SgProbCut.h

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//----------------------------------------------------------------------------
/** @file SgProbCut.h

    Implementation of Buro's Multi-ProbCut method for use with SgSearch.
    See <a href="http://www.cs.ualberta.ca/~mburo/publications.html">
    Michael Buro's publications</a> on ProbCut and Multi-ProbCut
 */
//----------------------------------------------------------------------------

#ifndef SG_PROBCUT_H
#define SG_PROBCUT_H

#include "SgArray.h"
#include "SgBlackWhite.h"
#include "SgMove.h"
#include "SgSearch.h"
#include "SgStack.h"
#include "SgVector.h"

//----------------------------------------------------------------------------

class SgProbCut
{
public:
    static const int MAX_PROBCUT = 20;

    SgProbCut();

    struct Cutoff {
        float a, b, sigma;
        int shallow, deep;

        Cutoff() : shallow(-1), deep(-1) {}
    };

    void AddCutoff(const Cutoff &c);

    bool GetCutoff(int deep, int index, Cutoff &cutoff);

    float GetThreshold() const;

    bool IsEnabled() const;

    bool ProbCut(SgSearch& search, int depth, int alpha, int beta, 
                 SgSearchStack& moveStack,
                 bool* isExactValue, int* value);

    void SetEnabled(bool flag);

    void SetThreshold(float t);

private:
    float m_threshold;
    bool m_enabled;

    SgArray<SgArray<Cutoff, MAX_PROBCUT+1>, MAX_PROBCUT+1> m_cutoffs;
    SgArray<int, MAX_PROBCUT+1> m_cutoff_sizes;
};

inline SgProbCut::SgProbCut()
{
    m_threshold = 1.0;
    m_enabled = false;
    for (int i = 0; i < MAX_PROBCUT+1; ++i) m_cutoff_sizes[i] = 0;
}

inline void SgProbCut::AddCutoff(const Cutoff &c)
{
    int i = m_cutoff_sizes[c.deep];
    m_cutoffs[c.deep][i] = c;
    ++m_cutoff_sizes[c.deep];
}

inline bool SgProbCut::GetCutoff(int deep, int index, Cutoff &cutoff)
{
    if (deep > MAX_PROBCUT) return false;
    if (index >= m_cutoff_sizes[deep]) return false;
    cutoff = m_cutoffs[deep][index];
    return true;
}

inline void SgProbCut::SetThreshold(float t)
{
    m_threshold = t;
}

inline float SgProbCut::GetThreshold() const
{
    return m_threshold;
}

inline void SgProbCut::SetEnabled(bool flag)
{
    m_enabled = flag;
}

inline bool SgProbCut::IsEnabled() const
{
    return m_enabled;
}

//----------------------------------------------------------------------------

#endif // SG_PROBCUT_H