diff options
| -rw-r--r-- | src/string/memccpy.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/src/string/memccpy.c b/src/string/memccpy.c new file mode 100644 index 00000000..4a875cf5 --- /dev/null +++ b/src/string/memccpy.c @@ -0,0 +1,32 @@ +#include <string.h> +#include <stdlib.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 *dest, const void *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; +} |