path: root/engines/sci/engine/seg_manager.cpp

/* 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.
 *
 * $URL$
 * $Id$
 *
 */

#include "sci/sci.h"
#include "sci/engine/seg_manager.h"
#include "sci/engine/state.h"
#include "sci/engine/intmap.h"

namespace Sci {


/**
 * Verify the the given condition is true, output the message if condition is false, and exit.
 * @param cond	condition to be verified
 * @param msg	the message to be printed if condition fails
 */
#define VERIFY( cond, msg ) if (!(cond)) {\
		error("%s, line, %d, %s", __FILE__, __LINE__, msg); \
	}


#define DEFAULT_SCRIPTS 32
#define DEFAULT_OBJECTS 8	    // default # of objects per script
#define DEFAULT_OBJECTS_INCREMENT 4 // Number of additional objects to instantiate if we're running out of them

//#define GC_DEBUG // Debug garbage collection
//#define GC_DEBUG_VERBOSE // Debug garbage verbosely

#undef DEBUG_segmentManager // Define to turn on debugging

#define INVALID_SCRIPT_ID -1

SegManager::SegManager(ResourceManager *resourceManager) {
	id_seg_map = new IntMapper();
	reserved_id = INVALID_SCRIPT_ID;
	id_seg_map->checkKey(reserved_id, true);	// reserve entry 0 for INVALID_SCRIPT_ID
	reserved_id--; // reserved_id runs in the reversed direction to make sure no one will use it.

	_heap.push_back(0);

	Clones_seg_id = 0;
	Lists_seg_id = 0;
	Nodes_seg_id = 0;
	Hunks_seg_id = 0;

	exports_wide = 0;
	_resourceManager = resourceManager;

	int result = 0;

	result = createClassTable();

	if (result)
		error("SegManager: Failed to initialize class table");
}

// Destroy the object, free the memorys if allocated before
SegManager::~SegManager() {
	// Free memory
	for (uint i = 0; i < _heap.size(); i++) {
		if (_heap[i])
			deallocate(i, false);
	}

	delete id_seg_map;
}

int SegManager::findFreeId(int *id) {
	bool was_added = false;
	int retval = 0;

	while (!was_added) {
		retval = id_seg_map->checkKey(reserved_id, true, &was_added);
		*id = reserved_id--;
		if (reserved_id < -1000000)
			reserved_id = -10;
		// Make sure we don't underflow
	}

	return retval;
}

MemObject *SegManager::allocNonscriptSegment(MemObjectType type, SegmentId *segid) {
	// Allocates a non-script segment
	int id;

	*segid = findFreeId(&id);
	return memObjAllocate(*segid, id, type);
}

// allocate a memory for script from heap
// Parameters: (EngineState *) s: The state to operate on
//             (int) script_nr: The script number to load
// Returns   : 0 - allocation failure
//             1 - allocated successfully
//             seg_id - allocated segment id
Script *SegManager::allocateScript(int script_nr, SegmentId *seg_id) {
	bool was_added;
	MemObject *mem;

	*seg_id = id_seg_map->checkKey(script_nr, true, &was_added);
	if (!was_added) {
		return (Script *)_heap[*seg_id];
	}

	// allocate the MemObject
	mem = memObjAllocate(*seg_id, script_nr, MEM_OBJ_SCRIPT);
	if (!mem) {
		error("allocateScript: Not enough memory");
		return NULL;
	}

	return (Script *)mem;
}

void SegManager::setScriptSize(Script &scr, int script_nr) {
	Resource *script = _resourceManager->findResource(ResourceId(kResourceTypeScript, script_nr), 0);
	Resource *heap = _resourceManager->findResource(ResourceId(kResourceTypeHeap, script_nr), 0);
	bool oldScriptHeader = (_resourceManager->sciVersion() == SCI_VERSION_0_EARLY);

	scr.script_size = script->size;
	scr.heap_size = 0; // Set later

	if (!script || (_resourceManager->sciVersion() >= SCI_VERSION_1_1 && !heap)) {
		error("SegManager::setScriptSize: failed to load %s", !script ? "script" : "heap");
	}
	if (oldScriptHeader) {
		scr.buf_size = script->size + READ_LE_UINT16(script->data) * 2;
		//locals_size = READ_LE_UINT16(script->data) * 2;
	} else if (_resourceManager->sciVersion() < SCI_VERSION_1_1) {
		scr.buf_size = script->size;
	} else {
		scr.buf_size = script->size + heap->size;
		scr.heap_size = heap->size;

