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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 | 170 | void cx_hash_murmur(CxHashKey *key) { | |
33 | 170 | const unsigned char *data = key->data; | |
34 |
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170 | if (data == NULL) { |
35 | // extension: special value for NULL | ||
36 | 3 | key->hash = 1574210520u; | |
37 | 3 | return; | |
38 | } | ||
39 | 167 | size_t len = key->len; | |
40 | |||
41 | 167 | unsigned m = 0x5bd1e995; | |
42 | 167 | unsigned r = 24; | |
43 | 167 | unsigned h = 25 ^ (unsigned) len; | |
44 | 167 | unsigned i = 0; | |
45 |
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578 | while (len >= 4) { |
46 | 411 | unsigned k = data[i + 0] & 0xFF; | |
47 | 411 | k |= (data[i + 1] & 0xFF) << 8; | |
48 | 411 | k |= (data[i + 2] & 0xFF) << 16; | |
49 | 411 | k |= (data[i + 3] & 0xFF) << 24; | |
50 | |||
51 | 411 | k *= m; | |
52 | 411 | k ^= k >> r; | |
53 | 411 | k *= m; | |
54 | |||
55 | 411 | h *= m; | |
56 | 411 | h ^= k; | |
57 | |||
58 | 411 | i += 4; | |
59 | 411 | len -= 4; | |
60 | } | ||
61 | |||
62 |
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167 | switch (len) { |
63 | 7 | case 3: | |
64 | 7 | h ^= (data[i + 2] & 0xFF) << 16; | |
65 | __attribute__((__fallthrough__)); | ||
66 | 22 | case 2: | |
67 | 22 | h ^= (data[i + 1] & 0xFF) << 8; | |
68 | __attribute__((__fallthrough__)); | ||
69 | 133 | case 1: | |
70 | 133 | h ^= (data[i + 0] & 0xFF); | |
71 | 133 | h *= m; | |
72 | __attribute__((__fallthrough__)); | ||
73 | 167 | default: // do nothing | |
74 | ; | ||
75 | } | ||
76 | |||
77 | 167 | h ^= h >> 13; | |
78 | 167 | h *= m; | |
79 | 167 | h ^= h >> 15; | |
80 | |||
81 | 167 | key->hash = h; | |
82 | } | ||
83 | |||
84 | 114 | CxHashKey cx_hash_key_str(const char *str) { | |
85 | CxHashKey key; | ||
86 | 114 | key.data = str; | |
87 |
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114 | key.len = str == NULL ? 0 : strlen(str); |
88 | 114 | cx_hash_murmur(&key); | |
89 | 114 | return key; | |
90 | } | ||
91 | |||
92 | 3 | CxHashKey cx_hash_key_bytes( | |
93 | const unsigned char *bytes, | ||
94 | size_t len | ||
95 | ) { | ||
96 | CxHashKey key; | ||
97 | 3 | key.data = bytes; | |
98 | 3 | key.len = len; | |
99 | 3 | cx_hash_murmur(&key); | |
100 | 3 | return key; | |
101 | } | ||
102 | |||
103 | 23 | CxHashKey cx_hash_key( | |
104 | const void *obj, | ||
105 | size_t len | ||
106 | ) { | ||
107 | CxHashKey key; | ||
108 | 23 | key.data = obj; | |
109 | 23 | key.len = len; | |
110 | 23 | cx_hash_murmur(&key); | |
111 | 23 | return key; | |
112 | } | ||
113 |