (filename == 0) {
-		// initialize with the default mapping
-		cmap_init_default();
-
-		// return success
-		return 0;
-	}
-
-	// open the file
-	fp = osfoprb(filename, OSFTCMAP);
-	if (fp == 0)
-		return 1;
-
-	// check the signature
-	if (osfrb(fp, buf, sizeof(sig1))
-		|| memcmp(buf, sig1, sizeof(sig1)) != 0) {
-		osfcls(fp);
-		return 2;
-	}
-
-	// load the ID
-	G_cmap_id[4] = '\0';
-	if (osfrb(fp, G_cmap_id, 4)) {
-		osfcls(fp);
-		return 3;
-	}
-
-	// load the long description
-	if (osfrb(fp, lenbuf, 2)
-		|| (len = osrp2(lenbuf)) > sizeof(G_cmap_ldesc)
-		|| osfrb(fp, G_cmap_ldesc, len)) {
-		osfcls(fp);
-		return 4;
-	}
-
-	// load the two tables - input, then output
-	if (osfrb(fp, G_cmap_input, sizeof(G_cmap_input))
-		|| osfrb(fp, G_cmap_output, sizeof(G_cmap_output))) {
-		osfcls(fp);
-		return 5;
-	}
-
-	// read the next section header
-	if (osfrb(fp, buf, 4)) {
-		osfcls(fp);
-		return 6;
-	}
-
-	// if it's "SYSI", read the system information string
-	if (!memcmp(buf, "SYSI", 4)) {
-		// read the length prefix, then the string
-		if (osfrb(fp, lenbuf, 2)
-			|| (len = osrp2(lenbuf)) > sizeof(buf)
-			|| osfrb(fp, buf, len)) {
-			osfcls(fp);
-			return 7;
-		}
-
-		// we have a system information block
-		sysblk = true;
-	} else {
-		// there's no system information block
-		sysblk = false;
-	}
-
-	/*
-	 * call the OS code, so that it can do any system-dependent
-	 * initialization for the new character mapping
-	 */
-	os_advise_load_charmap(G_cmap_id, G_cmap_ldesc, sysblk ? buf : "");
-
-	// read the next section header
-	if (sysblk && osfrb(fp, buf, 4)) {
-		osfcls(fp);
-		return 8;
-	}
-
-	// see if we have an entity list
-	if (!memcmp(buf, "ENTY", 4)) {
-		// read the entities
-		for (;;) {
-			unsigned int cval;
-			char expansion[CMAP_MAX_ENTITY_EXPANSION];
-
-			// read the next item's length and character value
-			if (osfrb(fp, buf, 4)) {
-				osfcls(fp);
-				return 9;
-			}
-
-			// decode the values
-			len = osrp2(buf);
-			cval = osrp2(buf+2);
-
-			// if we've reached the zero marker, we're done
-			if (len == 0 && cval == 0)
-				break;
-
-			// read the string
-			if (len > CMAP_MAX_ENTITY_EXPANSION
-				|| osfrb(fp, expansion, len)) {
-				osfcls(fp);
-				return 10;
-			}
-
-			// tell the output code about the expansion
-			tio_set_html_expansion(cval, expansion, len);
-		}
-	}
-
-	/*
-	 * ignore anything else we find - if the file format is updated to
-	 * include extra information in the future, and this old code tries
-	 * to load an updated file, we'll just ignore the new information,
-	 * which should always be placed after the "SYSI" block (if present)
-	 * to ensure compatibility with past versions (such as this code)
-	 */
-	// no problems - close the file and return success
-	osfcls(fp);
-	return 0;
-}
-
-int TADS2::cmap_load(const char *filename) {
-	int err;
-
-	// try loading the file
-	if ((err = cmap_load_internal(filename)) != 0)
-		return err;
-
-	/*
-	 * note that we've explicitly loaded a character set, if they named
-	 * a character set (if not, this simply establishes the default
-	 * setting, so we haven't explicitly loaded anything)
-	 */
-	if (filename != nullptr)
-		S_cmap_loaded = true;
-
-	// success
-	return 0;
-}
-
-void TADS2::cmap_override() {
-	// apply the default mapping
-	cmap_init_default();
-
-	/*
-	 * pretend we have a character map loaded, so that we don't try to
-	 * load another one if the game specifies a character set
-	 */
-	S_cmap_loaded = true;
-}
-
-void TADS2::cmap_set_game_charset(errcxdef *ec, const char *internal_id,
-		const char *internal_ldesc, const char *argv0) {
-	char filename[OSFNMAX];
-
-	/*
-	 * If a character set is already explicitly loaded, ignore the
-	 * game's character set - the player asked us to use a particular
-	 * mapping, so ignore what the game wants.  (This will probably
-	 * result in incorrect display of non-ASCII character values, but
-	 * the player is most likely to use this to avoid errors when an
-	 * appropriate mapping file for the game is not available.  In this
-	 * case, the player informs us by setting the option that he or she
-	 * knows and accepts that the game will not look exactly right.)
-	 */
-	if (S_cmap_loaded)
-		return;
-
-	/*
-	 * ask the operating system to name the mapping file -- this routine
-	 * will determine, if possible, the current native character set,
-	 * and apply a system-specific naming convention to tell us what
-	 * mapping file we should open
-	 */
-	os_gen_charmap_filename(filename, internal_id, argv0);
-
-	// try loading the mapping file
-	if (cmap_load_internal(filename))
-		errsig2(ec, ERR_CHRNOFILE,
-				ERRTSTR, errstr(ec, filename, strlen(filename)),
-				ERRTSTR, errstr(ec, internal_ldesc, strlen(internal_ldesc)));
-
-	/**
-	 * We were successful - the game's internal character set is now
-	 * mapped to the current native character set.  Even though we
-	 * loaded an ldesc from the mapping file, forget that and store the
-	 * internal ldesc that the game specified.  The reason we do this is
-	 * that it's possible that the player will dynamically switch native
-	 * character sets in the future, at which point we'll need to
-	 * re-load the mapping table, which could raise an error if a
-	 * mapping file for the new character set isn't available.  So, we
-	 * may need to provide the same explanation later that we needed to
-	 * provide here.  Save the game's character set ldesc for that
-	 * eventuality, since it describes exactly what the *game* wanted.
-	 */
-	strcpy(G_cmap_ldesc, internal_ldesc);
-}
-
-} // End of namespace TADS2
-} // End of namespace TADS
-} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/text_io.h b/engines/glk/tads/tads2/text_io.h
new file mode 100644
index 0000000000..33a914e0ba
--- /dev/null
+++ b/engines/glk/tads/tads2/text_io.h
@@ -0,0 +1,233 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_TEXT_IO
+#define GLK_TADS_TADS2_TEXT_IO
+
+/*
+ * Text I/O interface
+ *
+ * Formatted text input and output interface definition
+ */
+
+#include "glk/tads/tads.h"
+#include "glk/tads/tads2/error_handling.h"
+#include "glk/tads/tads2/run.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* forward decls */
+struct runcxdef;
+
+/**
+ * Text i/o context
+ */
+struct tiocxdef {
+    errcxdef *tiocxerr;                           /* error handling context */
+};
+
+/**
+ *   Initialize the output formatter subsystem.  This must be called once
+ *   at startup. 
+ */
+void out_init();
+
+
+/* redirect all tioxxx routines to TADS v1.x outxxx equivalents */
+#define tioflushn(ctx, nl) outflushn(nl)
+#define tioflush(ctx)      outflush()
+#define tioblank(ctx)      outblank()
+#define tioreset(ctx)      outreset()
+#define tiogets(ctx, prompt, str, siz) getstring(prompt, str, siz)
+#define tioputs(ctx, str)  outformat(str)
+#define tioputslen(ctx, str, len) outformatlen(str, len)
+#define tiocaps(ctx)       outcaps()
+#define tionocaps(ctx)     outnocaps()
+#define tioshow(ctx)       outshow()
+#define tiohide(ctx)       outhide()
+#define tioscore(ctx, s1, s2) os_score(s1, s2)
+#define tiostrsc(ctx, s)   os_strsc(s)
+
+/* set up format strings in output subsystem */
+void tiosetfmt(tiocxdef *ctx, runcxdef *rctx, uchar *fmtbase,
+               uint fmtlen);
+
+/* tell tio subsystem the current actor */
+void tiosetactor(tiocxdef *ctx, objnum actor);
+
+/* get the current tio subsystem actor */
+objnum tiogetactor(tiocxdef *ctx);
+
+/* turn output capture on/off */
+void tiocapture(tiocxdef *tioctx, mcmcxdef *memctx, int flag);
+
+/* get the capture object handle */
+mcmon tiogetcapture(tiocxdef *ctx);
+
+/* get the amount of text captured */
+uint tiocapturesize(tiocxdef *ctx);
+
+/* format a length-prefixed (runtime-style) string to the display */
+void outfmt(tiocxdef *ctx, uchar *txt);
+
+/* format a null-terminated (C-style) string to the display */
+int outformat(char *s);
+
+/* format a counted-length string, which may not be null-terminated */
+int outformatlen(char *s, uint len);
+
+/* flush output, with specified newline mode */
+void outflushn(int nl);
+
+/* flush output */
+void outflush(void);
+
+/* reset output state */
+void outreset(void);
+
+/* 
+ *   Get a string from the keyboard.  Returns non-zero if an error occurs
+ *   (in particular, if no more input is available from the keyboard),
+ *   zero on success.  
