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1 #include <string.h> | 1 #include <string.h> |
2 #include <stdint.h> | 2 #include <stdint.h> |
3 #include <limits.h> | 3 #include <limits.h> |
4 | 4 |
5 #define SS (sizeof(size_t)) | 5 #define SS (sizeof(size_t)) |
6 #define ALIGN (sizeof(size_t)-1) | 6 #define ALIGN (sizeof(size_t) - 1) |
7 #define ONES ((size_t)-1/UCHAR_MAX) | 7 #define ONES ((size_t)-1 / UCHAR_MAX) |
8 #define HIGHS (ONES * (UCHAR_MAX/2+1)) | 8 #define HIGHS (ONES * (UCHAR_MAX / 2 + 1)) |
9 #define HASZERO(x) ((x)-ONES & ~(x) & HIGHS) | 9 #define HASZERO(x) ((x)-ONES & ~(x)&HIGHS) |
10 | 10 |
11 void *memchr(const void *src, int c, size_t n) | 11 void* memchr(const void* src, int c, size_t n) { |
12 { | 12 const unsigned char* s = src; |
13 » const unsigned char *s = src; | 13 c = (unsigned char)c; |
14 » c = (unsigned char)c; | 14 for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--) |
15 » for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--); | 15 ; |
16 » if (n && *s != c) { | 16 if (n && *s != c) { |
17 » » const size_t *w; | 17 const size_t* w; |
18 » » size_t k = ONES * c; | 18 size_t k = ONES * c; |
19 » » for (w = (const void *)s; n>=SS && !HASZERO(*w^k); w++, n-=SS); | 19 for (w = (const void*)s; n >= SS && !HASZERO(*w ^ k); w++, n -= SS) |
20 » » for (s = (const void *)w; n && *s != c; s++, n--); | 20 ; |
21 » } | 21 for (s = (const void*)w; n && *s != c; s++, n--) |
22 » return n ? (void *)s : 0; | 22 ; |
| 23 } |
| 24 return n ? (void*)s : 0; |
23 } | 25 } |
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