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SdFat
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Boot sector for a FAT32 volume. More...
#include <SdFatStructs.h>
Public Attributes | |
| uint8_t | bootCode [420] |
| uint8_t | bootSectorSig0 |
| uint8_t | bootSectorSig1 |
| uint8_t | bootSignature |
| uint16_t | bytesPerSector |
| uint8_t | driveNumber |
| uint16_t | fat32BackBootBlock |
| uint16_t | fat32Flags |
| uint16_t | fat32FSInfo |
| uint8_t | fat32Reserved [12] |
| uint32_t | fat32RootCluster |
| uint16_t | fat32Version |
| uint8_t | fatCount |
| char | fileSystemType [8] |
| uint16_t | headCount |
| uint32_t | hidddenSectors |
| uint8_t | jump [3] |
| uint8_t | mediaType |
| char | oemId [8] |
| uint8_t | reserved1 |
| uint16_t | reservedSectorCount |
| uint16_t | rootDirEntryCount |
| uint8_t | sectorsPerCluster |
| uint16_t | sectorsPerFat16 |
| uint32_t | sectorsPerFat32 |
| uint16_t | sectorsPerTrack |
| uint16_t | totalSectors16 |
| uint32_t | totalSectors32 |
| char | volumeLabel [11] |
| uint32_t | volumeSerialNumber |
Boot sector for a FAT32 volume.
| uint8_t fat32_boot::bootCode[420] |
X86 boot code
| uint8_t fat32_boot::bootSectorSig0 |
must be 0X55
| uint8_t fat32_boot::bootSectorSig1 |
must be 0XAA
| uint8_t fat32_boot::bootSignature |
0X29 if next three fields are valid
| uint16_t fat32_boot::bytesPerSector |
The size of a hardware sector. Valid decimal values for this field are 512, 1024, 2048, and 4096. For most disks used in the United States, the value of this field is 512.
| uint8_t fat32_boot::driveNumber |
Related to the BIOS physical drive number. Floppy drives are identified as 0x00 and physical hard disks are identified as 0x80, regardless of the number of physical disk drives. Typically, this value is set prior to issuing an INT 13h BIOS call to specify the device to access. The value is only relevant if the device is a boot device.
| uint16_t fat32_boot::fat32BackBootBlock |
If nonzero, indicates the sector number in the reserved area of the volume of a copy of the boot record. Usually 6. No value other than 6 is recommended.
| uint16_t fat32_boot::fat32Flags |
This field is only defined for FAT32 media and does not exist on FAT12 and FAT16 media. Bits 0-3 -- Zero-based number of active FAT. Only valid if mirroring is disabled. Bits 4-6 -- Reserved. Bit 7 -- 0 means the FAT is mirrored at runtime into all FATs. -- 1 means only one FAT is active; it is the one referenced in bits 0-3. Bits 8-15 -- Reserved.
| uint16_t fat32_boot::fat32FSInfo |
Sector number of FSINFO structure in the reserved area of the FAT32 volume. Usually 1.
| uint8_t fat32_boot::fat32Reserved[12] |
Reserved for future expansion. Code that formats FAT32 volumes should always set all of the bytes of this field to 0.
| uint32_t fat32_boot::fat32RootCluster |
Cluster number of the first cluster of the root directory for FAT32. This usually 2 but not required to be 2.
| uint16_t fat32_boot::fat32Version |
FAT32 version. High byte is major revision number. Low byte is minor revision number. Only 0.0 define.
| uint8_t fat32_boot::fatCount |
The number of copies of the FAT on the volume. The value of this field is always 2.
| char fat32_boot::fileSystemType[8] |
A text field with a value of FAT32.
| uint16_t fat32_boot::headCount |
Number of heads for interrupt 0x13. Not used otherwise.
| uint32_t fat32_boot::hidddenSectors |
Count of hidden sectors preceding the partition that contains this FAT volume. This field is generally only relevant for media visible on interrupt 0x13.
| uint8_t fat32_boot::jump[3] |
The first three bytes of the boot sector must be valid, executable x 86-based CPU instructions. This includes a jump instruction that skips the next nonexecutable bytes.
| uint8_t fat32_boot::mediaType |
This dates back to the old MS-DOS 1.x media determination and is no longer usually used for anything. 0xF8 is the standard value for fixed (nonremovable) media. For removable media, 0xF0 is frequently used. Legal values are 0xF0 or 0xF8-0xFF.
| char fat32_boot::oemId[8] |
This is typically a string of characters that identifies the operating system that formatted the volume.
| uint8_t fat32_boot::reserved1 |
used by Windows NT - should be zero for FAT
| uint16_t fat32_boot::reservedSectorCount |
The number of sectors preceding the start of the first FAT, including the boot sector. Must not be zero
| uint16_t fat32_boot::rootDirEntryCount |
FAT12/FAT16 only. For FAT32 volumes, this field must be set to 0.
| uint8_t fat32_boot::sectorsPerCluster |
Number of sectors per allocation unit. This value must be a power of 2 that is greater than 0. The legal values are 1, 2, 4, 8, 16, 32, 64, and 128. 128 should be avoided.
| uint16_t fat32_boot::sectorsPerFat16 |
On FAT32 volumes this field must be 0, and sectorsPerFat32 contains the FAT size count.
| uint32_t fat32_boot::sectorsPerFat32 |
Count of sectors occupied by one FAT on FAT32 volumes.
| uint16_t fat32_boot::sectorsPerTrack |
Sectors per track for interrupt 0x13. Not used otherwise.
| uint16_t fat32_boot::totalSectors16 |
For FAT32 volumes, this field must be 0.
| uint32_t fat32_boot::totalSectors32 |
Contains the total number of sectors in the FAT32 volume.
| char fat32_boot::volumeLabel[11] |
A field once used to store the volume label. The volume label is now stored as a special file in the root directory.
| uint32_t fat32_boot::volumeSerialNumber |
A random serial number created when formatting a disk, which helps to distinguish between disks. Usually generated by combining date and time.
1.7.4