write.c

基于c51的SD驱动程序,在FAT32文件系统中.

#ifndef _FAT32_DEFINE
 #include "FAT32.c"
#endif

#define LAST_CLUSTER 0xFFFFFFFF
//#define EOF     0xFF
#define DISK_FULL 0xFF

CHAR FAT32WriteFile(BYTE fp,CHAR *WriteBuffer,WORD BytesToWrite);
DWORD FreeClus(void);
DWORD ReqstNewClus(OldClus);
BYTE DEleteFile(CHAR *filename);
BYTE CreatFile(CHAR * filename);

CHAR FAT32WriteFile(BYTE fp,CHAR *WriteBuffer,WORD BytesToWrite)
{
    WORD WritedBytes;
	WORD i,j;
	BYTE dir;
	bit FILE_END;
    while(FCB[fp].LastCluster<LAST_CLUSTER)                      //find the last cluster
    {
         FCB[fp].LastCluster=FAT32NextCluster(FCB[fp].LastCluster);
    }
    while (FILE_END !=1)                                      //find the end of the file
    {
        FAT32ReadCluster(&FCB[fp].LastCluster);
        for(j=0;j<512;j++)
        {
             if(DiskBuffer[j]==EOF)
             {
                  FCB[fp].ClusSecCnt = i;
                  FCB[fp].ByteCnt = j;
                  FILE_END = 1;
                  break;
             }
        }
    }
    do
    {
        if(FCB[fp].ByteCnt<=512)   
        {
            DiskBuffer[FCB[fp].ByteCnt] = WriteBuffer[WritedBytes]; //ready
            if((WritedBytes++)>=BytesToWrite) return 0;
        }
        else 
        {
            WriteDiskSector(FCB[fp].LastCluster*FAT32.SecPerClus);   //write a sector
            FCB[fp].ByteCnt=0;
            FCB[fp].ClusSecCnt++;
            if(FCB[fp].ClusSecCnt>=FAT32.SecPerClus)
            {
                FCB[fp].LastCluster=ReqstNewClus(FCB[fp].LastCluster);
                if(FCB[fp].LastCluster!=0) continue;
            }
        }
    }while(1);
    dir = FAT32FindDIREntry(FCB[fp].FileName);
    sDIR[dir].FileSize+= BytesToWrite;
	FCB[fp].Size += BytesToWrite;
   
    WriteDiskSector(ClusterToSector( FAT32.CurrentDirectory)+FAT32.ClusSecCnt);
}

DWORD FreeClus(void)
{
    BYTE i;
    for(FAT.Sector=0;FAT.Sector<FAT32.FATSz;FAT.Sector++)
    {
        ReadDiskSector(FAT32.FATSec+FAT.Sector);
        for(i=0;i<128;i++)
        {
	    if(((DWORD *)&DiskBuffer)[i]==0x0000)
            {
                return (i+128*FAT.Sector);
            }
        }
    }
    return DISK_FULL;
}

DWORD ReqstNewClus(OldClus)
{
    DWORD NewClus;
    NewClus = FreeClus();
    if(NewClus == DISK_FULL) return DISK_FULL;
    ((DWORD *)DiskBuffer)[NewClus%128] = LAST_CLUSTER;
    WriteDiskSector(FAT32.FATSec+FAT.Sector);                //write the first FAT
    WriteDiskSector(FAT32.FATSec+FAT.Sector+FAT32.FATSz);    //write the second FAT
    if(OldClus)
    {
        FAT.Sector = OldClus/128;
        ReadDiskSector(FAT32.FATSec+FAT.Sector);
        ((DWORD *)DiskBuffer)[OldClus%128] = NewClus;
        WriteDiskSector(FAT32.FATSec+FAT.Sector);
        WriteDiskSector(FAT32.FATSec+FAT.Sector+FAT32.FATSz); 
    }
    return NewClus;
}

BYTE DEleteFile(CHAR *filename)
{
	BYTE fp;
	BYTE dir;
	DWORD chain;
	fp=FAT32OpenFile(filename);
    if(fp==FAT32_MAX_FCB) return (0x00);
    /*delete the FAT*/
	while(FCB[fp].LastCluster!=LAST_CLUSTER)
	{
		ReadDiskSector(FAT32.FATSec+FCB[fp].LastCluster/128);
        ((DWORD *)DiskBuffer)[FCB[fp].LastCluster] = 0x0000;
        WriteDiskSector(FAT32.FATSec+FCB[fp].LastCluster%128);
        WriteDiskSector(FAT32.FATSec+FCB[fp].LastCluster%128+FAT32.FATSz); 
		FCB[fp].LastCluster = FAT32NextCluster(FCB[fp].LastCluster);
	}
	FAT32CloseFile(fp);
    /*delete the directory*/
    dir = FAT32FindDIREntry(filename);
    sDIR[dir].Name[0]=0x00;
    chain=FAT32.CurrentDirectory;
    WriteDiskSector(ClusterToSector(chain)+FAT32.ClusSecCnt);
}

BYTE CreatFile(CHAR * filename)
{
    DWORD FstClus;
	DWORD chain;
    BYTE i,j;
    FstClus = ReqstNewClus(0);
	chain=FAT32.CurrentDirectory;
	while(chain!=0x0fffffff)
	{
		FAT32ReadCluster(&chain);
		for (i=0;i<16;i++)
		{
			if (sDIR[i].Name[0]==0xe5||sDIR[i].Name[0]==0x00) 
			{  
			    for(j=0;j<11;j++)
				sDIR[i].Name[j] = filename[j];
				sDIR[i].Attr    = 
				sDIR[i].FstClusHI = ((WORD *)&FstClus)[1];
				sDIR[i].FstClusLO = ((WORD *)&FstClus)[0];
				sDIR[i].FileSize = 0;
				return 0;
             }
		 }
	}
	return DISK_FULL;
}