1 /* 2 * Copyright (C) 2018 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 #ifndef MINIKIN_HASHER_H 18 #define MINIKIN_HASHER_H 19 20 #include <cstdint> 21 22 #include <string> 23 24 #include "minikin/Macros.h" 25 26 namespace minikin { 27 28 // Provides a Jenkins hash implementation. 29 class Hasher { 30 public: Hasher()31 Hasher() : mHash(0u) {} 32 update(uint32_t data)33 IGNORE_INTEGER_OVERFLOW inline Hasher& update(uint32_t data) { 34 mHash += data; 35 mHash += (mHash << 10); 36 mHash ^= (mHash >> 6); 37 return *this; 38 } 39 updateShorts(const uint16_t * data,uint32_t length)40 inline Hasher& updateShorts(const uint16_t* data, uint32_t length) { 41 update(length); 42 uint32_t i; 43 for (i = 0; i < (length & -2); i += 2) { 44 update((uint32_t)data[i] | ((uint32_t)data[i + 1] << 16)); 45 } 46 if (length & 1) { 47 update((uint32_t)data[i]); 48 } 49 return *this; 50 } 51 updateString(const std::string & str)52 inline Hasher& updateString(const std::string& str) { 53 uint32_t size = str.size(); 54 update(size); 55 uint32_t i; 56 for (i = 0; i < (size & -4); i += 4) { 57 update((uint32_t)str[i] | ((uint32_t)str[i + 1] << 8) | ((uint32_t)str[i + 2] << 16) | 58 ((uint32_t)str[i + 3] << 24)); 59 } 60 if (size & 3) { 61 uint32_t data = str[i]; 62 data |= ((size & 3) > 1) ? ((uint32_t)str[i + 1] << 8) : 0; 63 data |= ((size & 3) > 2) ? ((uint32_t)str[i + 2] << 16) : 0; 64 update(data); 65 } 66 return *this; 67 } 68 hash()69 IGNORE_INTEGER_OVERFLOW inline uint32_t hash() { 70 uint32_t hash = mHash; 71 hash += (hash << 3); 72 hash ^= (hash >> 11); 73 hash += (hash << 15); 74 return hash; 75 } 76 77 private: 78 uint32_t mHash; 79 }; 80 81 } // namespace minikin 82 83 #endif // MINIKIN_HASHER_H 84