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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | FUNCTION |
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| 3 | < |
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| 4 | |||
| 5 | INDEX |
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| 6 | strchr |
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| 7 | |||
| 8 | ANSI_SYNOPSIS |
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| 9 | #include |
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| 10 | char * strchr(const char *<[string]>, int <[c]>); |
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| 11 | |||
| 12 | TRAD_SYNOPSIS |
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| 13 | #include |
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| 14 | char * strchr(<[string]>, <[c]>); |
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| 15 | const char *<[string]>; |
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| 16 | int <[c]>; |
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| 17 | |||
| 18 | DESCRIPTION |
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| 19 | This function finds the first occurence of <[c]> (converted to |
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| 20 | a char) in the string pointed to by <[string]> (including the |
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| 21 | terminating null character). |
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| 22 | |||
| 23 | RETURNS |
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| 24 | Returns a pointer to the located character, or a null pointer |
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| 25 | if <[c]> does not occur in <[string]>. |
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| 26 | |||
| 27 | PORTABILITY |
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| 28 | < |
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| 29 | |||
| 30 | < |
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| 31 | |||
| 32 | QUICKREF |
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| 33 | strchr ansi pure |
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| 34 | */ |
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| 35 | |||
| 36 | #include |
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| 37 | #include |
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| 38 | |||
| 39 | /* Nonzero if X is not aligned on a "long" boundary. */ |
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| 40 | #define UNALIGNED(X) ((long)X & (sizeof (long) - 1)) |
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| 41 | |||
| 42 | /* How many bytes are loaded each iteration of the word copy loop. */ |
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| 43 | #define LBLOCKSIZE (sizeof (long)) |
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| 44 | |||
| 45 | #if LONG_MAX == 2147483647L |
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| 46 | #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) |
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| 47 | #else |
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| 48 | #if LONG_MAX == 9223372036854775807L |
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| 49 | /* Nonzero if X (a long int) contains a NULL byte. */ |
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| 50 | #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080) |
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| 51 | #else |
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| 52 | #error long int is not a 32bit or 64bit type. |
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| 53 | #endif |
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| 54 | #endif |
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| 55 | |||
| 56 | /* DETECTCHAR returns nonzero if (long)X contains the byte used |
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| 57 | to fill (long)MASK. */ |
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| 58 | #define DETECTCHAR(X,MASK) (DETECTNULL(X ^ MASK)) |
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| 59 | |||
| 60 | char * |
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| 61 | _DEFUN (strchr, (s1, i), |
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| 62 | _CONST char *s1 _AND |
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| 63 | int i) |
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| 64 | { |
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| 65 | _CONST unsigned char *s = (_CONST unsigned char *)s1; |
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| 66 | unsigned char c = i; |
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| 67 | |||
| 68 | #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) |
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| 69 | unsigned long mask,j; |
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| 70 | unsigned long *aligned_addr; |
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| 71 | |||
| 72 | /* Special case for finding 0. */ |
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| 73 | if (!c) |
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| 74 | { |
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| 75 | while (UNALIGNED (s)) |
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| 76 | { |
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| 77 | if (!*s) |
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| 78 | return (char *) s; |
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| 79 | s++; |
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| 80 | } |
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| 81 | /* Operate a word at a time. */ |
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| 82 | aligned_addr = (unsigned long *) s; |
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| 83 | while (!DETECTNULL (*aligned_addr)) |
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| 84 | aligned_addr++; |
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| 85 | /* Found the end of string. */ |
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| 86 | s = (const unsigned char *) aligned_addr; |
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| 87 | while (*s) |
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| 88 | s++; |
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| 89 | return (char *) s; |
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| 90 | } |
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| 91 | |||
| 92 | /* All other bytes. Align the pointer, then search a long at a time. */ |
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| 93 | while (UNALIGNED (s)) |
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| 94 | { |
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| 95 | if (!*s) |
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| 96 | return NULL; |
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| 97 | if (*s == c) |
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| 98 | return (char *) s; |
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| 99 | s++; |
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| 100 | } |
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| 101 | |||
| 102 | mask = c; |
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| 103 | for (j = 8; j < LBLOCKSIZE * 8; j <<= 1) |
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| 104 | mask = (mask << j) | mask; |
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| 105 | |||
| 106 | aligned_addr = (unsigned long *) s; |
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| 107 | while (!DETECTNULL (*aligned_addr) && !DETECTCHAR (*aligned_addr, mask)) |
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| 108 | aligned_addr++; |
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| 109 | |||
| 110 | /* The block of bytes currently pointed to by aligned_addr |
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| 111 | contains either a null or the target char, or both. We |
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| 112 | catch it using the bytewise search. */ |
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| 113 | |||
| 114 | s = (unsigned char *) aligned_addr; |
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| 115 | |||
| 116 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
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| 117 | |||
| 118 | while (*s && *s != c) |
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| 119 | s++; |
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| 120 | if (*s == c) |
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| 121 | return (char *)s; |
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| 122 | return NULL; |
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| 123 | } |