diff options
author | Rich Felker <dalias@aerifal.cx> | 2012-09-27 17:19:09 -0400 |
---|---|---|
committer | Rich Felker <dalias@aerifal.cx> | 2012-09-27 17:19:09 -0400 |
commit | 68dbd05039f8b256f586ed9a589645fa3a1b7f5f (patch) | |
tree | b27c6d58c7be3e028276a4840e76187ccdfa9696 /src/string/strchr.c | |
parent | 3f9ff1514e49b06c20a61af9ae9e52bd53b48d9a (diff) | |
download | musl-68dbd05039f8b256f586ed9a589645fa3a1b7f5f.tar.gz musl-68dbd05039f8b256f586ed9a589645fa3a1b7f5f.tar.xz musl-68dbd05039f8b256f586ed9a589645fa3a1b7f5f.zip |
optimize strchrnul/strcspn not to scan string twice on no-match
when strchr fails, and important piece of information already computed, the string length, is thrown away. have strchrnul (with namespace protection) be the underlying function so this information can be kept, and let strchr be a wrapper for it. this also allows strcspn to be considerably faster in the case where the match set has a single element that's not matched.
Diffstat (limited to 'src/string/strchr.c')
-rw-r--r-- | src/string/strchr.c | 23 |
1 files changed, 3 insertions, 20 deletions
diff --git a/src/string/strchr.c b/src/string/strchr.c index d3563f18..bfae8f9f 100644 --- a/src/string/strchr.c +++ b/src/string/strchr.c @@ -1,26 +1,9 @@ #include <string.h> -#include <stdlib.h> -#include <stdint.h> -#include <limits.h> -#define ALIGN (sizeof(size_t)-1) -#define ONES ((size_t)-1/UCHAR_MAX) -#define HIGHS (ONES * (UCHAR_MAX/2+1)) -#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS) +char *__strchrnul(const char *, int); char *strchr(const char *s, int c) { - size_t *w, k; - - c = (unsigned char)c; - if (!c) return (char *)s + strlen(s); - - for (; ((uintptr_t)s & ALIGN); s++) - if (*(unsigned char *)s == c) return (char *)s; - else if (!*s) return 0; - k = ONES * c; - for (w = (void *)s; !HASZERO(*w) && !HASZERO(*w^k); w++); - for (s = (void *)w; *s; s++) - if (*(unsigned char *)s == c) return (char *)s; - return 0; + char *r = __strchrnul(s, c); + return *(unsigned char *)r == (unsigned char)c ? r : 0; } |