+ */
+int getstring(char *prompt, char *buf, int bufl);
+
+/* set capitalize-next-character mode on/off */
+void outcaps(void);
+void outnocaps(void);
+
+/* open/close output log file */
+int tiologopn(tiocxdef *ctx, char *fn);
+int tiologcls(tiocxdef *ctx);
+
+/*
+ *   Write text explicitly to the log file.  This can be used to add
+ *   special text (such as prompt text) that would normally be suppressed
+ *   from the log file.  When more mode is turned off, we don't
+ *   automatically copy text to the log file; any text that the caller
+ *   knows should be in the log file during times when more mode is turned
+ *   off can be explicitly added with this function.
+ *   
+ *   If nl is true, we'll add a newline at the end of this text.  The
+ *   caller should not include any newlines in the text being displayed
+ *   here.  
+ */
+void out_logfile_print(char *txt, int nl);
+
+
+/*
+ *   Check output status.  Indicate whether output is currently hidden,
+ *   and whether any hidden output has occurred. 
+ */
+void outstat(int *hidden, int *output_occurred);
+
+/* hide/show output */
+void outhide(void);
+int outshow(void);
+
+/* set the flag to indicate that output has occurred */
+void outsethidden(void);
+
+/* write a blank line */
+void outblank(void);
+
+/* start/end watchpoint evaluation */
+void outwx(int flag);
+
+/* Begin/end capturing */
+void tiocapture(tiocxdef *tioctx, mcmcxdef *memctx, int flag);
+
+/* clear all captured output */
+void tioclrcapture(tiocxdef *tioctx);
+
+/* 
+ *   clear captured output back to a given point -- this can be used to
+ *   remove captured output in an inner capture from an enclosing capture 
+ */
+void tiopopcapture(tiocxdef *tioctx, uint orig_size);
+
+/* get the object handle of the captured output */
+mcmon tiogetcapture(tiocxdef *ctx);
+
+/* get the amount of text captured */
+uint tiocapturesize(tiocxdef *ctx);
+
+/* turn MORE mode on or off */
+int setmore(int state);
+
+/* explicitly activate the "MORE" prompt */
+void out_more_prompt();
+
+/*
+ *   QA controller functions
+ */
+int qasopn(char *scrnam, int quiet);
+void qasclose(void);
+char *qasgets(char *buf, int bufl);
+
+/*
+ *   Set an HTML entity expansion.  This is called during initialization
+ *   when we read a character mapping table that includes HTML entity
+ *   expansions.  The HTML run-time uses its own expansion mechanism, so
+ *   it will ignore this information.  The standard character-mode TADS
+ *   run-time, however, uses this information to map HTML entities to the
+ *   local character set. 
+ */
+void tio_set_html_expansion(unsigned int html_char_val,
+                            const char *expansion, size_t expansion_len);
+
+/* check for HTML mode - returns true if an "\H+" sequence is active */
+int tio_is_html_mode();
+
+/* set the user output filter function */
+void out_set_filter(objnum filter_fn);
+
+/* set the double-space mode */
+void out_set_doublespace(int dbl);
+
+/*
+ *   Ask for a filename, using a system-defined dialog (via os_askfile) if
+ *   possible.  Uses the same interface as os_askfile(), which we will
+ *   call directly for graphical implementations.  We'll use formatted
+ *   text for text-only implementations.  
+ */
+int tio_askfile(const char *prompt, char *fname_buf, int fname_buf_len,
+                int prompt_type, os_filetype_t file_type);
+
+/*
+ *   Display a dialog, using a system-defined dialog (via os_input_dialog)
+ *   if possible.  Uses the same interface as os_input_dialog(), which we
+ *   will call directly for graphical implementations.  We'll use
+ *   formatted text for text-only implementations.  
+ */
+int tio_input_dialog(int icon_id, const char *prompt, int standard_button_set,
+                     const char **buttons, int button_count,
+                     int default_index, int cancel_index);
+
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/tokenizer.cpp b/engines/glk/tads/tads2/tokenizer.cpp
new file mode 100644
index 0000000000..59dceebaf6
--- /dev/null
+++ b/engines/glk/tads/tads2/tokenizer.cpp
@@ -0,0 +1,33 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "glk/tads/tads2/tokenizer.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+// TODO: Rest of tokenizer stuff
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
diff --git a/engines/glk/tads/tads2/tokenizer.h b/engines/glk/tads/tads2/tokenizer.h
new file mode 100644
index 0000000000..50a8492cd3
--- /dev/null
+++ b/engines/glk/tads/tads2/tokenizer.h
@@ -0,0 +1,473 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef GLK_TADS_TADS2_TOKENIZER
+#define GLK_TADS_TADS2_TOKENIZER
+
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/error_handling.h"
+#include "glk/tads/tads2/line_source.h"
+#include "glk/tads/tads2/memory_cache.h"
+
+namespace Glk {
+namespace TADS {
+namespace TADS2 {
+
+/* number of entries in hash table - must be power of 2 */
+#define TOKHASHSIZE 256
+
+/* symbol types */
+#define TOKSTUNK      0                  /* unknown symbol, not yet defined */
+#define TOKSTFUNC     1                 /* function; value is object number */
+#define TOKSTOBJ      2                   /* object; value is object number */
+#define TOKSTPROP     3               /* property; value is property number */
+#define TOKSTLOCAL    4             /* a local variable or formal parameter */
+#define TOKSTSELF     5                         /* the pseudo-object "self" */
+#define TOKSTBIFN     6                              /* a built-in function */
+#define TOKSTFWDOBJ   7                        /* forward-referenced object */
+#define TOKSTFWDFN    8                        /* forward-referenced object */
+#define TOKSTINHERIT  9                    /* the pseudo-object "inherited" */
+#define TOKSTEXTERN  10                             /* an external function */
+#define TOKSTKW      11                   /* keyword; value is token number */
+#define TOKSTLABEL   12                                  /* statement label */
+#define TOKSTARGC    13                       /* 'argcount' pseudo-variable */
+#define TOKSTPROPSPEC 14                 /* speculative evaluation property */
+
+/* token types */
+#define TOKTEOF     1
+
+/* binary operators - keep these together (see prsbopl[] in prs.c) */
+#define TOKTPLUS    2
+#define TOKTMINUS   3
+#define TOKTDIV     4
+#define TOKTTIMES   5
+#define TOKTNOT     6                                         /* ! or "not" */
+#define TOKTEQ      7
+#define TOKTNE      8
+#define TOKTGT      9
+#define TOKTGE      10
+#define TOKTLT      11
+#define TOKTLE      12
+#define TOKTMOD     13
+#define TOKTBAND    14
+#define TOKTBOR     15
+#define TOKTXOR     16
+#define TOKTSHL     17
+#define TOKTSHR     18
+#define TOKTTILDE   30
+
+/* 
+ *   special 'dot' replacement for speculative evaluation mode -- this is
+ *   strictly for marking parse tree nodes, and has the same meaning in a
+ *   parse tree node as a regular TOKTDOT, but generates code that can't
+ *   call methods 
+ */
+#define TOKTDOTSPEC 31
+
+/* special node marker for explicit superclass inheritance nodes */
+#define TOKTEXPINH  32
+
+#define TOKTLPAR    50                                                 /* ( */
+#define TOKTRPAR    51                                                 /* ) */
+#define TOKTCOLON   52
+#define TOKTDSTRING 53                           /* string in double quotes */
+#define TOKTSSTRING 54                           /* string in single quotes */
+#define TOKTNUMBER  55
+#define TOKTSYMBOL  56
+#define TOKTINVALID 57                             /* invalid lexical token */
+#define TOKTLBRACK  58                                                 /* [ */
+#define TOKTRBRACK  59                                                 /* ] */
+#define TOKTLBRACE  60                                                 /* { */
+#define TOKTRBRACE  61                                                 /* } */
+#define TOKTSEM     62                                                 /* ; */
+#define TOKTCOMMA   63
+#define TOKTDOT     64                                                 /* . */
+#define TOKTOR      65                                         /* | or "if" */
+#define TOKTAND     66                                        /* & or "and" */
+#define TOKTIF      67                                          /* keywords */
+#define TOKTELSE    68
+#define TOKTWHILE   69
+#define TOKTFUNCTION 70
+#define TOKTRETURN  71
+#define TOKTLOCAL   72
+#define TOKTOBJECT  73
+#define TOKTBREAK   74
+#define TOKTCONTINUE 75
+#define TOKTLIST    76                                            /* a list */
+#define TOKTNIL     77
+#define TOKTTRUE    78
+#define TOKTPASS    79
+#define TOKTCLASS   80
+#define TOKTEXIT    81
+#define TOKTABORT   82
+#define TOKTASKDO   83
+#define TOKTASKIO   84
+#define TOKTPOUND   85                                                 /* # */
+#define TOKTQUESTION 86                                                /* ? */
+#define TOKTCOMPOUND 87
+#define TOKTIOSYN   88
+#define TOKTDOSYN   89
+#define TOKTEXTERN  90
+#define TOKTFORMAT  91
+#define TOKTDO      92
+#define TOKTFOR     93
+#define TOKTNEW     94
+#define TOKTDELETE  95
+
+/* assignment operators - keep these together */
+#define TOKTINC     150                                               /* ++ */
+#define TOKTPOSTINC 151                              /* MUST BE TOKTINC + 1 */
+#define TOKTDEC     152                                               /* -- */
+#define TOKTPOSTDEC 153                              /* MUST BE TOKTDEC + 1 */
+#define TOKTPLEQ    154                                               /* += */
+#define TOKTMINEQ   155                                               /* -= */
+#define TOKTDIVEQ   156                                               /* /= */
+#define TOKTTIMEQ   157                                               /* *= */
+#define TOKTASSIGN  158                                /* simple assignment */
+#define TOKTMODEQ   159                     /* %= (mod and assign) operator */
+#define TOKTBANDEQ  160                                               /* &= */
+#define TOKTBOREQ   161                                               /* |= */
+#define TOKTXOREQ   162                              /* ^= (xor and assign) */
+#define TOKTSHLEQ   163                      /* <<= (shift left and assign) */
+#define TOKTSHREQ   164                      /* >>= (shift right and assign */
+
+#define TOKTSWITCH  200
+#define TOKTCASE    201
+#define TOKTDEFAULT 202
+#define TOKTGOTO    203
+#define TOKTELLIPSIS 204                                             /* ... */
+#define TOKTSPECIAL 205                                   /* "specialWords" */
