FreeBSD/Linux Kernel Cross Reference
sys/fs/msdosfs/bpb.h

     /*      $NetBSD: bpb.h,v 1.5 2006/11/30 15:59:23 christos Exp $ */
     
     /*
      * Written by Paul Popelka (paulp@uts.amdahl.com)
      *
      * You can do anything you want with this software, just don't say you wrote
      * it, and don't remove this notice.
      *
      * This software is provided "as is".
     *
     * The author supplies this software to be publicly redistributed on the
     * understanding that the author is not responsible for the correct
     * functioning of this software in any circumstances and is not liable for
     * any damages caused by this software.
     *
     * October 1992
     */
    
    #ifndef _MSDOSFS_BPB_H_
    #define _MSDOSFS_BPB_H_
    
    /*
     * BIOS Parameter Block (BPB) for DOS 3.3
     */
    struct bpb33 {
            u_int16_t       bpbBytesPerSec; /* bytes per sector */
            u_int8_t        bpbSecPerClust; /* sectors per cluster */
            u_int16_t       bpbResSectors;  /* number of reserved sectors */
            u_int8_t        bpbFATs;        /* number of FATs */
            u_int16_t       bpbRootDirEnts; /* number of root directory entries */
            u_int16_t       bpbSectors;     /* total number of sectors */
            u_int8_t        bpbMedia;       /* media descriptor */
            u_int16_t       bpbFATsecs;     /* number of sectors per FAT */
            u_int16_t       bpbSecPerTrack; /* sectors per track */
            u_int16_t       bpbHeads;       /* number of heads */
            u_int16_t       bpbHiddenSecs;  /* number of hidden sectors */
    };
    
    /*
     * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
     * and bpbHugeSectors is not in the 3.3 bpb.
     */
    struct bpb50 {
            u_int16_t       bpbBytesPerSec; /* bytes per sector */
            u_int8_t        bpbSecPerClust; /* sectors per cluster */
            u_int16_t       bpbResSectors;  /* number of reserved sectors */
            u_int8_t        bpbFATs;        /* number of FATs */
            u_int16_t       bpbRootDirEnts; /* number of root directory entries */
            u_int16_t       bpbSectors;     /* total number of sectors */
            u_int8_t        bpbMedia;       /* media descriptor */
            u_int16_t       bpbFATsecs;     /* number of sectors per FAT */
            u_int16_t       bpbSecPerTrack; /* sectors per track */
            u_int16_t       bpbHeads;       /* number of heads */
            u_int32_t       bpbHiddenSecs;  /* # of hidden sectors */
            u_int32_t       bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
    };
    
    /*
     * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
     */
    struct bpb710 {
            u_int16_t       bpbBytesPerSec; /* bytes per sector */
            u_int8_t        bpbSecPerClust; /* sectors per cluster */
            u_int16_t       bpbResSectors;  /* number of reserved sectors */
            u_int8_t        bpbFATs;        /* number of FATs */
            u_int16_t       bpbRootDirEnts; /* number of root directory entries */
            u_int16_t       bpbSectors;     /* total number of sectors */
            u_int8_t        bpbMedia;       /* media descriptor */
            u_int16_t       bpbFATsecs;     /* number of sectors per FAT */
            u_int16_t       bpbSecPerTrack; /* sectors per track */
            u_int16_t       bpbHeads;       /* number of heads */
            u_int32_t       bpbHiddenSecs;  /* # of hidden sectors */
            u_int32_t       bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
            u_int32_t       bpbBigFATsecs;  /* like bpbFATsecs for FAT32 */
            u_int16_t       bpbExtFlags;    /* extended flags: */
    #define FATNUM          0xf             /* mask for numbering active FAT */
    #define FATMIRROR       0x80            /* FAT is mirrored (like it always was) */
            u_int16_t       bpbFSVers;      /* filesystem version */
    #define FSVERS          0               /* currently only 0 is understood */
            u_int32_t       bpbRootClust;   /* start cluster for root directory */
            u_int16_t       bpbFSInfo;      /* filesystem info structure sector */
            u_int16_t       bpbBackup;      /* backup boot sector */
            u_int8_t        bpbReserved[12]; /* Reserved for future expansion */
    };
    
    #ifdef  atari
    /*
     * BPB for gemdos filesystems. Atari leaves the obsolete stuff undefined.
     * Currently there is no need for a separate BPB structure.
     */
    #if 0
    struct bpb_a {
            u_int16_t       bpbBytesPerSec; /* bytes per sector             */
            u_int8_t        bpbSecPerClust; /* sectors per cluster          */
            u_int16_t       bpbResSectors;  /* number of reserved sectors   */
            u_int8_t        bpbFATs;        /* number of FATs               */
            u_int16_t       bpbRootDirEnts; /* number of root directory entries */
            u_int16_t       bpbSectors;     /* total number of sectors      */
            u_int8_t        bpbUseless1;    /* meaningless on gemdos fs     */
           u_int16_t       bpbFATsecs;     /* number of sectors per FAT    */
           u_int16_t       bpbUseless2;    /* meaningless for harddisk fs  */
           u_int16_t       bpbUseless3;    /* meaningless for harddisk fs  */
           u_int16_t       bpbHiddenSecs;  /* the TOS-BIOS ignores this    */
   };
   #endif
   #endif  /* atari */
   
