diff options
Diffstat (limited to 'c/src/lib/libbsp/arm/nds/libfat/source/cache.c')
| -rw-r--r-- | c/src/lib/libbsp/arm/nds/libfat/source/cache.c | 237 |
1 files changed, 0 insertions, 237 deletions
diff --git a/c/src/lib/libbsp/arm/nds/libfat/source/cache.c b/c/src/lib/libbsp/arm/nds/libfat/source/cache.c deleted file mode 100644 index a1a597c284..0000000000 --- a/c/src/lib/libbsp/arm/nds/libfat/source/cache.c +++ /dev/null @@ -1,237 +0,0 @@ -/* - cache.c - The cache is not visible to the user. It should be flushed - when any file is closed or changes are made to the filesystem. - - This cache implements a least-used-page replacement policy. This will - distribute sectors evenly over the pages, so if less than the maximum - pages are used at once, they should all eventually remain in the cache. - This also has the benefit of throwing out old sectors, so as not to keep - too many stale pages around. - - Copyright (c) 2006 Michael "Chishm" Chisholm - - Redistribution and use in source and binary forms, with or without modification, - are permitted provided that the following conditions are met: - - 1. Redistributions of source code must retain the above copyright notice, - this list of conditions and the following disclaimer. - 2. Redistributions in binary form must reproduce the above copyright notice, - this list of conditions and the following disclaimer in the documentation and/or - other materials provided with the distribution. - 3. The name of the author may not be used to endorse or promote products derived - from this software without specific prior written permission. - - THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED - WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY - AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE - LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; - LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, - EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -*/ - -#include <string.h> - -#include "common.h" -#include "cache.h" -#include "disc_io/disc.h" - -#include "mem_allocate.h" - -#define CACHE_FREE 0xFFFFFFFF - -CACHE* _FAT_cache_constructor (u32 numberOfPages, const IO_INTERFACE* discInterface) { - CACHE* cache; - u32 i; - CACHE_ENTRY* cacheEntries; - - if (numberOfPages < 2) { - numberOfPages = 2; - } - - cache = (CACHE*) _FAT_mem_allocate (sizeof(CACHE)); - if (cache == NULL) { - return false; - } - - cache->disc = discInterface; - cache->numberOfPages = numberOfPages; - - - cacheEntries = (CACHE_ENTRY*) _FAT_mem_allocate ( sizeof(CACHE_ENTRY) * numberOfPages); - if (cacheEntries == NULL) { - _FAT_mem_free (cache); - return false; - } - - for (i = 0; i < numberOfPages; i++) { - cacheEntries[i].sector = CACHE_FREE; - cacheEntries[i].count = 0; - cacheEntries[i].dirty = false; - } - - cache->cacheEntries = cacheEntries; - - cache->pages = (u8*) _FAT_mem_allocate ( CACHE_PAGE_SIZE * numberOfPages); - if (cache->pages == NULL) { - _FAT_mem_free (cache->cacheEntries); - _FAT_mem_free (cache); - return false; - } - - return cache; -} - -void _FAT_cache_destructor (CACHE* cache) { - // Clear out cache before destroying it - _FAT_cache_flush(cache); - - // Free memory in reverse allocation order - _FAT_mem_free (cache->pages); - _FAT_mem_free (cache->cacheEntries); - _FAT_mem_free (cache); - - return; -} - -/* -Retrieve a sector's page from the cache. If it is not found in the cache, -load it into the cache and return the page it was loaded to. -Return CACHE_FREE on error. -*/ -static u32 _FAT_cache_getSector (CACHE* cache, u32 sector) { - u32 i; - CACHE_ENTRY* cacheEntries = cache->cacheEntries; - u32 numberOfPages = cache->numberOfPages; - - u32 leastUsed = 0; - u32 lowestCount = 0xFFFFFFFF; - - for (i = 0; (i < numberOfPages) && (cacheEntries[i].sector != sector); i++) { - // While searching for the desired sector, also search for the leased used page - if ( (cacheEntries[i].sector == CACHE_FREE) || (cacheEntries[i].count < lowestCount) ) { - leastUsed = i; - lowestCount = cacheEntries[i].count; - } - } - - // If it found the sector in the cache, return it - if ((i < numberOfPages) && (cacheEntries[i].sector == sector)) { - // Increment usage counter - cacheEntries[i].count += 1; - return i; - } - - // If it didn't, replace the least used cache page with the desired sector - if ((cacheEntries[leastUsed].sector != CACHE_FREE) && (cacheEntries[leastUsed].dirty == true)) { - // Write the page back to disc if it has been written to - if (!_FAT_disc_writeSectors (cache->disc, cacheEntries[leastUsed].sector, 1, cache->pages + CACHE_PAGE_SIZE * leastUsed)) { - return CACHE_FREE; - } - cacheEntries[leastUsed].dirty = false; - } - - // Load the new sector into the cache - if (!_FAT_disc_readSectors (cache->disc, sector, 1, cache->pages + CACHE_PAGE_SIZE * leastUsed)) { - return CACHE_FREE; - } - cacheEntries[leastUsed].sector = sector; - // Increment the usage count, don't reset it - // This creates a paging policy of least used PAGE, not sector - cacheEntries[leastUsed].count += 1; - return leastUsed; -} - -/* -Reads some data from a cache page, determined by the sector number -*/ -bool _FAT_cache_readPartialSector (CACHE* cache, void* buffer, u32 sector, u32 offset, u32 size) { - u32 page; - - if (offset + size > BYTES_PER_READ) { - return false; - } - - page = _FAT_cache_getSector (cache, sector); - if (page == CACHE_FREE) { - return false; - } - memcpy (buffer, cache->pages + (CACHE_PAGE_SIZE * page) + offset, size); - return true; -} - -/* -Writes some data to a cache page, making sure it is loaded into memory first. -*/ -bool _FAT_cache_writePartialSector (CACHE* cache, const void* buffer, u32 sector, u32 offset, u32 size) { - u32 page; - - if (offset + size > BYTES_PER_READ) { - return false; - } - - page = _FAT_cache_getSector (cache, sector); - if (page == CACHE_FREE) { - return false; - } - - memcpy (cache->pages + (CACHE_PAGE_SIZE * page) + offset, buffer, size); - cache->cacheEntries[page].dirty = true; - - return true; -} - -/* -Writes some data to a cache page, zeroing out the page first -*/ -bool _FAT_cache_eraseWritePartialSector (CACHE* cache, const void* buffer, u32 sector, u32 offset, u32 size) { - u32 page; - - if (offset + size > BYTES_PER_READ) { - return false; - } - - page = _FAT_cache_getSector (cache, sector); - if (page == CACHE_FREE) { - return false; - } - - memset (cache->pages + (CACHE_PAGE_SIZE * page), 0, CACHE_PAGE_SIZE); - memcpy (cache->pages + (CACHE_PAGE_SIZE * page) + offset, buffer, size); - cache->cacheEntries[page].dirty = true; - - return true; -} - - -/* -Flushes all dirty pages to disc, clearing the dirty flag. -Also resets all pages' page count to 0. -*/ -bool _FAT_cache_flush (CACHE* cache) { - u32 i; - - for (i = 0; i < cache->numberOfPages; i++) { - if (cache->cacheEntries[i].dirty) { - if (!_FAT_disc_writeSectors (cache->disc, cache->cacheEntries[i].sector, 1, cache->pages + CACHE_PAGE_SIZE * i)) { - return CACHE_FREE; - } - } - cache->cacheEntries[i].count = 0; - cache->cacheEntries[i].dirty = false; - } - - return true; -} - -void _FAT_cache_invalidate (CACHE* cache) { - int i; - for (i = 0; i < cache->numberOfPages; i++) { - cache->cacheEntries[i].sector = CACHE_FREE; - cache->cacheEntries[i].count = 0; - cache->cacheEntries[i].dirty = false; - } -} |