1 #include "usr_lib_define.h" 2 #include <string.h> 3 #include <stdint.h> 4 #include <limits.h> 5 6 #define ALIGN (sizeof(size_t)) 7 #define ONES ((size_t)-1/UCHAR_MAX) 8 #define HIGHS (ONES * (UCHAR_MAX/2+1)) 9 #define HASZERO(x) ((x)-ONES & ~(x) & HIGHS) 10 strlen(const char * s)11_LIBC_TEXT_SECTION size_t strlen(const char *s) 12 { 13 const char *a = s; 14 #ifdef __GNUC__ 15 typedef size_t __attribute__((__may_alias__)) word; 16 const word *w; 17 for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a; 18 for (w = (const void *)s; !HASZERO(*w); w++); 19 s = (const void *)w; 20 #endif 21 for (; *s; s++); 22 return s-a; 23 } 24