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- #include <string.h>
- #include <stdlib.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 *d, const char *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);
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