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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* Implementation of Jenkins one-at-a-time hash function. These choices are
* optimized for code size and portability, rather than raw speed. But speed
* should still be quite good.
**/
#include <utils/JenkinsHash.h>
namespace android {
hash_t JenkinsHashWhiten(uint32_t hash) {
hash += (hash << 3);
hash ^= (hash >> 11);
hash += (hash << 15);
return hash;
}
uint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size) {
hash = JenkinsHashMix(hash, (uint32_t)size);
size_t i;
for (i = 0; i < (size & -4); i += 4) {
uint32_t data = bytes[i] | (bytes[i+1] << 8) | (bytes[i+2] << 16) | (bytes[i+3] << 24);
hash = JenkinsHashMix(hash, data);
}
if (size & 3) {
uint32_t data = bytes[i];
data |= ((size & 3) > 1) ? (bytes[i+1] << 8) : 0;
data |= ((size & 3) > 2) ? (bytes[i+2] << 16) : 0;
hash = JenkinsHashMix(hash, data);
}
return hash;
}
uint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size) {
hash = JenkinsHashMix(hash, (uint32_t)size);
size_t i;
for (i = 0; i < (size & -2); i += 2) {
uint32_t data = shorts[i] | (shorts[i+1] << 16);
hash = JenkinsHashMix(hash, data);
}
if (size & 1) {
uint32_t data = shorts[i];
hash = JenkinsHashMix(hash, data);
}
return hash;
}
}
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