From ac0ca9855bc0fcc64e9467bedddaa46bc90e2593 Mon Sep 17 00:00:00 2001 From: iedowse Date: Tue, 19 Mar 2002 17:39:01 +0000 Subject: Replace a number of similar `for' loops with a new `ilog2()' function that computes the base-2 log of a power of 2. --- sbin/newfs/mkfs.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) (limited to 'sbin') diff --git a/sbin/newfs/mkfs.c b/sbin/newfs/mkfs.c index 0d702c4..f8e0026 100644 --- a/sbin/newfs/mkfs.c +++ b/sbin/newfs/mkfs.c @@ -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 @@ next: */ 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); +} -- cgit v1.1