/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
- Glaurung is free software: you can redistribute it and/or modify
+ 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.
- Glaurung is distributed in the hope that it will be useful,
+ 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.
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
+#include <algorithm>
#include <cassert>
+#include <cstring>
#include "material.h"
-
-////
-//// Local definitions
-////
+using namespace std;
namespace {
- const Value BishopPairMidgameBonus = Value(100);
- const Value BishopPairEndgameBonus = Value(100);
-
- Key KPKMaterialKey, KKPMaterialKey;
- Key KBNKMaterialKey, KKBNMaterialKey;
- Key KRKPMaterialKey, KPKRMaterialKey;
- Key KRKBMaterialKey, KBKRMaterialKey;
- Key KRKNMaterialKey, KNKRMaterialKey;
- Key KQKRMaterialKey, KRKQMaterialKey;
- Key KRPKRMaterialKey, KRKRPMaterialKey;
- Key KRPPKRPMaterialKey, KRPKRPPMaterialKey;
- Key KNNKMaterialKey, KKNNMaterialKey;
- Key KBPKBMaterialKey, KBKBPMaterialKey;
- Key KBPKNMaterialKey, KNKBPMaterialKey;
- Key KNPKMaterialKey, KKNPMaterialKey;
- Key KPKPMaterialKey;
+ // Values modified by Joona Kiiski
+ const Value MidgameLimit = Value(15581);
+ const Value EndgameLimit = Value(3998);
-}
+ // Scale factors used when one side has no more pawns
+ const int NoPawnsSF[4] = { 6, 12, 32 };
+ // Polynomial material balance parameters
+ const Value RedundantQueenPenalty = Value(320);
+ const Value RedundantRookPenalty = Value(554);
-////
-//// Functions
-////
-
-/// MaterialInfo::init() is called during program initialization. It
-/// precomputes material hash keys for a few basic endgames, in order
-/// to make it easy to recognize such endgames when they occur.
-
-void MaterialInfo::init() {
- KPKMaterialKey = Position::zobMaterial[WHITE][PAWN][1];
- KKPMaterialKey = Position::zobMaterial[BLACK][PAWN][1];
- KBNKMaterialKey =
- Position::zobMaterial[WHITE][BISHOP][1] ^
- Position::zobMaterial[WHITE][KNIGHT][1];
- KKBNMaterialKey =
- Position::zobMaterial[BLACK][BISHOP][1] ^
- Position::zobMaterial[BLACK][KNIGHT][1];
- KRKPMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KPKRMaterialKey =
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][ROOK][1];
- KRKBMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[BLACK][BISHOP][1];
- KBKRMaterialKey =
- Position::zobMaterial[WHITE][BISHOP][1] ^
- Position::zobMaterial[BLACK][ROOK][1];
- KRKNMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[BLACK][KNIGHT][1];
- KNKRMaterialKey =
- Position::zobMaterial[WHITE][KNIGHT][1] ^
- Position::zobMaterial[BLACK][ROOK][1];
- KQKRMaterialKey =
- Position::zobMaterial[WHITE][QUEEN][1] ^
- Position::zobMaterial[BLACK][ROOK][1];
- KRKQMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[BLACK][QUEEN][1];
- KRPKRMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][ROOK][1];
- KRKRPMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[BLACK][ROOK][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KRPPKRPMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[WHITE][PAWN][2] ^
- Position::zobMaterial[BLACK][ROOK][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KRPKRPPMaterialKey =
- Position::zobMaterial[WHITE][ROOK][1] ^
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][ROOK][1] ^
- Position::zobMaterial[BLACK][PAWN][1] ^
- Position::zobMaterial[BLACK][PAWN][2];
- KNNKMaterialKey =
- Position::zobMaterial[WHITE][KNIGHT][1] ^
- Position::zobMaterial[WHITE][KNIGHT][2];
- KKNNMaterialKey =
- Position::zobMaterial[BLACK][KNIGHT][1] ^
- Position::zobMaterial[BLACK][KNIGHT][2];
- KBPKBMaterialKey =
- Position::zobMaterial[WHITE][BISHOP][1] ^
