xref: /freebsd/sys/fs/msdosfs/bpb.h (revision 71625ec9ad2a9bc8c09784fbd23b759830e0ee5f)

/*	$NetBSD: bpb.h,v 1.7 1997/11/17 15:36:24 ws Exp $	*/

/*-
 * Written by Paul Popelka (paulp@uts.amdahl.com)
 *
 * You can do anything you want with this software, just don't say you wrote
 * it, and don't remove this notice.
 *
 * This software is provided "as is".
 *
 * The author supplies this software to be publicly redistributed on the
 * understanding that the author is not responsible for the correct
 * functioning of this software in any circumstances and is not liable for
 * any damages caused by this software.
 *
 * October 1992
 */

#ifndef _FS_MSDOSFS_BPB_H_
#define	_FS_MSDOSFS_BPB_H_

/*
 * BIOS Parameter Block (BPB) for DOS 3.3
 */
struct bpb33 {
	uint16_t	bpbBytesPerSec;	/* bytes per sector */
	uint8_t		bpbSecPerClust;	/* sectors per cluster */
	uint16_t	bpbResSectors;	/* number of reserved sectors */
	uint8_t		bpbFATs;	/* number of FATs */
	uint16_t	bpbRootDirEnts;	/* number of root directory entries */
	uint16_t	bpbSectors;	/* total number of sectors */
	uint8_t		bpbMedia;	/* media descriptor */
	uint16_t	bpbFATsecs;	/* number of sectors per FAT */
	uint16_t	bpbSecPerTrack;	/* sectors per track */
	uint16_t	bpbHeads;	/* number of heads */
	uint16_t	bpbHiddenSecs;	/* number of hidden sectors */
};

/*
 * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
 * and bpbHugeSectors is not in the 3.3 bpb.
 */
struct bpb50 {
	uint16_t	bpbBytesPerSec;	/* bytes per sector */
	uint8_t		bpbSecPerClust;	/* sectors per cluster */
	uint16_t	bpbResSectors;	/* number of reserved sectors */
	uint8_t		bpbFATs;	/* number of FATs */
	uint16_t	bpbRootDirEnts;	/* number of root directory entries */
	uint16_t	bpbSectors;	/* total number of sectors */
	uint8_t		bpbMedia;	/* media descriptor */
	uint16_t	bpbFATsecs;	/* number of sectors per FAT */
	uint16_t	bpbSecPerTrack;	/* sectors per track */
	uint16_t	bpbHeads;	/* number of heads */
	uint32_t	bpbHiddenSecs;	/* # of hidden sectors */
	uint32_t	bpbHugeSectors;	/* # of sectors if bpbSectors == 0 */
};

/*
 * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
 */
struct bpb710 {
	uint16_t	bpbBytesPerSec;	/* bytes per sector */
	uint8_t		bpbSecPerClust;	/* sectors per cluster */
	uint16_t	bpbResSectors;	/* number of reserved sectors */
	uint8_t		bpbFATs;	/* number of FATs */
	uint16_t	bpbRootDirEnts;	/* number of root directory entries */
	uint16_t	bpbSectors;	/* total number of sectors */
	uint8_t		bpbMedia;	/* media descriptor */
	uint16_t	bpbFATsecs;	/* number of sectors per FAT */
	uint16_t	bpbSecPerTrack;	/* sectors per track */
	uint16_t	bpbHeads;	/* number of heads */
	uint32_t	bpbHiddenSecs;	/* # of hidden sectors */
	uint32_t	bpbHugeSectors;	/* # of sectors if bpbSectors == 0 */
	uint32_t	bpbBigFATsecs;	/* like bpbFATsecs for FAT32 */
	uint16_t	bpbExtFlags;	/* extended flags: */
#define	FATNUM		0xf		/* mask for numbering active FAT */
#define	FATMIRROR	0x80		/* FAT is mirrored (like it always was) */
	uint16_t	bpbFSVers;	/* filesystem version */
#define	FSVERS		0		/* currently only 0 is understood */
	uint32_t	bpbRootClust;	/* start cluster for root directory */
	uint16_t	bpbFSInfo;	/* filesystem info structure sector */
	uint16_t	bpbBackup;	/* backup boot sector */
	uint8_t		bpbReserved[12]; /* reserved for future expansion */
};

