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| | #include <string.h>
#include <stdint.h>
#define aliases __attribute__((__may_alias__))
#define byte_repeat(x) ((size_t)~0 / 0xff * (x))
#define word_has_zero(x) (((x) - byte_repeat(0x01)) & ~(x) & byte_repeat(0x80))
#define weak_alias(o, n) extern __typeof__(o) n __attribute__((weak, alias(#o)))
char *__stpncpy(char *restrict d, const char *restrict s, size_t n)
{
size_t *wd;
const size_t *ws;
if (n < sizeof(size_t) * 3 || ((uintptr_t)d | (uintptr_t)s)
& sizeof(size_t) - 1) goto bytewise;
for (; ((uintptr_t)s & sizeof(size_t) - 1) && (*d = *s); d++, s++, n--);
if (!*s) return memset(d, 0, n);
wd = (void *)d;
ws = (const void *)s;
for (; n >= sizeof(size_t) && !word_has_zero(*ws)
; n -= sizeof(size_t), wd++, ws++) *wd = *ws;
d = (void *)wd;
s = (const void *)ws;
bytewise:
for (; n && (*d = *s); d++, s++, n--);
return memset(d, 0, n);
}
weak_alias(__stpncpy, stpncpy);
|