RepoMirrors/musl
1
0
Fork 0
mirror of git://git.musl-libc.org/musl synced 2024-12-19 05:14:47 +00:00
Code Issues Packages Projects Releases Wiki Activity

bsearch: simplify and optimize

Browse Source 
maintainer's note: the key observation here is that the compared
element is the first slot of the second ceil(half) of the array, and
thus can be removed for further comparison when it does not match, so
that we descend into the second ceil(half)-1 rather than ceil(half)
elements. this change ensures that nel strictly decreases with each
iteration, so that the case of != but nel==1 does not need to be
special-cased anymore.
This commit is contained in:
Fangrui Song 2018-07-21 17:34:00 -07:00 committed by Rich Felker
parent f2c6dbe244
commit 3d8322c7ad
1 changed files with 6 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/stdlib/bsearch.c
View File

@ -7,13 +7,13 @@ void *bsearch(const void *key, const void *base, size_t nel, size_t width, int (
while (nel > 0) {
try = (char *)base + width*(nel/2);
sign = cmp(key, try);
if (!sign) return try;
else if (nel == 1) break;
else if (sign < 0)
if (sign < 0) {
nel /= 2;
else {
base = try;
nel -= nel/2;
} else if (sign > 0) {
base = (char *)try + width;
nel -= nel/2+1;
} else {
return try;
}
}
return NULL;