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

     /* $FreeBSD$ */
     /*      $NetBSD: bpb.h,v 1.7 1997/11/17 15:36:24 ws 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 _FS_MSDOSFS_BPB_H_
    #define _FS_MSDOSFS_BPB_H_
    
    /*
     * BIOS Parameter Block (BPB) for DOS 3.3
     */
    struct bpb33 {
            uint16_t        bpbBytesPerSec; /* bytes per sector */
            uint8_t         bpbSecPerClust; /* sectors per cluster */
            uint16_t        bpbResSectors;  /* number of reserved sectors */
            uint8_t         bpbFATs;        /* number of FATs */
            uint16_t        bpbRootDirEnts; /* number of root directory entries */
            uint16_t        bpbSectors;     /* total number of sectors */
            uint8_t         bpbMedia;       /* media descriptor */
            uint16_t        bpbFATsecs;     /* number of sectors per FAT */
            uint16_t        bpbSecPerTrack; /* sectors per track */
            uint16_t        bpbHeads;       /* number of heads */
            uint16_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 {
            uint16_t        bpbBytesPerSec; /* bytes per sector */
            uint8_t         bpbSecPerClust; /* sectors per cluster */
            uint16_t        bpbResSectors;  /* number of reserved sectors */
            uint8_t         bpbFATs;        /* number of FATs */
            uint16_t        bpbRootDirEnts; /* number of root directory entries */
            uint16_t        bpbSectors;     /* total number of sectors */
            uint8_t         bpbMedia;       /* media descriptor */
            uint16_t        bpbFATsecs;     /* number of sectors per FAT */
            uint16_t        bpbSecPerTrack; /* sectors per track */
            uint16_t        bpbHeads;       /* number of heads */
            uint32_t        bpbHiddenSecs;  /* # of hidden sectors */
            uint32_t        bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
    };
    
    /*
     * BPB for DOS 7.10 (FAT32).  This one has a few extensions to bpb50.
     */
    struct bpb710 {
            uint16_t        bpbBytesPerSec; /* bytes per sector */
            uint8_t         bpbSecPerClust; /* sectors per cluster */
            uint16_t        bpbResSectors;  /* number of reserved sectors */
            uint8_t         bpbFATs;        /* number of FATs */
            uint16_t        bpbRootDirEnts; /* number of root directory entries */
            uint16_t        bpbSectors;     /* total number of sectors */
            uint8_t         bpbMedia;       /* media descriptor */
            uint16_t        bpbFATsecs;     /* number of sectors per FAT */
            uint16_t        bpbSecPerTrack; /* sectors per track */
            uint16_t        bpbHeads;       /* number of heads */
            uint32_t        bpbHiddenSecs;  /* # of hidden sectors */
            uint32_t        bpbHugeSectors; /* # of sectors if bpbSectors == 0 */
            uint32_t        bpbBigFATsecs;  /* like bpbFATsecs for FAT32 */
            uint16_t        bpbExtFlags;    /* extended flags: */
    #define FATNUM          0xf             /* mask for numbering active FAT */
    #define FATMIRROR       0x80            /* FAT is mirrored (like it always was) */
            uint16_t        bpbFSVers;      /* filesystem version */
    #define FSVERS          0               /* currently only 0 is understood */
            uint32_t        bpbRootClust;   /* start cluster for root directory */
            uint16_t        bpbFSInfo;      /* filesystem info structure sector */
            uint16_t        bpbBackup;      /* backup boot sector */
            uint8_t         bpbReserved[12]; /* reserved for future expansion */
    };
    
    /*
     * 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.
     */
    
    #include <sys/endian.h>
    
    #define getushort(x)    le16dec(x)
    #define getulong(x)     le32dec(x)
    #define putushort(p, v) le16enc(p, v)
    #define putulong(p, v)  le32enc(p, v)
   
   /*
    * 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 {
           uint8_t bpbBytesPerSec[2];      /* bytes per sector */
           uint8_t bpbSecPerClust;         /* sectors per cluster */
           uint8_t bpbResSectors[2];       /* number of reserved sectors */
           uint8_t bpbFATs;                /* number of FATs */
           uint8_t bpbRootDirEnts[2];      /* number of root directory entries */
           uint8_t bpbSectors[2];          /* total number of sectors */
           uint8_t bpbMedia;               /* media descriptor */
           uint8_t bpbFATsecs[2];          /* number of sectors per FAT */
           uint8_t bpbSecPerTrack[2];      /* sectors per track */
           uint8_t bpbHeads[2];            /* number of heads */
           uint8_t bpbHiddenSecs[4];       /* # of hidden sectors */
           uint8_t bpbHugeSectors[4];      /* # of sectors if bpbSectors == 0 */
           uint8_t bpbBigFATsecs[4];       /* like bpbFATsecs for FAT32 */
           uint8_t bpbExtFlags[2];         /* extended flags: */
           uint8_t bpbFSVers[2];           /* filesystem version */
           uint8_t bpbRootClust[4];        /* start cluster for root directory */
           uint8_t bpbFSInfo[2];           /* filesystem info structure sector */
           uint8_t bpbBackup[2];           /* backup boot sector */
           uint8_t bpbReserved[12];        /* reserved for future expansion */
   };
   
   /*
    * FAT32 FSInfo block.
    */
   struct fsinfo {
           uint8_t fsisig1[4];
           uint8_t fsifill1[480];
           uint8_t fsisig2[4];
           uint8_t fsinfree[4];
           uint8_t fsinxtfree[4];
           uint8_t fsifill2[12];
           uint8_t fsisig3[4];
   };
   #endif /* !_FS_MSDOSFS_BPB_H_ */

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