| #include <string.h> |
| #include <stdint.h> |
| #include <limits.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) |
| |
| void *memccpy(void *restrict dest, const void *restrict src, int c, size_t n) |
| { |
| unsigned char *d = dest; |
| const unsigned char *s = src; |
| |
| c = (unsigned char)c; |
| #ifdef __GNUC__ |
| typedef size_t __attribute__((__may_alias__)) word; |
| word *wd; |
| const word *ws; |
| if (((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) { |
| for (; ((uintptr_t)s & ALIGN) && n && (*d=*s)!=c; n--, s++, d++); |
| if ((uintptr_t)s & ALIGN) goto tail; |
| size_t k = ONES * c; |
| wd=(void *)d; ws=(const void *)s; |
| for (; n>=sizeof(size_t) && !HASZERO(*ws^k); |
| n-=sizeof(size_t), ws++, wd++) *wd = *ws; |
| d=(void *)wd; s=(const void *)ws; |
| } |
| #endif |
| for (; n && (*d=*s)!=c; n--, s++, d++); |
| tail: |
| if (n) return d+1; |
| return 0; |
| } |