+++ /dev/null
-/*
- 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
-
- 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/>.
-*/
-
-#include <algorithm> // For std::min
-#include <cassert>
-#include <cstring>
-
-#include "material.h"
-
-using namespace std;
-
-namespace {
-
- // 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
-
- // pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -52 };
-
- 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
- { 58, 29, 83, 148, -163, 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
- { 106, 101, 3, 151, 171, 0 } // Queen
- };
-
- // Endgame evaluation and scaling functions are accessed directly and not through
- // the function maps because they 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) };
-
- // 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.count<PAWN>(Them)
- && pos.non_pawn_material(Them) == VALUE_ZERO
- && pos.non_pawn_material(Us) >= RookValueMg;
- }
-
- 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;
- }
-
- 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;
- }
-
- /// imbalance() calculates the imbalance by comparing the piece count of each
- /// piece type for both colors.
-
- template<Color Us>
- int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
-
- const Color Them = (Us == WHITE ? BLACK : WHITE);
-
- 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;
-
- 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;
- }
-
-} // 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.
-
-Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
-
- Key key = pos.material_key();
- Entry* e = entries[key];
-
- // 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 (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<WHITE>(pos))
- {
- e->evaluationFunction = &EvaluateKXK[WHITE];
- return e;
- }
-
- if (is_KXK<BLACK>(pos))
- {
- e->evaluationFunction = &EvaluateKXK[BLACK];
- return e;
- }
-
- 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.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE) <= 2
- && pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK) <= 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?
- //
- // 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;
- }
-
- // Generic scaling functions that refer to more then 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)
- {
- if (!pos.count<PAWN>(BLACK))
- {
- assert(pos.count<PAWN>(WHITE) >= 2);
- e->scalingFunction[WHITE] = &ScaleKPsK[WHITE];
- }
- else if (!pos.count<PAWN>(WHITE))
- {
- assert(pos.count<PAWN>(BLACK) >= 2);
- e->scalingFunction[BLACK] = &ScaleKPsK[BLACK];
- }
- else if (pos.count<PAWN>(WHITE) == 1 && pos.count<PAWN>(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];
- }
- }
-
- // No pawns makes it difficult to win, even with a material advantage. This
- // catches some trivial draws like KK, KBK and KNK
- if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
- {
- e->factor[WHITE] = (uint8_t)
- (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(WHITE), 2)]);
- }
-
- if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
- {
- e->factor[BLACK] = (uint8_t)
- (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
- }
-
- if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
- {
- e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
- }
-
- if (pos.count<PAWN>(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<KNIGHT>(WHITE) + pos.count<BISHOP>(WHITE)
- + pos.count<KNIGHT>(BLACK) + pos.count<BISHOP>(BLACK);
-
- e->spaceWeight = make_score(minorPieceCount * minorPieceCount, 0);
- }
-
- // 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;
-}
-
-
-/// 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.
-
-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
projects / stockfish / blobdiff