/*
Texel - A UCI chess engine.
Copyright (C) 2014 Peter Österlund, peterosterlund2@gmail.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* tbprobe.hpp
*
* Created on: Jun 2, 2014
* Author: petero
*/
#ifndef TBPROBE_HPP_
#define TBPROBE_HPP_
#include "transpositionTable.hpp"
#include "moveGen.hpp"
#include <string>
class Position;
/**
* Handle tablebase probing.
*/
class TBProbe {
friend class TBTest;
public:
/** Initialize tablebases. */
static void initialize(const std::string& gtbPath, int cacheMB,
const std::string& rtbPath);
/** Return true if GTB or RTB probing is enabled. */
static bool tbEnabled();
/** Probe one or more tablebases to get an exact score or a usable bound.
* @param pos The position to probe. The position can be temporarily modified
* but is restored to original state before function returns.
*/
static bool tbProbe(Position& pos, int ply, int alpha, int beta,
TranspositionTable::TTEntry& ent);
/** If some TB files are missing, it may be necessary to only search a subset
* of the root moves in order to make progress. This might happen for example
* in KPK if the KQK table is missing and search is not able to see the mate
* after promoting the pawn.
* @param pos The root position.
* @param legalMoves The set of legal root moves.
* @param movesToSearch The moves to search.
* @return True if a subset should be searched, false to search all moves.
*/
static bool getSearchMoves(Position& pos, const MoveList& legalMoves,
std::vector<Move>& movesToSearch);
/** Enhance PV with DTM information from gaviota tablebases. */
static void extendPV(const Position& rootPos, std::vector<Move>& pv);
/** Probe gaviota DTM tablebases.
* @param pos The position to probe. The position can be temporarily modified
* but is restored to original state before function returns.
* @param ply The ply value used to adjust mate scores.
* @param score The tablebase score. Only modified for tablebase hits.
* @return True if pos was found in the tablebases.
*/
static bool gtbProbeDTM(Position& pos, int ply, int& score);
/**
* Probe gaviota WDL tablebases.
* @param pos The position to probe. The position can be temporarily modified
* but is restored to original state before function returns.
* @param ply The ply value used to adjust mate scores.
* @param score The tablebase score. Only modified for tablebase hits.
* The returned score is either 0 or a mate bound.
*/
static bool gtbProbeWDL(Position& pos, int ply, int& score);
/**
* Probe syzygy DTZ tablebases.
* @param pos The position to probe. The position can be temporarily modified
* but is restored to original state before function returns.
* @param ply The ply value used to adjust mate scores.
* @param score The tablebase score. Only modified for tablebase hits.
* The returned score is either 0 or a mate bound. The bound
* is computed by considering the DTZ value and the maximum number
* of zeroing moves before mate.
*/
static bool rtbProbeDTZ(Position& pos, int ply, int& score);
/**
* Probe syzygy WDL tablebases.
* @param pos The position to probe. The position can be temporarily modified
* but is restored to original state before function returns.
* @param ply The ply value used to adjust mate scores.
* @param score The tablebase score. Only modified for tablebase hits.
* The returned score is either 0 or a mate bound.
*/
static bool rtbProbeWDL(Position& pos, int ply, int& score);
private:
/** Initialize */
static void gtbInitialize(const std::string& path, int cacheMB, int wdlFraction);
static void initWDLBounds();
static int getMaxDTZ(int matId);
static int getMaxSubMate(const Position& pos);
static int getMaxSubMate(std::vector<int>& pieces, int pawnMoves);
static void initMaxDTM();
static void initMaxDTZ();
struct GtbProbeData {
unsigned int stm, epsq, castles;
static const int MAXLEN = 17;
unsigned int wSq[MAXLEN];
unsigned int bSq[MAXLEN];
unsigned char wP[MAXLEN];
unsigned char bP[MAXLEN];
int materialId;
};
/** Convert position to GTB probe format. */
static void getGTBProbeData(const Position& pos, GtbProbeData& gtbData);
static bool gtbProbeDTM(const GtbProbeData& gtbData, int ply, int& score);
static bool gtbProbeWDL(const GtbProbeData& gtbData, int ply, int& score);
};
#endif /* TBPROBE_HPP_ */