1 /* 2 * Copyright (C) 2013 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 #include "suggest/policyimpl/dictionary/utils/format_utils.h" 18 19 #include "suggest/policyimpl/dictionary/utils/byte_array_utils.h" 20 21 namespace latinime { 22 23 const uint32_t FormatUtils::MAGIC_NUMBER = 0x9BC13AFE; 24 25 // Magic number (4 bytes), version (2 bytes), flags (2 bytes), header size (4 bytes) = 12 26 const int FormatUtils::DICTIONARY_MINIMUM_SIZE = 12; 27 28 /* static */ FormatUtils::FORMAT_VERSION FormatUtils::detectFormatVersion( 29 const uint8_t *const dict, const int dictSize) { 30 // The magic number is stored big-endian. 31 // If the dictionary is less than 4 bytes, we can't even read the magic number, so we don't 32 // understand this format. 33 if (dictSize < DICTIONARY_MINIMUM_SIZE) { 34 return UNKNOWN_VERSION; 35 } 36 const uint32_t magicNumber = ByteArrayUtils::readUint32(dict, 0); 37 switch (magicNumber) { 38 case MAGIC_NUMBER: 39 // Version 2 header is as follows: 40 // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE 41 // Dictionary format version number (2 bytes) 42 // Options (2 bytes) 43 // Header size (4 bytes) : integer, big endian 44 if (ByteArrayUtils::readUint16(dict, 4) == 2) { 45 return VERSION_2; 46 } else if (ByteArrayUtils::readUint16(dict, 4) == 3) { 47 return VERSION_3; 48 } else { 49 return UNKNOWN_VERSION; 50 } 51 default: 52 return UNKNOWN_VERSION; 53 } 54 } 55 56 } // namespace latinime 57
