FreeBSD/Linux Kernel Cross Reference
sys/fs/msdosfs/bpb.h
1 /* $FreeBSD: releng/6.0/sys/fs/msdosfs/bpb.h 139776 2005-01-06 18:10:42Z imp $ */
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 * XXX The little-endian code here assumes that the processor can access
91 * 16-bit and 32-bit quantities on byte boundaries. If this is not true,
92 * use the macros for the big-endian case.
93 */
94
95 #include <machine/endian.h>
96
97 #ifdef __i386__
98 #define UNLALIGNED_ACCESS
99 #endif
100
101 #if (BYTE_ORDER == LITTLE_ENDIAN) && defined(UNALIGNED_ACCESS)
102 #define getushort(x) *((u_int16_t *)(x))
103 #define getulong(x) *((u_int32_t *)(x))
104 #define putushort(p, v) (*((u_int16_t *)(p)) = (v))
105 #define putulong(p, v) (*((u_int32_t *)(p)) = (v))
106 #else
107 #define getushort(x) (((u_int8_t *)(x))[0] + (((u_int8_t *)(x))[1] << 8))
108 #define getulong(x) (((u_int8_t *)(x))[0] + (((u_int8_t *)(x))[1] << 8) \
109 + (((u_int8_t *)(x))[2] << 16) \
110 + (((u_int8_t *)(x))[3] << 24))
111 #define putushort(p, v) (((u_int8_t *)(p))[0] = (v), \
112 ((u_int8_t *)(p))[1] = (v) >> 8)
113 #define putulong(p, v) (((u_int8_t *)(p))[0] = (v), \
114 ((u_int8_t *)(p))[1] = (v) >> 8, \
115 ((u_int8_t *)(p))[2] = (v) >> 16,\
116 ((u_int8_t *)(p))[3] = (v) >> 24)
117 #endif
118
119 /*
120 * BIOS Parameter Block (BPB) for DOS 3.3
121 */
122 struct byte_bpb33 {
123 int8_t bpbBytesPerSec[2]; /* bytes per sector */
124 int8_t bpbSecPerClust; /* sectors per cluster */
125 int8_t bpbResSectors[2]; /* number of reserved sectors */
126 int8_t bpbFATs; /* number of FATs */
127 int8_t bpbRootDirEnts[2]; /* number of root directory entries */
128 int8_t bpbSectors[2]; /* total number of sectors */
129 int8_t bpbMedia; /* media descriptor */
130 int8_t bpbFATsecs[2]; /* number of sectors per FAT */
131 int8_t bpbSecPerTrack[2]; /* sectors per track */
132 int8_t bpbHeads[2]; /* number of heads */
133 int8_t bpbHiddenSecs[2]; /* number of hidden sectors */
134 };
135
136 /*
137 * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
138 * and bpbHugeSectors is not in the 3.3 bpb.
139 */
140 struct byte_bpb50 {
141 int8_t bpbBytesPerSec[2]; /* bytes per sector */
142 int8_t bpbSecPerClust; /* sectors per cluster */
143 int8_t bpbResSectors[2]; /* number of reserved sectors */
144 int8_t bpbFATs; /* number of FATs */
145 int8_t bpbRootDirEnts[2]; /* number of root directory entries */
146 int8_t bpbSectors[2]; /* total number of sectors */
147 int8_t bpbMedia; /* media descriptor */
148 int8_t bpbFATsecs[2]; /* number of sectors per FAT */
149 int8_t bpbSecPerTrack[2]; /* sectors per track */
150 int8_t bpbHeads[2]; /* number of heads */
151 int8_t bpbHiddenSecs[4]; /* number of hidden sectors */
152 int8_t bpbHugeSectors[4]; /* # of sectors if bpbSectors == 0 */
153 };
154
155 /*
156 * BPB for DOS 7.10 (FAT32). This one has a few extensions to bpb50.
157 */
158 struct byte_bpb710 {
159 u_int8_t bpbBytesPerSec[2]; /* bytes per sector */
160 u_int8_t bpbSecPerClust; /* sectors per cluster */
161 u_int8_t bpbResSectors[2]; /* number of reserved sectors */
162 u_int8_t bpbFATs; /* number of FATs */
163 u_int8_t bpbRootDirEnts[2]; /* number of root directory entries */
164 u_int8_t bpbSectors[2]; /* total number of sectors */
165 u_int8_t bpbMedia; /* media descriptor */
166 u_int8_t bpbFATsecs[2]; /* number of sectors per FAT */
167 u_int8_t bpbSecPerTrack[2]; /* sectors per track */
168 u_int8_t bpbHeads[2]; /* number of heads */
169 u_int8_t bpbHiddenSecs[4]; /* # of hidden sectors */
170 u_int8_t bpbHugeSectors[4]; /* # of sectors if bpbSectors == 0 */
171 u_int8_t bpbBigFATsecs[4]; /* like bpbFATsecs for FAT32 */
172 u_int8_t bpbExtFlags[2]; /* extended flags: */
173 u_int8_t bpbFSVers[2]; /* filesystem version */
174 u_int8_t bpbRootClust[4]; /* start cluster for root directory */
175 u_int8_t bpbFSInfo[2]; /* filesystem info structure sector */
176 u_int8_t bpbBackup[2]; /* backup boot sector */
177 /* There is a 12 byte filler here, but we ignore it */
178 };
179
180 /*
181 * FAT32 FSInfo block.
182 */
183 struct fsinfo {
184 u_int8_t fsisig1[4];
185 u_int8_t fsifill1[480];
186 u_int8_t fsisig2[4];
187 u_int8_t fsinfree[4];
188 u_int8_t fsinxtfree[4];
189 u_int8_t fsifill2[12];
190 u_int8_t fsisig3[4];
191 u_int8_t fsifill3[508];
192 u_int8_t fsisig4[4];
193 };
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