114 lines
3.6 KiB
C
114 lines
3.6 KiB
C
/*
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* GRUB -- GRand Unified Bootloader
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* Copyright (C) 1996 Erich Boleyn <erich@uruk.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*
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* Defines for the FAT BIOS Parameter Block (embedded in the first block
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* of the partition.
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*/
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#define FAT_BPB_SIGNATURE 0x29
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/* is checking for this signature thing even valid? */
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#define FAT_BPB_CHECK_SIG(bpb) \
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(*((unsigned char *) (((int)bpb) + 38)) == FAT_BPB_SIGNATURE)
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#define FAT_BPB_NUM_SECTORS(bpb) \
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( *((unsigned short *) (((int)bpb) + 19)) ? \
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*((unsigned short *) (((int)bpb) + 19)) : \
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*((unsigned long *) (((int)bpb) + 32)) )
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#define FAT_BPB_BYTES_PER_SECTOR(bpb) \
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(*((unsigned short *) (((int)bpb) + 11)))
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#define FAT_BPB_SECT_PER_CLUST(bpb) \
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(*((unsigned char *) (((int)bpb) + 13)))
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#define FAT_BPB_NUM_FAT(bpb) \
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(*((unsigned char *) (((int)bpb) + 16)))
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#define FAT_BPB_RESERVED_SECTORS(bpb) \
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(*((unsigned short *) (((int)bpb) + 14)))
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#define FAT_BPB_FAT_SECTORS(bpb) \
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(*((unsigned short *) (((int)bpb) + 22)))
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#define FAT_BPB_FAT_START(bpb) FAT_BPB_RESERVED_SECTORS(bpb)
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/*
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* This appears to be a MAJOR kludge!! Don't use it if possible...
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*/
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#define FAT_BPB_HIDDEN_SECTORS(bpb) \
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(*((unsigned long *) (((int)bpb) + 28)))
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#define FAT_BPB_ROOT_DIR_START(bpb) \
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( FAT_BPB_NUM_FAT(bpb) * FAT_BPB_FAT_SECTORS(bpb) \
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+ FAT_BPB_FAT_START(bpb) )
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#define FAT_BPB_ROOT_DIR_LENGTH(bpb) \
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( (*((unsigned short *) (((int)bpb) + 17)) + 0xF) >> 4 )
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#define FAT_BPB_DATA_OFFSET(bpb) \
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( FAT_BPB_ROOT_DIR_START(bpb) + FAT_BPB_ROOT_DIR_LENGTH(bpb) )
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#define FAT_BPB_NUM_CLUST(bpb) \
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( ( FAT_BPB_NUM_SECTORS(bpb) - FAT_BPB_DATA_OFFSET(bpb) ) \
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/ FAT_BPB_SECT_PER_CLUST(bpb) )
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/*
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* Defines minimum disk size to be considered a FAT partition
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*/
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#define FAT_MIN_NUM_SECTORS 720 /* 360 K disk */
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/*
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* Defines how to differentiate a 12-bit and 16-bit FAT.
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*/
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#define FAT_MAX_12BIT_CLUST 4087 /* 4085 + 2 */
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#define FAT_BPB_FLOPPY_NUM_SECTORS(bpb) \
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( *((unsigned short *) (((int)bpb) + 19)) \
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&& !*((unsigned long *) (((int)bpb) + 32)) \
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&& *((unsigned short *) (((int)bpb) + 19)) >= FAT_MIN_NUM_SECTORS \
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&& ((*((unsigned short *) (((int)bpb) + 19)) - FAT_BPB_DATA_OFFSET(bpb)) \
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/ FAT_BPB_SECT_PER_CLUST(bpb)) < (FAT_BPB_FAT_SECTORS(bpb) * 342) )
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/*
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* Defines for the file "attribute" byte
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*/
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#define FAT_ATTRIB_OK_MASK 0x37
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#define FAT_ATTRIB_NOT_OK_MASK 0xC8
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#define FAT_ATTRIB_DIR 0x10
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/*
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* Defines for FAT directory entries
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*/
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#define FAT_DIRENTRY_LENGTH 32
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#define FAT_DIRENTRY_ATTRIB(entry) \
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(*((unsigned char *) (entry+11)))
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#define FAT_DIRENTRY_VALID(entry) \
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( ((*((unsigned char *) entry)) != 0) \
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& ((*((unsigned char *) entry)) != 0xE5) \
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& !(FAT_DIRENTRY_ATTRIB(entry) & FAT_ATTRIB_NOT_OK_MASK) )
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#define FAT_DIRENTRY_FIRST_CLUSTER(entry) \
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(*((unsigned short *) (entry+26)))
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#define FAT_DIRENTRY_FILELENGTH(entry) \
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(*((unsigned long *) (entry+28)))
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