1b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien/*
2b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * Copyright (C) 2012 The Android Open Source Project
3b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien *
4b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * Licensed under the Apache License, Version 2.0 (the "License");
5b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * you may not use this file except in compliance with the License.
6b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * You may obtain a copy of the License at
7b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien *
8b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien *      http://www.apache.org/licenses/LICENSE-2.0
9b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien *
10b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * Unless required by applicable law or agreed to in writing, software
11b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * distributed under the License is distributed on an "AS IS" BASIS,
12b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * See the License for the specific language governing permissions and
14b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * limitations under the License.
15b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien */
16b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
17b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien/* Implementation of Jenkins one-at-a-time hash function. These choices are
18b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * optimized for code size and portability, rather than raw speed. But speed
19b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * should still be quite good.
20b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien **/
21b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
22bdce9baa880990f521061bc7d1498cb07d7efc01Romain Guy#ifndef ANDROID_JENKINS_HASH_H
23bdce9baa880990f521061bc7d1498cb07d7efc01Romain Guy#define ANDROID_JENKINS_HASH_H
24bdce9baa880990f521061bc7d1498cb07d7efc01Romain Guy
25b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien#include <utils/TypeHelpers.h>
26b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
27b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Leviennamespace android {
28b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
29b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien/* The Jenkins hash of a sequence of 32 bit words A, B, C is:
30b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien * Whiten(Mix(Mix(Mix(0, A), B), C)) */
31b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
321f286989986a384e34d9de1acf8899439506695aNick Kralevich#ifdef __clang__
331f286989986a384e34d9de1acf8899439506695aNick Kralevich__attribute__((no_sanitize("integer")))
341f286989986a384e34d9de1acf8899439506695aNick Kralevich#endif
35b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levieninline uint32_t JenkinsHashMix(uint32_t hash, uint32_t data) {
36b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien    hash += data;
37b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien    hash += (hash << 10);
38b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien    hash ^= (hash >> 6);
39b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien    return hash;
40b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien}
41b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
42b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levienhash_t JenkinsHashWhiten(uint32_t hash);
43b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
44b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien/* Helpful utility functions for hashing data in 32 bit chunks */
45b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levienuint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size);
46b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
47b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levienuint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size);
48b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
49b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien}
50b6ea175b6b4d0aaac85ed6cd8ccac01ab896486bRaph Levien
51bdce9baa880990f521061bc7d1498cb07d7efc01Romain Guy#endif // ANDROID_JENKINS_HASH_H
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