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Diffstat (limited to 'sword2/memory.cpp')
| -rw-r--r-- | sword2/memory.cpp | 244 |
1 files changed, 0 insertions, 244 deletions
diff --git a/sword2/memory.cpp b/sword2/memory.cpp deleted file mode 100644 index 7da4e86b51..0000000000 --- a/sword2/memory.cpp +++ /dev/null @@ -1,244 +0,0 @@ -/* Copyright (C) 1994-1998 Revolution Software Ltd. - * Copyright (C) 2003-2006 The ScummVM project - * - * 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. - * - * $URL$ - * $Id$ - */ - -// The new memory manager, now only used by the resource manager. The original -// one would allocated a 12 MB memory pool at startup, which may have been -// appropriate for the original Playstation version but didn't work very well -// with our PocketPC version. -// -// There is one thing that prevents us from replacing the whole memory manager -// with the standard memory allocation functions: Broken Sword 2 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. -// -// If it had only used pointers as opcode parameters it would have been -// possible, albeit messy, to extend the stack data type. However, there is -// code in walker.cpp that obviously violates that assumption, and there are -// probably other cases as well. -// -// Instead, we take advantage of the fact that the original memory manager -// could only handle up to 999 blocks of memory. That means we can encode a -// pointer as a 10-bit id and a 22-bit offset into the block. Judging by early -// testing, both should be plenty. -// -// The number zero is used to represent the NULL pointer. - -#include "common/stdafx.h" -#include "sword2/sword2.h" -#include "sword2/memory.h" - -namespace Sword2 { - -MemoryManager::MemoryManager(Sword2Engine *vm) : _vm(vm) { - // The id stack contains all the possible ids for the memory blocks. - // We use this to ensure that no two blocks ever have the same id. - - // The memory blocks are stored in an array, indexed on the block's - // id. This means that given a block id we can find the pointer with a - // simple array lookup. - - // The memory block index is an array of pointers to the memory block - // array, sorted on the memory block's pointer. This means that given - // a pointer into a memory block we can find its id with binary - // searching. - // - // A balanced tree might have been more efficient - the index has to - // be re-sorted every time a block is allocated or freed - but such - // beasts are tricky to implement. Anyway, it wouldn't have made - // encoding or decoding pointers any faster, and these are by far the - // most common operations. - - _idStack = (int16 *)malloc(MAX_MEMORY_BLOCKS * sizeof(int16)); - _memBlocks = (MemBlock *)malloc(MAX_MEMORY_BLOCKS * sizeof(MemBlock)); - _memBlockIndex = (MemBlock **)malloc(MAX_MEMORY_BLOCKS * sizeof(MemBlock *)); - - _totAlloc = 0; - _numBlocks = 0; - - for (int i = 0; i < MAX_MEMORY_BLOCKS; i++) { - _idStack[i] = MAX_MEMORY_BLOCKS - i - 1; - _memBlocks[i].ptr = NULL; - _memBlockIndex[i] = NULL; - } - - _idStackPtr = MAX_MEMORY_BLOCKS; -} - -MemoryManager::~MemoryManager() { - for (int i = 0; i < MAX_MEMORY_BLOCKS; i++) - free(_memBlocks[i].ptr); - free(_memBlocks); - free(_memBlockIndex); - free(_idStack); -} - -int32 MemoryManager::encodePtr(byte *ptr) { - if (ptr == NULL) - return 0; - - int idx = findPointerInIndex(ptr); - - assert(idx != -1); - - uint32 id = _memBlockIndex[idx]->id; - uint32 offset = ptr - _memBlocks[id].ptr; - - assert(id < 0x03ff); - assert(offset <= 0x003fffff); - assert(offset < _memBlocks[id].size); - - return ((id + 1) << 22) | (ptr - _memBlocks[id].ptr); -} - -byte *MemoryManager::decodePtr(int32 n) { - if (n == 0) - return NULL; - - uint32 id = ((n & 0xffc00000) >> 22) - 1; - uint32 offset = n & 0x003fffff; - - assert(_memBlocks[id].ptr); - assert(offset < _memBlocks[id].size); - - 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) { - assert(_idStackPtr > 0); - - // Get the new block's id from the stack. - int16 id = _idStack[--_idStackPtr]; - - // Allocate the new memory block - byte *ptr = (byte *)malloc(size); - - assert(ptr); - - _memBlocks[id].id = id; - _memBlocks[id].uid = uid; - _memBlocks[id].ptr = ptr; - _memBlocks[id].size = size; - - // Update the memory block index. - 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; - - // Release the memory block - free(_memBlockIndex[idx]->ptr); - _memBlockIndex[idx]->ptr = NULL; - - _totAlloc -= _memBlockIndex[idx]->size; - - // Remove the memory block from the index - _numBlocks--; - - for (int i = idx; i < _numBlocks; i++) - _memBlockIndex[i] = _memBlockIndex[i + 1]; -} - -} // End of namespace Sword2 |