Source code of Windows XP (NT5)
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137 lines
3.8 KiB

/*++
Copyright (c) 1992 Microsoft Corporation
Module Name:
fat_rec.h
Abstract:
This module contains the mini-file system recognizer for FAT.
Author:
Darryl E. Havens (darrylh) 8-dec-1992
Environment:
Kernel mode, local to I/O system
Revision History:
--*/
//
// The following types and macros are used to help unpack the packed and
// misaligned fields found in the Bios parameter block
//
typedef union _UCHAR1 {
UCHAR Uchar[1];
UCHAR ForceAlignment;
} UCHAR1, *PUCHAR1;
typedef union _UCHAR2 {
UCHAR Uchar[2];
USHORT ForceAlignment;
} UCHAR2, *PUCHAR2;
typedef union _UCHAR4 {
UCHAR Uchar[4];
ULONG ForceAlignment;
} UCHAR4, *PUCHAR4;
//
// This macro copies an unaligned src byte to an aligned dst byte
//
#define CopyUchar1(Dst,Src) { \
*((UCHAR1 *)(Dst)) = *((UNALIGNED UCHAR1 *)(Src)); \
}
//
// This macro copies an unaligned src word to an aligned dst word
//
#define CopyUchar2(Dst,Src) { \
*((UCHAR2 *)(Dst)) = *((UNALIGNED UCHAR2 *)(Src)); \
}
//
// This macro copies an unaligned src longword to an aligned dsr longword
//
#define CopyUchar4(Dst,Src) { \
*((UCHAR4 *)(Dst)) = *((UNALIGNED UCHAR4 *)(Src)); \
}
//
// Define the Packed and Unpacked BIOS Parameter Block
//
typedef struct _PACKED_BIOS_PARAMETER_BLOCK {
UCHAR BytesPerSector[2]; // offset = 0x000 0
UCHAR SectorsPerCluster[1]; // offset = 0x002 2
UCHAR ReservedSectors[2]; // offset = 0x003 3
UCHAR Fats[1]; // offset = 0x005 5
UCHAR RootEntries[2]; // offset = 0x006 6
UCHAR Sectors[2]; // offset = 0x008 8
UCHAR Media[1]; // offset = 0x00A 10
UCHAR SectorsPerFat[2]; // offset = 0x00B 11
UCHAR SectorsPerTrack[2]; // offset = 0x00D 13
UCHAR Heads[2]; // offset = 0x00F 15
UCHAR HiddenSectors[4]; // offset = 0x011 17
UCHAR LargeSectors[4]; // offset = 0x015 21
} PACKED_BIOS_PARAMETER_BLOCK; // sizeof = 0x019 25
typedef PACKED_BIOS_PARAMETER_BLOCK *PPACKED_BIOS_PARAMETER_BLOCK;
typedef struct BIOS_PARAMETER_BLOCK {
USHORT BytesPerSector;
UCHAR SectorsPerCluster;
USHORT ReservedSectors;
UCHAR Fats;
USHORT RootEntries;
USHORT Sectors;
UCHAR Media;
USHORT SectorsPerFat;
USHORT SectorsPerTrack;
USHORT Heads;
ULONG HiddenSectors;
ULONG LargeSectors;
} BIOS_PARAMETER_BLOCK, *PBIOS_PARAMETER_BLOCK;
//
// Define the boot sector
//
typedef struct _PACKED_BOOT_SECTOR {
UCHAR Jump[3]; // offset = 0x000 0
UCHAR Oem[8]; // offset = 0x003 3
PACKED_BIOS_PARAMETER_BLOCK PackedBpb; // offset = 0x00B 11
UCHAR PhysicalDriveNumber; // offset = 0x024 36
UCHAR Reserved; // offset = 0x025 37
UCHAR Signature; // offset = 0x026 38
UCHAR Id[4]; // offset = 0x027 39
UCHAR VolumeLabel[11]; // offset = 0x02B 43
UCHAR SystemId[8]; // offset = 0x036 54
} PACKED_BOOT_SECTOR; // sizeof = 0x03E 62
typedef PACKED_BOOT_SECTOR *PPACKED_BOOT_SECTOR;
//
// Define the functions provided by this driver.
//
BOOLEAN
IsFatVolume(
IN PPACKED_BOOT_SECTOR Buffer
);
VOID
UnpackBiosParameterBlock(
IN PPACKED_BIOS_PARAMETER_BLOCK Bios,
OUT PBIOS_PARAMETER_BLOCK UnpackedBios
);