/*
 * The following structures represent how the bpb's look on disk.  shorts
 * and longs are just character arrays of the appropriate length.  This is
 * because the compiler forces shorts and longs to align on word or
 * halfword boundaries.
 */

#include <sys/endian.h>

#define	getushort(x)	le16dec(x)
#define	getulong(x)	le32dec(x)
#define	putushort(p, v)	le16enc(p, v)
#define	putulong(p, v)	le32enc(p, v)

/*
 * BIOS Parameter Block (BPB) for DOS 3.3
 */
struct byte_bpb33 {
	int8_t bpbBytesPerSec[2];	/* bytes per sector */
	int8_t bpbSecPerClust;		/* sectors per cluster */
	int8_t bpbResSectors[2];	/* number of reserved sectors */
	int8_t bpbFATs;			/* number of FATs */
	int8_t bpbRootDirEnts[2];	/* number of root directory entries */
	int8_t bpbSectors[2];		/* total number of sectors */
	int8_t bpbMedia;		/* media descriptor */
	int8_t bpbFATsecs[2];		/* number of sectors per FAT */
	int8_t bpbSecPerTrack[2];	/* sectors per track */
	int8_t bpbHeads[2];		/* number of heads */
	int8_t bpbHiddenSecs[2];	/* number of hidden sectors */
};

/*
 * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
 * and bpbHugeSectors is not in the 3.3 bpb.
 */
struct byte_bpb50 {
	int8_t bpbBytesPerSec[2];	/* bytes per sector */
	int8_t bpbSecPerClust;		/* sectors per cluster */
	int8_t bpbResSectors[2];	/* number of reserved sectors */
	int8_t bpbFATs;			/* number of FATs */
	int8_t bpbRootDirEnts[2];	/* number of root directory entries */
	int8_t bpbSectors[2];		/* total number of sectors */
	int8_t bpbMedia;		/* media descriptor */
	int8_t bpbFATsecs[2];		/* number of sectors per FAT */
	int8_t bpbSecPerTrack[2];	/* sectors per track */
	int8_t bpbHeads[2];		/* number of heads */
	int8_t bpbHiddenSecs[4];	/* number of hidden sectors */
	int8_t bpbHugeSectors[4];	/* # of sectors if bpbSectors == 0 */
};

/*
 * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
 */
struct byte_bpb710 {
	uint8_t bpbBytesPerSec[2];	/* bytes per sector */
	uint8_t bpbSecPerClust;		/* sectors per cluster */
	uint8_t bpbResSectors[2];	/* number of reserved sectors */
	uint8_t bpbFATs;		/* number of FATs */
	uint8_t bpbRootDirEnts[2];	/* number of root directory entries */
	uint8_t bpbSectors[2];		/* total number of sectors */
	uint8_t bpbMedia;		/* media descriptor */
	uint8_t bpbFATsecs[2];		/* number of sectors per FAT */
	uint8_t bpbSecPerTrack[2];	/* sectors per track */
	uint8_t bpbHeads[2];		/* number of heads */
	uint8_t bpbHiddenSecs[4];	/* # of hidden sectors */
	uint8_t bpbHugeSectors[4];	/* # of sectors if bpbSectors == 0 */
	uint8_t bpbBigFATsecs[4];	/* like bpbFATsecs for FAT32 */
	uint8_t bpbExtFlags[2];		/* extended flags: */
	uint8_t bpbFSVers[2];		/* filesystem version */
	uint8_t bpbRootClust[4];	/* start cluster for root directory */
	uint8_t bpbFSInfo[2];		/* filesystem info structure sector */
	uint8_t bpbBackup[2];		/* backup boot sector */
	uint8_t bpbReserved[12];	/* reserved for future expansion */
};

/*
 * FAT32 FSInfo block.
 */
struct fsinfo {
	uint8_t fsisig1[4];
	uint8_t fsifill1[480];
	uint8_t fsisig2[4];
	uint8_t fsinfree[4];
	uint8_t fsinxtfree[4];
	uint8_t fsifill2[12];
	uint8_t fsisig3[4];
};
#endif /* !_FS_MSDOSFS_BPB_H_ */