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56 lines
1.8 KiB
56 lines
1.8 KiB
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef NLP_SAFT_COMPONENTS_COMMON_MOBILE_MATH_CHECKSUM_H_
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#define NLP_SAFT_COMPONENTS_COMMON_MOBILE_MATH_CHECKSUM_H_
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#include "lang_id/common/lite_base/integral-types.h"
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#include "lang_id/common/lite_strings/stringpiece.h"
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namespace libtextclassifier3 {
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namespace mobile {
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// Class to compute a 32bit Cyclic Redundancy Check (CRC) in a cummulative way.
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//
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// To use, create an instance of this class, repeatedly call Update() to "feed"
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// it your pieces of data, and, when done, call Get().
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class Crc32 {
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public:
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Crc32() : current_(GetInitialCrc32()) {}
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// Updates current CRC32 code to also take into account the |len| bytes that
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// start at address |str|.
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void Update(const char *str, int len);
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// Updates current CRC32 code to also take into account the bytes from |s|.
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void Update(StringPiece s) { Update(s.data(), s.size()); }
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// Returns the CRC32 code for the data so far.
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uint32 Get() const { return current_; }
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private:
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// Returns the initial value for current_.
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static uint32 GetInitialCrc32();
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// CRC32 for the data so far.
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uint32 current_;
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};
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} // namespace mobile
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} // namespace nlp_saft
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#endif // NLP_SAFT_COMPONENTS_COMMON_MOBILE_MATH_CHECKSUM_H_
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