+++ /dev/null
-/*
- Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
-
- 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 <cassert>
-#include <cstring> // For std::memset
-
-#include "material.h"
-#include "thread.h"
-
-using namespace std;
-
-namespace Stockfish {
-
-namespace {
- #define S(mg, eg) make_score(mg, eg)
-
- // Polynomial material imbalance parameters
-
- // One Score parameter for each pair (our piece, another of our pieces)
- constexpr Score QuadraticOurs[][PIECE_TYPE_NB] = {
- // OUR PIECE 2
- // bishop pair pawn knight bishop rook queen
- {S(1419, 1455) }, // Bishop pair
- {S( 101, 28), S( 37, 39) }, // Pawn
- {S( 57, 64), S(249, 187), S(-49, -62) }, // Knight OUR PIECE 1
- {S( 0, 0), S(118, 137), S( 10, 27), S( 0, 0) }, // Bishop
- {S( -63, -68), S( -5, 3), S(100, 81), S(132, 118), S(-246, -244) }, // Rook
- {S(-210, -211), S( 37, 14), S(147, 141), S(161, 105), S(-158, -174), S(-9,-31) } // Queen
- };
-
- // One Score parameter for each pair (our piece, their piece)
- constexpr Score QuadraticTheirs[][PIECE_TYPE_NB] = {
- // THEIR PIECE
- // bishop pair pawn knight bishop rook queen
- { }, // Bishop pair
- {S( 33, 30) }, // Pawn
- {S( 46, 18), S(106, 84) }, // Knight OUR PIECE
- {S( 75, 35), S( 59, 44), S( 60, 15) }, // Bishop
- {S( 26, 35), S( 6, 22), S( 38, 39), S(-12, -2) }, // Rook
- {S( 97, 93), S(100, 163), S(-58, -91), S(112, 192), S(276, 225) } // Queen
- };
-
- #undef S
-
- // 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 used to detect a given material distribution
- bool is_KXK(const Position& pos, Color us) {
- return !more_than_one(pos.pieces(~us))
- && pos.non_pawn_material(us) >= RookValueMg;
- }
-
- bool is_KBPsK(const Position& pos, Color us) {
- return pos.non_pawn_material(us) == BishopValueMg
- && pos.count<PAWN >(us) >= 1;
- }
-
- bool is_KQKRPs(const Position& pos, Color us) {
- return !pos.count<PAWN>(us)
- && pos.non_pawn_material(us) == QueenValueMg
- && pos.count<ROOK>(~us) == 1
- && pos.count<PAWN>(~us) >= 1;
- }
-
-
- /// imbalance() calculates the imbalance by comparing the piece count of each
- /// piece type for both colors.
-
- template<Color Us>
- Score imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
-
- constexpr Color Them = ~Us;
-
- Score bonus = SCORE_ZERO;
-
- // Second-degree polynomial material imbalance, by Tord Romstad
- for (int pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1)
- {
- if (!pieceCount[Us][pt1])
- continue;
-
- int v = QuadraticOurs[pt1][pt1] * pieceCount[Us][pt1];
-
- for (int pt2 = NO_PIECE_TYPE; pt2 < pt1; ++pt2)
- v += QuadraticOurs[pt1][pt2] * pieceCount[Us][pt2]
- + QuadraticTheirs[pt1][pt2] * pieceCount[Them][pt2];
-
- bonus += pieceCount[Us][pt1] * v;
- }
-
- return bonus;
- }
-
-} // namespace
-
-namespace Material {
-
-
-/// Material::probe() looks up the current position's material configuration in
-/// the material hash table. It returns a pointer to the Entry if the position
-/// is found. Otherwise a new Entry is computed and stored there, so we don't
-/// have to recompute all when the same material configuration occurs again.
-
-Entry* probe(const Position& pos) {
-
- Key key = pos.material_key();
- Entry* e = pos.this_thread()->materialTable[key];
-
- 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;
-
- Value npm_w = pos.non_pawn_material(WHITE);
- Value npm_b = pos.non_pawn_material(BLACK);
- Value npm = std::clamp(npm_w + npm_b, EndgameLimit, MidgameLimit);
-
- // Map total non-pawn material into [PHASE_ENDGAME, PHASE_MIDGAME]
- e->gamePhase = Phase(((npm - EndgameLimit) * PHASE_MIDGAME) / (MidgameLimit - EndgameLimit));
-
- // 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 ((e->evaluationFunction = Endgames::probe<Value>(key)) != nullptr)
- return e;
-
- for (Color c : { WHITE, BLACK })
- if (is_KXK(pos, c))
- {
- e->evaluationFunction = &EvaluateKXK[c];
- return e;
- }
-
- // OK, we didn't find any special evaluation function for the current material
- // configuration. Is there a suitable specialized scaling function?
- const auto* sf = Endgames::probe<ScaleFactor>(key);
-
- if (sf)
- {
- e->scalingFunction[sf->strongSide] = sf; // Only strong color assigned
- return e;
- }
-
- // We didn't find any specialized scaling function, so fall back on generic
- // ones that refer to more than one material distribution. Note that in this
- // case we don't return after setting the function.
- for (Color c : { WHITE, BLACK })
- {
- if (is_KBPsK(pos, c))
- e->scalingFunction[c] = &ScaleKBPsK[c];
-
- else if (is_KQKRPs(pos, c))
- e->scalingFunction[c] = &ScaleKQKRPs[c];
- }
-
- if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) // Only pawns on the board
- {
- 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];
- }
- }
-
- // Zero or just one pawn makes it difficult to win, even with a small material
- // advantage. This catches some trivial draws like KK, KBK and KNK and gives a
- // 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 : 14);
-
- 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 : 14);
-
- // 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->score = (imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16;
- return e;
-}
-
-} // namespace Material
-
-} // namespace Stockfish
projects / stockfish / blobdiff