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| 1 // Copyright (c) 2016 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_ | |
| 6 #define NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_ | |
| 7 | |
| 8 #include <stdint.h> | |
| 9 | |
| 10 #include <vector> | |
| 11 | |
| 12 #include "net/tools/domain_security_preload_generator/huffman/huffman_frequency_
tracker.h" | |
| 13 | |
| 14 namespace net { | |
| 15 | |
| 16 namespace transport_security_state { | |
| 17 | |
| 18 class BitWriter; | |
| 19 | |
| 20 // TrieBitBuffer acts as a buffer for TrieWriter. It can be used to write bits, | |
| 21 // characters, and positions. The characters are stored as their | |
| 22 // HuffmanRepresentation. Positions are references to other locations in the | |
| 23 // trie. | |
| 24 class TrieBitBuffer { | |
| 25 public: | |
| 26 TrieBitBuffer(); | |
| 27 ~TrieBitBuffer(); | |
| 28 | |
| 29 // Writes |bit| to the buffer. | |
| 30 void WriteBit(uint8_t bit); | |
| 31 | |
| 32 // Writes the |number_of_bits| least-significant bits from |bits| to the | |
| 33 // buffer. | |
| 34 void WriteBits(uint32_t bits, uint8_t number_of_bits); | |
| 35 | |
| 36 // Write a position to the buffer. Actually writes the difference between | |
| 37 // |position| and |last_position|. |*last_position| will be updated to equal | |
| 38 // the input |position|. | |
| 39 void WritePosition(uint32_t position, int32_t* last_position); | |
| 40 | |
| 41 // Writes the character in |byte| to the buffer using its Huffman | |
| 42 // representation in |table|. Optionally tracks usage of the character in | |
| 43 // |*tracker|. | |
| 44 void WriteChar(uint8_t byte, | |
| 45 const HuffmanRepresentationTable& table, | |
| 46 HuffmanFrequencyTracker* tracker); | |
| 47 | |
| 48 // Writes the entire buffer to |*writer|. Returns the position |*writer| was | |
| 49 // at before the buffer was written to it. | |
| 50 uint32_t WriteToBitWriter(BitWriter* writer); | |
| 51 | |
| 52 // Appends the buffered bits in |current_byte_| to |elements_|. Empty bits | |
| 53 // are filled with zero's. | |
| 54 void Flush(); | |
| 55 | |
| 56 private: | |
| 57 // Represents either the |number_of_bits| least-significant bits in |bits| or | |
| 58 // a position (offset) in the trie. | |
| 59 struct BitsOrPosition { | |
| 60 uint8_t bits; | |
| 61 uint8_t number_of_bits; | |
| 62 uint32_t position; | |
| 63 }; | |
| 64 | |
| 65 // Returns the minimum number of bits needed to represent |input|. | |
| 66 uint8_t BitLength(uint32_t input) const; | |
| 67 | |
| 68 // Append a new element to |elements_|. | |
| 69 void AppendBitsElement(uint8_t bits, uint8_t number_of_bits); | |
| 70 void AppendPositionElement(uint32_t position); | |
| 71 | |
| 72 // Buffers bits until they fill a whole byte. | |
| 73 uint8_t current_byte_ = 0; | |
| 74 | |
| 75 // The number of bits currently in |current_byte_|. | |
| 76 uint32_t used_ = 0; | |
| 77 | |
| 78 std::vector<BitsOrPosition> elements_; | |
| 79 }; | |
| 80 | |
| 81 } // namespace transport_security_state | |
| 82 | |
| 83 } // namespace net | |
| 84 | |
| 85 #endif // NET_TOOLS_DOMAIN_SECURITY_PRELOAD_GENERATOR_TRIE_TRIE_BIT_BUFFER_H_ | |
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Chromium Code Reviews
Issue 2632073002:
Rename domain_security_preload_generator. (Closed)