		// Ensure that the start of the heap resource can be word-aligned.
		if (script->size & 2) {
			scr.buf_size++;
			scr.script_size++;
		}

		if (scr.buf_size > 65535) {
			error("Script and heap sizes combined exceed 64K."
			          "This means a fundamental design bug was made in SCI\n"
			          "regarding SCI1.1 games.\nPlease report this so it can be"
			          "fixed in the next major version");
			return;
		}
	}
}

int SegManager::initialiseScript(Script &scr, int script_nr) {
	// allocate the script.buf

	setScriptSize(scr, script_nr);
	scr.buf = (byte *)malloc(scr.buf_size);

#ifdef DEBUG_segmentManager
	printf("scr.buf = %p ", scr.buf);
#endif
	if (!scr.buf) {
		scr.freeScript();
		warning("SegManager: Not enough memory space for script size");
		scr.buf_size = 0;
		return 0;
	}

	// Initialize objects
	scr.locals_offset = 0;
	scr.locals_block = NULL;

	scr._codeBlocks.clear();

	scr.nr = script_nr;
	scr._markedAsDeleted = false;
	scr.relocated = 0;

	scr.obj_indices = new IntMapper();

	if (_resourceManager->sciVersion() >= SCI_VERSION_1_1)
		scr.heap_start = scr.buf + scr.script_size;
	else
		scr.heap_start = scr.buf;

	return 1;
}

int SegManager::deallocate(SegmentId seg, bool recursive) {
	MemObject *mobj;
	VERIFY(check(seg), "invalid seg id");

	mobj = _heap[seg];
	id_seg_map->removeKey(mobj->getSegmentManagerId());

	if (mobj->getType() == MEM_OBJ_SCRIPT) {
		Script *scr = (Script *)mobj;
		if (recursive && scr->locals_segment)
			deallocate(scr->locals_segment, recursive);
	}

	delete mobj;
	_heap[seg] = NULL;

	return 1;
}

bool SegManager::scriptIsMarkedAsDeleted(SegmentId seg) {
	Script *scr = getScriptIfLoaded(seg);
	if (!scr)
		return false;
	return scr->_markedAsDeleted;
}


int SegManager::deallocateScript(int script_nr) {
	SegmentId seg = segGet(script_nr);

	deallocate(seg, true);

	return 1;
}

MemObject *SegManager::memObjAllocate(SegmentId segid, int hash_id, MemObjectType type) {
	MemObject *mem = MemObject::createMemObject(type);
	if (!mem) {
		warning("SegManager: invalid mobj");
		return NULL;
	}

	if (segid >= (int)_heap.size()) {
		assert(segid == (int)_heap.size());
		_heap.push_back(0);
	}

	mem->_segManagerId = hash_id;

	// hook it to the heap
	_heap[segid] = mem;
	return mem;
}

// return the seg if script_id is valid and in the map, else -1
SegmentId SegManager::segGet(int script_id) const {
	return id_seg_map->lookupKey(script_id);
}

Script *SegManager::getScript(const SegmentId seg) {
	// FIXME: We accept segment 0, but that is actually an invalid segment...
	if (seg < 0 || (uint)seg >= _heap.size()) {
		error("SegManager::getScript(): seg id %x out of bounds", seg);
	}
	if (!_heap[seg]) {
		error("SegManager::getScript(): seg id %x is not in memory", seg);
	}
	if (_heap[seg]->getType() != MEM_OBJ_SCRIPT) {
		error("SegManager::getScript(): seg id %x refers to type %d != MEM_OBJ_SCRIPT", seg, _heap[seg]->getType());
	}
	return (Script *)_heap[seg];
}

