Wed, 08 Jun 2022 21:38:45 +0200
fix obsolete documentation
563 | 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 | } |