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Replace a number of similar for' loops with a new ilog2()' function

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that computes the base-2 log of a power of 2.
This commit is contained in:
Ian Dowse 2002-03-19 17:39:01 +00:00
parent bf57cced53
commit 475df34ac2
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=92712
1 changed files with 17 additions and 10 deletions
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27
sbin/newfs/mkfs.c
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@ -130,6 +130,7 @@ long calcipg();
static int charsperline();
void clrblock (struct fs *, unsigned char *, int);
void fsinit (time_t);
static int ilog2(int);
void initcg (int, time_t);
int isblock (struct fs *, unsigned char *, int);
void iput (struct dinode *, ino_t);
@ -232,13 +233,10 @@ mkfs(struct partition *pp, char *fsys, int fi, int fo)
sblock.fs_fmask = ~(sblock.fs_fsize - 1);
sblock.fs_qbmask = ~sblock.fs_bmask;
sblock.fs_qfmask = ~sblock.fs_fmask;
for (sblock.fs_bshift = 0, i = sblock.fs_bsize; i > 1; i >>= 1)
sblock.fs_bshift++;
for (sblock.fs_fshift = 0, i = sblock.fs_fsize; i > 1; i >>= 1)
sblock.fs_fshift++;
sblock.fs_bshift = ilog2(sblock.fs_bsize);
sblock.fs_fshift = ilog2(sblock.fs_fsize);
sblock.fs_frag = numfrags(&sblock, sblock.fs_bsize);
for (sblock.fs_fragshift = 0, i = sblock.fs_frag; i > 1; i >>= 1)
sblock.fs_fragshift++;
sblock.fs_fragshift = ilog2(sblock.fs_frag);
if (sblock.fs_frag > MAXFRAG) {
printf(
"fragment size %d is too small, minimum with block size %d is %d\n",
@ -250,8 +248,7 @@ mkfs(struct partition *pp, char *fsys, int fi, int fo)
sblock.fs_nindir = sblock.fs_bsize / sizeof(daddr_t);
sblock.fs_inopb = sblock.fs_bsize / sizeof(struct dinode);
sblock.fs_nspf = sblock.fs_fsize / sectorsize;
for (sblock.fs_fsbtodb = 0, i = NSPF(&sblock); i > 1; i >>= 1)
sblock.fs_fsbtodb++;
sblock.fs_fsbtodb = ilog2(NSPF(&sblock));
sblock.fs_sblkno =
roundup(howmany(bbsize + sbsize, sblock.fs_fsize), sblock.fs_frag);
sblock.fs_cblkno = (daddr_t)(sblock.fs_sblkno +
@ -568,8 +565,7 @@ mkfs(struct partition *pp, char *fsys, int fi, int fo)
*/
i = sblock.fs_bsize / sizeof(struct csum);
sblock.fs_csmask = ~(i - 1);
for (sblock.fs_csshift = 0; i > 1; i >>= 1)
sblock.fs_csshift++;
sblock.fs_csshift = ilog2(i);
fscs = (struct csum *)calloc(1, sblock.fs_cssize);
if (fscs == NULL)
errx(31, "calloc failed");
@ -1235,3 +1231,14 @@ charsperline()
columns = 80; /* last resort */
return (columns);
}
static int
ilog2(int val)
{
int n;
for (n = 0; n < sizeof(n) * NBBY; n++)
if (1 << n == val)
return (n);
errx(1, "ilog2: %d is not a power of 2\n", val);
}