Script *SegManager::getScriptIfLoaded(const SegmentId seg) {
	// FIXME: We accept segment 0, but that is actually an invalid segment...
	if (seg < 0 || (uint)seg >= _heap.size() || !_heap[seg] || _heap[seg]->getType() != MEM_OBJ_SCRIPT)
		return 0;
	return (Script *)_heap[seg];
}

// validate the seg
// return:
//	false - invalid seg
//	true  - valid seg
bool SegManager::check(SegmentId seg) {
	// FIXME: We accept segment 0, but that is actually an invalid segment...
	if (seg < 0 || (uint)seg >= _heap.size()) {
		return false;
	}
	if (!_heap[seg]) {
		warning("SegManager: seg %x is removed from memory, but not removed from hash_map", seg);
		return false;
	}
	return true;
}

bool SegManager::scriptIsLoaded(SegmentId seg) {
	return getScriptIfLoaded(seg) != 0;
}

void SegManager::setExportWidth(int flag) {
	exports_wide = flag;
}

int SegManager::relocateBlock(Common::Array<reg_t> &block, int block_location, SegmentId segment, int location) {
	int rel = location - block_location;

	if (rel < 0)
		return 0;

	uint idx = rel >> 1;

	if (idx >= block.size())
		return 0;

	if (rel & 1) {
		warning("Attempt to relocate odd variable #%d.5e (relative to %04x)\n", idx, block_location);
		return 0;
	}
	block[idx].segment = segment; // Perform relocation
	if (_resourceManager->sciVersion() >= SCI_VERSION_1_1)
		block[idx].offset += getScript(segment)->script_size;

	return 1;
}

int SegManager::relocateLocal(Script *scr, SegmentId segment, int location) {
	if (scr->locals_block)
		return relocateBlock(scr->locals_block->_locals, scr->locals_offset, segment, location);
	else
		return 0; // No hands, no cookies
}

int SegManager::relocateObject(Object *obj, SegmentId segment, int location) {
	return relocateBlock(obj->_variables, obj->pos.offset, segment, location);
}

void SegManager::scriptAddCodeBlock(reg_t location) {
	Script *scr = getScript(location.segment);

	CodeBlock cb;
	cb.pos = location;
	cb.size = READ_LE_UINT16(scr->buf + location.offset - 2);
	scr->_codeBlocks.push_back(cb);
}

void SegManager::scriptRelocate(reg_t block) {
	Script *scr = getScript(block.segment);

	VERIFY(block.offset < (uint16)scr->buf_size && READ_LE_UINT16(scr->buf + block.offset) * 2 + block.offset < (uint16)scr->buf_size,
	       "Relocation block outside of script\n");

	int count = READ_LE_UINT16(scr->buf + block.offset);

	for (int i = 0; i <= count; i++) {
		int pos = READ_LE_UINT16(scr->buf + block.offset + 2 + (i * 2));
		if (!pos)
			continue; // FIXME: A hack pending investigation

		if (!relocateLocal(scr, block.segment, pos)) {
			bool done = false;
			uint k;

			for (k = 0; !done && k < scr->_objects.size(); k++) {
				if (relocateObject(&scr->_objects[k], block.segment, pos))
					done = true;
			}

			for (k = 0; !done && k < scr->_codeBlocks.size(); k++) {
				if (pos >= scr->_codeBlocks[k].pos.offset &&
				        pos < scr->_codeBlocks[k].pos.offset + scr->_codeBlocks[k].size)
					done = true;
			}

			if (!done) {
				printf("While processing relocation block %04x:%04x:\n", PRINT_REG(block));
				printf("Relocation failed for index %04x (%d/%d)\n", pos, i + 1, count);
				if (scr->locals_block)
					printf("- locals: %d at %04x\n", scr->locals_block->_locals.size(), scr->locals_offset);
				else
					printf("- No locals\n");
				for (k = 0; k < scr->_objects.size(); k++)
					printf("- obj#%d at %04x w/ %d vars\n", k, scr->_objects[k].pos.offset, scr->_objects[k]._variables.size());
				// SQ3 script 71 has broken relocation entries.
				printf("Trying to continue anyway...\n");
			}
		}
	}
}

void SegManager::heapRelocate(reg_t block) {
	Script *scr = getScript(block.segment);

