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Cluster optimizations, mainly for FAT32: eliminated checkdstart,

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replaced (cl == FREE || cl == 1) by (cl <= 1), UWORD cluster cast for FAT12/16,
and merge if branches for link_fat().


git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@1448 6ac86273-5f31-0410-b378-82cca8765d1b
This commit is contained in:
Bart Oldeman 2009-06-16 21:45:17 +00:00
parent d854929efb
commit 132b1fe579
2 changed files with 12 additions and 22 deletions
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3
hdr/fat.h
View File

@ -131,14 +131,11 @@ struct lfn_entry {
struct dpb;
CLUSTER getdstart(struct dpb FAR *dpbp, struct dirent *dentry);
void setdstart(struct dpb FAR *dpbp, struct dirent *dentry, CLUSTER value);
BOOL checkdstart(struct dpb FAR *dpbp, struct dirent *dentry, CLUSTER value);
#else
#define getdstart(dpbp, dentry) \
((dentry)->dir_start)
#define setdstart(dpbp, dentry, value) \
(((dentry)->dir_start) = (UWORD)(value))
#define checkdstart(dpbp, dentry, value) \
(((dentry)->dir_start) == (UWORD)(value))
#endif
#define DIR_NAME 0

31
kernel/fatfs.c
View File

@ -71,14 +71,6 @@ void setdstart(struct dpb FAR *dpbp, struct dirent *dentry, CLUSTER value)
if (ISFAT32(dpbp))
dentry->dir_start_high = (UWORD)(value >> 16);
}
BOOL checkdstart(struct dpb FAR *dpbp, struct dirent *dentry, CLUSTER value)
{
if (!ISFAT32(dpbp))
return dentry->dir_start == (UWORD)value;
return (dentry->dir_start == (UWORD)value &&
dentry->dir_start_high == (UWORD)(value >> 16));
}
#endif
ULONG clus2phys(CLUSTER cl_no, struct dpb FAR * dpbp)
@ -585,7 +577,7 @@ STATIC VOID wipe_out_clusters(struct dpb FAR * dpbp, CLUSTER st)
next = next_cluster(dpbp, st);
/* just exit if a damaged file system exists */
if (next == FREE || next == 1)
if (next <= 1)
return;
/* zap the FAT pointed to */
@ -601,7 +593,7 @@ STATIC VOID wipe_out_clusters(struct dpb FAR * dpbp, CLUSTER st)
}
else
#endif
if ((dpbp->dpb_cluster == UNKNCLUSTER) || (dpbp->dpb_cluster > st))
if ((dpbp->dpb_cluster == UNKNCLUSTER) || (dpbp->dpb_cluster > (UWORD)st))
dpbp->dpb_cluster = (UWORD)st;
/* and just follow the linked list */
@ -618,8 +610,9 @@ STATIC VOID wipe_out_clusters(struct dpb FAR * dpbp, CLUSTER st)
STATIC VOID wipe_out(f_node_ptr fnp)
{
/* if not already free and valid file, do it */
if (fnp && !checkdstart(fnp->f_dpb, &fnp->f_dir, FREE))
wipe_out_clusters(fnp->f_dpb, getdstart(fnp->f_dpb, &fnp->f_dir));
CLUSTER cluster = getdstart(fnp->f_dpb, &fnp->f_dir);
if (cluster != FREE)
wipe_out_clusters(fnp->f_dpb, cluster);
/* no flushing here: could get lost chain or "crosslink seed" but */
/* it would be annoying if mass-deletes could not use BUFFERS... */
}
@ -1010,7 +1003,7 @@ COUNT map_cluster(REG f_node_ptr fnp, COUNT mode)
{
/* get next cluster in the chain */
cluster = next_cluster(fnp->f_dpb, fnp->f_cluster);
if (cluster == 1 || cluster == FREE) /* error or chain into the void */
if (cluster <= 1) /* 1/error or 0/FREE chain into the void */
return DE_SEEK;
/* If this is a read and the next is a LAST_CLUSTER, */
@ -1790,7 +1783,7 @@ STATIC VOID shrink_file(f_node_ptr fnp)
{
ULONG lastoffset = fnp->f_offset; /* has to be saved */
CLUSTER next, st;
CLUSTER last, next, st;
struct dpb FAR *dpbp = fnp->f_dpb;
fnp->f_offset = fnp->f_dir.dir_size; /* end of file */
@ -1805,7 +1798,7 @@ STATIC VOID shrink_file(f_node_ptr fnp)
next = next_cluster(dpbp, st); /* return nr. of 1st cluster after new end */
if (next == 1 || next == FREE) /* error or chain points into the void */
if (next <= 1) /* 1/error or 0/FREE chain points into the void */
goto done;
/* Loop from start until either a FREE entry is */
@ -1817,16 +1810,16 @@ STATIC VOID shrink_file(f_node_ptr fnp)
{
fnp->f_cluster = FREE;
setdstart(dpbp, &fnp->f_dir, FREE); /* file no longer has start cluster */
if (link_fat(dpbp, st, FREE) != SUCCESS) /* free first cluster of chain */
goto done; /* do not wipe remainder of chain if FAT is broken */
last = FREE;
}
else
{
if (next == LONG_LAST_CLUSTER) /* nothing to do, file already ends here */
goto done;
if (link_fat(dpbp, st, LONG_LAST_CLUSTER) != SUCCESS) /* make file end */
goto done; /* do not wipe remainder of chain if FAT is broken */
last = LONG_LAST_CLUSTER; /* make file end */
}
if (link_fat(dpbp, st, last) != SUCCESS)
goto done; /* do not wipe remainder of chain if FAT is broken */
wipe_out_clusters(dpbp, next); /* free clusters after the end */
/* flush buffers, make sure disk is updated - hazard: no error checking! */