aplfw/volume/fat/fatfile_read.c

   1
   2
   3 #include <string.h>
   4 #include "fatfile_local.h"
   5
   6
   7 /* 読み出し */
   8 FILE_SIZE FatFile_Read(
   9                         HANDLE    hFile,
  10                         void      *pBuf,
  11                         FILE_SIZE Size)
  12 {
  13         C_FATFILE     *self;
  14         void          *pClusterBuf;
  15         FATVOL_UINT   ulBlock;
  16         FILE_SIZE     ReadSize;
  17
  18         /* ハンドル取得 */
  19         self = (C_FATFILE *)hFile;
  20
  21         /* サイズオーバーするなら */
  22         if ( self->FilePos + Size > self->FileSize )
  23         {
  24                 /* サイズ更新されていないかディレクトリテーブルを参照 */
  25                 if ( self->hDir != NULL )
  26                 {
  27                 }
  28         }
  29
  30         /* サイズクリップ */
  31         if ( Size > self->FileSize - self->FilePos )
  32         {
  33                 Size = self->FileSize - self->FilePos;
  34         }
  35
  36         /* 要求読み出し量保存 */
  37         ReadSize = Size;
  38
  39         /* 読み出し */
  40         while ( Size > 0 && self->FilePos < self->FileSize )
  41         {
  42                 FILE_POS      ReadStart;
  43                 FILE_SIZE     ReadSize;
  44                 unsigned char *pubClusterBuf;
  45
  46                 /* 転送位置計算 */
  47                 ReadStart = self->FilePos % self->uiClusterSize;
  48                 ReadSize  = self->uiClusterSize - ReadStart;
  49                 if ( ReadSize > Size )
  50                 {
  51                         ReadSize = Size;
  52                 }
  53
  54                 /* バッファ取得 */
  55                 if ( FatVol_GetClusterBuf(self->pFatVol, self->uiCurrentCluster, &pClusterBuf, 1) != FATVOL_ERR_OK )
  56                 {
  57                         break;
  58                 }
  59
  60                 /* 転送 */
  61                 memcpy(pBuf, (char *)pClusterBuf + ReadStart, ReadSize);
  62
  63                 /* バッファ開放 */
  64                 FatVol_RelClusterBuf(self->pFatVol, pClusterBuf, 0);
  65
  66                 /* サイズ更新 */
  67                 self->FilePos += ReadSize;
  68                 pBuf =  (char *)pBuf + ReadSize;
  69                 Size -= ReadSize;
  70
  71                 /* 次のクラスタに進む */
  72                 self->uiCurrentCluster = FatVol_GetNextCluster(self->pFatVol, self->uiCurrentCluster);
  73         }
  74
  75         return ReadSize - Size;
  76 }
  77
  78
  79 /* end of file */