	VERIFY(block.offset < (uint16)scr->heap_size && READ_LE_UINT16(scr->heap_start + block.offset) * 2 + block.offset < (uint16)scr->buf_size,
	       "Relocation block outside of script\n");

	if (scr->relocated)
		return;
	scr->relocated = 1;
	int count = READ_LE_UINT16(scr->heap_start + block.offset);

	for (int i = 0; i < count; i++) {
		int pos = READ_LE_UINT16(scr->heap_start + block.offset + 2 + (i * 2)) + scr->script_size;

		if (!relocateLocal(scr, block.segment, pos)) {
			bool done = false;
			uint k;

			for (k = 0; !done && k < scr->_objects.size(); k++) {
				if (relocateObject(&scr->_objects[k], block.segment, pos))
					done = true;
			}

			if (!done) {
				printf("While processing relocation block %04x:%04x:\n", PRINT_REG(block));
				printf("Relocation failed for index %04x (%d/%d)\n", pos, i + 1, count);
				if (scr->locals_block)
					printf("- locals: %d at %04x\n", scr->locals_block->_locals.size(), scr->locals_offset);
				else
					printf("- No locals\n");
				for (k = 0; k < scr->_objects.size(); k++)
					printf("- obj#%d at %04x w/ %d vars\n", k, scr->_objects[k].pos.offset, scr->_objects[k]._variables.size());
				printf("Triggering breakpoint...\n");
				error("Breakpoint in %s, line %d", __FILE__, __LINE__);
			}
		}
	}
}

SegmentId SegManager::getSegment(int script_nr, SCRIPT_GET load) {
	SegmentId segment;

	if ((load & SCRIPT_GET_LOAD) == SCRIPT_GET_LOAD)
		script_instantiate(_resourceManager, this, script_nr);

	segment = segGet(script_nr);

	if (segment > 0) {
		if ((load & SCRIPT_GET_LOCK) == SCRIPT_GET_LOCK)
			getScript(segment)->incrementLockers();

		return segment;
	} else
		return 0;
}

#define INST_LOOKUP_CLASS(id) ((id == 0xffff) ? NULL_REG : get_class_address(id, SCRIPT_GET_LOCK, NULL_REG))

reg_t SegManager::get_class_address(int classnr, SCRIPT_GET lock, reg_t caller) {
	if (classnr < 0 || (int)_classtable.size() <= classnr || _classtable[classnr].script < 0) {
		error("[VM] Attempt to dereference class %x, which doesn't exist (max %x)", classnr, _classtable.size());
		return NULL_REG;
	} else {
		Class *the_class = &_classtable[classnr];
		if (!the_class->reg.segment) {
			getSegment(the_class->script, lock);

			if (!the_class->reg.segment) {
				error("[VM] Trying to instantiate class %x by instantiating script 0x%x (%03d) failed;"
				          " Entering debugger.", classnr, the_class->script, the_class->script);
				return NULL_REG;
			}
		} else
			if (caller.segment != the_class->reg.segment)
				getScript(the_class->reg.segment)->incrementLockers();

		return the_class->reg;
	}
}

Object *SegManager::scriptObjInit0(reg_t obj_pos) {
	Object *obj;
	int id;
	SciVersion version = _resourceManager->sciVersion();	// for the offset defines
	unsigned int base = obj_pos.offset - SCRIPT_OBJECT_MAGIC_OFFSET;
	reg_t temp;

	Script *scr = getScript(obj_pos.segment);

