mirror of
https://github.com/libretro/scummvm.git
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122 lines
3.2 KiB
C++
122 lines
3.2 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* $URL$
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* $Id$
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*
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*/
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#include "common/memorypool.h"
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#include "common/util.h"
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namespace Common {
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static const size_t CHUNK_PAGE_SIZE = 32;
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void* MemoryPool::allocPage() {
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void* result = ::malloc(CHUNK_PAGE_SIZE * _chunkSize);
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_pages.push_back(result);
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void* current = result;
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for (size_t i = 1; i < CHUNK_PAGE_SIZE; ++i) {
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void* next = ((char*)current + _chunkSize);
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*(void**)current = next;
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current = next;
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}
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*(void**)current = NULL;
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return result;
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}
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MemoryPool::MemoryPool(size_t chunkSize) {
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// You must at least fit the pointer in the node (technically unneeded considering the next rounding statement)
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_chunkSize = MAX(chunkSize, sizeof(void*));
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// There might be an alignment problem on some platforms when trying to load a void* on a non natural boundary
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// so we round to the next sizeof(void*)
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_chunkSize = (_chunkSize + sizeof(void*) - 1) & (~(sizeof(void*) - 1));
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_next = NULL;
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}
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MemoryPool::~MemoryPool() {
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for (size_t i = 0; i<_pages.size(); ++i)
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::free(_pages[i]);
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}
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void* MemoryPool::malloc() {
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#if 1
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if (!_next)
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_next = allocPage();
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void* result = _next;
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_next = *(void**)result;
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return result;
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#else
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return ::malloc(_chunkSize);
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#endif
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}
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void MemoryPool::free(void* ptr) {
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#if 1
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*(void**)ptr = _next;
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_next = ptr;
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#else
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::free(ptr);
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#endif
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}
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// Technically not compliant C++ to compare unrelated pointers. In practice...
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bool MemoryPool::isPointerInPage(void* ptr, void* page) {
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return (ptr >= page) && (ptr < (char*)page + CHUNK_PAGE_SIZE * _chunkSize);
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}
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void MemoryPool::freeUnusedPages() {
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//std::sort(_pages.begin(), _pages.end());
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Array<size_t> numberOfFreeChunksPerPage;
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numberOfFreeChunksPerPage.resize(_pages.size());
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for (size_t i = 0; i < numberOfFreeChunksPerPage.size(); ++i) {
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numberOfFreeChunksPerPage[i] = 0;
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}
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void* iterator = _next;
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while (iterator) {
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// This should be a binary search
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for (size_t i = 0; i < _pages.size(); ++i) {
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if (isPointerInPage(iterator, _pages[i])) {
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++numberOfFreeChunksPerPage[i];
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break;
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}
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}
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iterator = *(void**)iterator;
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}
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size_t freedPagesCount = 0;
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for (size_t i = 0; i < _pages.size(); ++i) {
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if (numberOfFreeChunksPerPage[i] == CHUNK_PAGE_SIZE) {
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::free(_pages[i]);
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_pages[i] = NULL; // TODO : Remove NULL values
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++freedPagesCount;
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}
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}
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//printf("%d freed pages\n", freedPagesCount);
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}
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} // End of namespace Common
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