+#define TOKTREPLACE 206                                          /* replace */
+#define TOKTMODIFY  207                                           /* modify */
+
+#define TOKTEQEQ    208                                /* the '==' operator */
+#define TOKTPOINTER 209                                  /* the -> operator */
+
+/* the longest a symbol name can be */
+#define TOKNAMMAX 39
+
+/* symbol table entry */
+struct toksdef {
+    uchar    tokstyp;                                 /* type of the symbol */
+    uchar    tokshsh;                               /* hash value of symbol */
+    ushort   toksval;              /* value of the symbol (depends on type) */
+    ushort   toksfr;               /* frame offset of symbol (for debugger) */
+    uchar    tokslen;                        /* length of the symbol's name */
+    char     toksnam[TOKNAMMAX];                          /* name of symbol */
+};
+
+/* symbol table entry without 'name' portion - for allocation purposes */
+struct toks1def {
+    uchar    tokstyp;
+    uchar    tokshsh;
+    ushort   toksval;
+    ushort   toksfr;
+    uchar    tokslen;
+    char     toksnam[1];
+};
+
+/* generic symbol table object - other symbol tables are subclasses */
+struct toktdef {
+    void     (*toktfadd)(toktdef *tab, char *name, int namel, int typ,
+                         int val, int hash);                  /* add symbol */
+    int      (*toktfsea)(toktdef *tab, char *name, int namel, int hash,
+                         toksdef *ret);              /* search symbol table */
+    void     (*toktfset)(toktdef *tab, toksdef *sym);
+                             /* update val & typ of symbol to those in *sym */
+    void     (*toktfeach)(toktdef *tab,
+                          void (*fn)(void *ctx, toksdef *sym),
+                          void *fnctx);            /* call fn for each sym */
+    toktdef   *toktnxt;                 /* next symbol table to be searched */
+    errcxdef  *tokterr;                           /* error handling context */
+};
+
+/* maximum number of pools (TOKTSIZE bytes each) for symbols */
+#define TOKPOOLMAX 128
+
+/* pointer to a symbol in a hashed symbol table */
+struct tokthpdef {
+    mcmon  tokthpobj;                /* cache manager object number of page */
+    uint   tokthpofs;                  /* offset within page of this symbol */
+};
+
+/* extended symbol entry in a hashed symbol table */
+struct tokshdef {
+    tokthpdef tokshnxt;              /* pointer to next symbol in the table */
+    toksdef   tokshsc;                  /* superclass - normal symbol entry */
+};
+
+/* hashing symbol table (subclass of generic symbol table) */
+struct tokthdef {
+    toktdef   tokthsc;              /* generic symbol table superclass data */
+    mcmcxdef *tokthmem;                           /* memory manager context */
+    tokthpdef tokthhsh[TOKHASHSIZE];                          /* hash table */
+    uint      tokthpcnt;            /* number of memory pools for toksdef's */
+    mcmon     tokthpool[TOKPOOLMAX];          /* memory pools for toksdef's */
+    uint      tokthfinal[TOKPOOLMAX];        /* actual sizes of these pools */
+    uchar    *tokthcpool;                           /* current pool pointer */
+    ushort    tokthsize;               /* remaining size of top memory pool */
+    ushort    tokthofs;             /* allocation offset in top memory pool */
+};
+
+/* size of toksdef pools to allocate for hashed symbol tables */
+#define TOKTHSIZE 4096
+
+/*
+ *   Linear cache-object-embedded symbol table.  This type of symbol
+ *   table is used for frame parameter/local variable lists.  It is best
+ *   for small tables, because it isn't broken up into hash buckets, so it
+ *   is searched linearly.  As a result, it's small enough to be embedded
+ *   in code.
+ */
+struct toktldef {
+    toktdef   toktlsc;              /* generic symbol table superclass data */
+    uchar    *toktlptr;                      /* base of linear symbol table */
+    uchar    *toktlnxt;                          /* next free byte in table */
+    uint      toktlcnt;                   /* number of objects in the table */
+    uint      toktlsiz;                     /* bytes remaining in the table */
+};
+
+struct tokdef {
+    int      toktyp;                                   /* type of the token */
+    int      toklen;           /* length of token text, if a symbolic token */
+    long     tokval;                        /* numeric value, if applicable */
+    ushort   tokofs;
+    uint     tokhash;              /* token hash value, if a symbolic token */
+    char     toknam[TOKNAMMAX+1];     /* text of token, if a symbolic token */
+    toksdef  toksym;                    /* symbol from table matching token */
+};
+
+/* special character sequence */
+#define TOKSCMAX  3            /* maximum length of a special char sequence */
+struct tokscdef {
+    tokscdef *tokscnxt;          /* next sequence with same first character */
+    int       toksctyp;             /* token type corresponding to sequence */
+    int       toksclen;                           /* length of the sequence */
+    char      tokscstr[TOKSCMAX+1];                  /* the sequence itself */
+};
+
+/*
+ *   Compare a special character sequence - for efficiency, define
+ *   something special for the maximum length available (TOKSCMAX).
+ *   Note that the first character will always be equal, or the
+ *   string wouldn't even get to the point of being tested by this
+ *   macro.
+ */
+#if TOKSCMAX == 3
+# define toksceq(str1, str2, len1, len2) \
+    ((len2) >= (len1) \
+     && ((len1) == 1 \
+         || ((str1)[1] == (str2)[1] \
+             && ((len1) == 2 \
+                 || (str1)[2] == (str2)[2]))))
+#endif /* TOKSCMAX == 3 */
+#ifndef toksceq
+# define toksceq(str1, str2, len) (!memcmp(str1, str2, (size_t)(len)))
+#endif /* toksceq */
+
+/* special character sequence list table entry */
+struct tokldef {
+    int  tokltyp;                   /* token type corresponding to sequence */
+    char toklstr[TOKSCMAX+1];                   /* the text of the sequence */
+};
+
+/* include path structure */
+struct tokpdef {
+    tokpdef *tokpnxt;                                  /* next path in list */
+    int      tokplen;                           /* length of directory name */
+    char     tokpdir[1];                             /* directory to search */
+};
+
+/* #define symbol structure */
+struct tokdfdef {
+    tokdfdef *nxt;                    /* next symbol in the same hash chain */
+    char     *nm;                                     /* name of the symbol */
+    int       len;                                  /* length of the symbol */
+    int       explen;                            /* length of the expansion */
+    char      expan[1];                                 /* expansion buffer */
+};
+
+/* #define hash table information */
+#define TOKDFHSHSIZ   64
+#define TOKDFHSHMASK  63
+
+/* maximum #if nesting */
+#define TOKIFNEST     64
+
+/* #if state */
+#define TOKIF_IF_YES    1             /* processing a true #if/#ifdef block */
+#define TOKIF_IF_NO     2            /* processing a false #if/#ifdef block */
+#define TOKIF_ELSE_YES  3                   /* processing a true #else part */
+#define TOKIF_ELSE_NO   4                  /* processing a false #else part */
+
+/* maximum macro expansion nesting */
+#define TOKMACNEST  20
+
+/* lexical analysis context */
+struct tokcxdef {
+    errcxdef *tokcxerr;                           /* error handling context */
+    mcmcxdef *tokcxmem;                            /* cache manager context */
+    struct    dbgcxdef *tokcxdbg;                       /* debugger context */
+    lindef   *tokcxlin;                                      /* line source */
+    tokpdef  *tokcxinc;                        /* head of include path list */
+    toktdef  *tokcxstab;              /* current head of symbol table chain */
+    void     *tokcxscx;    /* context for string storage callback functions */
+    ushort  (*tokcxsst)(void *ctx);
+               /* start storing a string; return offset of string's storage */
+    void    (*tokcxsad)(void *ctx, char *str, ushort len);
+                                              /* add characters to a string */
+    void    (*tokcxsend)(void *ctx);               /* finish storing string */
+    char     *tokcxmsav[TOKMACNEST]; /* saved positions for macro expansion */
+    ushort    tokcxmsvl[TOKMACNEST];   /* saved lengths for macro expansion */
+    int       tokcxmlvl;                             /* macro nesting level */
+    int       tokcxflg;                                            /* flags */
+#   define    TOKCXFINMAC    0x01         /* doing <<expr>> macro expansion */
+#   define    TOKCXCASEFOLD  0x02              /* fold upper and lower case */
+#   define    TOKCXFCMODE    0x04                /* parse using C operators */
+#   define    TOKCXF_EMBED_PAREN_PRE 0x08        /* embedded expr - did '(' */
+#   define    TOKCXF_EMBED_PAREN_AFT 0x10    /* embedded expr - must do ')' */
+#   define    TOKCXFLIN2     0x20                 /* new-style line records */
+    tokdef    tokcxcur;                                    /* current token */
+    char     *tokcxbuf;                            /* buffer for long lines */
+    ushort    tokcxbsz;                         /* size of long line buffer */
+    char     *tokcxptr;                         /* pointer into line source */
+    ushort    tokcxlen;                         /* length of text in buffer */
+    uchar     tokcxinx[256];                   /* special character indices */
+    tokdfdef *tokcxdf[TOKDFHSHSIZ];       /* hash table for #define symbols */
+    int       tokcxifcnt;           /* number of #endif's we expect to find */
+    char      tokcxif[TOKIFNEST];       /* #if state for each nesting level */
+    int       tokcxifcur;             /* current #if state, obeying nesting */
+    struct    linfdef  *tokcxhdr;    /* list of previously included headers */
+    tokscdef *tokcxsc[1];                        /* special character table */
+};
+
+
+/* allocate and initialize a lexical analysis context */
+tokcxdef *tokcxini(errcxdef *errctx, mcmcxdef *mctx, tokldef *sctab);
+
+/* add an include path to a token handling context */
+void tokaddinc(tokcxdef *ctx, char *path, int pathlen);
+
+/* compute the hash value of a string */
+uint tokhsh(char *nam);
+
+/* 
+ *   Fold case of a token if we're in case-insensitive mode.  This should
+ *   be called any time a token is constructed artificially; it need not
+ *   be used the token is read through the tokenizer, because the
+ *   tokenizer will always adjust a token as needed before returning it. 
