xref: /freebsd/sys/fs/msdosfs/bpb.h (revision 9336e0699bda8a301cd2bfa37106b6ec5e32012e)
1 /* $FreeBSD$ */
2 /*	$NetBSD: bpb.h,v 1.7 1997/11/17 15:36:24 ws Exp $	*/
3 
4 /*-
5  * Written by Paul Popelka (paulp@uts.amdahl.com)
6  *
7  * You can do anything you want with this software, just don't say you wrote
8  * it, and don't remove this notice.
9  *
10  * This software is provided "as is".
11  *
12  * The author supplies this software to be publicly redistributed on the
13  * understanding that the author is not responsible for the correct
14  * functioning of this software in any circumstances and is not liable for
15  * any damages caused by this software.
16  *
17  * October 1992
18  */
19 
20 /*
21  * BIOS Parameter Block (BPB) for DOS 3.3
22  */
23 struct bpb33 {
24 	u_int16_t	bpbBytesPerSec;	/* bytes per sector */
25 	u_int8_t	bpbSecPerClust;	/* sectors per cluster */
26 	u_int16_t	bpbResSectors;	/* number of reserved sectors */
27 	u_int8_t	bpbFATs;	/* number of FATs */
28 	u_int16_t	bpbRootDirEnts;	/* number of root directory entries */
29 	u_int16_t	bpbSectors;	/* total number of sectors */
30 	u_int8_t	bpbMedia;	/* media descriptor */
31 	u_int16_t	bpbFATsecs;	/* number of sectors per FAT */
32 	u_int16_t	bpbSecPerTrack;	/* sectors per track */
33 	u_int16_t	bpbHeads;	/* number of heads */
34 	u_int16_t	bpbHiddenSecs;	/* number of hidden sectors */
35 };
36 
37 /*
38  * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
39  * and bpbHugeSectors is not in the 3.3 bpb.
40  */
41 struct bpb50 {
42 	u_int16_t	bpbBytesPerSec;	/* bytes per sector */
43 	u_int8_t	bpbSecPerClust;	/* sectors per cluster */
44 	u_int16_t	bpbResSectors;	/* number of reserved sectors */
45 	u_int8_t	bpbFATs;	/* number of FATs */
46 	u_int16_t	bpbRootDirEnts;	/* number of root directory entries */
47 	u_int16_t	bpbSectors;	/* total number of sectors */
48 	u_int8_t	bpbMedia;	/* media descriptor */
49 	u_int16_t	bpbFATsecs;	/* number of sectors per FAT */
50 	u_int16_t	bpbSecPerTrack;	/* sectors per track */
51 	u_int16_t	bpbHeads;	/* number of heads */
52 	u_int32_t	bpbHiddenSecs;	/* # of hidden sectors */
53 	u_int32_t	bpbHugeSectors;	/* # of sectors if bpbSectors == 0 */
54 };
55 
56 /*
57  * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
58  */
59 struct bpb710 {
60 	u_int16_t	bpbBytesPerSec;	/* bytes per sector */
61 	u_int8_t	bpbSecPerClust;	/* sectors per cluster */
62 	u_int16_t	bpbResSectors;	/* number of reserved sectors */
63 	u_int8_t	bpbFATs;	/* number of FATs */
64 	u_int16_t	bpbRootDirEnts;	/* number of root directory entries */
65 	u_int16_t	bpbSectors;	/* total number of sectors */
66 	u_int8_t	bpbMedia;	/* media descriptor */
67 	u_int16_t	bpbFATsecs;	/* number of sectors per FAT */
68 	u_int16_t	bpbSecPerTrack;	/* sectors per track */
69 	u_int16_t	bpbHeads;	/* number of heads */
70 	u_int32_t	bpbHiddenSecs;	/* # of hidden sectors */
71 	u_int32_t	bpbHugeSectors;	/* # of sectors if bpbSectors == 0 */
72 	u_int32_t	bpbBigFATsecs;	/* like bpbFATsecs for FAT32 */
73 	u_int16_t	bpbExtFlags;	/* extended flags: */
74 #define	FATNUM		0xf		/* mask for numbering active FAT */
75 #define	FATMIRROR	0x80		/* FAT is mirrored (like it always was) */
76 	u_int16_t	bpbFSVers;	/* filesystem version */
77 #define	FSVERS		0		/* currently only 0 is understood */
78 	u_int32_t	bpbRootClust;	/* start cluster for root directory */
79 	u_int16_t	bpbFSInfo;	/* filesystem info structure sector */
80 	u_int16_t	bpbBackup;	/* backup boot sector */
81 	/* There is a 12 byte filler here, but we ignore it */
82 };
83 
84 /*
85  * The following structures represent how the bpb's look on disk.  shorts
86  * and longs are just character arrays of the appropriate length.  This is
87  * because the compiler forces shorts and longs to align on word or
88  * halfword boundaries.
