comparison: src/hash_key.c
src/hash_key.c
- changeset 563
- 69a83fad8a35
- child 603
- c49104015a6b
equal
deleted
inserted
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| 562:fd3368c20413 | 563:69a83fad8a35 |
|---|---|
| 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 size_t len = key->len; | |
| 34 unsigned char const *data = key->data.cbytes; | |
| 35 | |
| 36 unsigned m = 0x5bd1e995; | |
| 37 unsigned r = 24; | |
| 38 unsigned h = 25 ^ len; | |
| 39 unsigned i = 0; | |
| 40 while (len >= 4) { | |
| 41 unsigned k = data[i + 0] & 0xFF; | |
| 42 k |= (data[i + 1] & 0xFF) << 8; | |
| 43 k |= (data[i + 2] & 0xFF) << 16; | |
| 44 k |= (data[i + 3] & 0xFF) << 24; | |
| 45 | |
| 46 k *= m; | |
| 47 k ^= k >> r; | |
| 48 k *= m; | |
| 49 | |
| 50 h *= m; | |
| 51 h ^= k; | |
| 52 | |
| 53 i += 4; | |
| 54 len -= 4; | |
| 55 } | |
| 56 | |
| 57 switch (len) { | |
| 58 case 3: | |
| 59 h ^= (data[i + 2] & 0xFF) << 16; | |
| 60 __attribute__((__fallthrough__)); | |
| 61 case 2: | |
| 62 h ^= (data[i + 1] & 0xFF) << 8; | |
| 63 __attribute__((__fallthrough__)); | |
| 64 case 1: | |
| 65 h ^= (data[i + 0] & 0xFF); | |
| 66 h *= m; | |
| 67 __attribute__((__fallthrough__)); | |
| 68 default: | |
| 69 /* do nothing */; | |
| 70 } | |
| 71 | |
| 72 h ^= h >> 13; | |
| 73 h *= m; | |
| 74 h ^= h >> 15; | |
| 75 | |
| 76 key->hash = h; | |
| 77 } | |
| 78 | |
| 79 CxHashKey cx_hash_key_str(char const *str) { | |
| 80 CxHashKey key; | |
| 81 key.data.cstr = str; | |
| 82 key.len = str == NULL ? 0 : (1 + strlen(str)); | |
| 83 cx_hash_murmur(&key); | |
| 84 return key; | |
| 85 } | |
| 86 | |
| 87 CxHashKey cx_hash_key_bytes( | |
| 88 unsigned char const *bytes, | |
| 89 size_t len | |
| 90 ) { | |
| 91 CxHashKey key; | |
| 92 key.data.cbytes = bytes; | |
| 93 key.len = len; | |
| 94 cx_hash_murmur(&key); | |
| 95 return key; | |
| 96 } | |
| 97 | |
| 98 CxHashKey cx_hash_key( | |
| 99 void *obj, | |
| 100 size_t len | |
| 101 ) { | |
| 102 CxHashKey key; | |
| 103 key.data.obj = obj; | |
| 104 key.len = len; | |
| 105 cx_hash_murmur(&key); | |
| 106 return key; | |
| 107 } |
