81 lines
2.0 KiB
C++
81 lines
2.0 KiB
C++
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// Compress/RangeCoder/RangeCoderBit.cpp
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#include "StdAfx.h"
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#include "RangeCoderBit.h"
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namespace NCompress {
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namespace NRangeCoder {
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UInt32 CPriceTables::ProbPrices[kBitModelTotal >> kNumMoveReducingBits];
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static CPriceTables g_PriceTables;
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CPriceTables::CPriceTables() { Init(); }
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void CPriceTables::Init()
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{
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const int kNumBits = (kNumBitModelTotalBits - kNumMoveReducingBits);
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for(int i = kNumBits - 1; i >= 0; i--)
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{
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UInt32 start = 1 << (kNumBits - i - 1);
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UInt32 end = 1 << (kNumBits - i);
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for (UInt32 j = start; j < end; j++)
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ProbPrices[j] = (i << kNumBitPriceShiftBits) +
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(((end - j) << kNumBitPriceShiftBits) >> (kNumBits - i - 1));
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}
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/*
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// simplest: bad solution
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for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
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ProbPrices[i] = kBitPrice;
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*/
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/*
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const double kDummyMultMid = (1.0 / kBitPrice) / 2;
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const double kDummyMultMid = 0;
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// float solution
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double ln2 = log(double(2));
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double lnAll = log(double(kBitModelTotal >> kNumMoveReducingBits));
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for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
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ProbPrices[i] = UInt32((fabs(lnAll - log(double(i))) / ln2 + kDummyMultMid) * kBitPrice);
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*/
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/*
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// experimental, slow, solution:
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for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
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{
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const int kCyclesBits = 5;
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const UInt32 kCycles = (1 << kCyclesBits);
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UInt32 range = UInt32(-1);
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UInt32 bitCount = 0;
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for (UInt32 j = 0; j < kCycles; j++)
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{
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range >>= (kNumBitModelTotalBits - kNumMoveReducingBits);
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range *= i;
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while(range < (1 << 31))
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{
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range <<= 1;
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bitCount++;
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}
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}
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bitCount <<= kNumBitPriceShiftBits;
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range -= (1 << 31);
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for (int k = kNumBitPriceShiftBits - 1; k >= 0; k--)
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{
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range <<= 1;
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if (range > (1 << 31))
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{
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bitCount += (1 << k);
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range -= (1 << 31);
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}
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}
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ProbPrices[i] = (bitCount
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// + (1 << (kCyclesBits - 1))
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) >> kCyclesBits;
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}
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*/
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}
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}}
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