While profiling something completely unrelated, I noticed
that on the workloads I used memchr for, I saw a 30%-40% improvement
in performance, with the following trivial changes...
(basically, it saves 3 operations for each call)
$ diff -Nurp linux/lib/string.c{-old,}
--- linux/lib/string.c-old 2007-08-22 11:18:54.000000000 +0200
+++ linux/lib/string.c 2007-08-22 11:19:20.000000000 +0200
@@ -623,10 +623,12 @@ EXPORT_SYMBOL(strstr);
void *memchr(const void *s, int c, size_t n)
{
const unsigned char *p = s;
- while (n-- != 0) {
- if ((unsigned char)c == *p++) {
- return (void *)(p - 1);
+ while (n != 0) {
+ if ((unsigned char)c == *p) {
+ return (void *)p;
}
+ n--;
+ p++;
}
return NULL;
}
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