freebsd-dev/sys/msdosfs/bpb.h

/*	$Id: bpb.h,v 1.2 1995/05/30 08:07:30 rgrimes Exp $ */
/*	$NetBSD: bpb.h,v 1.3 1994/06/29 06:35:29 cgd 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
 */

/*
 * BIOS Parameter Block (BPB) for DOS 3.3
 */
struct bpb33 {
	u_short bpbBytesPerSec;	/* bytes per sector */
	u_char bpbSecPerClust;	/* sectors per cluster */
	u_short bpbResSectors;	/* number of reserved sectors */
	u_char bpbFATs;		/* number of FATs */
	u_short bpbRootDirEnts;	/* number of root directory entries */
	u_short bpbSectors;	/* total number of sectors */
	u_char bpbMedia;	/* media descriptor */
	u_short bpbFATsecs;	/* number of sectors per FAT */
	u_short bpbSecPerTrack;	/* sectors per track */
	u_short bpbHeads;	/* number of heads */
	u_short 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 {
	u_short bpbBytesPerSec;	/* bytes per sector */
	u_char bpbSecPerClust;	/* sectors per cluster */
	u_short bpbResSectors;	/* number of reserved sectors */
	u_char bpbFATs;		/* number of FATs */
	u_short bpbRootDirEnts;	/* number of root directory entries */
	u_short bpbSectors;	/* total number of sectors */
	u_char bpbMedia;	/* media descriptor */
	u_short bpbFATsecs;	/* number of sectors per FAT */
	u_short bpbSecPerTrack;	/* sectors per track */
	u_short bpbHeads;	/* number of heads */
	u_long bpbHiddenSecs;	/* number of hidden sectors */
	u_long bpbHugeSectors;	/* number of sectors if bpbSectors == 0 */
};

/*
 * 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.
 *
 * XXX The little-endian code here assumes that the processor can access
 * 16-bit and 32-bit quantities on byte boundaries.  If this is not true,
 * use the macros for the big-endian case.
 */
#include <machine/endian.h>
#if BYTE_ORDER == LITTLE_ENDIAN		/* && can do unaligned accesses */
#define	getushort(x)	*((u_short *)(x))
#define	getulong(x)	*((u_long *)(x))
#define	putushort(p, v)	(*((u_short *)(p)) = (v))
#define	putulong(p, v)	(*((u_long *)(p)) = (v))

#else
#define getushort(x)	(((u_char *)(x))[0] + (((u_char *)(x))[1] << 8))
#define getulong(x)	(((u_char *)(x))[0] + (((u_char *)(x))[1] << 8) \
			 + (((u_char *)(x))[2] << 16)	\
			 + (((u_char *)(x))[3] << 24))
#define putushort(p, v)	(((u_char *)(p))[0] = (v),	\
			 ((u_char *)(p))[1] = (v) >> 8)
#define putulong(p, v)	(((u_char *)(p))[0] = (v),	\
			 ((u_char *)(p))[1] = (v) >> 8, \
			 ((u_char *)(p))[2] = (v) >> 16,\
			 ((u_char *)(p))[3] = (v) >> 24)
#endif

/*
 * BIOS Parameter Block (BPB) for DOS 3.3
 */
struct byte_bpb33 {
	char bpbBytesPerSec[2];	/* bytes per sector */
	char bpbSecPerClust;	/* sectors per cluster */
	char bpbResSectors[2];	/* number of reserved sectors */
	char bpbFATs;		/* number of FATs */
	char bpbRootDirEnts[2];	/* number of root directory entries */
	char bpbSectors[2];	/* total number of sectors */
	char bpbMedia;		/* media descriptor */
	char bpbFATsecs[2];	/* number of sectors per FAT */
	char bpbSecPerTrack[2];	/* sectors per track */
	char bpbHeads[2];	/* number of heads */
	char 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 {
	char bpbBytesPerSec[2];	/* bytes per sector */
	char bpbSecPerClust;	/* sectors per cluster */
	char bpbResSectors[2];	/* number of reserved sectors */
	char bpbFATs;		/* number of FATs */
	char bpbRootDirEnts[2];	/* number of root directory entries */
	char bpbSectors[2];	/* total number of sectors */
	char bpbMedia;		/* media descriptor */
	char bpbFATsecs[2];	/* number of sectors per FAT */
	char bpbSecPerTrack[2];	/* sectors per track */
	char bpbHeads[2];	/* number of heads */
	char bpbHiddenSecs[4];	/* number of hidden sectors */
	char bpbHugeSectors[4];	/* number of sectors if bpbSectors == 0 */
};