Method parseHeader

src/core/FatSystem.cpp:134–194

* Parses FAT header */

 * Parses FAT header
 */
void FatSystem::parseHeader()
{
    char buffer[128];

    readData(0x0, buffer, sizeof(buffer));
    bytesPerSector = FAT_READ_SHORT(buffer, FAT_BYTES_PER_SECTOR)&0xffff;
    sectorsPerCluster = buffer[FAT_SECTORS_PER_CLUSTER]&0xff;
    reservedSectors = FAT_READ_SHORT(buffer, FAT_RESERVED_SECTORS)&0xffff;
    oemName = string(buffer+FAT_DISK_OEM, FAT_DISK_OEM_SIZE);
    fats = buffer[FAT_FATS];

    sectorsPerFat = FAT_READ_SHORT(buffer, FAT16_SECTORS_PER_FAT)&0xffff;

    if (sectorsPerFat != 0) {
        type = FAT16;
        diskLabel = string(buffer+FAT16_DISK_LABEL, FAT16_DISK_LABEL_SIZE);
        fsType = string(buffer+FAT16_DISK_FS, FAT16_DISK_FS_SIZE);
        rootEntries = FAT_READ_SHORT(buffer, FAT16_ROOT_ENTRIES)&0xffff;
        rootDirectory = 0;

        totalSectors = FAT_READ_SHORT(buffer, FAT16_TOTAL_SECTORS)&0xffff;
        if (!totalSectors) {
            totalSectors = FAT_READ_LONG(buffer, FAT_TOTAL_SECTORS)&0xffffffff;
        }

        unsigned int rootDirSectors =
            (rootEntries*FAT_ENTRY_SIZE + bytesPerSector-1)/bytesPerSector;
        unsigned long dataSectors = totalSectors -
            (reservedSectors + fats*sectorsPerFat + rootDirSectors);
        unsigned long totalClusters = dataSectors/sectorsPerCluster;
        bits = (totalClusters > MAX_FAT12) ? 16 : 12;
    } else {
        type = FAT32;
        bits = 32;
        sectorsPerFat = FAT_READ_LONG(buffer, FAT_SECTORS_PER_FAT)&0xffffffff;
        totalSectors = FAT_READ_LONG(buffer, FAT_TOTAL_SECTORS)&0xffffffff;
        diskLabel = string(buffer+FAT_DISK_LABEL, FAT_DISK_LABEL_SIZE);
        rootDirectory = FAT_READ_LONG(buffer, FAT_ROOT_DIRECTORY)&0xffffffff;
        fsType = string(buffer+FAT_DISK_FS, FAT_DISK_FS_SIZE);
    }

    if (bytesPerSector != 512) {
        printf("WARNING: Bytes per sector is not 512 (%llu)\n", bytesPerSector);
        strange++;
    }

    if (sectorsPerCluster > 128) {
        printf("WARNING: Sectors per cluster high (%llu)\n", sectorsPerCluster);
        strange++;
    }

    if (fats == 0) {
        printf("WARNING: Fats numbner is 0\n");
         strange++;
    }

    if (rootDirectory != 2 && type == FAT32) {
        printf("WARNING: Root directory is not 2 (%llu)\n", rootDirectory);