89  */
90 
91 #include <sys/endian.h>
92 
93 #define	getushort(x)	le16dec(x)
94 #define	getulong(x)	le32dec(x)
95 #define	putushort(p, v)	le16enc(p, v)
96 #define	putulong(p, v)	le32enc(p, v)
97 
98 /*
99  * BIOS Parameter Block (BPB) for DOS 3.3
100  */
101 struct byte_bpb33 {
102 	int8_t bpbBytesPerSec[2];	/* bytes per sector */
103 	int8_t bpbSecPerClust;		/* sectors per cluster */
104 	int8_t bpbResSectors[2];	/* number of reserved sectors */
105 	int8_t bpbFATs;			/* number of FATs */
106 	int8_t bpbRootDirEnts[2];	/* number of root directory entries */
107 	int8_t bpbSectors[2];		/* total number of sectors */
108 	int8_t bpbMedia;		/* media descriptor */
109 	int8_t bpbFATsecs[2];		/* number of sectors per FAT */
110 	int8_t bpbSecPerTrack[2];	/* sectors per track */
111 	int8_t bpbHeads[2];		/* number of heads */
112 	int8_t bpbHiddenSecs[2];	/* number of hidden sectors */
113 };
114 
115 /*
116  * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
117  * and bpbHugeSectors is not in the 3.3 bpb.
118  */
119 struct byte_bpb50 {
120 	int8_t bpbBytesPerSec[2];	/* bytes per sector */
121 	int8_t bpbSecPerClust;		/* sectors per cluster */
122 	int8_t bpbResSectors[2];	/* number of reserved sectors */
123 	int8_t bpbFATs;			/* number of FATs */
124 	int8_t bpbRootDirEnts[2];	/* number of root directory entries */
125 	int8_t bpbSectors[2];		/* total number of sectors */
126 	int8_t bpbMedia;		/* media descriptor */
127 	int8_t bpbFATsecs[2];		/* number of sectors per FAT */
128 	int8_t bpbSecPerTrack[2];	/* sectors per track */
129 	int8_t bpbHeads[2];		/* number of heads */
130 	int8_t bpbHiddenSecs[4];	/* number of hidden sectors */
131 	int8_t bpbHugeSectors[4];	/* # of sectors if bpbSectors == 0 */
132 };
133 
134 /*
135  * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
136  */
137 struct byte_bpb710 {
138 	u_int8_t bpbBytesPerSec[2];	/* bytes per sector */
139 	u_int8_t bpbSecPerClust;	/* sectors per cluster */
140 	u_int8_t bpbResSectors[2];	/* number of reserved sectors */
141 	u_int8_t bpbFATs;		/* number of FATs */
142 	u_int8_t bpbRootDirEnts[2];	/* number of root directory entries */
143 	u_int8_t bpbSectors[2];		/* total number of sectors */
144 	u_int8_t bpbMedia;		/* media descriptor */
145 	u_int8_t bpbFATsecs[2];		/* number of sectors per FAT */
146 	u_int8_t bpbSecPerTrack[2];	/* sectors per track */
147 	u_int8_t bpbHeads[2];		/* number of heads */
148 	u_int8_t bpbHiddenSecs[4];	/* # of hidden sectors */
149 	u_int8_t bpbHugeSectors[4];	/* # of sectors if bpbSectors == 0 */
150 	u_int8_t bpbBigFATsecs[4];	/* like bpbFATsecs for FAT32 */
151 	u_int8_t bpbExtFlags[2];	/* extended flags: */
152 	u_int8_t bpbFSVers[2];		/* filesystem version */
153 	u_int8_t bpbRootClust[4];	/* start cluster for root directory */
154 	u_int8_t bpbFSInfo[2];		/* filesystem info structure sector */
155 	u_int8_t bpbBackup[2];		/* backup boot sector */
156 	/* There is a 12 byte filler here, but we ignore it */
157 };
158 
159 /*
160  * FAT32 FSInfo block.
161  */
162 struct fsinfo {
163 	u_int8_t fsisig1[4];
164 	u_int8_t fsifill1[480];
165 	u_int8_t fsisig2[4];
166 	u_int8_t fsinfree[4];
167 	u_int8_t fsinxtfree[4];
168 	u_int8_t fsifill2[12];
169 	u_int8_t fsisig3[4];
170 };
171