1 // Copyright (C) 2023 Google LLC 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #include "icing/util/encode-util.h" 16 17 #include <cstdint> 18 #include <string> 19 #include <string_view> 20 21 namespace icing { 22 namespace lib { 23 24 namespace encode_util { 25 EncodeIntToCString(uint64_t value)26std::string EncodeIntToCString(uint64_t value) { 27 std::string encoded_str; 28 // Encode it in base128 and add 1 to make sure that there is no 0-byte. This 29 // increases the size of the encoded_str from 8-bytes to 10-bytes at worst. 30 do { 31 encoded_str.push_back((value & 0x7F) + 1); 32 value >>= 7; 33 } while (value); 34 return encoded_str; 35 } 36 DecodeIntFromCString(std::string_view encoded_str)37uint64_t DecodeIntFromCString(std::string_view encoded_str) { 38 uint64_t value = 0; 39 for (int i = encoded_str.length() - 1; i >= 0; --i) { 40 value <<= 7; 41 char c = encoded_str[i] - 1; 42 value |= (c & 0x7F); 43 } 44 return value; 45 } 46 EncodeStringToCString(const std::string & input)47std::string EncodeStringToCString(const std::string& input) { 48 std::string encoded_str; 49 // use uint32_t to store 4 bytes, using unsigned types to keep automatically 50 // remove extra left most bits. 51 uint32_t bit_buffer = 0; 52 int bit_count = 0; 53 for (unsigned char c : input) { 54 // Add the next byte to the buffer. 55 bit_buffer = (bit_buffer << 8) | c; 56 bit_count += 8; 57 // Encode the first 7 bits of the byte buffer by adding 1 in front. 58 while (bit_count >= 7) { 59 bit_count -= 7; 60 encoded_str += ((bit_buffer >> bit_count) & 0x7F) | 0x80; 61 } 62 } 63 // Encode the remaining byte. 64 if (bit_count > 0) { 65 encoded_str += ((bit_buffer << (7 - bit_count)) & 0x7F) | 0x80; 66 } 67 return encoded_str; 68 } 69 70 } // namespace encode_util 71 72 } // namespace lib 73 } // namespace icing 74