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/*
* 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
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