+++ /dev/null
-/*
- Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
-
- Stockfish 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.
-
- Stockfish 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/>.
-*/
-
-
-////
-//// Includes
-////
-
-#include <cassert>
-#include <sstream>
-#include <map>
-
-#include "material.h"
-
-using std::string;
-
-////
-//// Local definitions
-////
-
-namespace {
-
- // Values modified by Joona Kiiski
- const Value BishopPairMidgameBonus = Value(109);
- const Value BishopPairEndgameBonus = Value(97);
-
- Key KNNKMaterialKey, KKNNMaterialKey;
-
- // Unmapped endgame evaluation and scaling functions, these
- // are accessed direcly and not through the function maps.
- EvaluationFunction<KmmKm> EvaluateKmmKm(WHITE);
- EvaluationFunction<KXK> EvaluateKXK(WHITE), EvaluateKKX(BLACK);
- ScalingFunction<KBPK> ScaleKBPK(WHITE), ScaleKKBP(BLACK);
- ScalingFunction<KQKRP> ScaleKQKRP(WHITE), ScaleKRPKQ(BLACK);
- ScalingFunction<KPsK> ScaleKPsK(WHITE), ScaleKKPs(BLACK);
- ScalingFunction<KPKP> ScaleKPKPw(WHITE), ScaleKPKPb(BLACK);
-}
-
-
-////
-//// Classes
-////
-
-
-/// See header for a class description. It is declared here to avoid
-/// to include <map> in the header file.
-
-class EndgameFunctions {
-
- typedef EndgameEvaluationFunctionBase EF;
- typedef EndgameScalingFunctionBase SF;
-
-public:
- EndgameFunctions();
- ~EndgameFunctions();
- EF* getEEF(Key key) const;
- SF* getESF(Key key, Color* c) const;
-
-private:
- Key buildKey(const string& keyCode);
- const string swapColors(const string& keyCode);
- template<EndgameType> void add_ef(const string& keyCode);
- template<EndgameType> void add_sf(const string& keyCode);
-
- struct ScalingInfo
- {
- Color col;
- SF* fun;
- };
-
- std::map<Key, EF*> EEFmap;
- std::map<Key, ScalingInfo> ESFmap;
-};
-
-
-////
-//// Functions
-////
-
-
-/// Constructor for the MaterialInfoTable class
-
-MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
-
- size = numOfEntries;
- entries = new MaterialInfo[size];
- funcs = new EndgameFunctions();
- if (!entries || !funcs)
- {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
- Application::exit_with_failure();
- }
-}
-
-
-/// Destructor for the MaterialInfoTable class
-
-MaterialInfoTable::~MaterialInfoTable() {
-
- delete funcs;
- delete [] entries;
-}
-
-
-/// MaterialInfoTable::get_material_info() takes a position object as input,
-/// computes or looks up a MaterialInfo object, and returns a pointer to it.
-/// If the material configuration is not already present in the table, it
-/// is stored there, so we don't have to recompute everything when the
-/// same material configuration occurs again.
-
-MaterialInfo* MaterialInfoTable::get_material_info(const Position& pos) {
-
- Key key = pos.get_material_key();
- int index = key & (size - 1);
- MaterialInfo* mi = entries + index;
-
- // If mi->key matches the position's material hash key, it means that we
- // have analysed this material configuration before, and we can simply
- // return the information we found the last time instead of recomputing it.
- if (mi->key == key)
- return mi;
-
- // Clear the MaterialInfo object, and set its key
- mi->clear();
- mi->key = key;
-
- // A special case before looking for a specialized evaluation function
- // KNN vs K is a draw.
- if (key == KNNKMaterialKey || key == KKNNMaterialKey)
- {
- mi->factor[WHITE] = mi->factor[BLACK] = 0;
- return mi;
- }
-
- // Let's look if we have a specialized evaluation function for this
- // particular material configuration. First we look for a fixed
- // configuration one, then a generic one if previous search failed.
- if ((mi->evaluationFunction = funcs->getEEF(key)) != NULL)
- return mi;
-
- else if ( pos.non_pawn_material(BLACK) == Value(0)
- && pos.piece_count(BLACK, PAWN) == 0
- && pos.non_pawn_material(WHITE) >= RookValueMidgame)
- {
- mi->evaluationFunction = &EvaluateKXK;
- return mi;
- }
- else if ( pos.non_pawn_material(WHITE) == Value(0)
- && pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(BLACK) >= RookValueMidgame)
- {
- mi->evaluationFunction = &EvaluateKKX;
- return mi;
- }
- else if ( pos.pawns() == EmptyBoardBB
- && pos.rooks() == EmptyBoardBB
- && pos.queens() == EmptyBoardBB)
- {
- // Minor piece endgame with at least one minor piece per side,
- // and no pawns.
