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 26 typedef __signed__ char __s8; 27 typedef unsigned char __u8; 28 typedef __signed__ short __s16; 29 typedef unsigned short __u16; 30 typedef __signed__ int __s32; 31 typedef unsigned int __u32; 32 33 /* Note that some shorts are not aligned, and must therefore 34 * be declared as array of two bytes. 35 */ 36 struct 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