fat_cache.c

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//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
//                            FAT16/32 File IO Library
//                                    V2.6
//                              Ultra-Embedded.com
//                            Copyright 2003 - 2012
//
//                         Email: admin@ultra-embedded.com
//
//                                License: GPL
//   If you would like a version with a more permissive license for use in
//   closed source commercial applications please contact me for details.
//-----------------------------------------------------------------------------
//
// This file is part of FAT File IO Library.
//
// FAT File IO Library 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.
//
// FAT File IO Library 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 FAT File IO Library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//-----------------------------------------------------------------------------
//-----------------------------------------------------------------------------
#include <string.h>
#include "fat_cache.h"
 
// Per file cluster chain caching used to improve performance.
// This does not have to be enabled for architectures with low
// memory space.
 
//-----------------------------------------------------------------------------
// fatfs_cache_init:
//-----------------------------------------------------------------------------
int fatfs_cache_init(struct fatfs *fs, FL_FILE *file)
{
#ifdef FAT_CLUSTER_CACHE_ENTRIES
    int i;
 
    for (i=0;i<FAT_CLUSTER_CACHE_ENTRIES;i++)
    {
        file->cluster_cache_idx[i] = 0xFFFFFFFF; // Not used
        file->cluster_cache_data[i] = 0;
    }
#endif
 
    return 1;
}
//-----------------------------------------------------------------------------
// fatfs_cache_get_next_cluster:
//-----------------------------------------------------------------------------
int fatfs_cache_get_next_cluster(struct fatfs *fs, FL_FILE *file, uint32 clusterIdx, uint32 *pNextCluster)
{
#ifdef FAT_CLUSTER_CACHE_ENTRIES
    uint32 slot = clusterIdx % FAT_CLUSTER_CACHE_ENTRIES;
 
    if (file->cluster_cache_idx[slot] == clusterIdx)
    {
        *pNextCluster = file->cluster_cache_data[slot];
        return 1;
    }
#endif
 
    return 0;
}
//-----------------------------------------------------------------------------
// fatfs_cache_set_next_cluster:
//-----------------------------------------------------------------------------
int fatfs_cache_set_next_cluster(struct fatfs *fs, FL_FILE *file, uint32 clusterIdx, uint32 nextCluster)
{
#ifdef FAT_CLUSTER_CACHE_ENTRIES
    uint32 slot = clusterIdx % FAT_CLUSTER_CACHE_ENTRIES;
 
    if (file->cluster_cache_idx[slot] == clusterIdx)
        file->cluster_cache_data[slot] = nextCluster;
    else
    {
        file->cluster_cache_idx[slot] = clusterIdx;
        file->cluster_cache_data[slot] = nextCluster;
    }
#endif
 
    return 1;
}