FAT16 Sektoren im Cluster Reihenfolge der Belegung

init()

{

cluster_size = Buffer[13];  // ist 64

fat_root_dir();

// nach rückkehren der funktion // plötzlich 36

}

unsigned int fat_root_dir (unsigned char *Buffer) 

{

unsigned int FirstRootDirSecNum;

unsigned char NumFATs;

unsigned short FATSz16;

mmc_read_sector (volume_boot_record_addr,Buffer);

NumFATs = Buffer[16];

FATSz16 = Buffer[22] + (Buffer[23] << 8);

//berechnet den ersten Sector des Root Directory --> VBR_ADR + reservierte Sektoren + (NumFATs * Sektoren per FAT)

FirstRootDirSecNum = ( fat_offset + (NumFATs * FATSz16));

FirstRootDirSecNum+= volume_boot_record_addr;

return(FirstRootDirSecNum);

}

unsigned char cluster_size;  // 64 Blöcke je 512 Byte

unsigned int fat_offset;  // reservierte sektoren

unsigned int cluster_offset; // erste cluster

unsigned int volume_boot_record_addr; //sek root verzeichnis

unsigned char TEMP_Buffer[BlockSize];

void fat_init (void)

{

  int i;

  int tmp_size_sek;

        unsigned short byte_per_sekor;

  unsigned char Buffer[BlockSize];

  mmc_read_sector (MASTER_BOOT_RECORD,Buffer); //Read Master Boot Record 

    if (Buffer[510] == 0x55 && Buffer[511] == 0xAA)

    {

         FAT_DEBUG("\r\nMBR Signatur found!\r\n");

  tmp_size_sek = Buffer[458] + (Buffer[458] << 8);

  FAT_DEBUG("Part 1 groessee : %d \n", tmp_size_sek );

    }

    else

    {

       FAT_DEBUG("\r\nMBR Signatur not found!\r\n"); 

       while(1);

    }

    volume_boot_record_addr = Buffer[VBR_ADDR] + (Buffer[VBR_ADDR+1] << 8);

    mmc_read_sector (volume_boot_record_addr,Buffer);

    if (Buffer[510] == 0x55 && Buffer[511] == 0xAA) FAT_DEBUG("\r\nVBR Signatur found!\r\n");

    cluster_size = Buffer[13];

    fat_offset = Buffer[14] + (Buffer[15] << 8);

    byte_per_sekor = Buffer[11] + (Buffer[12] << 8);

    cluster_offset = ((byte_per_sekor * 32)/BlockSize);  

FAT_DEBUG("cluser size :%d \n",cluster_size);  // ist 64 !!!

    cluster_offset += fat_root_dir_addr(Buffer);

FAT_DEBUG("cluser size :%d \n",cluster_size);  // ist 36 !!!

}

//Auslesen der Adresse des Root Directory von Volume Boot Record

unsigned int fat_root_dir_addr (unsigned char *Buffer) 

{

unsigned int FirstRootDirSecNum;

unsigned char NumFATs;

unsigned short FATSz16;

//auslesen des Volume Boot Record von der MMC/SD Karte 

mmc_read_sector (volume_boot_record_addr,Buffer);

NumFATs = Buffer[16];

FATSz16 = Buffer[22] + (Buffer[23] << 8);

//berechnet den ersten Sector des Root Directory --> VBR_ADR + reservierte Sektoren + (NumFATs * Sektoren per FAT)

FirstRootDirSecNum = ( fat_offset + (NumFATs * FATSz16));

FirstRootDirSecNum+= volume_boot_record_addr;

return(FirstRootDirSecNum);

}

unsigned char Buffer[]={0x01, 0x11};

unsigned short fat_offset;

fat_offset = Buffer[0] + (Buffer[1] << 8);

printf("ausgabe: %x\n", fat_offset);