+ */
+void tok_case_fold(tokcxdef *ctx, tokdef *tok);
+
+/* initialize a hashed symbol table */
+void tokthini(errcxdef *errctx, mcmcxdef *memctx, toktdef *toktab1);
+
+/* add a symbol to a hashed symbol table */
+void tokthadd(toktdef *toktab, char *name, int namel,
+              int typ, int val, int hash);
+
+/* update a symbol in a hashed symbol table */
+void tokthset(toktdef *toktab, toksdef *sym);
+
+/* search a hashed symbol table for a symbol */
+int tokthsea(toktdef *tab, char *name, int namel, int hash,
+             toksdef *ret);
+
+/* call a function for each symbol in a hashed symbol table */
+void toktheach(toktdef *tab, void (*cb)(void *ctx, toksdef *sym),
+               void *ctx);
+
+/* find a symbol given type and value */
+int tokthfind(toktdef *tab, int typ, uint val, toksdef *sym);
+
+/* initialize a linear symbol table */
+void toktlini(errcxdef *errctx, toktldef *toktab,
+              uchar *mem, uint siz);
+
+/* add a symbol to a linear symbol table */
+void toktladd(toktdef *toktab, char *name, int namel,
+              int typ, int val, int hash);
+                
+/* search a linear symbol table */
+int toktlsea(toktdef *tab, char *name, int namel, int hash,
+             toksdef *ret);
+
+/* update a symbol in a linear symbol table */
+void toktlset(toktdef *toktab, toksdef *sym);
+
+/* call a function for each symbol in a local symbol table */
+void toktleach(toktdef *tab, void (*cb)(void *ctx, toksdef *sym),
+               void *ctx);
+
+/* delete all symbols from a linear table */
+void toktldel(toktldef *tab);
+
+/* get next token, removing it from input stream */
+int toknext(tokcxdef *ctx);
+
+/* general function to get/peek at next token */
+int tokget1(tokcxdef *ctx, tokdef *tok, int consume);
+
+/* add a symbol to the #define symbol table */
+void tok_add_define(tokcxdef *ctx, char *sym, int len,
+                    char *expan, int explen);
+
+/* 
+ *   add a symbol to the #define symbol table, folding case if we're
+ *   operating in case-insensitive mode 
+ */
+void tok_add_define_cvtcase(tokcxdef *ctx, char *sym, int len,
+                            char *expan, int explen);
+
+/* add a symbol to the #define symbol table as a number */
+void tok_add_define_num_cvtcase(tokcxdef *ctx, char *sym, int len, int num);
+
+/* undefine a #define symbol */
+void tok_del_define(tokcxdef *ctx, char *sym, int len);
+
+/* read/write preprocessor symbols from/to a file */
+void tok_read_defines(tokcxdef *ctx, osfildef *fp, errcxdef *ec);
+
+/* write preprocessor state to a file */
+void tok_write_defines(tokcxdef *ctx, osfildef *fp, errcxdef *ec);
+
+
+/* determine if a char is a valid non-initial character in a symbol name */
+#define TOKISSYM(c) \
+    (isalpha((uchar)(c)) || isdigit((uchar)(c)) || (c)=='_' || (c)=='$')
+
+/* numeric conversion and checking macros */
+#define TOKISHEX(c) \
+    (isdigit((uchar)(c))||((c)>='a'&&(c)<='f')||((c)>='A'&&(c)<='F'))
+#define TOKISOCT(c) \
+    (isdigit((uchar)(c))&&!((c)=='8'||(c)=='9'))
+
+#define TOKHEX2INT(c) \
+    (isdigit((uchar)c)?(c)-'0':((c)>='a'?(c)-'a'+10:(c)-'A'+10))
+#define TOKOCT2INT(c) ((c)-'0')
+#define TOKDEC2INT(c) ((c)-'0')
+
+} // End of namespace TADS2
+} // End of namespace TADS
+} // End of namespace Glk
+
+#endif
diff --git a/engines/glk/tads/tads2/types.h b/engines/glk/tads/tads2/types.h
deleted file mode 100644
index 5da759fda7..0000000000
--- a/engines/glk/tads/tads2/types.h
+++ /dev/null
@@ -1,190 +0,0 @@
-/* ScummVM - Graphic Adventure Engine
- *
- * ScummVM is the legal property of its developers, whose names
- * are too numerous to list here. Please refer to the COPYRIGHT
- * file distributed with this source distribution.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- *
- */
-
-#ifndef GLK_TADS_TADS2_TYPES
-#define GLK_TADS_TADS2_TYPES
-
-#include "common/stream.h"
-
-namespace Glk {
-namespace TADS {
-namespace TADS2 {
-
-typedef unsigned char uchar;
-typedef Common::SeekableReadStream osfildef;
-
-/**
- * Allocate a memory block
- */
-#define mchalo(CTX, SIZE, COMMENT) ((byte *)new byte[SIZE])
-
-/**
- * Free a memory block
- */
-#define mchfre(PTR) delete[] (byte *)PTR
-
-/**
- * Close a file
- */
-#define osfcls(FP) delete FP
-
-/**
- * Read from a file
- */
-#define osfrb(FP, BUF, SIZE) FP->read(BUF, SIZE)
-
-/**
- * Read a 16-bit integer from memory
- */
-#define osrp2(MEM) READ_LE_UINT16(MEM)
-
-/**
- * The character (or characters) which mark the beginning of a special fileref string.
- * The important thing is that the string be one that is either not allowed in
- * filenames on your platform or is unlikely to be the first part of a filename.
- */
-#define OSS_FILEREF_STRING_PREFIX ":"
-
-/**
- * The character (or characters) which mark the end of a special fileref string.
- * Using this and OSS_FILEREF_STRING_PREFIX, you should be able to come up with
- * something which forms an invalid filename
- */
-#define OSS_FILEREF_STRING_SUFFIX ""
-
-/**
- * Maximum length of status line text
- */
-#define OSS_STATUS_STRING_LEN 80
-
-/**
- * Maximum size for filenames
- */
-#define OSFNMAX 1024
-
-/**
- * Important note: do not change these values when porting TADS.  These
- * values can be used by games, so they must be the same on all platforms.
- */
-enum {
-	OS_AFP_OPEN = 1,			///< choose an existing file to open for reading
-	OS_AFP_SAVE = 2				///< choose a filename for saving to a file
-};
-
-/**
- * File types.These type codes are used when opening or creating a file,
- * so that the OS routine can set appropriate file system metadata
- * to describe or find the file type.
- *
- * The type os_filetype_t is defined for documentary purposes; it's
- * always just an int.
- */
-enum os_filetype_t {
-	OSFTGAME  =  0,  ///< a game data file (.gam)
-	OSFTSAVE  =  1,  ///< a saved game (.sav)
-	OSFTLOG   =  2,  ///< a transcript (log) file
-	OSFTSWAP  =  3,  ///< swap file
-	OSFTDATA  =  4,  ///< user data file (used with the TADS fopen() call)
-	OSFTCMD   =  5,  ///< QA command/log file
-	OSFTERRS  =  6,  ///< error message file
-	OSFTTEXT  =  7,  ///< text file - used for source files
-	OSFTBIN   =  8,  ///< binary file of unknown type - resources, etc
-	OSFTCMAP  =  9,  ///< character mapping file
-	OSFTPREF  = 10,  ///< preferences file
-	OSFTUNK   = 11,  ///< unknown - as a filter, matches any file type
-	OSFTT3IMG = 12,  ///< T3 image file (.t3 - formerly .t3x)
-	OSFTT3OBJ = 13,  ///< T3 object file (.t3o)
-	OSFTT3SYM = 14,  ///< T3 symbol export file (.t3s)
-	OSFTT3SAV = 15   ///< T3 saved state file (.t3v)
-};
-
-/**
- * Constants for os_getc() when returning commands.  When used for command line
- * editing, special keys (arrows, END, etc.)  should cause os_getc() to return 0,
- * and return the appropriate CMD_ value on the NEXT call.  Hence, os_getc() must
- * keep the appropriate information around statically for the next call when a
- * command key is issued.
- *
- * The comments indicate which CMD_xxx codes are "translated" codes and which are
- * "raw"; the difference is that, when a particular keystroke could be interpreted
- * as two different CMD_xxx codes, one translated and the other raw, os_getc()
- * should always return the translated version of the key, and os_getc_raw()
- * should return the raw version.
