third_party/lzma/v4_65/files/CS/7zip/Compress/RangeCoder/RangeCoderBit.cs - Issue 624713003: Keep only base/extractor.[cc|h].

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Issue 624713003: Keep only base/extractor.[cc|h]. (Closed) Base URL: https://chromium.googlesource.com/external/omaha.git@master

Patch Set: Created 6 years, 2 months ago

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1 using System;

2

3 namespace SevenZip.Compression.RangeCoder

4 {

5 struct BitEncoder

6 {

7 public const int kNumBitModelTotalBits = 11;

8 public const uint kBitModelTotal = (1 << kNumBitModelTotalBits);

9 const int kNumMoveBits = 5;

10 const int kNumMoveReducingBits = 2;

11 public const int kNumBitPriceShiftBits = 6;

12

13 uint Prob;

14

15 public void Init() { Prob = kBitModelTotal >> 1; }

16

17 public void UpdateModel(uint symbol)

18 {

19 if (symbol == 0)

20 Prob += (kBitModelTotal - Prob) >> kNumMoveBits;

21 else

22 Prob -= (Prob) >> kNumMoveBits;

23 }

24

25 public void Encode(Encoder encoder, uint symbol)

26 {

27 // encoder.EncodeBit(Prob, kNumBitModelTotalBits, symbol );

28 // UpdateModel(symbol);

29 uint newBound = (encoder.Range >> kNumBitModelTotalBits) * Prob;

30 if (symbol == 0)

31 {

32 encoder.Range = newBound;

33 Prob += (kBitModelTotal - Prob) >> kNumMoveBits;

34 }

35 else

36 {

37 encoder.Low += newBound;

38 encoder.Range -= newBound;

39 Prob -= (Prob) >> kNumMoveBits;

40 }

41 if (encoder.Range < Encoder.kTopValue)

42 {

43 encoder.Range <<= 8;

44 encoder.ShiftLow();

45 }

46 }

47

48 private static UInt32[] ProbPrices = new UInt32[kBitModelTotal > > kNumMoveReducingBits];

49

50 static BitEncoder()

51 {

52 const int kNumBits = (kNumBitModelTotalBits - kNumMoveRe ducingBits);

53 for (int i = kNumBits - 1; i >= 0; i--)

54 {

55 UInt32 start = (UInt32)1 << (kNumBits - i - 1);

56 UInt32 end = (UInt32)1 << (kNumBits - i);

57 for (UInt32 j = start; j < end; j++)

58 ProbPrices[j] = ((UInt32)i << kNumBitPri ceShiftBits) +

59 (((end - j) << kNumBitPriceShift Bits) >> (kNumBits - i - 1));

60 }

61 }

62

63 public uint GetPrice(uint symbol)

64 {

65 return ProbPrices[(((Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];

66 }

67 public uint GetPrice0() { return ProbPrices[Prob >> kNumMoveReducingBi ts]; }

68 public uint GetPrice1() { return ProbPrices[(kBitModelTotal - Pr ob) >> kNumMoveReducingBits]; }

69 }

70

71 struct BitDecoder

72 {

73 public const int kNumBitModelTotalBits = 11;

74 public const uint kBitModelTotal = (1 << kNumBitModelTotalBits);

75 const int kNumMoveBits = 5;

76

77 uint Prob;

78

79 public void UpdateModel(int numMoveBits, uint symbol)

80 {

81 if (symbol == 0)

82 Prob += (kBitModelTotal - Prob) >> numMoveBits;

83 else

84 Prob -= (Prob) >> numMoveBits;

85 }

86

87 public void Init() { Prob = kBitModelTotal >> 1; }

88

89 public uint Decode(RangeCoder.Decoder rangeDecoder)

90 {

91 uint newBound = (uint)(rangeDecoder.Range >> kNumBitMode lTotalBits) * (uint)Prob;

92 if (rangeDecoder.Code < newBound)

93 {

94 rangeDecoder.Range = newBound;

95 Prob += (kBitModelTotal - Prob) >> kNumMoveBits;

96 if (rangeDecoder.Range < Decoder.kTopValue)

97 {

98 rangeDecoder.Code = (rangeDecoder.Code < < 8) \| (byte)rangeDecoder.Stream.ReadByte();

99 rangeDecoder.Range <<= 8;

100 }

101 return 0;

102 }

103 else

104 {

105 rangeDecoder.Range -= newBound;

106 rangeDecoder.Code -= newBound;

107 Prob -= (Prob) >> kNumMoveBits;

108 if (rangeDecoder.Range < Decoder.kTopValue)

109 {

110 rangeDecoder.Code = (rangeDecoder.Code < < 8) \| (byte)rangeDecoder.Stream.ReadByte();

111 rangeDecoder.Range <<= 8;

112 }

113 return 1;

114 }

115 }

116 }

117 }

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