aplfw/driver/volume/fat/fatvol_getclusterbuf.c

   1 /**
   2  *  Hyper Operating System  Application Framework
   3  *
   4  * @file  fatvol.c
   5  * @brief %jp{FATボリューム用デバイスドライバ}
   6  *
   7  * Copyright (C) 2006-2007 by Project HOS
   8  * http://sourceforge.jp/projects/hos/
   9  */
  10
  11
  12 #include <string.h>
  13 #include "fatvol_local.h"
  14
  15
  16 static int FatVol_AlloctClusterBuf(C_FATVOL *self, FATVOL_UINT uiCluster, int iRead);
  17
  18
  19 T_FATVOL_CLUSTERBUF *FatVol_GetClusterBuf(C_FATVOL *self, FATVOL_UINT uiCluster, int iRead)
  20 {
  21         int iIndex;
  22
  23         /* バッファを割り当てる */
  24         iIndex = FatVol_AlloctClusterBuf(self, uiCluster, iRead);
  25         if ( iIndex < 0 )
  26         {
  27                 return NULL;
  28         }
  29
  30         /* 並び替える */
  31         if ( iIndex != 0 )
  32         {
  33                 T_FATVOL_CLUSTERBUF Tmp;
  34                 Tmp = self->pClusterBuf[iIndex];
  35                 memmove(&self->pClusterBuf[1], &self->pClusterBuf[0], iIndex * sizeof(T_FATVOL_CLUSTERBUF));
  36                 self->pClusterBuf[0] = Tmp;
  37         }
  38
  39         return  &self->pClusterBuf[0];
  40 }
  41
  42
  43 int FatVol_AlloctClusterBuf(C_FATVOL *self, FATVOL_UINT uiCluster, int iRead)
  44 {
  45         int iIndex;
  46
  47         /* 既にバッファに居ないか探索 */
  48         for ( iIndex = 0; iIndex < self->iClusterBufNum; iIndex++ )
  49         {
  50                 /* 見つかれば既存バッファを返す */
  51                 if ( self->pClusterBuf[iIndex].uiClusterNum == uiCluster )
  52                 {
  53                         return iIndex;
  54                 }
  55         }
  56
  57
  58         /* 空のバッファを探す */
  59         for ( iIndex = 0; iIndex < self->iClusterBufNum; iIndex++ )
  60         {
  61                 if ( self->pClusterBuf[iIndex].uiClusterNum == FATVOL_CLUSTER_ENDMARKER )
  62                 {
  63                         break;
  64                 }
  65         }
  66
  67         /* 空きが無ければ空ける */
  68         if ( iIndex >= self->iClusterBufNum )
  69         {
  70                 /* 末尾を空ける */
  71                 iIndex = self->iClusterBufNum - 1;
  72
  73                 /* dirtyなら吐き出す */
  74                 if ( self->pClusterBuf[iIndex].iDirty )
  75                 {
  76                         if ( FatVol_ClusterWrite(self, self->pClusterBuf[iIndex].uiClusterNum, self->pClusterBuf[iIndex].pubBuf) != FATVOL_ERR_OK )
  77                         {
  78                                 return -1;
  79                         }
  80                         self->pClusterBuf[iIndex].iDirty = 0;
  81                 }
  82                 self->pClusterBuf[iIndex].uiClusterNum = FATVOL_CLUSTER_ENDMARKER;
  83         }
  84
  85         /* バッファに読み込み */
  86         if ( iRead )
  87         {
  88                 if ( FatVol_ClusterRead(self, uiCluster, self->pClusterBuf[iIndex].pubBuf) != FATVOL_ERR_OK )
  89                 {
  90                         return -1;
  91                 }
  92         }
  93         self->pClusterBuf[iIndex].iDirty       = 0;
  94         self->pClusterBuf[iIndex].uiClusterNum = uiCluster;
  95
  96         return iIndex;
  97 }
  98
  99
 100 /* end of file */