- */
-enum KeyCmd {
-	CMD_UP = 1,		    ///< move up/up arrow (translated)
-	CMD_DOWN = 2,		///< move down/down arrow (translated)
-	CMD_RIGHT = 3,		///< move right/right arrow (translated)
-	CMD_LEFT = 4,		///< move left/left arrow (translated)
-	CMD_END = 5,		///< move cursor to end of line (translated)
-	CMD_HOME = 6,		///< move cursor to start of line (translated)
-	CMD_DEOL = 7,		///< delete to end of line (translated)
-	CMD_KILL = 8,		///< delete entire line (translated)
-	CMD_DEL = 9,		///< delete current character (translated)
-	CMD_SCR = 10,		///< toggle scrollback mode (translated)
-	CMD_PGUP = 11,		///< page up (translated)
-	CMD_PGDN = 12,		///< page down (translated)
-	CMD_TOP = 13,		///< top of file (translated)
-	CMD_BOT = 14,		///< bottom of file (translated)
-	CMD_F1 = 15,		///< function key F1 (raw)
-	CMD_F2 = 16,		///< function key F2 (raw)
-	CMD_F3 = 17,		///< function key F3 (raw)
-	CMD_F4 = 18,		///< function key F4 (raw)
-	CMD_F5 = 19,		///< function key F5 (raw)
-	CMD_F6 = 20,		///< function key F6 (raw)
-	CMD_F7 = 21,		///< function key F7 (raw)
-	CMD_F8 = 22,		///< function key F8 (raw)
-	CMD_F9 = 23,		///< function key F9 (raw)
-	CMD_F10 = 24,		///< function key F10 (raw)
-	CMD_CHOME = 25,		///< control-home (raw)
-	CMD_TAB = 26,		///< tab (translated)
-	CMD_SF2 = 27,		///< shift-F2 (raw)
-						///< not used (obsolete) - 28
-	CMD_WORD_LEFT = 29,	///< word left (ctrl-left on dos) (translated)
-	CMD_WORD_RIGHT = 30,///< word right (ctrl-right on dos) (translated)
-	CMD_WORDKILL = 31,	///< delete word right (translated)
-	CMD_EOF = 32,       ///< end-of-file (raw)
-	CMD_BREAK = 33,     ///< break (Ctrl-C or local equivalent) (translated)
-	CMD_INS = 34,       ///< insert key (raw)
-
-					/**
-					 * ALT-keys - add alphabetical code to CMD_ALT: ALT-A == CMD_ALT + 0,
-					 * ALT-B == CMD_ALT + 1, ALT-C == CMD_ALT + 2, etc
-					 *
-					 * These keys are all raw (untranslated).
-					 */
-	CMD_ALT = 128       ///< start of ALT keys
-};
-
-/**
- * Status mode codes
- */
-enum StatusMode {
-	OSS_STATUS_MODE_STORY = 0,
-	OSS_STATUS_MODE_STATUS = 1
-};
-
-} // End of namespace TADS2
-} // End of namespace TADS
-} // End of namespace Glk
-
-#endif
diff --git a/engines/glk/tads/tads2/vocabulary.cpp b/engines/glk/tads/tads2/vocabulary.cpp
index 4647b1bd30..e20bbe3de8 100644
--- a/engines/glk/tads/tads2/vocabulary.cpp
+++ b/engines/glk/tads/tads2/vocabulary.cpp
@@ -20,6 +20,7 @@
  *
  */
 
+#include "glk/tads/tads2/run.h"
 #include "glk/tads/tads2/vocabulary.h"
 
 namespace Glk {
diff --git a/engines/glk/tads/tads2/vocabulary.h b/engines/glk/tads/tads2/vocabulary.h
index b4079932a5..5574675aa2 100644
--- a/engines/glk/tads/tads2/vocabulary.h
+++ b/engines/glk/tads/tads2/vocabulary.h
@@ -24,19 +24,774 @@
  * Defines TADS vocabulary (player command parser) functionality
  */
 
-#ifndef GLK_TADS_TADS2_OS
-#define GLK_TADS_TADS2_OS
+#ifndef GLK_TADS_TADS2_VOCABULARY
+#define GLK_TADS_TADS2_VOCABULARY
 
-#include "glk/tads/tads2/types.h"
+#include "glk/tads/tads2/lib.h"
+#include "glk/tads/tads2/object.h"
+#include "glk/tads/tads2/property.h"
+#include "glk/tads/tads2/run.h"
 
 namespace Glk {
 namespace TADS {
 namespace TADS2 {
 
-// TODO: Rest of vocabulary stuff
+/*
+ *   Cover macro for parser errors.  Any parser error should be covered
+ *   with this macro for documentation and search purposes.  (The macro
+ *   doesn't do anything - this is just something to search for when we're
+ *   trying to enumerate parser error codes.) 
+ */
+#define VOCERR(errcode) errcode
+
+/* maximum number of objects matching an ambiguous word */
+#define VOCMAXAMBIG 200
+
+/* size of input buffer */
+#define VOCBUFSIZ 128
+
+/*
+ *   Vocabulary relation structure - this structure relates a vocabulary
+ *   word to an object and part of speech.  A list of these structures is
+ *   attached to each vocabulary word structure to provide the word's
+ *   meanings.
+ */
+struct vocwdef {
+    uint   vocwnxt;      /* index of next vocwdef attached to the same word */
+    objnum vocwobj;                      /* object associated with the word */
+    uchar  vocwtyp;   /* property associated with the word (part of speech) */
+    uchar  vocwflg;                                   /* flags for the word */
+#define VOCFCLASS  1                          /* word is for a class object */
+#define VOCFINH    2                 /* word is inherited from a superclass */
+#define VOCFNEW    4                          /* word was added at run-time */
+#define VOCFDEL    8                               /* word has been deleted */
+};
+
+/* vocabulary word structure */
+struct vocdef {
+    vocdef *vocnxt;                         /* next word at same hash value */
+    uchar   voclen;                                   /* length of the word */
+    uchar   vocln2;          /* length of second word (0 if no second word) */
+    uint    vocwlst;      /* head of list of vocwdef's attached to the word */
+    uchar   voctxt[1];                                  /* text of the word */
+};
+
+/* vocabulary inheritance cell */
+struct vocidef {
+    uchar            vocinsc;   /* # of superclasses (gives size of record) */
+    union {
+        struct {
+            uchar    vociusflg;                          /* flags for entry */
+#define VOCIFCLASS  1  /* entry refers to a class object (loc records only) */
+#define VOCIFVOC    2                 /* entry has vocabulary words defined */
+#define VOCIFXLAT   4  /* superclasses must be translated from portable fmt */
+#define VOCIFLOCNIL 8                  /* location is explicitly set to nil */
+#define VOCIFNEW    16       /* object was allocated at run-time with "new" */
+            objnum   vociusloc;                   /* location of the object */
+            objnum   vociusilc;                       /* inherited location */
+            objnum   vociussc[1];                  /* array of superclasses */
+        } vocius;
+        vocidef     *vociunxt;
+    } vociu;
+#define   vociflg vociu.vocius.vociusflg
+#define   vociloc vociu.vocius.vociusloc
+#define   vociilc vociu.vocius.vociusilc
+#define   vocisc  vociu.vocius.vociussc
+#define   vocinxt vociu.vociunxt
+};
+
+/* size of a page in a vocabulary pool */
+#define VOCPGSIZ  8192
+
+/* number of bytes in an inheritance cell page */
+#define VOCISIZ 8192
+
+/* maximum number of inheritance pages */
+#define VOCIPGMAX 32
+
+/* maximum number of inheritance pages (256 objects per page) */
+#define VOCINHMAX 128
+
+/* size of vocabulary hash table */
+#define VOCHASHSIZ  256
+
+/* size of a template structure */
 #define VOCTPLSIZ 10
+
+/* new-style template structure */
 #define VOCTPL2SIZ  16
 
+
+/*
+ *   vocwdef's are fixed in size.  They're allocated in a set of arrays
+ *   (the voccxwp member of the voc context has the list of arrays).  Each
+ *   array is of a fixed number of vocwdef entries; a maximum number of
+ *   vocwdef arrays is possible. 
+ */
+#define VOCWPGSIZ   2000                   /* number of vocwdef's per array */
+#define VOCWPGMAX   16                  /* maximum number of vocwdef arrays */
+
+/*
+ *   To find a vocwdef entry given its index, divide the index by the
+ *   number of entries per array to find the array number, and use the
+ *   remainder to find the index within that array. 
+ */
+/*#define VOCW_IN_CACHE*/
+#ifdef VOCW_IN_CACHE
+vocwdef *vocwget(struct voccxdef *ctx, uint idx);
+#else
+#define vocwget(ctx, idx) \
+    ((idx) == VOCCXW_NONE ? (vocwdef *)0 : \
+      ((ctx)->voccxwp[(idx)/VOCWPGSIZ] + ((idx) % VOCWPGSIZ)))
+#endif
+
+/*
+ *   Special values for vocdtim - these values indicate that the daemon
+ *   does not have a normal turn-based expiration time. 
