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#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; size_t *wd, k; const size_t *ws; c = (unsigned char)c; 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; 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; } for (; n && (*d=*s)!=c; n--, s++, d++); tail: if (*s==c) return d+1; return 0; } |