3f9ff1514e
testing with gcc 4.6.3 on x86, -Os, the old version does a duplicate null byte check after the first loop. this is purely the compiler being stupid, but the old code was also stupid and unintuitive in how it expressed the check.
19 lines
457 B
C
19 lines
457 B
C
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <stdint.h>
|
|
#include <limits.h>
|
|
|
|
#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;
|
|
const size_t *w;
|
|
for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a;
|
|
for (w = (const void *)s; !HASZERO(*w); w++);
|
|
for (s = (const void *)w; *s; s++);
|
|
return s-a;
|
|
}
|