SD卡上的FAT32文件系统源代码

#include "uart.h" #include "sd.h" #include "FAT16.h" unsigned int FirstDataSector; // The first sector number of data unsigned int BytesPerSector; // unsigned chars per sector unsigned int FATsectors; // The amount sector a FAT occupied unsigned int SectorsPerClust; // Sector per cluster unsigned int FirstFATSector; // The first FAT sector unsigned int FirstDirSector; // The first Dir sector unsigned int RootDirSectors; // The sector number a Root dir occupied unsigned int RootDirCount; // The count of directory in root dir struct FileInfoStruct FileInfo;//temporarily buffer for file information unsigned char xdata buffer[512]; unsigned long lb2bb(unsigned char *dat,unsigned char len) { unsigned long temp=0; unsigned long fact=1; unsigned char i=0; for(i=0;i<len;i++) { temp+=dat[i]*fact; fact*=256; } return temp; } unsigned char FAT16_ReadSector(unsigned long lba,unsigned char *buf) { MMC_get_data_LBA(lba,512,buf); return 0; } unsigned char FAT16_WriteSector(unsigned long lba,unsigned char *buf) { return MMC_write_sector(lba,buf); } //unsigned char (* FAT16_ReadSector)(unsigned long,unsigned char *); //unsigned char (* FAT16_WriteSector)(unsigned long,unsigned char *); //unsigned char (* FAT16_ReadSector)(unsigned long sector, unsigned char * buffer)=MMC_SD_ReadSingleBlock;//device read //unsigned char (* FAT16_WriteSector)(unsigned long sector, unsigned char * buffer)=MMC_SD_WriteSingleBlock;//device write void free(unsigned char *b) { unsigned int i=0; for(i=0;i<512;i++) { b[i]=0; } } unsigned char FAT16_Init()//Initialize of FAT16 { struct bootsector50 *bs; struct bpb50 *bpb; unsigned int hidsec; for(hidsec=100;hidsec<200;hidsec++)//Some card the BPB is not locat at secter 0 { if(FAT16_ReadSector(hidsec,buffer)) return 1; if(buffer[0]==0xeb || buffer[0]==0xe9) break; } if(hidsec==200) return 1; //error maybe the card hasn't been formated bs=(struct bootsector50 *)buffer; bs->bsOemName[7]=0; send_s(bs->bsOemName); if(bs->bsJump[0]!=0xE9 && bs->bsJump[0]!=0xEB) return 1; bpb=(struct bpb50 *)bs->bsBPB; BytesPerSector =lb2bb((unsigned char *)(&(bpb->bpbBytesPerSec)),2); Printf("BytesPerSector",BytesPerSector); FATsectors = lb2bb((unsigned char *)(&(bpb->bpbFATsecs)),2); Printf("FATsectors=",FATsectors); SectorsPerClust = (unsigned char)bpb->bpbSecPerClust; Printf("SectorsPerClust=",SectorsPerClust); FirstFATSector = lb2bb((unsigned char *)(&(bpb->bpbResSectors)),2)+hidsec; Printf("FirstFATSector=",FirstFATSector); RootDirCount = lb2bb((unsigned char *)(&(bpb->bpbRootDirEnts)),2); Printf("RootDirCount=",RootDirCount); RootDirSectors = (RootDirCount*32)>>9; Printf("RootDirSectors=",RootDirSectors); FirstDirSector = FirstFATSector+bpb->bpbFATs*FATsectors; Printf("FirstDirSector=",FirstDirSector); FirstDataSector = FirstDirSector+RootDirSectors; Printf("FirstDataSector=",FirstDataSector); return 0; } unsigned char FAT16_LoadPartCluster(unsigned int cluster,unsigned long part,unsigned char * buffer) { unsigned long sector; sector=FirstDataSector+(unsigned long)(cluster-2)*(unsigned long)SectorsPerClust;//calculate the actual sector number if(FAT16_ReadSector(sector+part,buffer)) return 1; else return 0; } //Read the a cluster //Not suitable for system which has few data RAM unsigned char FAT16_LoadCluster(unsigned int cluster,unsigned char * buffer) { unsigned long sector; unsigned char i; sector=FirstDataSector+(unsigned long)(cluster-2)*(unsigned long)SectorsPerClust;//calculate the actual sector number for(i=0;i<SectorsPerClust;i++) { if(FAT16_ReadSector(sector+i,buffer+(i<<9))) break; } if(i==SectorsPerClust) return 0; else return 1; } //Return