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63 lines
1.7 KiB
C++
63 lines
1.7 KiB
C++
// Copyright (c) 2016 The Chromium 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 NET_TOOLS_HUFFMAN_TRIE_BIT_WRITER_H_
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#define NET_TOOLS_HUFFMAN_TRIE_BIT_WRITER_H_
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#include <stdint.h>
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#include <vector>
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#include "base/macros.h"
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namespace net {
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namespace huffman_trie {
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// BitWriter acts as a buffer to which bits can be written. The bits are stored
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// as bytes in a vector. BitWriter will buffer bits until it contains 8 bits at
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// which point they will be appended to the vector automatically.
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class BitWriter {
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public:
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BitWriter();
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~BitWriter();
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// Appends |bit| to the end of the buffer.
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void WriteBit(uint8_t bit);
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// Appends the |number_of_bits| least-significant bits of |bits| to the end of
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// the buffer.
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void WriteBits(uint32_t bits, uint8_t number_of_bits);
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// Appends the buffered bits in |current_byte_| to the |bytes_| vector. When
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// there are less than 8 bits in the buffer, the empty bits will be filled
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// with zero's.
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void Flush();
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uint32_t position() const { return position_; }
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// Returns a reference to |bytes_|. Make sure to call Flush() first so that
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// the buffered bits are written to |bytes_| as well.
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const std::vector<uint8_t>& bytes() const { return bytes_; }
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private:
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// Buffers bits until they fill a whole byte.
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uint8_t current_byte_ = 0;
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// The number of bits currently in |current_byte_|.
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uint8_t used_ = 0;
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// Total number of bits written to this BitWriter.
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uint32_t position_ = 0;
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std::vector<uint8_t> bytes_;
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DISALLOW_COPY_AND_ASSIGN(BitWriter);
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};
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} // namespace huffman_trie
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} // namespace net
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#endif // NET_TOOLS_HUFFMAN_TRIE_BIT_WRITER_H_
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