1967160500
git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@6720 212acab6-be3b-0410-9dea-997c60f758d6
135 lines
3.4 KiB
C++
135 lines
3.4 KiB
C++
/*
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* RangeCoderBit.h
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*
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* This file is a part of LZMA compression module for NSIS.
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*
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* Original LZMA SDK Copyright (C) 1999-2006 Igor Pavlov
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* Modifications Copyright (C) 2003-2016 Amir Szekely <kichik@netvision.net.il>
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*
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* Licensed under the Common Public License version 1.0 (the "License");
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* you may not use this file except in compliance with the License.
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*
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* Licence details can be found in the file COPYING.
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*
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* This software is provided 'as-is', without any express or implied
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* warranty.
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*/
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#ifndef __COMPRESS_RANGECODER_BIT_H
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#define __COMPRESS_RANGECODER_BIT_H
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#include "RangeCoder.h"
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namespace NCompress {
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namespace NRangeCoder {
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const int kNumBitModelTotalBits = 11;
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const UInt32 kBitModelTotal = (1 << kNumBitModelTotalBits);
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const int kNumMoveReducingBits = 2;
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const int kNumBitPriceShiftBits = 6;
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const UInt32 kBitPrice = 1 << kNumBitPriceShiftBits;
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class CPriceTables
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{
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public:
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static UInt32 ProbPrices[kBitModelTotal >> kNumMoveReducingBits];
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static void Init();
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CPriceTables();
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};
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template <int numMoveBits>
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class CBitModel
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{
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public:
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UInt32 Prob;
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void UpdateModel(UInt32 symbol)
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{
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/*
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Prob -= (Prob + ((symbol - 1) & ((1 << numMoveBits) - 1))) >> numMoveBits;
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Prob += (1 - symbol) << (kNumBitModelTotalBits - numMoveBits);
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*/
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if (symbol == 0)
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Prob += (kBitModelTotal - Prob) >> numMoveBits;
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else
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Prob -= (Prob) >> numMoveBits;
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}
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public:
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void Init() { Prob = kBitModelTotal / 2; }
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};
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template <int numMoveBits>
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class CBitEncoder: public CBitModel<numMoveBits>
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{
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public:
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void Encode(CEncoder *encoder, UInt32 symbol)
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{
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/*
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encoder->EncodeBit(this->Prob, kNumBitModelTotalBits, symbol);
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this->UpdateModel(symbol);
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*/
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UInt32 newBound = (encoder->Range >> kNumBitModelTotalBits) * this->Prob;
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if (symbol == 0)
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{
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encoder->Range = newBound;
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this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
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}
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else
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{
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encoder->Low += newBound;
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encoder->Range -= newBound;
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this->Prob -= (this->Prob) >> numMoveBits;
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}
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if (encoder->Range < kTopValue)
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{
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encoder->Range <<= 8;
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encoder->ShiftLow();
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}
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}
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UInt32 GetPrice(UInt32 symbol) const
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{
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return CPriceTables::ProbPrices[
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(((this->Prob - symbol) ^ ((-(int)symbol))) & (kBitModelTotal - 1)) >> kNumMoveReducingBits];
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}
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UInt32 GetPrice0() const { return CPriceTables::ProbPrices[this->Prob >> kNumMoveReducingBits]; }
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UInt32 GetPrice1() const { return CPriceTables::ProbPrices[(kBitModelTotal - this->Prob) >> kNumMoveReducingBits]; }
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};
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template <int numMoveBits>
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class CBitDecoder: public CBitModel<numMoveBits>
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{
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public:
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UInt32 Decode(CDecoder *decoder)
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{
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UInt32 newBound = (decoder->Range >> kNumBitModelTotalBits) * this->Prob;
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if (decoder->Code < newBound)
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{
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decoder->Range = newBound;
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this->Prob += (kBitModelTotal - this->Prob) >> numMoveBits;
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if (decoder->Range < kTopValue)
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{
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decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
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decoder->Range <<= 8;
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}
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return 0;
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}
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else
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{
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decoder->Range -= newBound;
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decoder->Code -= newBound;
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this->Prob -= (this->Prob) >> numMoveBits;
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if (decoder->Range < kTopValue)
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{
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decoder->Code = (decoder->Code << 8) | decoder->Stream.ReadByte();
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decoder->Range <<= 8;
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}
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return 1;
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}
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}
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};
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}}
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#endif
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