sys/pcfs/fat.h

/*
 *  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
 *
 *      $Id$
 */

/*
 *  Some useful cluster numbers.
 */
#define PCFSROOT        0       /* cluster 0 means the root dir         */
#define CLUST_FREE      0       /* cluster 0 also means a free cluster  */
#define PCFSFREE        CLUST_FREE
#define CLUST_FIRST     2       /* first legal cluster number           */
#define CLUST_RSRVS     0xfff0  /* start of reserved cluster range      */
#define CLUST_RSRVE     0xfff6  /* end of reserved cluster range        */
#define CLUST_BAD       0xfff7  /* a cluster with a defect              */
#define CLUST_EOFS      0xfff8  /* start of eof cluster range           */
#define CLUST_EOFE      0xffff  /* end of eof cluster range             */

#define FAT12_MASK      0x0fff  /* mask for 12 bit cluster numbers      */
#define FAT16_MASK      0xffff  /* mask for 16 bit cluster numbers      */

/*
 *  Return true if filesystem uses 12 bit fats.
 *  Microsoft Programmer's Reference says if the
 *  maximum cluster number in a filesystem is greater
 *  than 4086 then we've got a 16 bit fat filesystem.
 */
#define FAT12(pmp)      (pmp->pm_maxcluster <= 4086)
#define FAT16(pmp)      (pmp->pm_maxcluster >  4086)

#define PCFSEOF(cn)     (((cn) & 0xfff8) == 0xfff8)

/*
 *  These are the values for the function argument to
 *  the function fatentry().
 */
#define FAT_GET         0x0001          /* get a fat entry              */
#define FAT_SET         0x0002          /* set a fat entry              */
#define FAT_GET_AND_SET (FAT_GET | FAT_SET)

#if defined(KERNEL)
int pcbmap __P((struct denode *dep,
                u_long findcn,
                daddr_t *bnp,
                u_long *cnp));
int clusterfree __P((struct pcfsmount *pmp, u_long cn, u_long *oldcnp));
int clusteralloc __P((struct pcfsmount *pmp, u_long *retcluster,
        u_long fillwith));
int fatentry __P((int function, struct pcfsmount *pmp,
        u_long cluster, u_long *oldcontents, u_long newcontents));
int freeclusterchain __P((struct pcfsmount *pmp, u_long startchain));
#endif /* defined(KERNEL) */