	VERIFY(base < scr->buf_size, "Attempt to initialize object beyond end of script\n");

	temp = make_reg(obj_pos.segment, base);

	id = scr->obj_indices->checkKey(base, true);
	if ((uint)id == scr->_objects.size())
		scr->_objects.push_back(Object());

	obj = &scr->_objects[id];

	VERIFY(base + SCRIPT_FUNCTAREAPTR_OFFSET  < scr->buf_size, "Function area pointer stored beyond end of script\n");

	{
		byte *data = (byte *)(scr->buf + base);
		int funct_area = READ_LE_UINT16(data + SCRIPT_FUNCTAREAPTR_OFFSET);
		int variables_nr;
		int functions_nr;
		int is_class;
		int i;

		obj->flags = 0;
		obj->pos = temp;

		VERIFY(base + funct_area < scr->buf_size, "Function area pointer references beyond end of script");

		variables_nr = READ_LE_UINT16(data + SCRIPT_SELECTORCTR_OFFSET);
		functions_nr = READ_LE_UINT16(data + funct_area - 2);
		is_class = READ_LE_UINT16(data + SCRIPT_INFO_OFFSET) & SCRIPT_INFO_CLASS;

		VERIFY(base + funct_area + functions_nr * 2
		       // add again for classes, since those also store selectors
		       + (is_class ? functions_nr * 2 : 0) < scr->buf_size, "Function area extends beyond end of script");

		obj->_variables.resize(variables_nr);

		obj->methods_nr = functions_nr;
		obj->base = scr->buf;
		obj->base_obj = data;
		obj->base_method = (uint16 *)(data + funct_area);
		obj->base_vars = NULL;

		for (i = 0; i < variables_nr; i++)
			obj->_variables[i] = make_reg(0, READ_LE_UINT16(data + (i * 2)));
	}

	return obj;
}

Object *SegManager::scriptObjInit11(reg_t obj_pos) {
	Object *obj;
	int id;
	int base = obj_pos.offset;

	Script *scr = getScript(obj_pos.segment);

	VERIFY(base < (uint16)scr->buf_size, "Attempt to initialize object beyond end of script\n");

	id = scr->obj_indices->checkKey(obj_pos.offset, true);
	if ((uint)id == scr->_objects.size())
		scr->_objects.push_back(Object());

	obj = &scr->_objects[id];

	VERIFY(base + SCRIPT_FUNCTAREAPTR_OFFSET < (uint16)scr->buf_size, "Function area pointer stored beyond end of script\n");

	{
		byte *data = (byte *)(scr->buf + base);
		uint16 *funct_area = (uint16 *)(scr->buf + READ_LE_UINT16(data + 6));
		uint16 *prop_area = (uint16 *)(scr->buf + READ_LE_UINT16(data + 4));
		int variables_nr;
		int functions_nr;
		int is_class;
		int i;

		obj->flags = 0;
		obj->pos = obj_pos;

		VERIFY((byte *) funct_area < scr->buf + scr->buf_size, "Function area pointer references beyond end of script");

		variables_nr = READ_LE_UINT16(data + 2);
		functions_nr = READ_LE_UINT16(funct_area);
		is_class = READ_LE_UINT16(data + 14) & SCRIPT_INFO_CLASS;

		obj->base_method = funct_area;
		obj->base_vars = prop_area;

		VERIFY(((byte *) funct_area + functions_nr) < scr->buf + scr->buf_size, "Function area extends beyond end of script");

		obj->variable_names_nr = variables_nr;
		obj->_variables.resize(variables_nr);

		obj->methods_nr = functions_nr;
		obj->base = scr->buf;
		obj->base_obj = data;

		for (i = 0; i < variables_nr; i++)
			obj->_variables[i] = make_reg(0, READ_LE_UINT16(data + (i * 2)));
	}

	return obj;
}

Object *SegManager::scriptObjInit(reg_t obj_pos) {
	if (_resourceManager->sciVersion() < SCI_VERSION_1_1)
		return scriptObjInit0(obj_pos);
	else
		return scriptObjInit11(obj_pos);
}

