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