From 0b44a0315b47dd8eced9f3b7f31580cf14bbfc01 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 12 Feb 2011 00:22:29 -0500 Subject: initial check-in, version 0.5.0 --- src/string/memchr.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 src/string/memchr.c (limited to 'src/string/memchr.c') diff --git a/src/string/memchr.c b/src/string/memchr.c new file mode 100644 index 00000000..a0472f78 --- /dev/null +++ b/src/string/memchr.c @@ -0,0 +1,24 @@ +#include +#include +#include +#include + +#define SS (sizeof(size_t)) +#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) + +void *memchr(const void *src, int c, size_t n) +{ + const unsigned char *s = src; + c = (unsigned char)c; + for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--); + if (n && *s != c) { + const size_t *w; + size_t k = ONES * c; + for (w = (const void *)s; n>=SS && !HASZERO(*w^k); w++, n-=SS); + for (s = (const void *)w; n && *s != c; s++, n--); + } + return n ? (void *)s : 0; +} -- cgit v1.2.1