1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
// Copyright 2016 The Chromium Authors
// 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>
namespace net::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(const BitWriter&) = delete;
BitWriter& operator=(const BitWriter&) = delete;
~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_;
};
} // namespace net::huffman_trie
#endif // NET_TOOLS_HUFFMAN_TRIE_BIT_WRITER_H_
|
