// Copyright 2017 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef SRC_PUFF_WRITER_H_
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#define SRC_PUFF_WRITER_H_
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#include <cstddef>
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#include <cstdint>
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#include "puffin/src/include/puffin/common.h"
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#include "puffin/src/puff_data.h"
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namespace puffin {
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// An abstract class for writing data into a puffed buffer. Data can be
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// literals, lengths, distances, or metadata. Extensions of this class can
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// define how the puffed data should reside in the puffed buffer.
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class PuffWriterInterface {
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public:
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virtual ~PuffWriterInterface() = default;
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// Inserts data. This function does not need to check for the validity of data
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// . e.g. length > 285, etc.
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//
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// |pd| IN The data to put into the puffed buffer. |pd.type|
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// defines the type of the data.
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// Returns false if it fails.
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virtual bool Insert(const PuffData& pd) = 0;
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// Fluesh any buffer or internal state to the output.
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// Returns false if it fails.
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virtual bool Flush() = 0;
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// Returns the number of bytes processed and written into the puff buffer.
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virtual size_t Size() = 0;
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};
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class BufferPuffWriter : public PuffWriterInterface {
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public:
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// Sets the parameters of puff buffer.
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//
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// |puff_buf| IN The input puffed stream. It is owned by the caller and must
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// be valid during the lifetime of the object.
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// |puff_size| IN The size of the puffed stream.
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BufferPuffWriter(uint8_t* puff_buf, size_t puff_size)
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: puff_buf_out_(puff_buf),
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puff_size_(puff_size),
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index_(0),
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len_index_(0),
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cur_literals_length_(0),
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state_(State::kWritingNonLiteral) {}
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~BufferPuffWriter() override = default;
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bool Insert(const PuffData& pd) override;
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bool Flush() override;
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size_t Size() override;
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private:
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// Flushes the literals into the output and resets the state.
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bool FlushLiterals();
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// The pointer to the puffed stream. This should not be deallocated.
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uint8_t* puff_buf_out_;
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// The size of the puffed buffer.
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size_t puff_size_;
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// The offset to the next data in the buffer.
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size_t index_;
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// Marks where the length of data should be written after the |index_| has
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// moved forward.
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size_t len_index_;
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// The number of literals currently been written (or cached).
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size_t cur_literals_length_;
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// States when writing into the puffed buffer.
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enum class State {
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kWritingNonLiteral = 0,
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kWritingSmallLiteral,
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kWritingLargeLiteral,
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} state_;
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DISALLOW_COPY_AND_ASSIGN(BufferPuffWriter);
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};
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} // namespace puffin
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#endif // SRC_PUFF_WRITER_H_
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