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      1 /*	$NetBSD: bootsect.h,v 1.7 2021/08/09 21:38:05 andvar Exp $	*/
      2 
      3 /*
      4  * Written by Paul Popelka (paulp (at) uts.amdahl.com)
      5  *
      6  * You can do anything you want with this software, just don't say you wrote
      7  * it, and don't remove this notice.
      8  *
      9  * This software is provided "as is".
     10  *
     11  * The author supplies this software to be publicly redistributed on the
     12  * understanding that the author is not responsible for the correct
     13  * functioning of this software in any circumstances and is not liable for
     14  * any damages caused by this software.
     15  *
     16  * October 1992
     17  */
     18 #ifndef _MSDOSFS_BOOTSECT_H_
     19 #define _MSDOSFS_BOOTSECT_H_
     20 
     21 /*
     22  * Format of a boot sector.  This is the first sector on a DOS floppy disk
     23  * or the first sector of a partition on a hard disk.  But, it is not the
     24  * first sector of a partitioned hard disk.
     25  */
     26 struct bootsector33 {
     27 	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
     28 	int8_t		bsOemName[8];		/* OEM name and version */
     29 	int8_t		bsBPB[19];		/* BIOS parameter block */
     30 	int8_t		bsDriveNumber;		/* drive number (0x80) */
     31 	int8_t		bsBootCode[479];	/* pad so struct is 512b */
     32 	uint8_t		bsBootSectSig0;
     33 	uint8_t		bsBootSectSig1;
     34 #define	BOOTSIG0	0x55
     35 #define	BOOTSIG1	0xaa
     36 };
     37 
     38 struct extboot {
     39 	int8_t		exDriveNumber;		/* drive number (0x80) */
     40 	int8_t		exReserved1;		/* reserved */
     41 	int8_t		exBootSignature;	/* ext. boot signature (0x29) */
     42 #define	EXBOOTSIG	0x29
     43 	int8_t		exVolumeID[4];		/* volume ID number */
     44 	int8_t		exVolumeLabel[11];	/* volume label */
     45 	int8_t		exFileSysType[8];	/* fs type (FAT12 or FAT16) */
     46 };
     47 
     48 struct bootsector50 {
     49 	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
     50 	int8_t		bsOemName[8];		/* OEM name and version */
     51 	int8_t		bsBPB[25];		/* BIOS parameter block */
     52 	int8_t		bsExt[26];		/* Bootsector Extension */
     53 	int8_t		bsBootCode[448];	/* pad so structure is 512b */
     54 	uint8_t		bsBootSectSig0;
     55 	uint8_t		bsBootSectSig1;
     56 #define	BOOTSIG0	0x55
     57 #define	BOOTSIG1	0xaa
     58 };
     59 
     60 struct bootsector710 {
     61 	uint8_t		bsJump[3];		/* jump inst E9xxxx or EBxx90 */
     62 	int8_t		bsOEMName[8];		/* OEM name and version */
     63 	int8_t		bsBPB[53];		/* BIOS parameter block */
     64 	int8_t		bsExt[26];		/* Bootsector Extension */
     65 	int8_t		bsBootCode[420];	/* pad so structure is 512b */
     66 	uint8_t		bsBootSectSig0;
     67 	uint8_t		bsBootSectSig1;
     68 #define	BOOTSIG0	0x55
     69 #define	BOOTSIG1	0xaa
     70 };
     71 #ifdef	atari
     72 /*
     73  * The boot sector on a GEMDOS FS is a little bit different from the MSDOS FS
     74  * format. Currently there is no need to declare a separate structure, the
     75  * bootsector33 struct will do.
     76  */
     77 #if 0
     78 struct bootsec_atari {
     79 	uint8_t		bsBranch[2];		/* branch inst if auto-boot	*/
     80 	int8_t		bsFiller[6];		/* anything or nothing		*/
     81 	int8_t		bsSerial[3];		/* serial no. for mediachange	*/
     82 	int8_t		bsBPB[19];		/* BIOS parameter block		*/
     83 	int8_t		bsBootCode[482];	/* pad so struct is 512b	*/
     84 };
     85 #endif
     86 #endif /* atari */
     87 
     88 union bootsector {
     89 	struct bootsector33 bs33;
     90 	struct bootsector50 bs50;
     91 	struct bootsector710 bs710;
     92 };
     93 
     94 #if 0
     95 /*
     96  * Shorthand for fields in the bpb.
     97  */
     98 #define	bsBytesPerSec	bsBPB.bpbBytesPerSec
     99 #define	bsSectPerClust	bsBPB.bpbSectPerClust
    100 #define	bsResSectors	bsBPB.bpbResSectors
    101 #define	bsFATS		bsBPB.bpbFATS
    102 #define	bsRootDirEnts	bsBPB.bpbRootDirEnts
    103 #define	bsSectors	bsBPB.bpbSectors
    104 #define	bsMedia		bsBPB.bpbMedia
    105 #define	bsFATsecs	bsBPB.bpbFATsecs
    106 #define	bsSectPerTrack	bsBPB.bpbSectPerTrack
    107 #define	bsHeads		bsBPB.bpbHeads
    108 #define	bsHiddenSecs	bsBPB.bpbHiddenSecs
    109 #define	bsHugeSectors	bsBPB.bpbHugeSectors
    110 #endif
    111 
    112 #endif /* _MSDOSFS_BOOTSECT_H_ */
    113