+ */
+#define VOCDTIM_EACH_TURN  0xffff            /* the daemon fires every turn */
+
+/* daemon/fuse/alarm slot */
+struct vocddef {
+    objnum   vocdfn;             /* object number of function to be invoked */
+    runsdef  vocdarg;                  /* argument for daemon/fuse function */
+    prpnum   vocdprp;             /* property number (used only for alarms) */
+    uint     vocdtim;  /* time for fuses/alarms (0xffff -> each-turn alarm) */
+};
+
+/* vocabulary object list entry */
+struct vocoldef {
+    objnum  vocolobj;                           /* object matching the word */
+    char   *vocolfst;         /* first word in cmd[] that identified object */
+    char   *vocollst;          /* last word in cmd[] that identified object */
+    char   *vocolhlst;      /* hypothetical last word, if we trimmed a prep */
+    int     vocolflg;                           /* special flags (ALL, etc) */
+};
+
+/* vocabulary context */
+struct voccxdef {
+    errcxdef  *voccxerr;                          /* error handling context */
+    tiocxdef  *voccxtio;                                /* text i/o context */
+    runcxdef  *voccxrun;                               /* execution context */
+    mcmcxdef  *voccxmem;                          /* memory manager context */
+    objucxdef *voccxundo;                                   /* undo context */
+    uchar     *voccxpool;                  /* next free byte in vocdef pool */
+    vocdef    *voccxfre;                        /* head of vocdef free list */
+    char      *voccxcpp;                   /* pointer to compound word area */
+    int        voccxcpl;                    /* length of compound word area */
+    char      *voccxspp;                    /* pointer to special word area */
+    int        voccxspl;                     /* length of special word area */
+    uint       voccxrem;        /* number of bytes remaining in vocdef pool */
+    vocidef  **voccxinh[VOCINHMAX];     /* vocidef page table: 256 per page */
+    uchar     *voccxip[VOCIPGMAX];                 /* inheritance cell pool */
+    vocidef   *voccxifr;              /* head of inheritance cell free list */
+    uint       voccxiplst;          /* last inheritance cell page allocated */
+    uint       voccxilst;      /* next unused byte in last inheritance page */
+    int        voccxredo;                   /* flag: redo command in buffer */
+
+    /* 
+     *   redo buffer - if voccxredo is set, and this buffer is not empty,
+     *   we'll redo the command in this buffer rather than the one in our
+     *   internal stack buffer 
+     */
+    char       voccxredobuf[VOCBUFSIZ];
+
+    /*
+     *   "again" buffer - when we save the last command for repeating via
+     *   the "again" command, we'll save the direct and indirect object
+     *   words here, so that they can be recovered if "again" is used 
+     */
+    char       voccxagainbuf[VOCBUFSIZ];
+
+    vocdef    *voccxhsh[VOCHASHSIZ];                          /* hash table */
+
+#ifdef VOCW_IN_CACHE
+    mcmon      voccxwp[VOCWPGMAX];        /* list of pages of vocab records */
+    mcmon      voccxwplck;                  /* locked page of vocab records */
+    vocwdef   *voccxwpgptr;             /* pointer to currently locked page */
+#else
+    vocwdef   *voccxwp[VOCWPGMAX];                  /* vocabulary word pool */
+#endif
+
+    uint       voccxwalocnt;             /* number of vocwdef's used so far */
+    uint       voccxwfre;            /* index of first vocwdef in free list */
+#define VOCCXW_NONE  ((uint)(-1))     /* index value indicating end of list */
+
+    vocddef   *voccxdmn;                           /* array of daemon slots */
+    uint       voccxdmc;                 /* number of slots in daemon array */
+    vocddef   *voccxfus;                             /* array of fuse slots */
+    uint       voccxfuc;                   /* number of slots in fuse array */
+    vocddef   *voccxalm;                            /* array of alarm slots */
+    uint       voccxalc;                  /* number of slots in alarm array */
+    char       voccxtim[26];            /* game's timestamp (asctime value) */
+    
+    objnum     voccxvtk;                /* object number of "take" deepverb */
+    objnum     voccxme;                      /* object number of "Me" actor */
+    objnum     voccxme_init;                     /* initial setting of "Me" */
+    objnum     voccxstr;                       /* object number of "strObj" */
+    objnum     voccxnum;                       /* object number of "numObj" */
+    objnum     voccxit;                                  /* last "it" value */
+    objnum     voccxhim;                                /* last "him" value */
+    objnum     voccxher;                                /* last "her" value */
+    objnum     voccxthc;                   /* count of items in "them" list */
+    objnum     voccxthm[VOCMAXAMBIG];            /* list of items in "them" */
+    objnum     voccxprd;                 /* "pardon" function object number */
+    objnum     voccxpre;               /* "preparse" function object number */
+    objnum     voccxppc;            /* "preparseCmd" function object number */
+    objnum     voccxpre2;           /* "preparseExt" function object number */
+    objnum     voccxvag;                             /* "again" verb object */
+    objnum     voccxini;                                 /* "init" function */
+    objnum     voccxper;             /* "parseError" function object number */
+    objnum     voccxprom;             /* "cmdPrompt" function object number */
+    objnum     voccxpostprom;     /* "cmdPostPrompt" function object number */
+    objnum     voccxpdis;                         /* parseDisambig function */
+    objnum     voccxper2;                           /* parseError2 function */
+    objnum     voccxperp;                       /* parseErrorParam function */
+    objnum     voccxpdef;                          /* parseDefault function */
+    objnum     voccxpdef2;                      /* parseDefaultExt function */
+    objnum     voccxpask;                           /* parseAskobj function */
+    objnum     voccxpask2;                     /* parseAskobjActor function */
+    objnum     voccxpask3;                  /* parseAskobjIndirect function */
+    objnum     voccxinitrestore;    /* "initRestore" function object number */
+    objnum     voccxpuv;         /* parseUnknownVerb function object number */
+    objnum     voccxpnp;          /* parseNounPhrase function object number */
+    objnum     voccxpostact;           /* postAction function object number */
+    objnum     voccxprecmd;            /* preCommand function object number */
+    objnum     voccxendcmd;            /* endCommand function object number */
+
+    /* current command word list values */
+    vocoldef  *voccxdobj;                /* current direct object word list */
+    vocoldef  *voccxiobj;              /* current indirect object word list */
+
+    /* current command objects */
+    objnum     voccxactor;                                 /* current actor */
+    objnum     voccxverb;                       /* current command deepverb */
+    objnum     voccxprep;                    /* current command preposition */
+    
+    /* previous command values - used by "again" */
+    objnum     voccxlsa;                                  /* previous actor */
+    objnum     voccxlsv;                                   /* previous verb */
+    vocoldef   voccxlsd;                          /* previous direct object */
+    vocoldef   voccxlsi;                        /* previous indirect object */
+    objnum     voccxlsp;                                     /* preposition */
+    int        voccxlssty;              /* style (new/old) of last template */
+    uchar      voccxlst[VOCTPL2SIZ];                            /* template */
+
+    objnum     voccxpreinit;                            /* preinit function */
+
+    /* special flags */
+    uchar      voccxflg;
+#define VOCCXFCLEAR    1      /* ignore remainder of command line (restore) */
+#define VOCCXFVWARN    2                /* generate redundant verb warnings */
+#define VOCCXFDBG      4           /* debug mode:  show parsing information */
+#define VOCCXAGAINDEL  8             /* "again" lost due to object deletion */
+
+    /* number of remaining unresolved unknown words in the command */
+    int        voccxunknown;
+
+    /* total number of unresolved words in the last command */
+    int        voccxlastunk;
+
+    /* parser stack area */
+    uchar *voc_stk_ptr;
+    uchar *voc_stk_cur;
+    uchar *voc_stk_end;
+};
+
+/* allocate and push a list, returning a pointer to the list's memory */
+uchar *voc_push_list_siz(voccxdef *ctx, uint lstsiz);
+
+/* push a list of objects from a vocoldef array */
+void voc_push_vocoldef_list(voccxdef *ctx, vocoldef *objlist, int cnt);
+
+/* push a list of objects from an objnum array */
+void voc_push_objlist(voccxdef *ctx, objnum objlist[], int cnt);
+
+/* change the player character ("Me") object */
+void voc_set_me(voccxdef *ctx, objnum new_me);
+
+/* add a vocabulary word */
+void vocadd(voccxdef *ctx, prpnum p, objnum objn,
+            int classflag, char *wrdval);
+
+/* internal addword - must already be split into two words and lengths */
+void vocadd2(voccxdef *ctx, prpnum p, objnum objn, int classflg,
+             uchar *wrd1, int len1, uchar *wrd2, int len2);
+
+/* delete vocabulary for a given object */
+void vocdel(voccxdef *ctx, objnum objn);
+
+/* lower-level vocabulary deletion routine */
+void vocdel1(voccxdef *ctx, objnum objn, char *wrd, prpnum prp,
+             int really_delete, int revert, int keep_undo);
+
+/* delete all inherited vocabulary */
+void vocdelinh(voccxdef *ctx);
+
+/* allocate space for an inheritance record if needed */
+void vocialo(voccxdef *ctx, objnum obj);
+
+/* add an inheritance/location record */
+void vociadd(voccxdef *ctx, objnum obj, objnum loc,
+             int numsc, objnum *sc, int flags);
+
+/* delete inheritance records for an object */
+void vocidel(voccxdef *ctx, objnum chi);
+
+/* renumber an object's inheritance records - used for 'modify' */
+void vociren(voccxdef *ctx, objnum oldnum, objnum newnum);
+
+/* caller-provided context structure for vocffw/vocfnw searches */
+struct vocseadef {
+    vocdef  *v;
+    vocwdef *vw;
+    uchar   *wrd1;
+    int      len1;
+    uchar   *wrd2;
+    int      len2;
+};
+
+/* find first word matching a given word */
+vocwdef *vocffw(voccxdef *ctx, char *wrd, int len, char *wrd2, int len2,
+                int p, vocseadef *search_ctx);
+
+/* find next word */
+vocwdef *vocfnw(voccxdef *voccx, vocseadef *search_ctx);
+
+/* read a line of input text */
+int vocread(voccxdef *ctx, objnum actor, objnum verb,
+            char *buf, int bufl, int type);
+#define VOCREAD_OK    0
+#define VOCREAD_REDO  1
+
+/* compute size of a vocoldef list */
+int voclistlen(vocoldef *lst);
+
+/* tokenize an input buffer */
+int voctok(voccxdef *ctx, char *cmd, char *outbuf,
+           char **wrd, int lower, int cvt_ones, int show_errors);
+
+/* get types for a word list */
+int vocgtyp(voccxdef *ctx, char **cmd, int *types, char *orgbuf);
+
+/* execute a player command */
+int voccmd(voccxdef *ctx, char *cmd, uint cmdlen);
+
+/* disambiguator */
+int vocdisambig(voccxdef *ctx, vocoldef *outlist, vocoldef *inlist,
+                prpnum defprop, prpnum accprop, prpnum verprop,
+                char *cmd[], objnum otherobj, objnum cmdActor,
+                objnum cmdVerb, objnum cmdPrep, char *cmdbuf,
+                int silent);
+
+/* display a multiple-object prefix */
+void voc_multi_prefix(voccxdef *ctx, objnum objn,
+                      int show_prefix, int multi_flags,
+                      int cur_index, int count);
+
+/* low-level executor */
+int execmd(voccxdef *ctx, objnum actor, objnum prep,
+           char *vverb, char *vprep, vocoldef *dolist, vocoldef *iolist,
+           char **cmd, int *typelist,
+           char *cmdbuf, int wrdcnt, uchar **preparse_list, int *next_start);
+
+/* recursive command execution */
+int execmd_recurs(voccxdef *ctx, objnum actor, objnum verb,
+                  objnum dobj, objnum prep, objnum iobj,
+                  int validate_dobj, int validate_iobj);
+
+/* try running preparseCmd user function */
+int try_preparse_cmd(voccxdef *ctx, char **cmd, int wrdcnt,
+                     uchar **preparse_list);
+
+/*
+ *   Handle an unknown verb or sentence structure.  We'll call this when
+ *   we encounter a sentence where we don't know the verb word, or we
+ *   don't know the combination of verb and verb preposition, or we don't
+ *   recognize the sentence structure (for example, an indirect object is
+ *   present, but we don't have a template defined using an indirect
+ *   object for the verb).
