comparison: ucx/hash_key.c
ucx/hash_key.c
- changeset 431
- bb7da585debc
- parent 324
- ce13a778654a
- child 440
- 7c4b9cba09ca
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| 169:fe49cff3c571 | 431:bb7da585debc |
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| 1 /* | |
| 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. | |
| 3 * | |
| 4 * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved. | |
| 5 * | |
| 6 * Redistribution and use in source and binary forms, with or without | |
| 7 * modification, are permitted provided that the following conditions are met: | |
| 8 * | |
| 9 * 1. Redistributions of source code must retain the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer. | |
| 11 * | |
| 12 * 2. Redistributions in binary form must reproduce the above copyright | |
| 13 * notice, this list of conditions and the following disclaimer in the | |
| 14 * documentation and/or other materials provided with the distribution. | |
| 15 * | |
| 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE | |
| 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 26 * POSSIBILITY OF SUCH DAMAGE. | |
| 27 */ | |
| 28 | |
| 29 #include "cx/hash_key.h" | |
| 30 #include <string.h> | |
| 31 | |
| 32 void cx_hash_murmur(CxHashKey *key) { | |
| 33 const unsigned char *data = key->data; | |
| 34 if (data == NULL) { | |
| 35 // extension: special value for NULL | |
| 36 key->hash = 1574210520u; | |
| 37 return; | |
| 38 } | |
| 39 size_t len = key->len; | |
| 40 | |
| 41 unsigned m = 0x5bd1e995; | |
| 42 unsigned r = 24; | |
| 43 unsigned h = 25 ^ len; | |
| 44 unsigned i = 0; | |
| 45 while (len >= 4) { | |
| 46 unsigned k = data[i + 0] & 0xFF; | |
| 47 k |= (data[i + 1] & 0xFF) << 8; | |
| 48 k |= (data[i + 2] & 0xFF) << 16; | |
| 49 k |= (data[i + 3] & 0xFF) << 24; | |
| 50 | |
| 51 k *= m; | |
| 52 k ^= k >> r; | |
| 53 k *= m; | |
| 54 | |
| 55 h *= m; | |
| 56 h ^= k; | |
| 57 | |
| 58 i += 4; | |
| 59 len -= 4; | |
| 60 } | |
| 61 | |
| 62 switch (len) { | |
| 63 case 3: | |
| 64 h ^= (data[i + 2] & 0xFF) << 16; | |
| 65 __attribute__((__fallthrough__)); | |
| 66 case 2: | |
| 67 h ^= (data[i + 1] & 0xFF) << 8; | |
| 68 __attribute__((__fallthrough__)); | |
| 69 case 1: | |
| 70 h ^= (data[i + 0] & 0xFF); | |
| 71 h *= m; | |
| 72 __attribute__((__fallthrough__)); | |
| 73 default: // do nothing | |
| 74 ; | |
| 75 } | |
| 76 | |
| 77 h ^= h >> 13; | |
| 78 h *= m; | |
| 79 h ^= h >> 15; | |
| 80 | |
| 81 key->hash = h; | |
| 82 } | |
| 83 | |
| 84 CxHashKey cx_hash_key_str(const char *str) { | |
| 85 CxHashKey key; | |
| 86 key.data = str; | |
| 87 key.len = str == NULL ? 0 : strlen(str); | |
| 88 cx_hash_murmur(&key); | |
| 89 return key; | |
| 90 } | |
| 91 | |
| 92 CxHashKey cx_hash_key_bytes( | |
| 93 const unsigned char *bytes, | |
| 94 size_t len | |
| 95 ) { | |
| 96 CxHashKey key; | |
| 97 key.data = bytes; | |
| 98 key.len = len; | |
| 99 cx_hash_murmur(&key); | |
| 100 return key; | |
| 101 } | |
| 102 | |
| 103 CxHashKey cx_hash_key( | |
| 104 const void *obj, | |
| 105 size_t len | |
| 106 ) { | |
| 107 CxHashKey key; | |
| 108 key.data = obj; | |
| 109 key.len = len; | |
| 110 cx_hash_murmur(&key); | |
| 111 return key; | |
| 112 } |
