/*
 * 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: fat.h,v 1.1 1993/08/13 11:35:33 cgd Exp $
 */

/*
 * Some useful cluster numbers.
 */
#define	MSDOSFSROOT	0	/* cluster 0 means the root dir */
#define	CLUST_FREE	0	/* cluster 0 also means a free cluster */
#define	MSDOSFSFREE	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	MSDOSFSEOF(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 msdosfsmount * pmp, u_long cn, u_long * oldcnp));
int clusteralloc __P((struct msdosfsmount * pmp, u_long * retcluster, u_long fillwith));
int fatentry __P((int function, struct msdosfsmount * pmp, u_long cluster, u_long * oldcontents, u_long newcontents));
int freeclusterchain __P((struct msdosfsmount * pmp, u_long startchain));
#endif /* defined(KERNEL) */