mirror of
https://github.com/klzgrad/naiveproxy.git
synced 2024-11-25 06:46:09 +03:00
89 lines
2.6 KiB
C++
89 lines
2.6 KiB
C++
// 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_TRIE_TRIE_BIT_BUFFER_H_
|
|
#define NET_TOOLS_HUFFMAN_TRIE_TRIE_TRIE_BIT_BUFFER_H_
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <vector>
|
|
|
|
#include "base/macros.h"
|
|
#include "net/tools/huffman_trie/huffman/huffman_builder.h"
|
|
|
|
namespace net {
|
|
|
|
namespace huffman_trie {
|
|
|
|
class BitWriter;
|
|
|
|
// TrieBitBuffer acts as a buffer for TrieWriter. It can be used to write bits,
|
|
// characters, and positions. The characters are stored as their
|
|
// HuffmanRepresentation. Positions are references to other locations in the
|
|
// trie.
|
|
class TrieBitBuffer {
|
|
public:
|
|
TrieBitBuffer();
|
|
~TrieBitBuffer();
|
|
|
|
// Writes |bit| to the buffer.
|
|
void WriteBit(uint8_t bit);
|
|
|
|
// Writes the |number_of_bits| least-significant bits from |bits| to the
|
|
// buffer.
|
|
void WriteBits(uint32_t bits, uint8_t number_of_bits);
|
|
|
|
// Write a position to the buffer. Actually writes the difference between
|
|
// |position| and |*last_position|. |*last_position| will be updated to equal
|
|
// the input |position|.
|
|
void WritePosition(uint32_t position, int32_t* last_position);
|
|
|
|
// Writes the character in |byte| to the buffer using its Huffman
|
|
// representation in |table|. Optionally tracks usage of the character in
|
|
// |*huffman_builder|.
|
|
void WriteChar(uint8_t byte,
|
|
const HuffmanRepresentationTable& table,
|
|
HuffmanBuilder* huffman_builder);
|
|
|
|
// Writes the entire buffer to |*writer|. Returns the position |*writer| was
|
|
// at before the buffer was written to it.
|
|
uint32_t WriteToBitWriter(BitWriter* writer);
|
|
|
|
// Appends the buffered bits in |current_byte_| to |elements_|. No padding
|
|
// will occur.
|
|
void Flush();
|
|
|
|
private:
|
|
// Represents either the |number_of_bits| least-significant bits in |bits| or
|
|
// a position (offset) in the trie.
|
|
struct BitsOrPosition {
|
|
uint8_t bits;
|
|
uint8_t number_of_bits;
|
|
uint32_t position;
|
|
};
|
|
|
|
// Returns the minimum number of bits needed to represent |input|.
|
|
uint8_t BitLength(uint32_t input) const;
|
|
|
|
// Append a new element to |elements_|.
|
|
void AppendBitsElement(uint8_t bits, uint8_t number_of_bits);
|
|
void AppendPositionElement(uint32_t position);
|
|
|
|
// Buffers bits until they fill a whole byte.
|
|
uint8_t current_byte_ = 0;
|
|
|
|
// The number of bits currently in |current_byte_|.
|
|
uint32_t used_ = 0;
|
|
|
|
std::vector<BitsOrPosition> elements_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(TrieBitBuffer);
|
|
};
|
|
|
|
} // namespace huffman_trie
|
|
|
|
} // namespace net
|
|
|
|
#endif // NET_TOOLS_HUFFMAN_TRIE_TRIE_TRIE_BIT_BUFFER_H_
|