Update from latest ddm4
[m6w6/libmemcached] / libhashkit / fnv_64.cc
1 /* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
2 *
3 * HashKit library
4 *
5 * Copyright (C) 2011 Data Differential, http://datadifferential.com/
6 * Copyright (C) 2009 Brian Aker All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are
10 * met:
11 *
12 * * Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * * Redistributions in binary form must reproduce the above
16 * copyright notice, this list of conditions and the following disclaimer
17 * in the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * * The names of its contributors may not be used to endorse or
21 * promote products derived from this software without specific prior
22 * written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
25 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
26 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
27 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
28 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
30 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
34 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 *
36 */
37
38
39 #include <libhashkit/common.h>
40
41 #if __WORDSIZE == 64 && defined(HAVE_FNV64_HASH)
42
43 /* FNV hash'es lifted from Dustin Sallings work */
44 static uint64_t FNV_64_INIT= 0xcbf29ce484222325;
45 static uint64_t FNV_64_PRIME= 0x100000001b3;
46
47 uint32_t hashkit_fnv1_64(const char *key, size_t key_length, void *)
48 {
49 /* Thanks to pierre@demartines.com for the pointer */
50 uint64_t hash= FNV_64_INIT;
51
52 for (size_t x= 0; x < key_length; x++)
53 {
54 hash *= FNV_64_PRIME;
55 hash ^= (uint64_t)key[x];
56 }
57
58 return (uint32_t)hash;
59 }
60
61 uint32_t hashkit_fnv1a_64(const char *key, size_t key_length, void *)
62 {
63 uint32_t hash= (uint32_t) FNV_64_INIT;
64
65 for (size_t x= 0; x < key_length; x++)
66 {
67 uint32_t val= (uint32_t)key[x];
68 hash ^= val;
69 hash *= (uint32_t) FNV_64_PRIME;
70 }
71
72 return hash;
73 }
74
75 #else
76 uint32_t hashkit_fnv1_64(const char *, size_t, void *)
77 {
78 return 0;
79 }
80
81 uint32_t hashkit_fnv1a_64(const char *, size_t, void *)
82 {
83 return 0;
84 }
85 #endif