LocalVariables *SegManager::allocLocalsSegment(Script *scr, int count) {
	if (!count) { // No locals
		scr->locals_segment = 0;
		scr->locals_block = NULL;
		return NULL;
	} else {
		LocalVariables *locals;

		if (scr->locals_segment) {
			locals = (LocalVariables *)_heap[scr->locals_segment];
			VERIFY(locals != NULL, "Re-used locals segment was NULL'd out");
			VERIFY(locals->getType() == MEM_OBJ_LOCALS, "Re-used locals segment did not consist of local variables");
			VERIFY(locals->script_id == scr->nr, "Re-used locals segment belonged to other script");
		} else
			locals = (LocalVariables *)allocNonscriptSegment(MEM_OBJ_LOCALS, &scr->locals_segment);

		scr->locals_block = locals;
		locals->script_id = scr->nr;
		locals->_locals.resize(count);

		return locals;
	}
}

void SegManager::scriptInitialiseLocalsZero(SegmentId seg, int count) {
	Script *scr = getScript(seg);

	scr->locals_offset = -count * 2; // Make sure it's invalid

	allocLocalsSegment(scr, count);
}

void SegManager::scriptInitialiseLocals(reg_t location) {
	Script *scr = getScript(location.segment);
	unsigned int count;

	VERIFY(location.offset + 1 < (uint16)scr->buf_size, "Locals beyond end of script\n");

	if (_resourceManager->sciVersion() >= SCI_VERSION_1_1)
		count = READ_LE_UINT16(scr->buf + location.offset - 2);
	else
		count = (READ_LE_UINT16(scr->buf + location.offset - 2) - 4) >> 1;
	// half block size

	scr->locals_offset = location.offset;

	if (!(location.offset + count * 2 + 1 < scr->buf_size)) {
		warning("Locals extend beyond end of script: offset %04x, count %x vs size %x", location.offset, count, (uint)scr->buf_size);
		count = (scr->buf_size - location.offset) >> 1;
	}

	LocalVariables *locals = allocLocalsSegment(scr, count);
	if (locals) {
		uint i;
		byte *base = (byte *)(scr->buf + location.offset);

		for (i = 0; i < count; i++)
			locals->_locals[i].offset = READ_LE_UINT16(base + i * 2);
	}
}

void SegManager::scriptRelocateExportsSci11(SegmentId seg) {
	Script *scr = getScript(seg);
	for (int i = 0; i < scr->exports_nr; i++) {
		/* We are forced to use an ugly heuristic here to distinguish function
		   exports from object/class exports. The former kind points into the
		   script resource, the latter into the heap resource.  */
		uint16 location = READ_LE_UINT16((byte *)(scr->export_table + i));
		if ((location < scr->heap_size - 1) && (READ_LE_UINT16(scr->heap_start + location) == SCRIPT_OBJECT_MAGIC_NUMBER)) {
			WRITE_LE_UINT16((byte *)(scr->export_table + i), location + scr->heap_start - scr->buf);
		} else {
			// Otherwise it's probably a function export,
			// and we don't need to do anything.
		}
	}
}

void SegManager::scriptInitialiseObjectsSci11(SegmentId seg) {
	Script *scr = getScript(seg);
	byte *seeker = scr->heap_start + 4 + READ_LE_UINT16(scr->heap_start + 2) * 2;
	SciVersion version = _resourceManager->sciVersion();	// for the selector defines

	while (READ_LE_UINT16(seeker) == SCRIPT_OBJECT_MAGIC_NUMBER) {
		if (READ_LE_UINT16(seeker + 14) & SCRIPT_INFO_CLASS) {
			int classpos = seeker - scr->buf;
			int species = READ_LE_UINT16(seeker + 10);

			if (species < 0 || species >= (int)_classtable.size()) {
				error("Invalid species %d(0x%x) not in interval [0,%d) while instantiating script %d",
				          species, species, _classtable.size(), scr->nr);
				return;
			}