- assert(pos.knights(WHITE) | pos.bishops(WHITE));
- assert(pos.knights(BLACK) | pos.bishops(BLACK));
-
- if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2
- && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2)
- {
- mi->evaluationFunction = &EvaluateKmmKm;
- return mi;
- }
- }
-
- // OK, we didn't find any special evaluation function for the current
- // material configuration. Is there a suitable scaling function?
- //
- // The code below is rather messy, and it could easily get worse later,
- // if we decide to add more special cases. We face problems when there
- // are several conflicting applicable scaling functions and we need to
- // decide which one to use.
- Color c;
- EndgameScalingFunctionBase* sf;
-
- if ((sf = funcs->getESF(key, &c)) != NULL)
- {
- mi->scalingFunction[c] = sf;
- return mi;
- }
-
- if ( pos.non_pawn_material(WHITE) == BishopValueMidgame
- && pos.piece_count(WHITE, BISHOP) == 1
- && pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKBPK;
-
- if ( pos.non_pawn_material(BLACK) == BishopValueMidgame
- && pos.piece_count(BLACK, BISHOP) == 1
- && pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKKBP;
-
- if ( pos.piece_count(WHITE, PAWN) == 0
- && pos.non_pawn_material(WHITE) == QueenValueMidgame
- && pos.piece_count(WHITE, QUEEN) == 1
- && pos.piece_count(BLACK, ROOK) == 1
- && pos.piece_count(BLACK, PAWN) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKQKRP;
-
- else if ( pos.piece_count(BLACK, PAWN) == 0
- && pos.non_pawn_material(BLACK) == QueenValueMidgame
- && pos.piece_count(BLACK, QUEEN) == 1
- && pos.piece_count(WHITE, ROOK) == 1
- && pos.piece_count(WHITE, PAWN) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKRPKQ;
-
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0))
- {
- if (pos.piece_count(BLACK, PAWN) == 0)
- {
- assert(pos.piece_count(WHITE, PAWN) >= 2);
- mi->scalingFunction[WHITE] = &ScaleKPsK;
- }
- else if (pos.piece_count(WHITE, PAWN) == 0)
- {
- assert(pos.piece_count(BLACK, PAWN) >= 2);
- mi->scalingFunction[BLACK] = &ScaleKKPs;
- }
- else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
- {
- mi->scalingFunction[WHITE] = &ScaleKPKPw;
- mi->scalingFunction[BLACK] = &ScaleKPKPb;
- }
- }
-
- // Compute the space weight
- if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >=
- 2*QueenValueMidgame + 4*RookValueMidgame + 2*KnightValueMidgame)
- {
- int minorPieceCount = pos.piece_count(WHITE, KNIGHT)
- + pos.piece_count(BLACK, KNIGHT)
- + pos.piece_count(WHITE, BISHOP)
- + pos.piece_count(BLACK, BISHOP);
-
- mi->spaceWeight = minorPieceCount * minorPieceCount;
- }
-
- // Evaluate the material balance
-
- int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
-
- for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
- {
- // No pawns makes it difficult to win, even with a material advantage
- if ( pos.piece_count(c, PAWN) == 0
- && pos.non_pawn_material(c) - pos.non_pawn_material(opposite_color(c)) <= BishopValueMidgame)
- {
- if ( pos.non_pawn_material(c) == pos.non_pawn_material(opposite_color(c))
- || pos.non_pawn_material(c) < RookValueMidgame)
- mi->factor[c] = 0;
- else
- {
- switch (pos.piece_count(c, BISHOP)) {
- case 2:
- mi->factor[c] = 32;
- break;
- case 1:
- mi->factor[c] = 12;
- break;
- case 0:
- mi->factor[c] = 6;
- break;
- }
- }
- }
-
- // Bishop pair
- if (pos.piece_count(c, BISHOP) >= 2)
- {
- mgValue += sign * BishopPairMidgameBonus;
- egValue += sign * BishopPairEndgameBonus;
- }
-
- // Knights are stronger when there are many pawns on the board. The
- // formula is taken from Larry Kaufman's paper "The Evaluation of Material
- // Imbalances in Chess":
- // http://mywebpages.comcast.net/danheisman/Articles/evaluation_of_material_imbalance.htm
- mgValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
- egValue += sign * Value(pos.piece_count(c, KNIGHT)*(pos.piece_count(c, PAWN)-5)*16);
-
- // Redundancy of major pieces, again based on Kaufman's paper:
- if (pos.piece_count(c, ROOK) >= 1)
- {
- Value v = Value((pos.piece_count(c, ROOK) - 1) * 32 + pos.piece_count(c, QUEEN) * 16);
- mgValue -= sign * v;
- egValue -= sign * v;
- }
- }
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
- return mi;
-}
-
-
-/// EndgameFunctions member definitions. This class is used to store the maps
-/// of end game and scaling functions that MaterialInfoTable will query for
-/// each key. The maps are constant and are populated only at construction,
-/// but are per-thread instead of globals to avoid expensive locks needed
-/// because std::map is not guaranteed to be thread-safe even if accessed
-/// only for a lookup.
