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