1#include <features.h>
2#include <string.h>
3#include <stdint.h>
4#include <limits.h>
5
6#define ALIGN (sizeof(size_t)-1)
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
11char *__stpncpy(char *d, const char *s, size_t n)
12{
13#if 0
14	typedef size_t __attribute__((__may_alias__)) word;
15	word *wd;
16	const word *ws;
17	if (((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) {
18		for (; ((uintptr_t)s & ALIGN) && n && (*d=*s); n--, s++, d++);
19		if (!n || !*s) goto tail;
20		wd=(void *)d; ws=(const void *)s;
21		for (; n>=sizeof(size_t) && !HASZERO(*ws);
22		       n-=sizeof(size_t), ws++, wd++) *wd = *ws;
23		d=(void *)wd; s=(const void *)ws;
24	}
25#endif
26	for (; n && (*d=*s); n--, s++, d++);
27tail:
28	memset(d, 0, n);
29	return d;
30}
31
32weak_alias(__stpncpy, stpncpy);
33
34