lfscreate.c File Reference

#include <xinu.h>
#include <ramdisk.h>

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Functions
status	lfscreate (did32 disk, ibid32 lfiblks, uint32 dsiz)

Function Documentation

lfscreate()

status lfscreate	(	did32	disk,
		ibid32	lfiblks,
		uint32	dsiz
	)

Definition at line 10 of file lfscreate.c.

References close(), lfiblk::ib_next, LF_AREA_DIR, LF_BLKSIZ, LF_DNULL, LF_INULL, lfibclear(), lfibput(), LFS_ID, memset(), NULLCH, OK, SYSERR, and write().

{
    uint32  sectors;        /* Number of sectors to use */
    uint32  ibsectors;      /* Number of sectors of i-blocks*/
    uint32  ibpersector;        /* Number of i-blocks per sector*/
    struct  lfdir   dir;        /* Buffer to hold the directory */
    uint32  dblks;          /* Total free data blocks   */
    struct  lfiblk  iblock;     /* Space for one i-block    */
    struct  lfdbfree dblock;    /* Data block on the free list  */
    dbid32  dbindex;        /* Index for data blocks    */
    int32   retval;         /* Return value from func call  */
    int32   i;          /* Loop index           */

    /* Compute total sectors on disk */

    sectors = dsiz  / LF_BLKSIZ;    /* Truncate to full sector */

    /* Compute number of sectors comprising i-blocks */

    ibpersector = LF_BLKSIZ / sizeof(struct lfiblk);
    ibsectors = (lfiblks+(ibpersector-1)) / ibpersector;/* Round up */
    lfiblks = ibsectors * ibpersector;
    if (ibsectors > sectors/2) {    /* Invalid arguments */
        return SYSERR;
    }

    /* Create an initial directory */

    memset((char *)&dir, NULLCH, sizeof(struct lfdir));
    dir.lfd_fsysid = LFS_ID;
    dir.lfd_nfiles = 0;
    dir.lfd_allzeros = 0;
    dir.lfd_allones = 0xffffffff;
    dir.lfd_revid = ((LFS_ID>>24) & 0x000000ff) | 
                  ((LFS_ID>> 8) & 0x0000ff00) |
                  ((LFS_ID<< 8) & 0x00ff0000) |
                  ((LFS_ID<<24) & 0xff000000) ;
    dbindex= (dbid32)(ibsectors + 1);
    dir.lfd_dfree = dbindex;
    dblks = sectors - ibsectors - 1;
    retval = write(disk,(char *)&dir, LF_AREA_DIR);
    if (retval == SYSERR) {
        return SYSERR;
    }

    /* Create list of free i-blocks on disk */

    lfibclear(&iblock, 0);
    for (i=0; i<lfiblks-1; i++) {
        iblock.ib_next = (ibid32)(i + 1);
        lfibput(disk, i, &iblock);
    }
    iblock.ib_next = LF_INULL;
    lfibput(disk, i, &iblock);

    /* Create list of free data blocks on disk */

    memset((char*)&dblock, NULLCH, LF_BLKSIZ);
    for (i=0; i<dblks-1; i++) {
        dblock.lf_nextdb = dbindex + 1;
        write(disk, (char *)&dblock, dbindex);
        dbindex++;
    }
    dblock.lf_nextdb = LF_DNULL;
    write(disk, (char *)&dblock, dbindex);
    close(disk);
    return OK;
}

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