/*
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
+ Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm> // For std::min
#include <cassert>
-#include <sstream>
-#include <map>
+#include <cstring>
#include "material.h"
-using std::string;
-
-////
-//// Local definitions
-////
+using namespace std;
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;
+ // Polynomial material balance parameters
+
+ // pair pawn knight bishop rook queen
+ const int Linear[6] = { 1852, -162, -1122, -183, 249, -154 };
+
+ const int QuadraticSameSide[][PIECE_TYPE_NB] = {
+ // OUR PIECES
+ // pair pawn knight bishop rook queen
+ { 0 }, // Bishop pair
+ { 39, 2 }, // Pawn
+ { 35, 271, -4 }, // knight OUR PIECES
+ { 0, 105, 4, 0 }, // Bishop
+ { -27, -2, 46, 100, -141 }, // Rook
+ {-177, 25, 129, 142, -137, 0 } // Queen
+ };
+
+ const int QuadraticOppositeSide[][PIECE_TYPE_NB] = {
+ // THEIR PIECES
+ // pair pawn knight bishop rook queen
+ { 0 }, // Bishop pair
+ { 37, 0 }, // Pawn
+ { 10, 62, 0 }, // Knight OUR PIECES
+ { 57, 64, 39, 0 }, // Bishop
+ { 50, 40, 23, -22, 0 }, // Rook
+ { 98, 105, -39, 141, 274, 0 } // Queen
+ };
+
+ // Endgame evaluation and scaling functions are accessed directly and not through
+ // the function maps because they correspond to more than one material hash key.
+ Endgame<KXK> EvaluateKXK[] = { Endgame<KXK>(WHITE), Endgame<KXK>(BLACK) };
+
+ Endgame<KBPsK> ScaleKBPsK[] = { Endgame<KBPsK>(WHITE), Endgame<KBPsK>(BLACK) };
+ Endgame<KQKRPs> ScaleKQKRPs[] = { Endgame<KQKRPs>(WHITE), Endgame<KQKRPs>(BLACK) };
+ Endgame<KPsK> ScaleKPsK[] = { Endgame<KPsK>(WHITE), Endgame<KPsK>(BLACK) };
+ Endgame<KPKP> ScaleKPKP[] = { Endgame<KPKP>(WHITE), Endgame<KPKP>(BLACK) };
+
+ // Helper templates used to detect a given material distribution
+ template<Color Us> bool is_KXK(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return !more_than_one(pos.pieces(Them))
+ && pos.non_pawn_material(Us) >= RookValueMg;
+ }
-public:
- EndgameFunctions();
- ~EndgameFunctions();
- template<class T> T* get(Key key) const;
+ template<Color Us> bool is_KBPsKs(const Position& pos) {
+ return pos.non_pawn_material(Us) == BishopValueMg
+ && pos.count<BISHOP>(Us) == 1
+ && pos.count<PAWN >(Us) >= 1;
+ }
-private:
- template<class T> void add(const string& keyCode);
+ template<Color Us> bool is_KQKRPs(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return !pos.count<PAWN>(Us)
+ && pos.non_pawn_material(Us) == QueenValueMg
+ && pos.count<QUEEN>(Us) == 1
+ && pos.count<ROOK>(Them) == 1
+ && pos.count<PAWN>(Them) >= 1;
+ }
- static Key buildKey(const string& keyCode);
- static const string swapColors(const string& keyCode);
+ /// imbalance() calculates the imbalance by comparing the piece count of each
+ /// piece type for both colors.
- std::map<Key, EF*> EEFmap;
- std::map<Key, SF*> ESFmap;
+ template<Color Us>
+ int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
- // Maps accessing functions for const and non-const references
- template<typename T> const std::map<Key, T*>& map() const { return EEFmap; }
- template<> const std::map<Key, SF*>& map<SF>() const { return ESFmap; }
- template<typename T> std::map<Key, T*>& map() { return EEFmap; }
- template<> std::map<Key, SF*>& map<SF>() { return ESFmap; }
-};
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ int bonus = 0;
-////
-//// Functions
-////
+ // Second-degree polynomial material imbalance by Tord Romstad
+ for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
+ {
+ if (!pieceCount[Us][pt1])
+ continue;
+ int v = Linear[pt1];
-/// Constructor for the MaterialInfoTable class
+ for (int pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
+ v += QuadraticSameSide[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticOppositeSide[pt1][pt2] * pieceCount[Them][pt2];
-MaterialInfoTable::MaterialInfoTable(unsigned int numOfEntries) {
+ bonus += pieceCount[Us][pt1] * v;
+ }
- 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();
+ return bonus;
}
-}
-
-
-/// Destructor for the MaterialInfoTable class
-MaterialInfoTable::~MaterialInfoTable() {
-
- delete funcs;
- delete [] entries;
-}
+} // namespace
+namespace Material {
-/// 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.
