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Fat.c
资源名称：51-SD.rar　[点击查看]
上传用户：jcsy2001
上传日期：2013-11-29
资源大小：201k
文件大小：5k
源码类别：

嵌入式/单片机编程

开发平台：

C/C++

Fat.c：源码内容
  1. #include "common.h"
  2. #include "Fat.h"
  3. #include "Fat32.h"
  4. #include "DEVICE.H"
  5. #include "HAL.H"
  6. ////////////////////////////////////////
  7. extern SYS_INFO_BLOCK xdata DeviceInfo;
  8. extern FILE_INFO xdata ThisFile;
  9. extern unsigned char xdata DBUF[BUFFER_LENGTH];
  10. unsigned char xdata FATBUF[512];
  11. ////////////////////////////////////////
  13. unsigned long FirstSectorofCluster(unsigned int clusterNum)
  14. {
  15. unsigned long temp;
  16. temp=clusterNum-2;
  17. temp=temp*DeviceInfo.BPB_SecPerClus;
  18. temp=temp+DeviceInfo.FirstDataSector;
  19. return temp;
  20. }
  22. unsigned int ThisFatSecNum(unsigned int clusterNum)
  23. {
  25.    unsigned int temp;
  26.    temp=clusterNum/(DeviceInfo.BPB_BytesPerSec/2);
  27.    temp=temp+DeviceInfo.FatStartSector;
  28.    return temp;
  30. }
  32. unsigned int ThisFatEntOffset(unsigned int clusterNum)
  33. {    
  34. return (clusterNum%(DeviceInfo.BPB_BytesPerSec/2))*2;
  35. }
  37. unsigned int GetNextClusterNum(unsigned int clusterNum)
  38. {
  39. unsigned int FatSecNum,FatEntOffset;
  41. FatSecNum=ThisFatSecNum(clusterNum);
  42. FatEntOffset=ThisFatEntOffset(clusterNum);
  43. if(ThisFile.FatSectorPointer!=FatSecNum)
  44. {
  46. if(!SdReadSector(FatSecNum,1,FATBUF))
  47. return 0xFFFF;
  48. ThisFile.FatSectorPointer=FatSecNum;
  49. }
  51. ///////////////////////////////////////////////////
  52. clusterNum=FATBUF[FatEntOffset+1];
  53. clusterNum=clusterNum<<8;
  54. clusterNum+=FATBUF[FatEntOffset];
  55. return clusterNum;
  56. }
  58. unsigned char GoToPointer(unsigned long pointer)
  59. {
  61. unsigned int clusterSize;
  63. clusterSize=DeviceInfo.BPB_SecPerClus*DeviceInfo.BPB_BytesPerSec;
  64. ThisFile.ClusterPointer=ThisFile.StartCluster;
  65. while(pointer>clusterSize)
  66. {
  67. pointer-=clusterSize;
  68. ThisFile.ClusterPointer=GetNextClusterNum(ThisFile.ClusterPointer);
  69. if(ThisFile.ClusterPointer==0xffff)
  70. {
  71. return FALSE;
  72. }
  73. }
  74. ThisFile.SectorofCluster=pointer/DeviceInfo.BPB_BytesPerSec;
  75. ThisFile.SectorPointer=FirstSectorofCluster(ThisFile.ClusterPointer)+ThisFile.SectorofCluster;
  76. ThisFile.OffsetofSector=pointer%DeviceInfo.BPB_BytesPerSec;
  77. ThisFile.FatSectorPointer=0;
  78. return TRUE;
  80. }
  82. unsigned char DeleteClusterLink(unsigned int clusterNum)
  83. {
  84. unsigned int FatSecNum,FatEntOffset;
  85. unsigned char i;
  86. while((clusterNum>1)&&(clusterNum<0xfff0))
  87. {
