1#include <string.h> 2#include <stdint.h> 3#include <limits.h> 4 5#define ALIGN (sizeof(size_t)-1) 6#define ONES ((size_t)-1/UCHAR_MAX) 7#define HIGHS (ONES * (UCHAR_MAX/2+1)) 8#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS) 9 10void *memccpy(void *restrict dest, const void *restrict src, int c, size_t n) 11{ 12 unsigned char *d = dest; 13 const unsigned char *s = src; 14 size_t *wd, k; 15 const size_t *ws; 16 17 c = (unsigned char)c; 18 if (((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) { 19 for (; ((uintptr_t)s & ALIGN) && n && (*d=*s)!=c; n--, s++, d++); 20 if ((uintptr_t)s & ALIGN) goto tail; 21 k = ONES * c; 22 wd=(void *)d; ws=(const void *)s; 23 for (; n>=sizeof(size_t) && !HASZERO(*ws^k); 24 n-=sizeof(size_t), ws++, wd++) *wd = *ws; 25 d=(void *)wd; s=(const void *)ws; 26 } 27 for (; n && (*d=*s)!=c; n--, s++, d++); 28tail: 29 if (*s==c) return d+1; 30 return 0; 31} 32