the cluster number of next cluster of file //Suitable for system which has limited RAM unsigned int FAT16_NextCluster(unsigned int cluster) { //unsigned char buffer[512]; unsigned long sector; unsigned long offset=cluster/256; if(cluster<2)return 0xfff8; sector=FirstFATSector+offset;//calculate the actual sector if(FAT16_ReadSector(sector,buffer))return 0xfff8;//read fat table / return 0xfff8 when error occured offset=cluster%256;//find the position //offset<<=1; //sector=buffer[offset+1]; // sector<<=8; //sector+=buffer[offset]; sector=((unsigned int *)buffer)[offset]; return (unsigned int)sector;//return the cluste number } //Find a free cluster return the cluster number unsigned int FAT16_FindFreeCluster() { //unsigned char buffer[512]; //unsigned long sector; unsigned int i; unsigned int cnt; // sector=FirstFATSector+offset;//calculate the actual sector //sector=FirstFATSector; for(cnt=0;cnt<FATsectors;cnt++)//find in the FAT table { if(FAT16_ReadSector(FirstFATSector+cnt,buffer)) return 1;//error for(i=0;i<256;i++) { if(((unsigned int *)buffer)[i]==0x0000) break;//an unused cluster } if(i!=256) { cnt=cnt*512+i; return cnt;//return the free cluster number } } return 1;//error } //find a position to place a item withe the given directory, the parameter is FileInfo who brought the message unsigned int FAT16_FindFreeItem(unsigned int cluster, struct FileInfoStruct *FileInfo) { //unsigned char *buffer; unsigned long tempclust; unsigned long sector; unsigned char cnt; unsigned int offset; // unsigned char i; struct direntry *item; if(cluster==0)// root directory { //buffer=malloc(512);//apply memory //if(buffer==0)return 1;//if failed for(cnt=0;cnt<RootDirSectors;cnt++) { if(FAT16_ReadSector(FirstDirSector+cnt,buffer)) { free(buffer); return 1; }//read sector for(offset=0;offset<512;offset+=32) { item=(struct direntry *)(&buffer[offset]); //used item if((item->deName[0] != 0x00) & (item->deName[0] != 0xe5) & (item->deAttributes != 0x0f)); //unused item else { FileInfo->StartCluster = item->deStartCluster;//don't care FileInfo->Size = item->deFileSize;//don't care FileInfo->Attr = item->deAttributes;//don't care FileInfo->Sector = FirstDirSector+cnt;//The key parameter record the secoter nuber which the item stored FileInfo->Offset = offset; //The key parameter record the offset in the sector free(buffer);//realease return 0;//done } } } free(buffer);//release } else//other folders { tempclust=cluster; while(1) { sector=FirstDataSector+(tempclust-2)*SectorsPerClust;//calculate the actual sector number //buffer=malloc(512);//apply memory //if(buffer==0)return 1;//if failed for(cnt=0;cnt<SectorsPerClust;cnt++) { if(FAT16_ReadSector(sector+cnt,buffer)) { free(buffer); return 1; } for(offset=0;offset<512;offset+=32) { item=(struct direntry *)(&buffer[offset]); if((item->deName[0] != 0x2e) & (item->deName[0] != 0x00) & (item->deName[0] != 0xe5) & (item->deAttributes != 0x0f)); else { FileInfo->StartCluster = item->deStartCluster; FileInfo->Size = item->deFileSize; FileInfo->Attr = item->deAttributes; FileInfo->Sector = sector+cnt; FileInfo->Offset = offset; free(buffer); return 0; } } } free(buffer);//release tempclust=FAT16_NextCluster(tempclust);//next cluster if(tempclust == 0xffff || tempclust == 0xfff8) return 1; } } return 1; } //Find a item in the directory which specify by the parameter "cluster" //Return the start cluster number unsigned int FAT16_FindItem(unsigned int cluster, unsigned char *name, struct FileInfoStruct *FileInfo) { //unsigned char *buffer; unsigned long tempclust; unsigned long sector; unsigned char cnt; unsigned int offset; unsigned c