| /* |
| * Copyright (C) 2013 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. |
| */ |
| |
| #include "dictionary/utils/format_utils.h" |
| |
| #include "dictionary/utils/byte_array_utils.h" |
| |
| namespace latinime { |
| |
| const uint32_t FormatUtils::MAGIC_NUMBER = 0x9BC13AFE; |
| |
| // Magic number (4 bytes), version (2 bytes), flags (2 bytes), header size (4 bytes) = 12 |
| const size_t FormatUtils::DICTIONARY_MINIMUM_SIZE = 12; |
| |
| /* static */ FormatUtils::FORMAT_VERSION FormatUtils::getFormatVersion(const int formatVersion) { |
| switch (formatVersion) { |
| case VERSION_2: |
| case VERSION_201: |
| AKLOGE("Dictionary versions 2 and 201 are incompatible with this version"); |
| return UNKNOWN_VERSION; |
| case VERSION_202: |
| return VERSION_202; |
| case VERSION_4_ONLY_FOR_TESTING: |
| return VERSION_4_ONLY_FOR_TESTING; |
| case VERSION_402: |
| return VERSION_402; |
| case VERSION_403: |
| return VERSION_403; |
| default: |
| return UNKNOWN_VERSION; |
| } |
| } |
| /* static */ FormatUtils::FORMAT_VERSION FormatUtils::detectFormatVersion( |
| const ReadOnlyByteArrayView dictBuffer) { |
| // The magic number is stored big-endian. |
| // If the dictionary is less than 4 bytes, we can't even read the magic number, so we don't |
| // understand this format. |
| if (dictBuffer.size() < DICTIONARY_MINIMUM_SIZE) { |
| return UNKNOWN_VERSION; |
| } |
| const uint32_t magicNumber = ByteArrayUtils::readUint32(dictBuffer.data(), 0); |
| switch (magicNumber) { |
| case MAGIC_NUMBER: |
| // The layout of the header is as follows: |
| // Magic number (4 bytes) 0x9B 0xC1 0x3A 0xFE |
| // Dictionary format version number (2 bytes) |
| // Options (2 bytes) |
| // Header size (4 bytes) : integer, big endian |
| // Conceptually this converts the hardcoded value of the bytes in the file into |
| // the symbolic value we use in the code. But we want the constants to be the |
| // same so we use them for both here. |
| return getFormatVersion(ByteArrayUtils::readUint16(dictBuffer.data(), 4)); |
| default: |
| return UNKNOWN_VERSION; |
| } |
| } |
| |
| } // namespace latinime |