81 lines
2.6 KiB
C++
81 lines
2.6 KiB
C++
// Copyright 2019 The Crashpad Authors
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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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#ifndef CRASHPAD_UTIL_STREAM_BASE94_OUTPUT_STREAM_H_
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#define CRASHPAD_UTIL_STREAM_BASE94_OUTPUT_STREAM_H_
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#include <stddef.h>
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#include <stdint.h>
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#include <memory>
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#include <vector>
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#include "util/stream/output_stream_interface.h"
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namespace crashpad {
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//! \brief This class implements Base94 encoding/decoding, it uses all
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//! printable characters except space for encoding, and no padding is required.
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//!
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//! This implementation uses two base94 symbols to encoding 13 or 14 bit data,
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//! To maximize encoding efficiency, 14-bit data is encoded into two base94
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//! symbols if its low 13-bit is less than 644 ( = 94^2 - 2^13), otherwise
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//! 13-bit data is encoded.
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class Base94OutputStream : public OutputStreamInterface {
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public:
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//! \brief Whether this object is configured to encode or decode data.
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enum class Mode : bool {
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//! \brief Data passed through this object is encoded.
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kEncode = false,
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//! \brief Data passed through this object is decoded.
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kDecode = true
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};
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//! \param[in] mode The work mode of this object.
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//! \param[in] output_stream The output_stream that this object writes to.
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Base94OutputStream(Mode mode,
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std::unique_ptr<OutputStreamInterface> output_stream);
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Base94OutputStream(const Base94OutputStream&) = delete;
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Base94OutputStream& operator=(const Base94OutputStream&) = delete;
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~Base94OutputStream() override;
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// OutputStreamInterface:
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bool Write(const uint8_t* data, size_t size) override;
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bool Flush() override;
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private:
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bool Encode(const uint8_t* data, size_t size);
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bool Decode(const uint8_t* data, size_t size);
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bool FinishEncoding();
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bool FinishDecoding();
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// Write encoded/decoded data to |output_stream_| and empty the |buffer_|.
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bool WriteOutputStream();
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Mode mode_;
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std::unique_ptr<OutputStreamInterface> output_stream_;
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std::vector<uint8_t> buffer_;
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uint32_t bit_buf_;
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// The number of valid bit in bit_buf_.
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size_t bit_count_;
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char symbol_buffer_;
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bool flush_needed_;
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bool flushed_;
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};
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} // namespace crashpad
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#endif // CRASHPAD_UTIL_STREAM_BASE94_OUTPUT_STREAM_H_
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