+ *   
+ *   'wrdcnt' is the number of words in the cmd[] array.  If wrdcnt is
+ *   zero, we'll automatically count the array entries, with the end of
+ *   the array indicated by a null pointer entry.
+ *   
+ *   If do_fuses is true, we'll execute the fuses and daemons if the
+ *   function exists and doesn't throw an ABORT error, or any other
+ *   run-time error other than EXIT.
+ *   
+ *   This function calls the game-defined function parseUnknownVerb, if it
+ *   exists.  If the function doesn't exist, we'll simply display the
+ *   given error message, using the normal parseError mechanism.  The
+ *   function should use "abort" or "exit" if it wants to cancel further
+ *   processing of the command.
+ *   
+ *   We'll return true if the function exists and executes successfully,
+ *   in which case normal processing should continue with any remaining
+ *   command on the command line.  We'll return false if the function
+ *   doesn't exist or throws an error other than EXIT, in which case the
+ *   remainder of the command should be aborted.  
+ */
+int try_unknown_verb(voccxdef *ctx, objnum actor,
+                     char **cmd, int *typelist, int wrdcnt, int *next_start,
+                     int do_fuses, int err, char *msg, ...);
+
+/* find a template */
+int voctplfnd(voccxdef *ctx, objnum verb_in, objnum prep,
+              uchar *tplout, int *newstyle);
+
+/* build a printable name for an object from the words in a command list */
+void voc_make_obj_name(voccxdef *ctx, char *namebuf, char *cmd[],
+                       int firstwrd, int lastwrd);
+void voc_make_obj_name_from_list(voccxdef *ctx, char *namebuf,
+                                 char *cmd[], char *firstwrd, char *lastwrd);
+
+/*
+ *   check noun - determines whether the next set of words is a valid noun
+ *   phrase.  No complaint is issued if not; this check is generally made
+ *   to figure out what type of sentence we're dealing with.  This is
+ *   simple; we just call vocgobj() with the complaint flag turned off.
+ */
+/* int vocchknoun(voccxdef *ctx, char **cmd, int *typelist, int cur,
+                  int *next, vocoldef *nounlist, int chkact); */
+#define vocchknoun(ctx, cmd, typelist, cur, next, nounlist, chkact) \
+ vocgobj(ctx, cmd, typelist, cur, next, FALSE, nounlist, TRUE, chkact, 0)
+#define vocchknoun2(ctx, cmd, typlst, cur, next, nounlist, chkact, nomatch) \
+ vocgobj(ctx, cmd, typlst, cur, next, FALSE, nounlist, TRUE, chkact, nomatch)
+
+/*
+ *   get noun - reads an object list.  We simply call vocgobj() with the
+ *   complaint and multiple-noun flags turned on.
+ */
+/* int vocgetnoun(voccxdef *ctx, char **cmd, int *typelist, int cur,
+                  int *next, vocoldef *nounlist); */
+#define vocgetnoun(ctx, cmd, typelist, cur, next, nounlist) \
+ vocgobj(ctx, cmd, typelist, cur, next, TRUE, nounlist, TRUE, FALSE, 0)
+
+/* get object */
+int vocgobj(voccxdef *ctx, char **cmd, int *typelist, int cur,
+            int *next, int complain, vocoldef *nounlist,
+            int multi, int chkact, int *nomatch);
+
+/* tokenize a string - TADS program code interface */
+void voc_parse_tok(voccxdef *ctx);
+
+/* get token types - TADS program code interface */
+void voc_parse_types(voccxdef *ctx);
+
+/* get objects matching all of the given words - TADS program code interface */
+void voc_parse_dict_lookup(voccxdef *ctx);
+
+/* parse a noun list - TADS program code interface */
+void voc_parse_np(voccxdef *ctx);
+
+/* disambiguate a noun list - TADS program code interface */
+void voc_parse_disambig(voccxdef *ctx);
+
+/* replace the current command - TADS program code interface */
+void voc_parse_replace_cmd(voccxdef *ctx);
+
+/* check access to an object */
+int vocchkaccess(voccxdef *ctx, objnum obj, prpnum verprop,
+                 int seqno, objnum actor, objnum verb);
+
+/* check to see if an object is visible */
+int vocchkvis(voccxdef *ctx, objnum obj, objnum cmdActor);
+
+/* display an appropriate message for an unreachable object */
+void vocnoreach(voccxdef *ctx, objnum *list1, int cnt,
+                objnum actor, objnum verb, objnum prep, prpnum defprop,
+                int show_multi_prefix, int multi_flags,
+                int multi_base_index, int multi_total_count);
+
+/* set {numObj | strObj}.value, as appropriate */
+void vocsetobj(voccxdef *ctx, objnum obj, dattyp typ, void *val,
+               vocoldef *inobj, vocoldef *outobj);
+
+/* macros to read values out of templates */
+#define voctplpr(tpl) ((objnum)osrp2(((uchar *)tpl)))        /* preposition */
+#define voctplvi(tpl) ((prpnum)osrp2(((uchar *)tpl) + 2))      /* verIoVerb */
+#define voctplio(tpl) ((prpnum)osrp2(((uchar *)tpl) + 4))         /* ioVerb */
+#define voctplvd(tpl) ((prpnum)osrp2(((uchar *)tpl) + 6))      /* verDoVerb */
+#define voctpldo(tpl) ((prpnum)osrp2(((uchar *)tpl) + 8))         /* doVerb */
+#define voctplflg(tpl) (*(((uchar *)tpl) + 10))                    /* flags */
+
+/* flag values for the voctplflg */
+#define VOCTPLFLG_DOBJ_FIRST   0x01     /* disambiguate direct object first */
+
+
+/* word type flags */
+#define VOCT_ARTICLE  1
+#define VOCT_ADJ      2
+#define VOCT_NOUN     4
+#define VOCT_PREP     8
+#define VOCT_VERB     16
+#define VOCT_SPEC     32            /* special words - "of", ",", ".", etc. */
+#define VOCT_PLURAL   64
+#define VOCT_UNKNOWN  128                                /* word is unknown */
+
+/* special type flags */
+#define VOCS_ALL     1                                             /* "all" */
+#define VOCS_EXCEPT  2                                          /* "except" */
+#define VOCS_IT      4                                              /* "it" */
+#define VOCS_THEM    8                                            /* "them" */
+#define VOCS_NUM     16                                         /* a number */
+#define VOCS_COUNT   32                   /* a number being used as a count */
+#define VOCS_PLURAL  64                                           /* plural */
+#define VOCS_ANY     128                                           /* "any" */
+#define VOCS_HIM     256                                           /* "him" */
+#define VOCS_HER     512                                           /* "her" */
+#define VOCS_STR     1024                                /* a quoted string */
+#define VOCS_UNKNOWN 2048           /* noun phrase contains an unknown word */
+#define VOCS_ENDADJ  4096        /* word matched adjective at end of phrase */
+#define VOCS_TRUNC   8192    /* truncated match - word is leading substring */
+#define VOCS_TRIMPREP 16384 /* trimmed prep phrase: assumed it was for verb */
+
+/* special internally-defined one-character word flags */
+#define VOCW_AND     ','
+#define VOCW_THEN    '.'
