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/* Copyright (C) 1994-2004 Revolution Software Ltd
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* $Header$
*/
// The new memory manager, now only used by the resource manager. Unlike the
// original, this one does not allocate a 12 MB memory pool at startup.
//
// There is one thing that prevents us from replacing the whole memory manager
// with the standard memory allocation functions: Broken Sword II absolutely,
// positively needs to be able to encode pointers as 32-bit integers. The
// original engine did this simply by casting between pointers and integers,
// but as far as I know that's not a very portable thing to do.
//
// For a while I was hopeing that the engine only needed pointers as function
// parameters, in which case I could have extended the stack to use a struct or
// a union instead, but no such luck. There is code in walker.cpp that
// obviously violates that assumption, and there are probably other, more
// well-hidden places, as well.
//
// This attacks the problem from the direction of another limitation in the
// original memory manager: it could only handle up to 999 blocks of memory.
// This memory manager has the same limitation, although it's probably way too
// large now, which means that a pointer can be encoded as 10 bits to store the
// block id, and another 22 bits to store an index into that block.
#include "common/stdafx.h"
#include "sword2/sword2.h"
#include "sword2/console.h"
namespace Sword2 {
#define MAX_BLOCKS 999
#define Debug_Printf _vm->_debugger->DebugPrintf
MemoryManager::MemoryManager(Sword2Engine *vm) : _vm(vm) {
_memBlocks = (MemBlock *) malloc(MAX_BLOCKS * sizeof(MemBlock));
_memBlockIndex = (MemBlock **) malloc(MAX_BLOCKS * sizeof(MemBlock *));
_idStack = (int16 *) malloc(MAX_BLOCKS * sizeof(int16));
_totAlloc = 0;
_numBlocks = 0;
for (int i = 0; i < MAX_BLOCKS; i++) {
_idStack[i] = MAX_BLOCKS - i - 1;
_memBlocks[i].ptr = NULL;
_memBlockIndex[i] = NULL;
}
_idStackPtr = MAX_BLOCKS;
}
MemoryManager::~MemoryManager() {
for (int i = 0; i < MAX_BLOCKS; i++)
free(_memBlocks[i].ptr);
free(_memBlocks);
free(_memBlockIndex);
free(_idStack);
}
int32 MemoryManager::encodePtr(byte *ptr) {
int idx = findPointerInIndex(ptr);
if (idx == -1)
error("Encoding non-allocated pointer %p", ptr);
int id = _memBlockIndex[idx]->id;
return (id << 22) | (ptr - _memBlocks[id].ptr);
}
byte *MemoryManager::decodePtr(int32 n) {
int16 id = (n >> 22) & 0x03ff;
int32 offset = n & 0x003fffff;
return _memBlocks[id].ptr + offset;
}
int16 MemoryManager::findExactPointerInIndex(byte *ptr) {
int left = 0;
int right = _numBlocks - 1;
while (right >= left) {
int n = (left + right) / 2;
if (_memBlockIndex[n]->ptr == ptr)
return n;
if (_memBlockIndex[n]->ptr > ptr)
right = n - 1;
else
left = n + 1;
}
return -1;
}
int16 MemoryManager::findPointerInIndex(byte *ptr) {
int left = 0;
int right = _numBlocks - 1;
while (right >= left) {
int n = (left + right) / 2;
if (_memBlockIndex[n]->ptr <= ptr && _memBlockIndex[n]->ptr + _memBlockIndex[n]->size > ptr)
return n;
if (_memBlockIndex[n]->ptr > ptr)
right = n - 1;
else
left = n + 1;
}
return -1;
}
int16 MemoryManager::findInsertionPointInIndex(byte *ptr) {
if (_numBlocks == 0)
return 0;
int left = 0;
int right = _numBlocks - 1;
int n = 0;
while (right >= left) {
n = (left + right) / 2;
if (_memBlockIndex[n]->ptr == ptr)
return -1;
if (_memBlockIndex[n]->ptr > ptr)
right = n - 1;
else
left = n + 1;
}
if (_memBlockIndex[n]->ptr < ptr)
n++;
return n;
}
byte *MemoryManager::memAlloc(uint32 size, int16 uid) {
byte *ptr = (byte *) malloc(size);
assert(ptr);
assert(_idStackPtr > 0);
// Get the new block's id from the stack.
int16 id = _idStack[--_idStackPtr];
_memBlocks[id].id = id;
_memBlocks[id].uid = uid;
_memBlocks[id].ptr = ptr;
_memBlocks[id].size = size;
// The memory index provides a method for figuring out which memory
// block an arbitrary pointer points to. A balanced tree might be more
// efficient, but such beasts are tricky to implement.
int16 idx = findInsertionPointInIndex(ptr);
assert(idx != -1);
for (int i = _numBlocks; i > idx; i--)
_memBlockIndex[i] = _memBlockIndex[i - 1];
_memBlockIndex[idx] = &_memBlocks[id];
_numBlocks++;
_totAlloc += size;
return _memBlocks[id].ptr;
}
void MemoryManager::memFree(byte *ptr) {
int16 idx = findExactPointerInIndex(ptr);
if (idx == -1) {
warning("Freeing non-allocated pointer %p", ptr);
return;
}
// Put back the id on the stack
_idStack[_idStackPtr++] = _memBlockIndex[idx]->id;
free(_memBlockIndex[idx]->ptr);
_memBlockIndex[idx]->ptr = NULL;
_totAlloc -= _memBlockIndex[idx]->size;
// Remove the pointer from the index
_numBlocks--;
for (int i = idx; i < _numBlocks; i++)
_memBlockIndex[i] = _memBlockIndex[i + 1];
}
void MemoryManager::memDisplay() {
for (int i = 0; i < _numBlocks; i++)
Debug_Printf("%d: %ld bytes allocated by resource %d\n", i, _memBlocks[i].size, _memBlocks[i].uid);
}
void MemoryManager::memStatusStr(char *buf) {
if (_totAlloc < 1024)
sprintf(buf, "%u bytes in %d memory blocks", _totAlloc, _numBlocks);
else if (_totAlloc < 1048576)
sprintf(buf, "%uK in %d memory blocks", _totAlloc / 1024, _numBlocks);
else
sprintf(buf, "%.02fM in %d memory blocks", _totAlloc / 1048576., _numBlocks);
}
} // End of namespace Sword2
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