X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=40afe2b52255b215515b89478cda6557c426f33c;hp=63033d80ee5a86a74025c5578ea49325f466bdfe;hb=a89b26bedd7e07f23c8292dcdccbd527c68d56f4;hpb=7dd0c39714cbb6829d7cbf9da36fa46995e7a61e
diff --git a/src/material.cpp b/src/material.cpp
index 63033d80..2f6af13f 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -1,13 +1,14 @@
/*
- 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) 2008-2014 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.
@@ -16,391 +17,252 @@
along with this program. If not, see .
*/
-
-////
-//// Includes
-////
-
+#include // For std::min
#include
+#include
#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);
+
+ // Polynomial material balance parameters
+
+ // pair pawn knight bishop rook queen
+ const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -154 };
+
+ const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
+ // pair pawn knight bishop rook queen
+ { 0 }, // Bishop pair
+ { 39, 2 }, // Pawn
+ { 35, 271, -4 }, // Knight
+ { 0, 105, 4, 0 }, // Bishop
+ { -27, -2, 46, 100, -141 }, // Rook
+ {-177, 25, 129, 142, -137, 0 } // Queen
+ };
+
+ const int QuadraticCoefficientsOppositeColor[][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 EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) };
+
+ Endgame ScaleKBPsK[] = { Endgame(WHITE), Endgame(BLACK) };
+ Endgame ScaleKQKRPs[] = { Endgame(WHITE), Endgame(BLACK) };
+ Endgame ScaleKPsK[] = { Endgame(WHITE), Endgame(BLACK) };
+ Endgame ScaleKPKP[] = { Endgame(WHITE), Endgame(BLACK) };
+
+ // Helper templates used to detect a given material distribution
+ template bool is_KXK(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return !pos.count(Them)
+ && pos.non_pawn_material(Them) == VALUE_ZERO
+ && pos.non_pawn_material(Us) >= RookValueMg;
+ }
-}
+ template bool is_KBPsKs(const Position& pos) {
+ return pos.non_pawn_material(Us) == BishopValueMg
+ && pos.count(Us) == 1
+ && pos.count(Us) >= 1;
+ }
+ template bool is_KQKRPs(const Position& pos) {
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ return !pos.count(Us)
+ && pos.non_pawn_material(Us) == QueenValueMg
+ && pos.count(Us) == 1
+ && pos.count(Them) == 1
+ && pos.count(Them) >= 1;
+ }
-////
-//// 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];
-}
+ /// imbalance() calculates the imbalance by comparing the piece count of each
+ /// piece type for both colors.
+ template
+ int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
-/// Constructor for the MaterialInfoTable class.
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
-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();
-}
+ int pt1, pt2, pc, v;
+ int value = 0;
+ // Second-degree polynomial material imbalance by Tord Romstad
+ for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
+ {
+ pc = pieceCount[Us][pt1];
+ if (!pc)
+ continue;
-/// Destructor for the MaterialInfoTable class.
+ v = LinearCoefficients[pt1];
-MaterialInfoTable::~MaterialInfoTable() {
- delete [] entries;
-}
+ for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2)
+ v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2]
+ + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2];
+ value += pc * v;
+ }
-/// MaterialInfoTable::clear() clears a material hash table by setting
-/// all entries to 0.
+ return value;
+ }
-void MaterialInfoTable::clear() {
- memset(entries, 0, size * sizeof(MaterialInfo));
-}
+} // namespace
+
+namespace Material {
+/// 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.
-/// 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.
+Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
-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();
+ 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;
-
- // 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;
+
+ std::memset(e, 0, sizeof(Entry));
+ e->key = key;
+ e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
+ e->gamePhase = game_phase(pos);
+
+ // 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;
+
+ if (is_KXK(pos))
+ {
+ e->evaluationFunction = &EvaluateKXK[WHITE];
+ return e;
}
- // 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;
- }
- 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.pawn_count(BLACK) == 0 &&
- pos.non_pawn_material(WHITE) >= RookValueEndgame) {
- mi->evaluationFunction = &EvaluateKXK;
- return mi;
- }
- else if(pos.non_pawn_material(WHITE) == Value(0) &&
- pos.pawn_count(WHITE) == 0 &&
- pos.non_pawn_material(BLACK) >= RookValueEndgame) {
- mi->evaluationFunction = &EvaluateKKX;
- return mi;
+ if (is_KXK(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?
+ // 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;
- }
- 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;
- }
- if(key == KNPKMaterialKey) {
- mi->scalingFunction[WHITE] = &ScaleKNPK;
- return mi;
- }
- if(key == KKNPMaterialKey) {
- mi->scalingFunction[BLACK] = &ScaleKKNP;
- return mi;
+ // We face problems when there are several conflicting applicable
+ // scaling functions and we need to decide which one to use.
