1f28698998
* Hashing functions rely on integer overflow behavior. Mark those functions as safe. * abort() if a passed in size_t value is greater than UINT32_MAX. This can occur on 64 bit builds where size_t is larger than uint32_t. * Special case the index lookup for an empty sorted vector. Without the special case, size() == 0, and size()-1 underflows. Change-Id: I343a14b589fc8f0d221c1998ae5d6f0b9e2781f8
51 lines
1.5 KiB
C++
51 lines
1.5 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* Implementation of Jenkins one-at-a-time hash function. These choices are
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* optimized for code size and portability, rather than raw speed. But speed
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* should still be quite good.
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**/
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#ifndef ANDROID_JENKINS_HASH_H
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#define ANDROID_JENKINS_HASH_H
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#include <utils/TypeHelpers.h>
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namespace android {
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/* The Jenkins hash of a sequence of 32 bit words A, B, C is:
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* Whiten(Mix(Mix(Mix(0, A), B), C)) */
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#ifdef __clang__
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__attribute__((no_sanitize("integer")))
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#endif
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inline uint32_t JenkinsHashMix(uint32_t hash, uint32_t data) {
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hash += data;
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hash += (hash << 10);
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hash ^= (hash >> 6);
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return hash;
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}
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hash_t JenkinsHashWhiten(uint32_t hash);
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/* Helpful utility functions for hashing data in 32 bit chunks */
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uint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size);
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uint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size);
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}
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#endif // ANDROID_JENKINS_HASH_H
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