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][BISHOP][1];
- KBKBPMaterialKey =
- Position::zobMaterial[WHITE][BISHOP][1] ^
- Position::zobMaterial[BLACK][BISHOP][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KBPKNMaterialKey =
- Position::zobMaterial[WHITE][BISHOP][1] ^
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][KNIGHT][1];
- KNKBPMaterialKey =
- Position::zobMaterial[WHITE][KNIGHT][1] ^
- Position::zobMaterial[BLACK][BISHOP][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KNPKMaterialKey =
- Position::zobMaterial[WHITE][KNIGHT][1] ^
- Position::zobMaterial[WHITE][PAWN][1];
- KKNPMaterialKey =
- Position::zobMaterial[BLACK][KNIGHT][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
- KPKPMaterialKey =
- Position::zobMaterial[WHITE][PAWN][1] ^
- Position::zobMaterial[BLACK][PAWN][1];
-}
+ const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
+ const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
+ { 7, 7, 7, 7, 7, 7 }, { 39, 2, 7, 7, 7, 7 }, { 35, 271, -4, 7, 7, 7 },
+ { 7, 25, 4, 7, 7, 7 }, { -27, -2, 46, 100, 56, 7 }, { 58, 29, 83, 148, -3, -25 } };
-/// Constructor for the MaterialInfoTable class.
+ const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = {
+ { 41, 41, 41, 41, 41, 41 }, { 37, 41, 41, 41, 41, 41 }, { 10, 62, 41, 41, 41, 41 },
+ { 57, 64, 39, 41, 41, 41 }, { 50, 40, 23, -22, 41, 41 }, { 106, 101, 3, 151, 171, 41 } };
-MaterialInfoTable::MaterialInfoTable(unsigned numOfEntries) {
- size = numOfEntries;
- entries = new MaterialInfo[size];
- if(entries == NULL) {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(MaterialInfo))
- << " bytes for material hash table." << std::endl;
- exit(EXIT_FAILURE);
- }
- this->clear();
-}
+ // Endgame evaluation and scaling functions accessed direcly and not through
+ // the function maps because correspond to more then one material hash key.
+ Endgame<KmmKm> EvaluateKmmKm[] = { Endgame<KmmKm>(WHITE), Endgame<KmmKm>(BLACK) };
+ 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) };
-/// Destructor for the MaterialInfoTable class.
+ // 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 pos.non_pawn_material(Them) == VALUE_ZERO
+ && pos.piece_count(Them, PAWN) == 0
+ && pos.non_pawn_material(Us) >= RookValueMg;
+ }
-MaterialInfoTable::~MaterialInfoTable() {
- delete [] entries;
-}
+ template<Color Us> bool is_KBPsKs(const Position& pos) {
+ return pos.non_pawn_material(Us) == BishopValueMg
+ && pos.piece_count(Us, BISHOP) == 1
+ && pos.piece_count(Us, PAWN) >= 1;
+ }
+ template<Color Us> bool is_KQKRPs(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return pos.piece_count(Us, PAWN) == 0
+ && pos.non_pawn_material(Us) == QueenValueMg
+ && pos.piece_count(Us, QUEEN) == 1
+ && pos.piece_count(Them, ROOK) == 1
+ && pos.piece_count(Them, PAWN) >= 1;
+ }
-/// MaterialInfoTable::clear() clears a material hash table by setting
-/// all entries to 0.
+} // namespace
-void MaterialInfoTable::clear() {
- memset(entries, 0, size * sizeof(MaterialInfo));
-}
+/// MaterialTable::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.
-/// 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.
+MaterialEntry* MaterialTable::probe(const Position& pos) {
-MaterialInfo *MaterialInfoTable::get_material_info(const Position &pos) {
- Key key = pos.get_material_key();
- int index = key & (size - 1);
- MaterialInfo *mi = entries + index;
+ Key key = pos.material_key();
+ MaterialEntry* 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;
-
- // 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;
- }
+ // return the information we found the last time instead of recomputing it.
