aplfw/volume/fat/fatvol_clusterread.c

   1 #include "fatvol_local.h"
   2
   3
   4 /** クラスタ読み込み */
   5 int FatVol_ClusterRead(
   6                 C_FATVOL    *self,
   7                 FATVOL_UINT uiCluster,
   8                 void        *pBuf)
   9 {
  10         FATVOL_UINT uiPos;
  11         FATVOL_UINT uiSize;
  12
  13         if ( uiCluster >= 0xffff0000 && (self->iFatType == FATVOL_TYPE_FAT12 || self->iFatType == FATVOL_TYPE_FAT16) )
  14         {
  15                 /* FAT12/16 のルートディレクトリを 0xf0000000 にマップ */
  16                 uiCluster -= 0xf0000000;
  17
  18                 /* 読み出し位置移動 */
  19                 uiPos = (self->uiRootDirSector + (uiCluster * self->uiSectorsPerCluster)) * self->uiBytesPerSector;
  20                 if ( File_Seek(self->hBlockFile, uiPos, FILE_SEEK_SET) != uiPos )
  21                 {
  22                         return FATVOL_ERR_NG;
  23                 }
  24
  25                 /* 読み出し */
  26                 uiSize = self->uiBytesPerSector * self->uiSectorsPerCluster;
  27                 if ( File_Read(self->hBlockFile, pBuf, uiSize) != uiSize )
  28                 {
  29                         return FATVOL_ERR_NG;
  30                 }
  31         }
  32         else
  33         {
  34                 /* 読み出し位置移動 */
  35                 uiPos = (self->uiCluster0Sector + (uiCluster * self->uiSectorsPerCluster)) * self->uiBytesPerSector;
  36                 if ( File_Seek(self->hBlockFile, uiPos, FILE_SEEK_SET) != uiPos )
  37                 {
  38                         return FATVOL_ERR_NG;
  39                 }
  40
  41                 /* 読み出し */
  42                 uiSize = self->uiBytesPerSector * self->uiSectorsPerCluster;
  43                 if ( File_Read(self->hBlockFile, pBuf, uiSize) != uiSize )
  44                 {
  45                         return FATVOL_ERR_NG;
  46                 }
  47         }
  48
  49         return FATVOL_ERR_OK;
  50 }
  51
  52
  53 /* end of file */