			_classtable[species].reg.segment = seg;
			_classtable[species].reg.offset = classpos;
		}
		seeker += READ_LE_UINT16(seeker + 2) * 2;
	}

	seeker = scr->heap_start + 4 + READ_LE_UINT16(scr->heap_start + 2) * 2;
	while (READ_LE_UINT16(seeker) == SCRIPT_OBJECT_MAGIC_NUMBER) {
		reg_t reg;
		Object *obj;

		reg.segment = seg;
		reg.offset = seeker - scr->buf;
		obj = scriptObjInit(reg);

#if 0
		if (obj->_variables[5].offset != 0xffff) {
			obj->_variables[5] = INST_LOOKUP_CLASS(obj->_variables[5].offset);
			base_obj = obj_get(s->segmentManager, obj->_variables[5]);
			obj->variable_names_nr = base_obj->variables_nr;
			obj->base_obj = base_obj->base_obj;
		}
#endif

		// Copy base from species class, as we need its selector IDs
		obj->_variables[SCRIPT_SUPERCLASS_SELECTOR] = INST_LOOKUP_CLASS(obj->_variables[SCRIPT_SUPERCLASS_SELECTOR].offset);

		// Set the -classScript- selector to the script number.
		// FIXME: As this selector is filled in at run-time, it is likely
		// that it is supposed to hold a pointer. The Obj::isKindOf method
		// uses this selector together with -propDict- to compare classes.
		// For the purpose of Obj::isKindOf, using the script number appears
		// to be sufficient.
		obj->_variables[SCRIPT_CLASSSCRIPT_SELECTOR] = make_reg(0, scr->nr);

		seeker += READ_LE_UINT16(seeker + 2) * 2;
	}
}

/*
static char *SegManager::dynprintf(char *msg, ...) {
	va_list argp;
	char *buf = (char *)malloc(strlen(msg) + 100);

	va_start(argp, msg);
	vsprintf(buf, msg, argp);
	va_end(argp);

	return buf;
}
*/

DataStack *SegManager::allocateStack(int size, SegmentId *segid) {
	MemObject *mobj = allocNonscriptSegment(MEM_OBJ_STACK, segid);
	DataStack *retval = (DataStack *)mobj;

	retval->entries = (reg_t *)calloc(size, sizeof(reg_t));
	retval->nr = size;

	return retval;
}

SystemStrings *SegManager::allocateSysStrings(SegmentId *segid) {
	return (SystemStrings *)allocNonscriptSegment(MEM_OBJ_SYS_STRINGS, segid);
}

SegmentId SegManager::allocateStringFrags() {
	SegmentId segid;

	allocNonscriptSegment(MEM_OBJ_STRING_FRAG, &segid);

	return segid;
}

uint16 SegManager::validateExportFunc(int pubfunct, SegmentId seg) {
	Script *scr = getScript(seg);
	if (scr->exports_nr <= pubfunct) {
		warning("validateExportFunc(): pubfunct is invalid");
		return 0;
	}

	if (exports_wide)
		pubfunct *= 2;
	uint16 offset = READ_LE_UINT16((byte *)(scr->export_table + pubfunct));
	VERIFY(offset < scr->buf_size, "invalid export function pointer");

	return offset;
}

void SegManager::free_hunk_entry(reg_t addr) {
	HunkTable *ht = (HunkTable *)GET_SEGMENT(*this, addr.segment, MEM_OBJ_HUNK);

	if (!ht) {
		warning("Attempt to free Hunk from address %04x:%04x: Invalid segment type", PRINT_REG(addr));
		return;
	}

	ht->freeEntry(addr.offset);
}

Hunk *SegManager::alloc_hunk_entry(const char *hunk_type, int size, reg_t *reg) {
	Hunk *h = alloc_Hunk(reg);

	if (!h)
		return NULL;

	h->mem = malloc(size);
	h->size = size;
	h->type = hunk_type;

	return h;
}

Clone *SegManager::alloc_Clone(reg_t *addr) {
	CloneTable *table;
	int offset;

	if (!Clones_seg_id) {
		table = (CloneTable *)allocNonscriptSegment(MEM_OBJ_CLONES, &(Clones_seg_id));
	} else
		table = (CloneTable *)_heap[Clones_seg_id];

	offset = table->allocEntry();

