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Diffstat (limited to 'Source/FreeImage/CacheFile.cpp')
| -rw-r--r-- | Source/FreeImage/CacheFile.cpp | 274 |
1 files changed, 274 insertions, 0 deletions
diff --git a/Source/FreeImage/CacheFile.cpp b/Source/FreeImage/CacheFile.cpp new file mode 100644 index 0000000..16f0531 --- /dev/null +++ b/Source/FreeImage/CacheFile.cpp @@ -0,0 +1,274 @@ +// ========================================================== +// Multi-Page functions +// +// Design and implementation by +// - Floris van den Berg (flvdberg@wxs.nl) +// - checkered (checkered@users.sourceforge.net) +// +// This file is part of FreeImage 3 +// +// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY +// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES +// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE +// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED +// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT +// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY +// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL +// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER +// THIS DISCLAIMER. +// +// Use at your own risk! +// ========================================================== + +#ifdef _MSC_VER +#pragma warning (disable : 4786) // identifier was truncated to 'number' characters +#endif + +#include "CacheFile.h" + +// ---------------------------------------------------------- + +CacheFile::CacheFile(const char *filename, BOOL keep_in_memory) : +m_file(NULL), +m_filename(), +m_free_pages(), +m_page_cache_mem(), +m_page_cache_disk(), +m_page_map(), +m_page_count(0), +m_current_block(NULL), +m_keep_in_memory(keep_in_memory) { + if (filename) { + m_filename = filename; + } +} + +CacheFile::~CacheFile() { +} + +BOOL +CacheFile::open() { + if ((!m_filename.empty()) && (!m_keep_in_memory)) { + m_file = fopen(m_filename.c_str(), "w+b"); + return (m_file != NULL); + } + + return (m_keep_in_memory == TRUE); +} + +void +CacheFile::close() { + // dispose the cache entries + + while (!m_page_cache_disk.empty()) { + Block *block = *m_page_cache_disk.begin(); + m_page_cache_disk.pop_front(); + delete [] block->data; + delete block; + } + while (!m_page_cache_mem.empty()) { + Block *block = *m_page_cache_mem.begin(); + m_page_cache_mem.pop_front(); + delete [] block->data; + delete block; + } + + if (m_file) { + // close the file + + fclose(m_file); + + // delete the file + + remove(m_filename.c_str()); + } +} + +void +CacheFile::cleanupMemCache() { + if (!m_keep_in_memory) { + if (m_page_cache_mem.size() > CACHE_SIZE) { + // flush the least used block to file + + Block *old_block = m_page_cache_mem.back(); + fseek(m_file, old_block->nr * BLOCK_SIZE, SEEK_SET); + fwrite(old_block->data, BLOCK_SIZE, 1, m_file); + + // remove the data + + delete [] old_block->data; + old_block->data = NULL; + + // move the block to another list + + m_page_cache_disk.splice(m_page_cache_disk.begin(), m_page_cache_mem, --m_page_cache_mem.end()); + m_page_map[old_block->nr] = m_page_cache_disk.begin(); + } + } +} + +int +CacheFile::allocateBlock() { + Block *block = new Block; + block->data = new BYTE[BLOCK_SIZE]; + block->next = 0; + + if (!m_free_pages.empty()) { + block->nr = *m_free_pages.begin(); + m_free_pages.pop_front(); + } else { + block->nr = m_page_count++; + } + + m_page_cache_mem.push_front(block); + m_page_map[block->nr] = m_page_cache_mem.begin(); + + cleanupMemCache(); + + return block->nr; +} + +Block * +CacheFile::lockBlock(int nr) { + if (m_current_block == NULL) { + PageMapIt it = m_page_map.find(nr); + + if (it != m_page_map.end()) { + m_current_block = *(it->second); + + // the block is swapped out to disc. load it back + // and remove the block from the cache. it might get cached + // again as soon as the memory buffer fills up + + if (m_current_block->data == NULL) { + m_current_block->data = new BYTE[BLOCK_SIZE]; + + fseek(m_file, m_current_block->nr * BLOCK_SIZE, SEEK_SET); + fread(m_current_block->data, BLOCK_SIZE, 1, m_file); + + m_page_cache_mem.splice(m_page_cache_mem.begin(), m_page_cache_disk, it->second); + m_page_map[nr] = m_page_cache_mem.begin(); + } + + // if the memory cache size is too large, swap an item to disc + + cleanupMemCache(); + + // return the current block + + return m_current_block; + } + } + + return NULL; +} + +BOOL +CacheFile::unlockBlock(int nr) { + if (m_current_block) { + m_current_block = NULL; + + return TRUE; + } + + return FALSE; +} + +BOOL +CacheFile::deleteBlock(int nr) { + if (!m_current_block) { + PageMapIt it = m_page_map.find(nr); + + // remove block from cache + + if (it != m_page_map.end()) + m_page_map.erase(nr); + + // add block to free page list + + m_free_pages.push_back(nr); + + return TRUE; + } + + return FALSE; +} + +BOOL +CacheFile::readFile(BYTE *data, int nr, int size) { + if ((data) && (size > 0)) { + int s = 0; + int block_nr = nr; + + do { + int copy_nr = block_nr; + + Block *block = lockBlock(copy_nr); + + block_nr = block->next; + + memcpy(data + s, block->data, (s + BLOCK_SIZE > size) ? size - s : BLOCK_SIZE); + + unlockBlock(copy_nr); + + s += BLOCK_SIZE; + } while (block_nr != 0); + + return TRUE; + } + + return FALSE; +} + +int +CacheFile::writeFile(BYTE *data, int size) { + if ((data) && (size > 0)) { + int nr_blocks_required = 1 + (size / BLOCK_SIZE); + int count = 0; + int s = 0; + int stored_alloc; + int alloc; + + stored_alloc = alloc = allocateBlock(); + + do { + int copy_alloc = alloc; + + Block *block = lockBlock(copy_alloc); + + block->next = 0; + + memcpy(block->data, data + s, (s + BLOCK_SIZE > size) ? size - s : BLOCK_SIZE); + + if (count + 1 < nr_blocks_required) + alloc = block->next = allocateBlock(); + + unlockBlock(copy_alloc); + + s += BLOCK_SIZE; + } while (++count < nr_blocks_required); + + return stored_alloc; + } + + return 0; +} + +void +CacheFile::deleteFile(int nr) { + do { + Block *block = lockBlock(nr); + + if (block == NULL) + break; + + int next = block->next; + + unlockBlock(nr); + + deleteBlock(nr); + + nr = next; + } while (nr != 0); +} + |