+ EndgameBase* sf;
+
+ if (endgames.probe(key, sf))
+ {
+ e->scalingFunction[sf->color()] = sf;
+ return e;
}
- if(pos.non_pawn_material(WHITE) == BishopValueMidgame &&
- pos.bishop_count(WHITE) == 1 && pos.pawn_count(WHITE) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKBPK;
- if(pos.non_pawn_material(BLACK) == BishopValueMidgame &&
- pos.bishop_count(BLACK) == 1 && pos.pawn_count(BLACK) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKKBP;
-
- if(pos.pawn_count(WHITE) == 0 &&
- pos.non_pawn_material(WHITE) == QueenValueMidgame &&
- pos.queen_count(WHITE) == 1 &&
- pos.rook_count(BLACK) == 1 && pos.pawn_count(BLACK) >= 1)
- mi->scalingFunction[WHITE] = &ScaleKQKRP;
- else if(pos.pawn_count(BLACK) == 0 &&
- pos.non_pawn_material(BLACK) == QueenValueMidgame &&
- pos.queen_count(BLACK) == 1 &&
- pos.rook_count(WHITE) == 1 && pos.pawn_count(WHITE) >= 1)
- mi->scalingFunction[BLACK] = &ScaleKRPKQ;
-
- if(pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) == Value(0)) {
- if(pos.pawn_count(BLACK) == 0) {
- assert(pos.pawn_count(WHITE) >= 2);
- mi->scalingFunction[WHITE] = &ScaleKPsK;
- }
- else if(pos.pawn_count(WHITE) == 0) {
- assert(pos.pawn_count(BLACK) >= 2);
- mi->scalingFunction[BLACK] = &ScaleKKPs;
- }
- else if(pos.pawn_count(WHITE) == 1 && pos.pawn_count(BLACK) == 1) {
- mi->scalingFunction[WHITE] = &ScaleKPKPw;
- mi->scalingFunction[BLACK] = &ScaleKPKPb;
- }
- }
+ // 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(pos))
+ e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
+
+ if (is_KBPsKs(pos))
+ e->scalingFunction[BLACK] = &ScaleKBPsK[BLACK];
+
+ if (is_KQKRPs(pos))
+ e->scalingFunction[WHITE] = &ScaleKQKRPs[WHITE];
+
+ else if (is_KQKRPs(pos))
+ e->scalingFunction[BLACK] = &ScaleKQKRPs[BLACK];
+
+ Value npm_w = pos.non_pawn_material(WHITE);
+ Value npm_b = pos.non_pawn_material(BLACK);
- // 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.pawn_count(c) == 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.bishop_count(c)) {
- case 2:
- mi->factor[c] = 32; break;
- case 1:
- mi->factor[c] = 12; break;
- case 0:
- mi->factor[c] = 6; break;
- }
+ if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN))
+ {
+ if (!pos.count(BLACK))
+ {
+ assert(pos.count(WHITE) >= 2);
+ e->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
}
- }
+ else if (!pos.count(WHITE))
+ {
+ assert(pos.count(BLACK) >= 2);
+ e->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
+ }
+ else if (pos.count(WHITE) == 1 && pos.count(BLACK) == 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];
+ }
+ }
- // Bishop pair:
- if(pos.bishop_count(c) >= 2) {
- mgValue += sign * BishopPairMidgameBonus;
- egValue += sign * BishopPairEndgameBonus;
- }
+ // 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(WHITE) && npm_w - npm_b <= BishopValueMg)
+ e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : npm_b <= BishopValueMg ? 4 : 12);
- // 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.knight_count(c)*(pos.pawn_count(c)-5)*16);
- egValue += sign * Value(pos.knight_count(c)*(pos.pawn_count(c)-5)*16);
-
- // Redundancy of major pieces, again based on Kaufman's paper:
- if(pos.rook_count(c) >= 1) {
- Value v = Value((pos.rook_count(c) - 1) * 32 + pos.queen_count(c) * 16);
- mgValue -= sign * v;
- egValue -= sign * v;
- }
+ if (!pos.count(BLACK) && npm_b - npm_w <= BishopValueMg)
+ e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12);
+
+ if (pos.count(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
+ e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
+
+ if (pos.count(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
+ e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
+ // Compute the space weight
+ if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)
+ {
+ int minorPieceCount = pos.count(WHITE) + pos.count(WHITE)
+ + pos.count(BLACK) + pos.count(BLACK);
+
+ e->spaceWeight = make_score(minorPieceCount * minorPieceCount, 0);
}
- mi->mgValue = int16_t(mgValue);
- mi->egValue = int16_t(egValue);
+ // 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(WHITE) > 1, pos.count(WHITE), pos.count(WHITE),
+ pos.count(WHITE) , pos.count(WHITE), pos.count(WHITE) },
+ { pos.count(BLACK) > 1, pos.count(BLACK), pos.count(BLACK),
+ pos.count(BLACK) , pos.count(BLACK), pos.count(BLACK) } };
+
+ e->value = (int16_t)((imbalance(pieceCount) - imbalance(pieceCount)) / 16);
+ return e;
+}
+
+
+/// Material::game_phase() calculates the phase given the current
+/// position. Because the phase is strictly a function of the material, it
+/// is stored in MaterialEntry.
- return mi;
+Phase game_phase(const Position& pos) {
+
+ Value npm = pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK);
+
+ return npm >= MidgameLimit ? PHASE_MIDGAME
+ : npm <= EndgameLimit ? PHASE_ENDGAME
+ : Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit));
}
+
+} // namespace Material