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/* 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/os_frob_tads.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
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