LinuxGUI/Ventoy2Disk/Lib/fat_io_lib/fat_cache.c

   1 //-----------------------------------------------------------------------------
   2 //-----------------------------------------------------------------------------
   3 //                            FAT16/32 File IO Library
   4 //                                    V2.6
   5 //                              Ultra-Embedded.com
   6 //                            Copyright 2003 - 2012
   7 //
   8 //                         Email: admin@ultra-embedded.com
   9 //
  10 //                                License: GPL
  11 //   If you would like a version with a more permissive license for use in
  12 //   closed source commercial applications please contact me for details.
  13 //-----------------------------------------------------------------------------
  14 //
  15 // This file is part of FAT File IO Library.
  16 //
  17 // FAT File IO Library is free software; you can redistribute it and/or modify
  18 // it under the terms of the GNU General Public License as published by
  19 // the Free Software Foundation; either version 2 of the License, or
  20 // (at your option) any later version.
  21 //
  22 // FAT File IO Library is distributed in the hope that it will be useful,
  23 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  24 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  25 // GNU General Public License for more details.
  26 //
  27 // You should have received a copy of the GNU General Public License
  28 // along with FAT File IO Library; if not, write to the Free Software
  29 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  30 //-----------------------------------------------------------------------------
  31 //-----------------------------------------------------------------------------
  32 #include <string.h>
  33 #include "fat_cache.h"
  34
  35 // Per file cluster chain caching used to improve performance.
  36 // This does not have to be enabled for architectures with low
  37 // memory space.
  38
  39 //-----------------------------------------------------------------------------
  40 // fatfs_cache_init:
  41 //-----------------------------------------------------------------------------
  42 int fatfs_cache_init(struct fatfs *fs, FL_FILE *file)
  43 {
  44 #ifdef FAT_CLUSTER_CACHE_ENTRIES
  45     int i;
  46
  47     for (i=0;i<FAT_CLUSTER_CACHE_ENTRIES;i++)
  48     {
  49         file->cluster_cache_idx[i] = 0xFFFFFFFF; // Not used
  50         file->cluster_cache_data[i] = 0;
  51     }
  52 #endif
  53
  54     return 1;
  55 }
  56 //-----------------------------------------------------------------------------
  57 // fatfs_cache_get_next_cluster:
  58 //-----------------------------------------------------------------------------
  59 int fatfs_cache_get_next_cluster(struct fatfs *fs, FL_FILE *file, uint32 clusterIdx, uint32 *pNextCluster)
  60 {
  61 #ifdef FAT_CLUSTER_CACHE_ENTRIES
  62     uint32 slot = clusterIdx % FAT_CLUSTER_CACHE_ENTRIES;
  63
  64     if (file->cluster_cache_idx[slot] == clusterIdx)
  65     {
  66         *pNextCluster = file->cluster_cache_data[slot];
  67         return 1;
  68     }
  69 #endif
  70
  71     return 0;
  72 }
  73 //-----------------------------------------------------------------------------
  74 // fatfs_cache_set_next_cluster:
  75 //-----------------------------------------------------------------------------
  76 int fatfs_cache_set_next_cluster(struct fatfs *fs, FL_FILE *file, uint32 clusterIdx, uint32 nextCluster)
  77 {
  78 #ifdef FAT_CLUSTER_CACHE_ENTRIES
  79     uint32 slot = clusterIdx % FAT_CLUSTER_CACHE_ENTRIES;
  80
  81     if (file->cluster_cache_idx[slot] == clusterIdx)
  82         file->cluster_cache_data[slot] = nextCluster;
  83     else
  84     {
  85         file->cluster_cache_idx[slot] = clusterIdx;
  86         file->cluster_cache_data[slot] = nextCluster;
  87     }
  88 #endif
  89
  90     return 1;
  91 }