  88. FatSecNum=ThisFatSecNum(clusterNum);
  89. FatEntOffset=ThisFatEntOffset(clusterNum);
  90. if(SdReadSector(FatSecNum,1,DBUF))
  91. {
  92.  if(clusterNum<DeviceInfo.LastFreeCluster) DeviceInfo.LastFreeCluster=clusterNum; 
  93.  clusterNum=DBUF[FatEntOffset+1];
  94.  clusterNum=clusterNum<<8;
  95.  clusterNum+=DBUF[FatEntOffset];  
  96. }
  97. else
  98. return FALSE;
  99. DBUF[FatEntOffset]=0x00;
  100. DBUF[FatEntOffset+1]=0x00;
  101. for(i=0;i<DeviceInfo.BPB_NumFATs;i++)
  102. {
  103. DelayMs(5);
  104. if(!SdWriteSector(FatSecNum+i*DeviceInfo.BPB_FATSz16,1,DBUF))
  105. return FALSE;
  106. }
  107. }
  108. return TRUE;
  109. }
  111. unsigned int GetFreeCusterNum(void)
  112. {
  113. unsigned int clusterNum,i;
  114. unsigned long sectorNum;
  115. unsigned char j;
  116. clusterNum=0;
  117. // sectorNum=DeviceInfo.FatStartSector;
  119.     sectorNum=ThisFatSecNum(DeviceInfo.LastFreeCluster);
  120.     clusterNum=(sectorNum-DeviceInfo.FatStartSector)*(DeviceInfo.BPB_BytesPerSec/2);
  122. while(sectorNum<DeviceInfo.BPB_FATSz16+DeviceInfo.FatStartSector)
  123. {
  125. if(!SdReadSector(sectorNum,1,DBUF))
  126. return 0x0;
  127. for(i=0;i<DeviceInfo.BPB_BytesPerSec;i=i+2)
  128.    {
  129.     if((DBUF[i]==0)&&(DBUF[i+1]==0))
  130.      {
  131.      DBUF[i]=0xff;
  132.      DBUF[i+1]=0xff;
  133. for(j=0;j<DeviceInfo.BPB_NumFATs;j++)
  134. {
  135. DelayMs(5);
  136. if(!SdWriteSector(sectorNum+j*DeviceInfo.BPB_FATSz16,1,DBUF))
  137. return FALSE;
  138. }
  139.                 clusterNum=clusterNum+i/2;
  140.         if((clusterNum-2)<DeviceInfo.TotCluster) 
  141.   {
  142.    if(clusterNum>DeviceInfo.LastFreeCluster) DeviceInfo.LastFreeCluster=clusterNum;
  143.    return clusterNum;
  144.   }
  145.       else return FALSE; 
  146.      }
  147.     
  148.    }
  149. clusterNum+=DeviceInfo.BPB_BytesPerSec/2;
  150. sectorNum++;
  151. DelayMs(1);
  152. }
  154. return 0x0;
  155. }
  157. unsigned int CreateClusterLink(unsigned int currentCluster)
  158. {
  159. unsigned int newCluster;
  160. unsigned int FatSecNum,FatEntOffset;
  161. unsigned char i;
  163. newCluster=GetFreeCusterNum();
  165. if(newCluster==0)
  166. return 0x00;
  168. FatSecNum=ThisFatSecNum(currentCluster);
  169. FatEntOffset=ThisFatEntOffset(currentCluster);
  170. if(SdReadSector(FatSecNum,1,DBUF))
  171. {
  172. DBUF[FatEntOffset]=newCluster;
  173. DBUF[FatEntOffset+1]=newCluster>>8;
  174. for(i=0;i<DeviceInfo.BPB_NumFATs;i++)
  175. {
  176. DelayMs(5);
  177. if(!SdWriteSector(FatSecNum+i*DeviceInfo.BPB_FATSz16,1,DBUF))
  178. return FALSE;
  179. }
  180. }
  181. else
  182. return 0x00;
  184. return newCluster;
  185. }