+ if (e->key == key)
+ return e;
+
+ memset(e, 0, sizeof(MaterialEntry));
+ e->key = key;
+ e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
+ e->gamePhase = MaterialTable::game_phase(pos);
// Let's look if we have a specialized evaluation function for this
- // particular material configuration:
- if(key == KPKMaterialKey) {
- mi->evaluationFunction = &EvaluateKPK;
- return mi;
- }
- else if(key == KKPMaterialKey) {
- mi->evaluationFunction = &EvaluateKKP;
- return mi;
- }
- else if(key == KBNKMaterialKey) {
- mi->evaluationFunction = &EvaluateKBNK;
- return mi;
+ // particular material configuration. First we look for a fixed
+ // configuration one, then a generic one if previous search failed.
+ if (endgames.probe(key, e->evaluationFunction))
+ return e;
+
+ if (is_KXK<WHITE>(pos))
+ {
+ e->evaluationFunction = &EvaluateKXK[WHITE];
+ return e;
}
- else if(key == KKBNMaterialKey) {
- mi->evaluationFunction = &EvaluateKKBN;
- return mi;
- }
- else if(key == KRKPMaterialKey) {
- mi->evaluationFunction = &EvaluateKRKP;
- return mi;
- }
- else if(key == KPKRMaterialKey) {
- mi->evaluationFunction = &EvaluateKPKR;
- return mi;
- }
- else if(key == KRKBMaterialKey) {
- mi->evaluationFunction = &EvaluateKRKB;
- return mi;
- }
- else if(key == KBKRMaterialKey) {
- mi->evaluationFunction = &EvaluateKBKR;
- return mi;
- }
- else if(key == KRKNMaterialKey) {
- mi->evaluationFunction = &EvaluateKRKN;
- return mi;
- }
- else if(key == KNKRMaterialKey) {
- mi->evaluationFunction = &EvaluateKNKR;
- return mi;
- }
- else if(key == KQKRMaterialKey) {
- mi->evaluationFunction = &EvaluateKQKR;
- return mi;
- }
- else if(key == KRKQMaterialKey) {
- mi->evaluationFunction = &EvaluateKRKQ;
- return mi;
- }
- else if(pos.non_pawn_material(BLACK) == Value(0) &&
- pos.piece_count(BLACK, PAWN) == 0 &&
- pos.non_pawn_material(WHITE) >= RookValueEndgame) {
- mi->evaluationFunction = &EvaluateKXK;
- return mi;
+
+ if (is_KXK<BLACK>(pos))
+ {
+ e->evaluationFunction = &EvaluateKXK[BLACK];
+ return e;
}
- else if(pos.non_pawn_material(WHITE) == Value(0) &&
- pos.piece_count(WHITE, PAWN) == 0 &&
- pos.non_pawn_material(BLACK) >= RookValueEndgame) {
- mi->evaluationFunction = &EvaluateKKX;
- return mi;
+
+ if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
+ {
+ // Minor piece endgame with at least one minor piece per side and
+ // no pawns. Note that the case KmmK is already handled by KXK.
+ assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
+ assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
+
+ if ( pos.piece_count(WHITE, BISHOP) + pos.piece_count(WHITE, KNIGHT) <= 2
+ && pos.piece_count(BLACK, BISHOP) + pos.piece_count(BLACK, KNIGHT) <= 2)
+ {
+ e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
+ return e;
+ }
}
// OK, we didn't find any special evaluation function for the current
- // material configuration. Is there a suitable scaling function?
+ // 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.
-
- if(key == KRPKRMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKRPKR;
- return mi;
- }
- if(key == KRKRPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKRKRP;
- return mi;
- }
- if(key == KRPPKRPMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKRPPKRP;
- return mi;
- }
- else if(key == KRPKRPPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKRPKRPP;
- return mi;
+ // We face problems when there are several conflicting applicable
+ // scaling functions and we need to decide which one to use.
