1/*
2 *  GRUB  --  GRand Unified Bootloader
3 *  Copyright (C) 2001  Free Software Foundation, Inc.
4 *
5 *  This program is free software; you can redistribute it and/or modify
6 *  it under the terms of the GNU General Public License as published by
7 *  the Free Software Foundation; either version 2 of the License, or
8 *  (at your option) any later version.
9 *
10 *  This program is distributed in the hope that it will be useful,
11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 *  GNU General Public License for more details.
14 *
15 *  You should have received a copy of the GNU General Public License
16 *  along with this program; if not, write to the Free Software
17 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 */
19
20
21/*
22 *  Defines for the FAT BIOS Parameter Block (embedded in the first block
23 *  of the partition.
24 */
25
26typedef __signed__ char __s8;
27typedef unsigned char __u8;
28typedef __signed__ short __s16;
29typedef unsigned short __u16;
30typedef __signed__ int __s32;
31typedef unsigned int __u32;
32
33/* Note that some shorts are not aligned, and must therefore
34 * be declared as array of two bytes.
35 */
36struct fat_bpb {
37	__s8	ignored[3];	/* Boot strap short or near jump */
38	__s8	system_id[8];	/* Name - can be used to special case
39				   partition manager volumes */
40	__u8	bytes_per_sect[2];	/* bytes per logical sector */
41	__u8	sects_per_clust;/* sectors/cluster */
42	__u8	reserved_sects[2];	/* reserved sectors */
43	__u8	num_fats;	/* number of FATs */
44	__u8	dir_entries[2];	/* root directory entries */
45	__u8	short_sectors[2];	/* number of sectors */
46	__u8	media;		/* media code (unused) */
47	__u16	fat_length;	/* sectors/FAT */
48	__u16	secs_track;	/* sectors per track */
49	__u16	heads;		/* number of heads */
50	__u32	hidden;		/* hidden sectors (unused) */
51	__u32	long_sectors;	/* number of sectors (if short_sectors == 0) */
52
53	/* The following fields are only used by FAT32 */
54	__u32	fat32_length;	/* sectors/FAT */
55	__u16	flags;		/* bit 8: fat mirroring, low 4: active fat */
56	__u8	version[2];	/* major, minor filesystem version */
57	__u32	root_cluster;	/* first cluster in root directory */
58	__u16	info_sector;	/* filesystem info sector */
59	__u16	backup_boot;	/* backup boot sector */
60	__u16	reserved2[6];	/* Unused */
61};
62
63#define FAT_CVT_U16(bytarr) (* (__u16*)(bytarr))
64
65/*
66 *  Defines how to differentiate a 12-bit and 16-bit FAT.
67 */
68
69#define FAT_MAX_12BIT_CLUST       4087	/* 4085 + 2 */
70
71/*
72 *  Defines for the file "attribute" byte
73 */
74
75#define FAT_ATTRIB_OK_MASK        0x37
76#define FAT_ATTRIB_NOT_OK_MASK    0xC8
77#define FAT_ATTRIB_DIR            0x10
78#define FAT_ATTRIB_LONGNAME       0x0F
79
80/*
81 *  Defines for FAT directory entries
82 */
83
84#define FAT_DIRENTRY_LENGTH       32
85
86#define FAT_DIRENTRY_ATTRIB(entry) \
87  (*((unsigned char *) (entry+11)))
88#define FAT_DIRENTRY_VALID(entry) \
89  ( ((*((unsigned char *) entry)) != 0) \
90    && ((*((unsigned char *) entry)) != 0xE5) \
91    && !(FAT_DIRENTRY_ATTRIB(entry) & FAT_ATTRIB_NOT_OK_MASK) )
92#define FAT_DIRENTRY_FIRST_CLUSTER(entry) \
93  ((*((unsigned short *) (entry+26)))+(*((unsigned short *) (entry+20)) << 16))
94#define FAT_DIRENTRY_FILELENGTH(entry) \
95  (*((unsigned long *) (entry+28)))
96
97#define FAT_LONGDIR_ID(entry) \
98  (*((unsigned char *) (entry)))
99#define FAT_LONGDIR_ALIASCHECKSUM(entry) \
100  (*((unsigned char *) (entry+13)))
101