xref: /netbsd-src/sys/fs/msdosfs/bootsect.h (revision 20fff34fc519c63c2d4f1e8a02359326041af9e1)

/*	$NetBSD: bootsect.h,v 1.7 2021/08/09 21:38:05 andvar 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 _MSDOSFS_BOOTSECT_H_
#define _MSDOSFS_BOOTSECT_H_

/*
 * Format of a boot sector.  This is the first sector on a DOS floppy disk
 * or the first sector of a partition on a hard disk.  But, it is not the
 * first sector of a partitioned hard disk.
 */
struct bootsector33 {
	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
	int8_t		bsOemName[8];		/* OEM name and version */
	int8_t		bsBPB[19];		/* BIOS parameter block */
	int8_t		bsDriveNumber;		/* drive number (0x80) */
	int8_t		bsBootCode[479];	/* pad so struct is 512b */
	uint8_t		bsBootSectSig0;
	uint8_t		bsBootSectSig1;
#define	BOOTSIG0	0x55
#define	BOOTSIG1	0xaa
};

struct extboot {
	int8_t		exDriveNumber;		/* drive number (0x80) */
	int8_t		exReserved1;		/* reserved */
	int8_t		exBootSignature;	/* ext. boot signature (0x29) */
#define	EXBOOTSIG	0x29
	int8_t		exVolumeID[4];		/* volume ID number */
	int8_t		exVolumeLabel[11];	/* volume label */
	int8_t		exFileSysType[8];	/* fs type (FAT12 or FAT16) */
};

struct bootsector50 {
	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
	int8_t		bsOemName[8];		/* OEM name and version */
	int8_t		bsBPB[25];		/* BIOS parameter block */
	int8_t		bsExt[26];		/* Bootsector Extension */
	int8_t		bsBootCode[448];	/* pad so structure is 512b */
	uint8_t		bsBootSectSig0;
	uint8_t		bsBootSectSig1;
#define	BOOTSIG0	0x55
#define	BOOTSIG1	0xaa
};

struct bootsector710 {
	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
	int8_t		bsOEMName[8];		/* OEM name and version */
	int8_t		bsBPB[53];		/* BIOS parameter block */
	int8_t		bsExt[26];		/* Bootsector Extension */
	int8_t		bsBootCode[420];	/* pad so structure is 512b */
	uint8_t		bsBootSectSig0;
	uint8_t		bsBootSectSig1;
#define	BOOTSIG0	0x55
#define	BOOTSIG1	0xaa
};
#ifdef	atari
/*
 * The boot sector on a GEMDOS FS is a little bit different from the MSDOS FS
 * format. Currently there is no need to declare a separate structure, the
 * bootsector33 struct will do.
 */
#if 0
struct bootsec_atari {
	uint8_t		bsBranch[2];		/* branch inst if auto-boot	*/
	int8_t		bsFiller[6];		/* anything or nothing		*/
	int8_t		bsSerial[3];		/* serial no. for mediachange	*/
	int8_t		bsBPB[19];		/* BIOS parameter block		*/
	int8_t		bsBootCode[482];	/* pad so struct is 512b	*/
};
#endif
#endif /* atari */

union bootsector {
	struct bootsector33 bs33;
	struct bootsector50 bs50;
	struct bootsector710 bs710;
};

#if 0
/*
 * Shorthand for fields in the bpb.
 */
#define	bsBytesPerSec	bsBPB.bpbBytesPerSec
#define	bsSectPerClust	bsBPB.bpbSectPerClust
#define	bsResSectors	bsBPB.bpbResSectors
#define	bsFATS		bsBPB.bpbFATS
#define	bsRootDirEnts	bsBPB.bpbRootDirEnts
#define	bsSectors	bsBPB.bpbSectors
#define	bsMedia		bsBPB.bpbMedia
#define	bsFATsecs	bsBPB.bpbFATsecs
#define	bsSectPerTrack	bsBPB.bpbSectPerTrack
#define	bsHeads		bsBPB.bpbHeads
#define	bsHiddenSecs	bsBPB.bpbHiddenSecs
#define	bsHugeSectors	bsBPB.bpbHugeSectors
#endif

#endif /* _MSDOSFS_BOOTSECT_H_ */