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 <stdlib.h> 23 #include <utils/JenkinsHash.h> 24 25 namespace android { 26 27 #ifdef __clang__ 28 __attribute__((no_sanitize("integer"))) 29 #endif 30 hash_t JenkinsHashWhiten(uint32_t hash) { 31 hash += (hash << 3); 32 hash ^= (hash >> 11); 33 hash += (hash << 15); 34 return hash; 35 } 36 37 uint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size) { 38 if (size > UINT32_MAX) { 39 abort(); 40 } 41 hash = JenkinsHashMix(hash, (uint32_t)size); 42 size_t i; 43 for (i = 0; i < (size & -4); i += 4) { 44 uint32_t data = bytes[i] | (bytes[i+1] << 8) | (bytes[i+2] << 16) | (bytes[i+3] << 24); 45 hash = JenkinsHashMix(hash, data); 46 } 47 if (size & 3) { 48 uint32_t data = bytes[i]; 49 data |= ((size & 3) > 1) ? (bytes[i+1] << 8) : 0; 50 data |= ((size & 3) > 2) ? (bytes[i+2] << 16) : 0; 51 hash = JenkinsHashMix(hash, data); 52 } 53 return hash; 54 } 55 56 uint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size) { 57 if (size > UINT32_MAX) { 58 abort(); 59 } 60 hash = JenkinsHashMix(hash, (uint32_t)size); 61 size_t i; 62 for (i = 0; i < (size & -2); i += 2) { 63 uint32_t data = shorts[i] | (shorts[i+1] << 16); 64 hash = JenkinsHashMix(hash, data); 65 } 66 if (size & 1) { 67 uint32_t data = shorts[i]; 68 hash = JenkinsHashMix(hash, data); 69 } 70 return hash; 71 } 72 73 } 74 75
