1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
| | #include <string.h>
#include <stdint.h>
#include <limits.h>
#include "libc.h"
#define ALIGN (sizeof(size_t)-1)
#define ONES ((size_t)-1/UCHAR_MAX)
#define HIGHS (ONES * (UCHAR_MAX/2+1))
#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS)
char *__stpncpy(char *restrict d, const char *restrict s, size_t n)
{
size_t *wd;
const size_t *ws;
if (((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) {
for (; ((uintptr_t)s & ALIGN) && n && (*d=*s); n--, s++, d++);
if (!n || !*s) goto tail;
wd=(void *)d; ws=(const void *)s;
for (; n>=sizeof(size_t) && !HASZERO(*ws);
n-=sizeof(size_t), ws++, wd++) *wd = *ws;
d=(void *)wd; s=(const void *)ws;
}
for (; n && (*d=*s); n--, s++, d++);
tail:
memset(d, 0, n);
return d;
}
weak_alias(__stpncpy, stpncpy);
|