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