+/// Material::probe() takes a position object as input, looks up a MaterialEntry
+/// object, and returns a pointer to it. If the material configuration is not
+/// already present in the table, it is computed and 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) {
+Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
- Key key = pos.get_material_key();
- int index = key & (size - 1);
- MaterialInfo* mi = entries + index;
+ Key key = pos.material_key();
+ Entry* e = entries[key];
- // If mi->key matches the position's material hash key, it means that we
+ // If e->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;
+ if (e->key == key)
+ return e;
- // Clear the MaterialInfo object, and set its key
- mi->clear();
- mi->key = key;
+ std::memset(e, 0, sizeof(Entry));
+ e->key = key;
+ e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
+ e->gamePhase = pos.game_phase();
- // 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. Firstly we look for a fixed configuration one, then
+ // for a generic one if the previous search failed.
+ if (endgames.probe(key, e->evaluationFunction))
+ return e;
- // 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->get<EndgameEvaluationFunctionBase>(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)
+ if (is_KXK<WHITE>(pos))
{
- mi->evaluationFunction = &EvaluateKKX;
- return mi;
+ e->evaluationFunction = &EvaluateKXK[WHITE];
+ return e;
}
- 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;
- }
+ if (is_KXK<BLACK>(pos))
+ {
+ e->evaluationFunction = &EvaluateKXK[BLACK];
+ return e;
}
// 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.
- EndgameScalingFunctionBase* sf;
+ // We face problems when there are several conflicting applicable
+ // scaling functions and we need to decide which one to use.
+ EndgameBase<ScaleFactor>* sf;
- if ((sf = funcs->get<EndgameScalingFunctionBase>(key)) != NULL)
+ if (endgames.probe(key, sf))
{
- mi->scalingFunction[sf->color()] = sf;
- return mi;
+ e->scalingFunction[sf->color()] = sf;
+ return e;
}
- 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))
+ // Generic scaling functions that refer to more than one material
+ // distribution. They should be probed after the specialized ones.
+ // Note that these ones don't return after setting the function.
+ if (is_KBPsKs<WHITE>(pos))
+ e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
+
+ if (is_KBPsKs<BLACK>(pos))
+ e->scalingFunction[BLACK] = &ScaleKBPsK[BLACK];
+
+ if (is_KQKRPs<WHITE>(pos))
+ e->scalingFunction[WHITE] = &ScaleKQKRPs[WHITE];
+
+ else if (is_KQKRPs<BLACK>(pos))
+ e->scalingFunction[BLACK] = &ScaleKQKRPs[BLACK];
+
+ Value npm_w = pos.non_pawn_material(WHITE);
+ Value npm_b = pos.non_pawn_material(BLACK);
+
+ if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN))
{
- if (pos.piece_count(BLACK, PAWN) == 0)
+ if (!pos.count<PAWN>(BLACK))
{
- assert(pos.piece_count(WHITE, PAWN) >= 2);
- mi->scalingFunction[WHITE] = &ScaleKPsK;
+ assert(pos.count<PAWN>(WHITE) >= 2);
+ e->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
}
- else if (pos.piece_count(WHITE, PAWN) == 0)
+ else if (!pos.count<PAWN>(WHITE))
{
- assert(pos.piece_count(BLACK, PAWN) >= 2);
- mi->scalingFunction[BLACK] = &ScaleKKPs;
+ assert(pos.count<PAWN>(BLACK) >= 2);
+ e->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
}
- else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
+ else if (pos.count<PAWN>(WHITE) == 1 && pos.count<PAWN>(BLACK) == 1)
{
- mi->scalingFunction[WHITE] = &ScaleKPKPw;
- mi->scalingFunction[BLACK] = &ScaleKPKPb;
+ // This is a special case because we set scaling functions
+ // for both colors instead of only one.
