net/tools/domain_security_preload_generator/trie/trie_bit_buffer.cc - Issue 2632073002: Rename domain_security_preload_generator.

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Issue 2632073002: Rename domain_security_preload_generator. (Closed)

Patch Set: rebase & comment rsleevi Created 3 years, 11 months ago

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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 #include "net/tools/domain_security_preload_generator/trie/trie_bit_buffer.h"

6

7 #include "base/logging.h"

8 #include "net/tools/domain_security_preload_generator/bit_writer.h"

9

10 namespace net {

11

12 namespace transport_security_state {

13

14 TrieBitBuffer::TrieBitBuffer() {}

15

16 TrieBitBuffer::~TrieBitBuffer() {}

17

18 void TrieBitBuffer::WriteBit(uint8_t bit) {

19 current_byte_ \|= bit << (7 - used_);

20 used_++;

21

22 if (used_ == 8) {

23 Flush();

24 }

25 }

26

27 void TrieBitBuffer::WriteBits(uint32_t bits, uint8_t number_of_bits) {

28 DCHECK(number_of_bits <= 32);

29 for (uint8_t i = 1; i <= number_of_bits; i++) {

30 uint8_t bit = 1 & (bits >> (number_of_bits - i));

31 WriteBit(bit);

32 }

33 }

34

35 void TrieBitBuffer::WritePosition(uint32_t position, int32_t* last_position) {

36 if (*last_position != -1) {

37 int32_t delta = position - *last_position;

38 DCHECK(delta > 0) << "delta position is not positive.";

39

40 uint8_t number_of_bits = BitLength(delta);

41 DCHECK(number_of_bits <= 7 + 15) << "positive position delta too large.";

42

43 if (number_of_bits <= 7) {

44 WriteBits(0, 1);

45 WriteBits(delta, 7);

46 } else {

47 WriteBits(1, 1);

48 WriteBits(number_of_bits - 8, 4);

49 WriteBits(delta, number_of_bits);

50 }

51

52 *last_position = position;

53 return;

54 }

55

56 if (used_ != 0) {

57 Flush();

58 }

59

60 AppendPositionElement(position);

61

62 *last_position = position;

63 }

64

65 uint8_t TrieBitBuffer::BitLength(uint32_t input) const {

66 uint8_t number_of_bits = 0;

67 while (input != 0) {

68 number_of_bits++;

69 input >>= 1;

70 }

71 return number_of_bits;

72 }

73

74 void TrieBitBuffer::WriteChar(uint8_t byte,

75 const HuffmanRepresentationTable& table,

76 HuffmanFrequencyTracker* tracker) {

77 HuffmanRepresentationTable::const_iterator item;

78 item = table.find(byte);

79 DCHECK(item != table.end());

80 if (tracker) {

81 tracker->RecordUsage(byte);

82 }

83 WriteBits(item->second.bits, item->second.number_of_bits);

84 }

85

86 void TrieBitBuffer::AppendBitsElement(uint8_t bits, uint8_t number_of_bits) {

87 BitsOrPosition element;

88 element.bits = current_byte_;

89 element.number_of_bits = used_;

90 elements_.push_back(element);

91 }

92

93 void TrieBitBuffer::AppendPositionElement(uint32_t position) {

94 BitsOrPosition element;

95 element.position = position;

96 element.number_of_bits = 0;

97 elements_.push_back(element);

98 }

99

100 uint32_t TrieBitBuffer::WriteToBitWriter(BitWriter* writer) {

101 Flush();

102

103 uint32_t old_position = writer->position();

104 for (auto const& element : elements_) {

105 if (element.number_of_bits) {

106 writer->WriteBits(element.bits >> (8 - element.number_of_bits),

107 element.number_of_bits);

108 } else {

109 uint32_t current = old_position;

110 uint32_t target = element.position;

111 DCHECK(target < current) << "Reference is not backwards";

112 uint32_t delta = current - target;

113 uint8_t delta_number_of_bits = BitLength(delta);

114 DCHECK(delta_number_of_bits < 32) << "Delta to large";

115 writer->WriteBits(delta_number_of_bits, 5);

116 writer->WriteBits(delta, delta_number_of_bits);

117 }

118 }

119 return old_position;

120 }

121

122 void TrieBitBuffer::Flush() {

123 if (used_) {

124 AppendBitsElement(current_byte_, used_);

125

126 used_ = 0;

127 current_byte_ = 0;

128 }

129 }

130

131 } // namespace transport_security_state

132

133 } // namespace net

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