+ EndgameBase<ScaleFactor>* sf;
+
+ if (endgames.probe(key, sf))
+ {
+ e->scalingFunction[sf->color()] = sf;
+ return e;
}
- if(key == KBPKBMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKBPKB;
- return mi;
- }
- if(key == KBKBPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKBKBP;
- return mi;
- }
- if(key == KBPKNMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKBPKN;
- return mi;
- }
- if(key == KNKBPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKNKBP;
- return mi;
+
+ // Generic scaling functions that refer to more then one material
+ // distribution. 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)
+ {
+ if (pos.piece_count(BLACK, PAWN) == 0)
+ {
+ assert(pos.piece_count(WHITE, PAWN) >= 2);
+ e->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
+ }
+ else if (pos.piece_count(WHITE, PAWN) == 0)
+ {
+ assert(pos.piece_count(BLACK, PAWN) >= 2);
+ e->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
+ }
+ else if (pos.piece_count(WHITE, PAWN) == 1 && pos.piece_count(BLACK, PAWN) == 1)
+ {
+ // 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];
+ }
}
- if(key == KNPKMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKNPK;
- return mi;
+
+ // No pawns makes it difficult to win, even with a material advantage
+ if (pos.piece_count(WHITE, PAWN) == 0 && npm_w - npm_b <= BishopValueMg)
+ {
+ e->factor[WHITE] = (uint8_t)
+ (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.piece_count(WHITE, BISHOP), 2)]);
}
- if(key == KKNPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKKNP;
- return mi;
+
+ if (pos.piece_count(BLACK, PAWN) == 0 && npm_b - npm_w <= BishopValueMg)
+ {
+ e->factor[BLACK] = (uint8_t)
+ (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.piece_count(BLACK, BISHOP), 2)]);
}
- 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 (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
+ {
+ int minorPieceCount = pos.piece_count(WHITE, KNIGHT) + pos.piece_count(WHITE, BISHOP)
+ + pos.piece_count(BLACK, KNIGHT) + pos.piece_count(BLACK, BISHOP);
+
+ e->spaceWeight = minorPieceCount * minorPieceCount;
}
- // Evaluate the material balance.
-
- Color c;
- int sign;
- Value egValue = Value(0), 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)))
- mi->factor[c] = 0;
- else if(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;
- }
+ // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder
+ // for the bishop pair "extended piece", this allow us to be more flexible
+ // in defining bishop pair bonuses.
+ const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = {
+ { pos.piece_count(WHITE, BISHOP) > 1, pos.piece_count(WHITE, PAWN), pos.piece_count(WHITE, KNIGHT),
+ pos.piece_count(WHITE, BISHOP) , pos.piece_count(WHITE, ROOK), pos.piece_count(WHITE, QUEEN) },
+ { pos.piece_count(BLACK, BISHOP) > 1, pos.piece_count(BLACK, PAWN), pos.piece_count(BLACK, KNIGHT),
+ pos.piece_count(BLACK, BISHOP) , pos.piece_count(BLACK, ROOK), pos.piece_count(BLACK, QUEEN) } };
+
+ e->value = (int16_t)((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
+ return e;
+}
+
+
+/// MaterialTable::imbalance() calculates imbalance comparing piece count of each
+/// piece type for both colors.
+
+template<Color Us>
+int MaterialTable::imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
+ int pt1, pt2, pc, v;
+ int value = 0;
+
+ // Redundancy of major pieces, formula based on Kaufman's paper
+ // "The Evaluation of Material Imbalances in Chess"
+ if (pieceCount[Us][ROOK] > 0)
+ value -= RedundantRookPenalty * (pieceCount[Us][ROOK] - 1)
+ + RedundantQueenPenalty * pieceCount[Us][QUEEN];
+ // Second-degree polynomial material imbalance by Tord Romstad
+ for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++)
+ {
+ pc = pieceCount[Us][pt1];
+ if (!pc)
+ continue;
+
+ v = LinearCoefficients[pt1];
+
+ for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++)
+ v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2];
+
+ value += pc * v;
}
+ return value;
+}
+
+
+/// MaterialTable::game_phase() calculates the phase given the current
+/// position. Because the phase is strictly a function of the material, it
+/// is stored in MaterialEntry.
+
+Phase MaterialTable::game_phase(const Position& pos) {
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
+ Value npm = pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK);
- return mi;
+ return npm >= MidgameLimit ? PHASE_MIDGAME
+ : npm <= EndgameLimit ? PHASE_ENDGAME
+ : Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
}
projects / stockfish / blobdiff