206 lines
8.2 KiB
C
206 lines
8.2 KiB
C
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/*-----------------------------------------------------------*/
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/* Block Sorting, Lossless Data Compression Library. */
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/* Probability counter and logistic mixer */
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/*-----------------------------------------------------------*/
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/*--
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This file is a part of bsc and/or libbsc, a program and a library for
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lossless, block-sorting data compression.
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Copyright (c) 2009-2012 Ilya Grebnov <ilya.grebnov@gmail.com>
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See file AUTHORS for a full list of contributors.
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The bsc and libbsc is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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The bsc and libbsc is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the bsc and libbsc. If not, see http://www.gnu.org/licenses/.
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Please see the files COPYING and COPYING.LIB for full copyright information.
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See also the bsc and libbsc web site:
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http://libbsc.com/ for more information.
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--*/
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#ifndef _LIBBSC_CODER_PREDICTOR_H
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#define _LIBBSC_CODER_PREDICTOR_H
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#include "../../platform/platform.h"
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#include "tables.h"
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struct ProbabilityCounter
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{
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public:
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static INLINE void UpdateBit0(short & probability, const int threshold, const int adaptationRate)
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{
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probability = probability + (((4096 - threshold - probability) * adaptationRate) >> 12);
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};
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static INLINE void UpdateBit1(short & probability, const int threshold, const int adaptationRate)
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{
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probability = probability - (((probability - threshold) * adaptationRate) >> 12);
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};
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};
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struct ProbabilityMixer
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{
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private:
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short stretchedProbability0;
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short stretchedProbability1;
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short stretchedProbability2;
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int mixedProbability;
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int index;
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short probabilityMap[17];
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int weight0;
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int weight1;
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int weight2;
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public:
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INLINE void Init()
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{
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weight0 = weight1 = 2048 << 5; weight2 = 0;
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for (int p = 0; p < 17; ++p)
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{
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probabilityMap[p] = bsc_squash((p - 8) * 256);
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}
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}
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INLINE int Mixup(const int probability0, const int probability1, const int probability2)
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{
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stretchedProbability0 = bsc_stretch(probability0);
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stretchedProbability1 = bsc_stretch(probability1);
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stretchedProbability2 = bsc_stretch(probability2);
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short stretchedProbability = (stretchedProbability0 * weight0 + stretchedProbability1 * weight1 + stretchedProbability2 * weight2) >> 17;
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if (stretchedProbability < -2047) stretchedProbability = -2047;
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if (stretchedProbability > 2047) stretchedProbability = 2047;
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index = (stretchedProbability + 2048) >> 8;
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const int weight = stretchedProbability & 255;
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const int probability = bsc_squash(stretchedProbability);
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const int mappedProbability = probabilityMap[index] + (((probabilityMap[index + 1] - probabilityMap[index]) * weight) >> 8);
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return mixedProbability = (3 * probability + mappedProbability) >> 2;
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};
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INLINE int MixupAndUpdateBit0(const int probability0, const int probability1, const int probability2,
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const int learningRate0, const int learningRate1, const int learningRate2,
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const int threshold, const int adaptationRate
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)
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{
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const short stretchedProbability0 = bsc_stretch(probability0);
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const short stretchedProbability1 = bsc_stretch(probability1);
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const short stretchedProbability2 = bsc_stretch(probability2);
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short stretchedProbability = (stretchedProbability0 * weight0 + stretchedProbability1 * weight1 + stretchedProbability2 * weight2) >> 17;
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if (stretchedProbability < -2047) stretchedProbability = -2047;
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if (stretchedProbability > 2047) stretchedProbability = 2047;
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const int weight = stretchedProbability & 255;
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const int index = (stretchedProbability + 2048) >> 8;
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const int probability = bsc_squash(stretchedProbability);
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const int mappedProbability = probabilityMap[index] + (((probabilityMap[index + 1] - probabilityMap[index]) * weight) >> 8);
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const int mixedProbability = (3 * probability + mappedProbability) >> 2;
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ProbabilityCounter::UpdateBit0(probabilityMap[index], threshold, adaptationRate);
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ProbabilityCounter::UpdateBit0(probabilityMap[index + 1], threshold, adaptationRate);
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const int eps = mixedProbability - 4095;
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weight0 -= (learningRate0 * eps * stretchedProbability0) >> 16;
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weight1 -= (learningRate1 * eps * stretchedProbability1) >> 16;
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weight2 -= (learningRate2 * eps * stretchedProbability2) >> 16;
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return mixedProbability;
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};
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INLINE int MixupAndUpdateBit1(const int probability0, const int probability1, const int probability2,
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const int learningRate0, const int learningRate1, const int learningRate2,
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const int threshold, const int adaptationRate
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)
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{
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const short stretchedProbability0 = bsc_stretch(probability0);
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const short stretchedProbability1 = bsc_stretch(probability1);
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const short stretchedProbability2 = bsc_stretch(probability2);
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short stretchedProbability = (stretchedProbability0 * weight0 + stretchedProbability1 * weight1 + stretchedProbability2 * weight2) >> 17;
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if (stretchedProbability < -2047) stretchedProbability = -2047;
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if (stretchedProbability > 2047) stretchedProbability = 2047;
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const int weight = stretchedProbability & 255;
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const int index = (stretchedProbability + 2048) >> 8;
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const int probability = bsc_squash(stretchedProbability);
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const int mappedProbability = probabilityMap[index] + (((probabilityMap[index + 1] - probabilityMap[index]) * weight) >> 8);
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const int mixedProbability = (3 * probability + mappedProbability) >> 2;
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ProbabilityCounter::UpdateBit1(probabilityMap[index], threshold, adaptationRate);
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ProbabilityCounter::UpdateBit1(probabilityMap[index + 1], threshold, adaptationRate);
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const int eps = mixedProbability - 1;
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weight0 -= (learningRate0 * eps * stretchedProbability0) >> 16;
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weight1 -= (learningRate1 * eps * stretchedProbability1) >> 16;
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weight2 -= (learningRate2 * eps * stretchedProbability2) >> 16;
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return mixedProbability;
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};
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INLINE void UpdateBit0(const int learningRate0, const int learningRate1, const int learningRate2,
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const int threshold, const int adaptationRate
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)
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{
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ProbabilityCounter::UpdateBit0(probabilityMap[index], threshold, adaptationRate);
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ProbabilityCounter::UpdateBit0(probabilityMap[index + 1], threshold, adaptationRate);
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const int eps = mixedProbability - 4095;
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weight0 -= (learningRate0 * eps * stretchedProbability0) >> 16;
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weight1 -= (learningRate1 * eps * stretchedProbability1) >> 16;
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weight2 -= (learningRate2 * eps * stretchedProbability2) >> 16;
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};
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INLINE void UpdateBit1(const int learningRate0, const int learningRate1, const int learningRate2,
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const int threshold, const int adaptationRate
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)
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{
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ProbabilityCounter::UpdateBit1(probabilityMap[index], threshold, adaptationRate);
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ProbabilityCounter::UpdateBit1(probabilityMap[index + 1], threshold, adaptationRate);
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const int eps = mixedProbability - 1;
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weight0 -= (learningRate0 * eps * stretchedProbability0) >> 16;
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weight1 -= (learningRate1 * eps * stretchedProbability1) >> 16;
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weight2 -= (learningRate2 * eps * stretchedProbability2) >> 16;
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};
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};
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#endif
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/*-----------------------------------------------------------*/
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/* End predictor.h */
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/*-----------------------------------------------------------*/
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