	*addr = make_reg(Clones_seg_id, offset);
	return &(table->_table[offset]);
}

List *SegManager::alloc_List(reg_t *addr) {
	ListTable *table;
	int offset;

	if (!Lists_seg_id)
		allocNonscriptSegment(MEM_OBJ_LISTS, &(Lists_seg_id));
	table = (ListTable *)_heap[Lists_seg_id];

	offset = table->allocEntry();

	*addr = make_reg(Lists_seg_id, offset);
	return &(table->_table[offset]);
}

Node *SegManager::alloc_Node(reg_t *addr) {
	NodeTable *table;
	int offset;

	if (!Nodes_seg_id)
		allocNonscriptSegment(MEM_OBJ_NODES, &(Nodes_seg_id));
	table = (NodeTable *)_heap[Nodes_seg_id];

	offset = table->allocEntry();

	*addr = make_reg(Nodes_seg_id, offset);
	return &(table->_table[offset]);
}

Hunk *SegManager::alloc_Hunk(reg_t *addr) {
	HunkTable *table;
	int offset;

	if (!Hunks_seg_id)
		allocNonscriptSegment(MEM_OBJ_HUNK, &(Hunks_seg_id));
	table = (HunkTable *)_heap[Hunks_seg_id];

	offset = table->allocEntry();

	*addr = make_reg(Hunks_seg_id, offset);
	return &(table->_table[offset]);
}

byte *SegManager::dereference(reg_t pointer, int *size) {
	if (!pointer.segment || (pointer.segment >= _heap.size()) || !_heap[pointer.segment]) {
		// This occurs in KQ5CD when interacting with certain objects
		warning("Attempt to dereference invalid pointer %04x:%04x", PRINT_REG(pointer));
		return NULL; /* Invalid */
	}

	MemObject *mobj = _heap[pointer.segment];
	return mobj->dereference(pointer, size);
}

unsigned char *SegManager::allocDynmem(int size, const char *descr, reg_t *addr) {
	SegmentId seg;
	MemObject *mobj = allocNonscriptSegment(MEM_OBJ_DYNMEM, &seg);
	*addr = make_reg(seg, 0);

	DynMem &d = *(DynMem *)mobj;

	d._size = size;

	if (size == 0)
		d._buf = NULL;
	else
		d._buf = (byte *)malloc(size);

	d._description = strdup(descr);

	return (unsigned char *)(d._buf);
}

const char *SegManager::getDescription(reg_t addr) {
	if (addr.segment >= _heap.size())
		return "";

	MemObject *mobj = _heap[addr.segment];

	switch (mobj->getType()) {
	case MEM_OBJ_DYNMEM:
		return (*(DynMem *)mobj)._description;
	default:
		return "";
	}
}

int SegManager::freeDynmem(reg_t addr) {
	if (addr.segment <= 0 || addr.segment >= _heap.size() || !_heap[addr.segment] || _heap[addr.segment]->getType() != MEM_OBJ_DYNMEM)
		return 1; // error

	deallocate(addr.segment, true);

	return 0; // OK
}

int SegManager::createClassTable() {
	Resource *vocab996 = _resourceManager->findResource(ResourceId(kResourceTypeVocab, 996), 1);

	if (!vocab996)
		error("SegManager: failed to open vocab 996");

	int totalClasses = vocab996->size >> 2;
	_classtable.resize(totalClasses);

	for (uint16 classNr = 0; classNr < totalClasses; classNr++) {
		uint16 scriptNr = READ_LE_UINT16(vocab996->data + classNr * 4 + 2);

		_classtable[classNr].reg = NULL_REG;
		_classtable[classNr].script = scriptNr;
	}

	_resourceManager->unlockResource(vocab996);

	return 0;
}

} // End of namespace Sci