From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001 From: Vladimir Azarov Date: Tue, 1 Oct 2024 15:47:05 +0200 Subject: Initial version --- src/string/strlen.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 src/string/strlen.c (limited to 'src/string/strlen.c') diff --git a/src/string/strlen.c b/src/string/strlen.c new file mode 100644 index 0000000..309990f --- /dev/null +++ b/src/string/strlen.c @@ -0,0 +1,22 @@ +#include +#include +#include + +#define ALIGN (sizeof(size_t)) +#define ONES ((size_t)-1/UCHAR_MAX) +#define HIGHS (ONES * (UCHAR_MAX/2+1)) +#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS) + +size_t strlen(const char *s) +{ + const char *a = s; +#ifdef __GNUC__ + typedef size_t __attribute__((__may_alias__)) word; + const word *w; + for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a; + for (w = (const void *)s; !HASZERO(*w); w++); + s = (const void *)w; +#endif + for (; *s; s++); + return s-a; +} -- cgit v1.2.3