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authorAlex Ray2013-08-02 16:40:08 -0500
committerAlex Ray2013-08-02 16:40:08 -0500
commitd98e07fdf9c338589f263c47ce5c844ed43efad5 (patch)
treed4ff9849df225df1e4c46386fdabe30407ba5513 /libutils/JenkinsHash.cpp
parentbe06210c508d5878dcc7d185e5613f4c7e38dfe8 (diff)
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move libs/utils to libutils
Change-Id: I6cf4268599460791414882f91eeb88a992fbd29d
Diffstat (limited to 'libutils/JenkinsHash.cpp')
-rw-r--r--libutils/JenkinsHash.cpp64
1 files changed, 64 insertions, 0 deletions
diff --git a/libutils/JenkinsHash.cpp b/libutils/JenkinsHash.cpp
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1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* Implementation of Jenkins one-at-a-time hash function. These choices are
18 * optimized for code size and portability, rather than raw speed. But speed
19 * should still be quite good.
20 **/
21
22#include <utils/JenkinsHash.h>
23
24namespace android {
25
26hash_t JenkinsHashWhiten(uint32_t hash) {
27 hash += (hash << 3);
28 hash ^= (hash >> 11);
29 hash += (hash << 15);
30 return hash;
31}
32
33uint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size) {
34 hash = JenkinsHashMix(hash, (uint32_t)size);
35 size_t i;
36 for (i = 0; i < (size & -4); i += 4) {
37 uint32_t data = bytes[i] | (bytes[i+1] << 8) | (bytes[i+2] << 16) | (bytes[i+3] << 24);
38 hash = JenkinsHashMix(hash, data);
39 }
40 if (size & 3) {
41 uint32_t data = bytes[i];
42 data |= ((size & 3) > 1) ? (bytes[i+1] << 8) : 0;
43 data |= ((size & 3) > 2) ? (bytes[i+2] << 16) : 0;
44 hash = JenkinsHashMix(hash, data);
45 }
46 return hash;
47}
48
49uint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size) {
50 hash = JenkinsHashMix(hash, (uint32_t)size);
51 size_t i;
52 for (i = 0; i < (size & -2); i += 2) {
53 uint32_t data = shorts[i] | (shorts[i+1] << 16);
54 hash = JenkinsHashMix(hash, data);
55 }
56 if (size & 1) {
57 uint32_t data = shorts[i];
58 hash = JenkinsHashMix(hash, data);
59 }
60 return hash;
61}
62
63}
64