1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/other-licenses/7zstub/src/7zip/Compress/RangeCoder/RangeCoderBit.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,120 @@
1.4 +// Compress/RangeCoder/RangeCoderBit.h
1.5 +
1.6 +#ifndef __COMPRESS_RANGECODER_BIT_H
1.7 +#define __COMPRESS_RANGECODER_BIT_H
1.8 +
1.9 +#include "RangeCoder.h"
1.10 +
1.11 +namespace NCompress {
1.12 +namespace NRangeCoder {
1.13 +
1.14 +const int kNumBitModelTotalBits = 11;
1.15 +const UInt32 kBitModelTotal = (1 << kNumBitModelTotalBits);
1.16 +
1.17 +const int kNumMoveReducingBits = 2;
1.18 +
1.19 +const int kNumBitPriceShiftBits = 6;
1.20 +const UInt32 kBitPrice = 1 << kNumBitPriceShiftBits;
1.21 +
1.22 +class CPriceTables
1.23 +{
1.24 +public:
1.25 + static UInt32 ProbPrices[kBitModelTotal >> kNumMoveReducingBits];
1.26 + static void Init();
1.27 + CPriceTables();
1.28 +};
1.29 +
1.30 +template <int numMoveBits>
1.31 +class CBitModel
1.32 +{
1.33 +public:
1.34 + UInt32 Prob;
1.35 + void UpdateModel(UInt32 symbol)
1.36 + {
1.37 + /*
1.38 + Prob -= (Prob + ((symbol - 1) & ((1 << numMoveBits) - 1))) >> numMoveBits;
1.39 + Prob += (1 - symbol) << (kNumBitModelTotalBits - numMoveBits);
1.40 + */
1.41 + if (symbol == 0)
1.42 + Prob += (kBitModelTotal - Prob) >> numMoveBits;
1.43 + else
1.44 + Prob -= (Prob) >> numMoveBits;
1.45 + }
1.46 +public:
1.47 + void Init() { Prob = kBitModelTotal / 2; }
1.48 +};
1.49 +
1.50 +template <int numMoveBits>
1.51 +class CBitEncoder: public CBitModel<numMoveBits>
1.52 +{
1.53 +public:
1.54 + void Encode(CEncoder *encoder, UInt32 symbol)
1.55 + {
1.56 + /*
1.57 + encoder->EncodeBit(this->Prob, kNumBitModelTotalBits, symbol);
1.58 + this->UpdateModel(symbol);
1.59 + */
1.60 + UInt32 newBound = (encoder->Range >> kNumBitModelTotalBits) * this->Prob;
1.61 + if (symbol == 0)
1.62 + {
1.63 + encoder->Range = newBound;
1.64 + this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
1.65 + }
1.66 + else
1.67 + {
1.68 + encoder->Low += newBound;
1.69 + encoder->Range -= newBound;
1.70 + this->Prob -= (this->Prob) >> numMoveBits;
1.71 + }
1.72 + if (encoder->Range < kTopValue)
1.73 + {
1.74 + encoder->Range <<= 8;
1.75 + encoder->ShiftLow();
1.76 + }
1.77 + }
1.78 + UInt32 GetPrice(UInt32 symbol) const
1.79 + {
1.80 + return CPriceTables::ProbPrices[
1.81 + (((this->Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];
1.82 + }
1.83 + UInt32 GetPrice0() const { return CPriceTables::ProbPrices[this->Prob >> kNumMoveReducingBits]; }
1.84 + UInt32 GetPrice1() const { return CPriceTables::ProbPrices[(kBitModelTotal - this->Prob) >> kNumMoveReducingBits]; }
1.85 +};
1.86 +
1.87 +
1.88 +template <int numMoveBits>
1.89 +class CBitDecoder: public CBitModel<numMoveBits>
1.90 +{
1.91 +public:
1.92 + UInt32 Decode(CDecoder *decoder)
1.93 + {
1.94 + UInt32 newBound = (decoder->Range >> kNumBitModelTotalBits) * this->Prob;
1.95 + if (decoder->Code < newBound)
1.96 + {
1.97 + decoder->Range = newBound;
1.98 + this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
1.99 + if (decoder->Range < kTopValue)
1.100 + {
1.101 + decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
1.102 + decoder->Range <<= 8;
1.103 + }
1.104 + return 0;
1.105 + }
1.106 + else
1.107 + {
1.108 + decoder->Range -= newBound;
1.109 + decoder->Code -= newBound;
1.110 + this->Prob -= (this->Prob) >> numMoveBits;
1.111 + if (decoder->Range < kTopValue)
1.112 + {
1.113 + decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
1.114 + decoder->Range <<= 8;
1.115 + }
1.116 + return 1;
1.117 + }
1.118 + }
1.119 +};
1.120 +
1.121 +}}
1.122 +
1.123 +#endif