-
-EndgameFunctions::EndgameFunctions() {
-
- KNNKMaterialKey = buildKey("KNNK");
- KKNNMaterialKey = buildKey("KKNN");
-
- add_ef<KPK>("KPK");
- add_ef<KBNK>("KBNK");
- add_ef<KRKP>("KRKP");
- add_ef<KRKB>("KRKB");
- add_ef<KRKN>("KRKN");
- add_ef<KQKR>("KQKR");
- add_ef<KBBKN>("KBBKN");
-
- add_sf<KNPK>("KNPK");
- add_sf<KRPKR>("KRPKR");
- add_sf<KBPKB>("KBPKB");
- add_sf<KBPPKB>("KBPPKB");
- add_sf<KBPKN>("KBPKN");
- add_sf<KRPPKRP>("KRPPKRP");
- add_sf<KRPPKRP>("KRPPKRP");
-}
-
-EndgameFunctions::~EndgameFunctions() {
-
- for (std::map<Key, EF*>::iterator it = EEFmap.begin(); it != EEFmap.end(); ++it)
- delete (*it).second;
-
- for (std::map<Key, ScalingInfo>::iterator it = ESFmap.begin(); it != ESFmap.end(); ++it)
- delete (*it).second.fun;
-}
-
-Key EndgameFunctions::buildKey(const string& keyCode) {
-
- assert(keyCode.length() > 0 && keyCode[0] == 'K');
- assert(keyCode.length() < 8);
-
- std::stringstream s;
- bool upcase = false;
-
- // Build up a fen substring with the given pieces, note
- // that the fen string could be of an illegal position.
- for (size_t i = 0; i < keyCode.length(); i++)
- {
- if (keyCode[i] == 'K')
- upcase = !upcase;
-
- s << char(upcase? toupper(keyCode[i]) : tolower(keyCode[i]));
- }
- s << 8 - keyCode.length() << "/8/8/8/8/8/8/8 w -";
- return Position(s.str()).get_material_key();
-}
-
-const string EndgameFunctions::swapColors(const string& keyCode) {
-
- // Build corresponding key for the opposite color: "KBPKN" -> "KNKBP"
- size_t idx = keyCode.find("K", 1);
- return keyCode.substr(idx) + keyCode.substr(0, idx);
-}
-
-template<EndgameType et>
-void EndgameFunctions::add_ef(const string& keyCode) {
-
- EEFmap.insert(std::pair<Key, EF*>(buildKey(keyCode), new EvaluationFunction<et>(WHITE)));
- EEFmap.insert(std::pair<Key, EF*>(buildKey(swapColors(keyCode)), new EvaluationFunction<et>(BLACK)));
-}
-
-template<EndgameType et>
-void EndgameFunctions::add_sf(const string& keyCode) {
-
- ScalingInfo s1 = {WHITE, new ScalingFunction<et>(WHITE)};
- ScalingInfo s2 = {BLACK, new ScalingFunction<et>(BLACK)};
-
- ESFmap.insert(std::pair<Key, ScalingInfo>(buildKey(keyCode), s1));
- ESFmap.insert(std::pair<Key, ScalingInfo>(buildKey(swapColors(keyCode)), s2));
-}
-
-EndgameEvaluationFunctionBase* EndgameFunctions::getEEF(Key key) const {
-
- std::map<Key, EF*>::const_iterator it(EEFmap.find(key));
- return (it != EEFmap.end() ? it->second : NULL);
-}
-
-EndgameScalingFunctionBase* EndgameFunctions::getESF(Key key, Color* c) const {
-
- std::map<Key, ScalingInfo>::const_iterator it(ESFmap.find(key));
- if (it == ESFmap.end())
- return NULL;
-
- *c = it->second.col;
- return it->second.fun;
-}