   /*
    * The following structures represent how the bpb's look on disk.  shorts
    * and longs are just character arrays of the appropriate length.  This is
    * because the compiler forces shorts and longs to align on word or
    * halfword boundaries.
    *
    * XXX The little-endian code here assumes that the processor can access
    * 16-bit and 32-bit quantities on byte boundaries.  If this is not true,
    * use the macros for the big-endian case.
    */
   #include <machine/endian.h>
   #ifdef __STDC__
   #define __ICAST(q,a,x)  ((q u_int ## a ## _t *)(q void *)(x))
   #else
   #define __ICAST(q,a,x)  ((q u_int/**/a/**/_t *)(q void *)(x))
   #endif
   #if (BYTE_ORDER == LITTLE_ENDIAN) && defined(UNALIGNED_ACCESS)
   #define getushort(x)    *__ICAST(const,16,x)
   #define getulong(x)     *__ICAST(const,32,x)
   #define putushort(p, v) (void)(*__ICAST(,16,p) = (v))
   #define putulong(p, v)  (void)(*__ICAST(,32,p) = (v))
   #else
   #define getushort(x)    ((u_int16_t)(__ICAST(const,8,x)[0] \
                            | (__ICAST(const,8,x)[1] << 8)))
   #define getulong(x)     ((u_int32_t)(__ICAST(const,8,x)[0] \
                            | (__ICAST(const,8,x)[1] << 8) \
                            | (__ICAST(const,8,x)[2] << 16) \
                            | (__ICAST(const,8,x)[3] << 24)))
   #define putushort(p, v) (void)(__ICAST(,8,p)[0] = (v),  \
                            __ICAST(,8,p)[1] = (v) >> 8)
   #define putulong(p, v)  (void)(__ICAST(,8,p)[0] = (v),  \
                            __ICAST(,8,p)[1] = (v) >> 8, \
                            __ICAST(,8,p)[2] = (v) >> 16,\
                            __ICAST(,8,p)[3] = (v) >> 24)
   #endif
   
   /*
    * BIOS Parameter Block (BPB) for DOS 3.3
    */
   struct byte_bpb33 {
           int8_t bpbBytesPerSec[2];       /* bytes per sector */
           int8_t bpbSecPerClust;          /* sectors per cluster */
           int8_t bpbResSectors[2];        /* number of reserved sectors */
           int8_t bpbFATs;                 /* number of FATs */
           int8_t bpbRootDirEnts[2];       /* number of root directory entries */
           int8_t bpbSectors[2];           /* total number of sectors */
           int8_t bpbMedia;                /* media descriptor */
           int8_t bpbFATsecs[2];           /* number of sectors per FAT */
           int8_t bpbSecPerTrack[2];       /* sectors per track */
           int8_t bpbHeads[2];             /* number of heads */
           int8_t bpbHiddenSecs[2];        /* number of hidden sectors */
   };
   
   /*
    * BPB for DOS 5.0 The difference is bpbHiddenSecs is a short for DOS 3.3,
    * and bpbHugeSectors is not in the 3.3 bpb.
    */
   struct byte_bpb50 {
           int8_t bpbBytesPerSec[2];       /* bytes per sector */
           int8_t bpbSecPerClust;          /* sectors per cluster */
           int8_t bpbResSectors[2];        /* number of reserved sectors */
           int8_t bpbFATs;                 /* number of FATs */
           int8_t bpbRootDirEnts[2];       /* number of root directory entries */
           int8_t bpbSectors[2];           /* total number of sectors */
           int8_t bpbMedia;                /* media descriptor */
           int8_t bpbFATsecs[2];           /* number of sectors per FAT */
           int8_t bpbSecPerTrack[2];       /* sectors per track */
           int8_t bpbHeads[2];             /* number of heads */
           int8_t bpbHiddenSecs[4];        /* number of hidden sectors */
           int8_t bpbHugeSectors[4];       /* # of sectors if bpbSectors == 0 */
   };
   
   /*
    * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
    */
   struct byte_bpb710 {
           u_int8_t bpbBytesPerSec[2];     /* bytes per sector */
           u_int8_t bpbSecPerClust;        /* sectors per cluster */
           u_int8_t bpbResSectors[2];      /* number of reserved sectors */
           u_int8_t bpbFATs;               /* number of FATs */
           u_int8_t bpbRootDirEnts[2];     /* number of root directory entries */
           u_int8_t bpbSectors[2];         /* total number of sectors */
           u_int8_t bpbMedia;              /* media descriptor */
           u_int8_t bpbFATsecs[2];         /* number of sectors per FAT */
           u_int8_t bpbSecPerTrack[2];     /* sectors per track */
           u_int8_t bpbHeads[2];           /* number of heads */
           u_int8_t bpbHiddenSecs[4];      /* # of hidden sectors */
           u_int8_t bpbHugeSectors[4];     /* # of sectors if bpbSectors == 0 */
           u_int8_t bpbBigFATsecs[4];      /* like bpbFATsecs for FAT32 */
           u_int8_t bpbExtFlags[2];        /* extended flags: */
           u_int8_t bpbFSVers[2];          /* filesystem version */
           u_int8_t bpbRootClust[4];       /* start cluster for root directory */
           u_int8_t bpbFSInfo[2];          /* filesystem info structure sector */
           u_int8_t bpbBackup[2];          /* backup boot sector */
           u_int8_t bpbReserved[12];       /* Reserved for future expansion */
   };
   
   /*
    * FAT32 FSInfo block.
    */
   struct fsinfo {
           u_int8_t fsisig1[4];
           u_int8_t fsifill1[480];
           u_int8_t fsisig2[4];
           u_int8_t fsinfree[4];
           u_int8_t fsinxtfree[4];
           u_int8_t fsifill2[12];
           u_int8_t fsisig3[4];
           u_int8_t fsifill3[508];
           u_int8_t fsisig4[4];
   };
   #endif /* _MSDOSFS_BPB_H_ */

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