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| | #include <stddef.h>
#include <stdint.h>
#define hidden __attribute__((visibility("hidden")))
#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))
hidden
size_t __strscpy(char *restrict d, const char *restrict s, size_t n)
{
const char *const d0 = d;
size_t aliases *wd;
const size_t aliases *ws;
if (!n--) return 0;
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 ((uintptr_t)s & sizeof(size_t) - 1) return d - d0;
wd = (void *)d;
ws = (const void *)s;
for (; !word_has_zero(*ws) && n >= sizeof(size_t)
; wd++, ws++, n -= sizeof(size_t)) *wd = *ws;
d = (void *)wd;
s = (const void *)ws;
bytewise:
for (; n && (*d = *s); d++, s++, n--);
*d = 0;
return d - d0;
}
|