+#define VOCW_OF      'O'
+#define VOCW_ALL     'A'
+#define VOCW_BOTH    'B'
+#define VOCW_IT      'I'
+#define VOCW_HIM     'M'
+#define VOCW_ONE     'N'
+#define VOCW_ONES    'P'
+#define VOCW_HER     'R'
+#define VOCW_THEM    'T'
+#define VOCW_BUT     'X'
+#define VOCW_ANY     'Y'
+
+/* structure for special internal word table */
+struct vocspdef {
+    char *vocspin;
+    char  vocspout;
+};
+
+/* check if a word is a special word - true if word is given special word */
+/* int vocspec(char *wordptr, int speccode); */
+#define vocspec(w, s) (*(w) == (s))
+
+/* 
+ *   Set a fuse/daemon/notifier.
+ */
+void vocsetfd(voccxdef *ctx, vocddef *what, objnum func, prpnum prop,
+              uint tm, runsdef *val, int err);
+
+/* remove a fuse/daemon/notifier */
+void vocremfd(voccxdef *ctx, vocddef *what, objnum func, prpnum prop,
+              runsdef *val, int err);
+
+/* count a turn (down all fuse/notifier timers) */
+void vocturn(voccxdef *ctx, int turncnt, int do_fuses);
+
+/* initialize voc context */
+void vocini(voccxdef *vocctx, errcxdef *errctx, mcmcxdef *memctx,
+            runcxdef *runctx, objucxdef *undoctx, int fuses,
+            int daemons, int notifiers);
+
+/* clean up the voc context - frees memory allocated by vocini() */
+void vocterm(voccxdef *vocctx);
+
+/* allocate/free fuse/daemon/notifier array for voc ctx initialization */
+void vocinialo(voccxdef *ctx, vocddef **what, int cnt);
+void voctermfree(vocddef *what);
+
+/* get a vocidef given an object number */
+/* vocidef *vocinh(voccxdef *ctx, objnum obj); */
+#define vocinh(ctx, obj) ((ctx)->voccxinh[(obj) >> 8][(obj) & 255])
+
+/* revert all objects back to original state, using inheritance records */
+void vocrevert(voccxdef *ctx);
+
+/* clear all fuses/daemons/notifiers (useful for restarting) */
+void vocdmnclr(voccxdef *ctx);
+
+/* display a parser error message */
+void vocerr(voccxdef *ctx, int err, char *f, ...);
+
+/* 
+ *   display a parser informational error message - this will display the
+ *   message whether or not we're suppressing messages due to unknown
+ *   words, and should be used when providing information, such as objects
+ *   we're assuming by default 
+ */
+void vocerr_info(voccxdef *ctx, int err, char *f, ...);
+
+/* client undo callback - undoes a daemon/fuse/notifier */
+void vocdundo(void *ctx, uchar *data);
+
+/* client undo size figuring callback - return size of client undo record */
+ushort OS_LOADDS vocdusz(void *ctx, uchar *data);
+
+/* save undo for object creation */
+void vocdusave_newobj(voccxdef *ctx, objnum objn);
+
+/* save undo for adding a word */
+void vocdusave_addwrd(voccxdef *ctx, objnum objn, prpnum typ, int flags,
+                      char *wrd);
+
+/* save undo for deleting a word */
+void vocdusave_delwrd(voccxdef *ctx, objnum objn, prpnum typ, int flags,
+                      char *wrd);
+
+/* save undo for object deletion */
+void vocdusave_delobj(voccxdef *ctx, objnum objn);
+
+/* save undo for changing the "Me" object */
+void vocdusave_me(voccxdef *ctx, objnum old_me);
+
+/* compute vocabulary word hash value */
+uint vochsh(uchar *t, int len);
+
+/* TADS versions of isalpha, isspace, isdigit, etc */
+#define vocisupper(c) ((uchar)(c) <= 127 && isupper((uchar)(c)))
+#define vocislower(c) ((uchar)(c) <= 127 && islower((uchar)(c)))
+#define vocisalpha(c) ((uchar)(c) > 127 || isalpha((uchar)(c)))
+#define vocisspace(c) ((uchar)(c) <= 127 && isspace((uchar)(c)))
+#define vocisdigit(c) ((uchar)(c) <= 127 && isdigit((uchar)(c)))
+
+
+/*
+ *   Undo types for voc subsystem 
+ */
+#define VOC_UNDO_DAEMON   1                    /* fuse/daemon status change */
+#define VOC_UNDO_NEWOBJ   2                              /* object creation */
+#define VOC_UNDO_DELOBJ   3                              /* object deletion */
+#define VOC_UNDO_ADDVOC   4                  /* add vocabulary to an object */
+#define VOC_UNDO_DELVOC   5             /* delete vocabulary from an object */
+#define VOC_UNDO_SETME    6                          /* set the "Me" object */
+
+
+/*
+ *   Our own stack.  We need to allocate some fairly large structures
+ *   (for the disambiguation lists, mostly) in a stack-like fashion, and
+ *   we don't want to consume vast quantities of the real stack, because
+ *   some machines have relatively restrictive limitations on stack usage.
+ *   To provide some elbow room, we'll use a stack-like structure of our
+ *   own: we'll allocate out of this structure as needed, and whenever we
+ *   leave a C stack frame, we'll also leave our own stack frame. 
+ */
+
+/* re-initialize the stack, allocating space for it if needed */
+void  voc_stk_ini(voccxdef *ctx, uint siz);
+
+/* enter a stack frame, marking our current position */
+#define voc_enter(ctx, marker)  (*(marker) = (ctx)->voc_stk_cur)
+
+/* leave a stack frame, restoring the entry position */
+#define voc_leave(ctx, marker)  ((ctx)->voc_stk_cur = marker)
+
+/* return a value */
+#define VOC_RETVAL(ctx, marker, retval) \
+       voc_leave(ctx, marker); return retval
+
+/* allocate space from the stack */
+void *voc_stk_alo(voccxdef *ctx, uint siz);
+
+/* allocation cover macros */
+#define VOC_STK_ARRAY(ctx, typ, var, cnt) \
+    (var = (typ *)voc_stk_alo(ctx, (uint)((cnt) * sizeof(typ))))
+
+#define VOC_MAX_ARRAY(ctx, typ, var) \
+    VOC_STK_ARRAY(ctx, typ, var, VOCMAXAMBIG)
+
+/*
+ *   Stack size for the vocab stack.  We'll scale our stack needs based
+ *   on the size of the vocoldef structure, since this is the most common
+ *   item to be allocated on the vocab stack.  We'll also scale based on
+ *   the defined VOCMAXAMBIG parameter, since it is the number of elements
+ *   usually allocated.  The actual amount of space needed depends on how
+ *   the functions in vocab.c and execmd.c work, so this parameter may
+ *   need to be adjusted for changes to the player command parser. 
+ */
+#define VOC_STACK_SIZE  (16 * VOCMAXAMBIG * sizeof(vocoldef))
+
+/*
+ *   Execute all fuses and daemons, then execute the endCommand user
+ *   function.  Returns zero on success, or ERR_ABORT if 'abort' was
+ *   thrown during execution.  This is a convenient cover single function
+ *   to do all end-of-turn processing; this calls exefuse() and exedaem()
+ *   as needed, trapping any 'abort' or 'exit' errors that occur.
+ *   
+ *   If 'do_fuses' is true, we'll run fuses and daemons.  Otherwise, 
+ */
+int exe_fuses_and_daemons(voccxdef *ctx, int err, int do_fuses,
+                          objnum actor, objnum verb,
+                          vocoldef *dobj_list, int do_cnt,
+                          objnum prep, objnum iobj);
+
+/*
+ *   Execute any pending fuses.  Return TRUE if any fuses were executed,
+ *   FALSE otherwise.  
+ */
+int exefuse(voccxdef *ctx, int do_run);
+
+/*
+ *   Execute daemons 
+ */
+void exedaem(voccxdef *ctx);
+
+/*
+ *   Get the number and size of words defined for an object.  The size
+ *   returns the total byte count from all the words involved.  Do not
+ *   include deleted words in the count.  
+ */
+void voc_count(voccxdef *ctx, objnum objn, prpnum prp, int *cnt, int *siz);
+
+/*
+ *   Iterate through all words for a particular object, calling a
+ *   function with each vocwdef found.  If objn == MCMONINV, we'll call
+ *   the callback for every word.  
+ */
+void voc_iterate(voccxdef *ctx, objnum objn,
+                 void (*fn)(void *, vocdef *, vocwdef *), void *fnctx);
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   disambiguation status codes - used for disambigDobj and disambigIobj
+ *   methods in the deepverb
+ */
+
+/* continue with disambiguation process (using possibly updated list) */
+#define VOC_DISAMBIG_CONT     1
+
+/* done - the list is fully resolved; return with (possibly updated) list */
+#define VOC_DISAMBIG_DONE     2
+
+/* error - abort the command */
+#define VOC_DISAMBIG_ERROR    3
+
+/* parse string returned in second element of list as interactive response */
+#define VOC_DISAMBIG_PARSE_RESP  4
+
+/* already asked for an interactive response, but didn't read it yet */
+#define VOC_DISAMBIG_PROMPTED 5
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   parseNounPhrase status codes 
+ */
+
+/* parse error occurred */
+#define VOC_PNP_ERROR    1
+
+/* use built-in default parser */
+#define VOC_PNP_DEFAULT  2
+
+/* successful parse */
+#define VOC_PNP_SUCCESS  3
+
+
+/* ------------------------------------------------------------------------ */
+/*
+ *   parserResolveObjects usage codes 
+ */
+#define VOC_PRO_RESOLVE_DOBJ  1                            /* direct object */
+#define VOC_PRO_RESOLVE_IOBJ  2                          /* indirect object */
+#define VOC_PRO_RESOLVE_ACTOR 3                                    /* actor */
+
 } // End of namespace TADS2
 } // End of namespace TADS
 } // End of namespace Glk