+ e->scalingFunction[WHITE] = &ScaleKPKP[WHITE];
+ e->scalingFunction[BLACK] = &ScaleKPKP[BLACK];
}
}
- // 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);
+ // No pawns makes it difficult to win, even with a material advantage. This
+ // catches some trivial draws like KK, KBK and KNK and gives a very drawish
+ // scale factor for cases such as KRKBP and KmmKm (except for KBBKN).
+ if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
+ e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : npm_b <= BishopValueMg ? 4 : 12);
- mi->spaceWeight = minorPieceCount * minorPieceCount;
- }
+ if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
+ e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12);
- // Evaluate the material balance
+ if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
+ e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- Color c;
- int sign;
- Value egValue = Value(0);
- Value mgValue = Value(0);
+ if (pos.count<PAWN>(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
+ e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- for (c = WHITE, sign = 1; c <= BLACK; c++, sign = -sign)
+ // Compute the space weight
+ if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
{
- // 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);
+ int minorPieceCount = pos.count<KNIGHT>(WHITE) + pos.count<BISHOP>(WHITE)
+ + pos.count<KNIGHT>(BLACK) + pos.count<BISHOP>(BLACK);
- // 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;
- }
+ e->spaceWeight = make_score(minorPieceCount * minorPieceCount, 0);
}
- 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<EvaluationFunction<KPK> >("KPK");
- add<EvaluationFunction<KBNK> >("KBNK");
- add<EvaluationFunction<KRKP> >("KRKP");
- add<EvaluationFunction<KRKB> >("KRKB");
- add<EvaluationFunction<KRKN> >("KRKN");
- add<EvaluationFunction<KQKR> >("KQKR");
- add<EvaluationFunction<KBBKN> >("KBBKN");
-
- add<ScalingFunction<KNPK> >("KNPK");
- add<ScalingFunction<KRPKR> >("KRPKR");
- add<ScalingFunction<KBPKB> >("KBPKB");
- add<ScalingFunction<KBPPKB> >("KBPPKB");
- add<ScalingFunction<KBPKN> >("KBPKN");
- add<ScalingFunction<KRPPKRP> >("KRPPKRP");
- add<ScalingFunction<KRPPKRP> >("KRPPKRP");
-}
-
-EndgameFunctions::~EndgameFunctions() {
- for (std::map<Key, EF*>::iterator it = EEFmap.begin(); it != EEFmap.end(); ++it)
- delete (*it).second;
-
- for (std::map<Key, SF*>::iterator it = ESFmap.begin(); it != ESFmap.end(); ++it)
- delete (*it).second;
-}
-
-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();
+ // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder
+ // for the bishop pair "extended piece", which allows us to be more flexible
+ // in defining bishop pair bonuses.
+ const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = {
+ { pos.count<BISHOP>(WHITE) > 1, pos.count<PAWN>(WHITE), pos.count<KNIGHT>(WHITE),
+ pos.count<BISHOP>(WHITE) , pos.count<ROOK>(WHITE), pos.count<QUEEN >(WHITE) },
+ { pos.count<BISHOP>(BLACK) > 1, pos.count<PAWN>(BLACK), pos.count<KNIGHT>(BLACK),
+ pos.count<BISHOP>(BLACK) , pos.count<ROOK>(BLACK), pos.count<QUEEN >(BLACK) } };
+
+ e->value = (int16_t)((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
+ return e;
}
-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<class T>
-void EndgameFunctions::add(const string& keyCode) {
-
- typedef typename T::Base F;
-
- map<F>().insert(std::pair<Key, F*>(buildKey(keyCode), new T(WHITE)));
- map<F>().insert(std::pair<Key, F*>(buildKey(swapColors(keyCode)), new T(BLACK)));
-}
-
-template<class T>
-T* EndgameFunctions::get(Key key) const {
-
- std::map<Key, T*>::const_iterator it(map<T>().find(key));
- return (it != map<T>().end() ? it->second : NULL);
-}
+} // namespace Material