mirror of
https://github.com/sockspls/badfish
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2238 lines
67 KiB
C++
2238 lines
67 KiB
C++
/*
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Glaurung, a UCI chess playing engine.
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Copyright (C) 2004-2008 Tord Romstad
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Glaurung is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Glaurung is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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////
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//// Includes
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////
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#include <cassert>
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#include <cstdio>
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#include <iostream>
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#include <fstream>
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#include "mersenne.h"
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#include "movegen.h"
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#include "movepick.h"
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#include "position.h"
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#include "psqtab.h"
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#include "ucioption.h"
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////
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//// Variables
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////
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int Position::castleRightsMask[64];
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Key Position::zobrist[2][8][64];
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Key Position::zobEp[64];
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Key Position::zobCastle[16];
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Key Position::zobMaterial[2][8][16];
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Key Position::zobSideToMove;
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Value Position::MgPieceSquareTable[16][64];
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Value Position::EgPieceSquareTable[16][64];
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////
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//// Functions
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////
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/// Constructors
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Position::Position() { } // Do we really need this one?
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Position::Position(const Position &pos) {
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this->copy(pos);
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}
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Position::Position(const std::string &fen) {
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this->from_fen(fen);
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}
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/// Position::from_fen() initializes the position object with the given FEN
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/// string. This function is not very robust - make sure that input FENs are
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/// correct (this is assumed to be the responsibility of the GUI).
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void Position::from_fen(const std::string &fen) {
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File file;
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Rank rank;
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int i;
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this->clear();
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// Board
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rank = RANK_8;
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file = FILE_A;
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for(i = 0; fen[i] != ' '; i++) {
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if(isdigit(fen[i]))
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// Skip the given number of files
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file += (fen[i] - '1' + 1);
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else {
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Square square = make_square(file, rank);
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switch(fen[i]) {
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case 'K': this->put_piece(WK, square); file++; break;
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case 'Q': this->put_piece(WQ, square); file++; break;
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case 'R': this->put_piece(WR, square); file++; break;
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case 'B': this->put_piece(WB, square); file++; break;
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case 'N': this->put_piece(WN, square); file++; break;
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case 'P': this->put_piece(WP, square); file++; break;
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case 'k': this->put_piece(BK, square); file++; break;
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case 'q': this->put_piece(BQ, square); file++; break;
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case 'r': this->put_piece(BR, square); file++; break;
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case 'b': this->put_piece(BB, square); file++; break;
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case 'n': this->put_piece(BN, square); file++; break;
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case 'p': this->put_piece(BP, square); file++; break;
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case '/': file = FILE_A; rank--; break;
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case ' ': break;
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default:
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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}
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}
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// Side to move
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i++;
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if(fen[i] == 'w')
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sideToMove = WHITE;
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else if(fen[i] == 'b')
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sideToMove = BLACK;
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else {
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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// Castling rights:
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i++;
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if(fen[i] != ' ') {
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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i++;
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while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) {
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if(fen[i] == '-') {
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i++; break;
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}
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else if(fen[i] == 'K') this->allow_oo(WHITE);
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else if(fen[i] == 'Q') this->allow_ooo(WHITE);
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else if(fen[i] == 'k') this->allow_oo(BLACK);
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else if(fen[i] == 'q') this->allow_ooo(BLACK);
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else if(fen[i] >= 'A' && fen[i] <= 'H') {
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File rookFile, kingFile = FILE_NONE;
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for(Square square = SQ_B1; square <= SQ_G1; square++)
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if(this->piece_on(square) == WK)
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kingFile = square_file(square);
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if(kingFile == FILE_NONE) {
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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initialKFile = kingFile;
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rookFile = File(fen[i] - 'A') + FILE_A;
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if(rookFile < initialKFile) {
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this->allow_ooo(WHITE);
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initialQRFile = rookFile;
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}
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else {
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this->allow_oo(WHITE);
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initialKRFile = rookFile;
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}
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}
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else if(fen[i] >= 'a' && fen[i] <= 'h') {
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File rookFile, kingFile = FILE_NONE;
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for(Square square = SQ_B8; square <= SQ_G8; square++)
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if(this->piece_on(square) == BK)
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kingFile = square_file(square);
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if(kingFile == FILE_NONE) {
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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initialKFile = kingFile;
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rookFile = File(fen[i] - 'a') + FILE_A;
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if(rookFile < initialKFile) {
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this->allow_ooo(BLACK);
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initialQRFile = rookFile;
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}
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else {
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this->allow_oo(BLACK);
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initialKRFile = rookFile;
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}
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}
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else {
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std::cout << "Error in FEN at character " << i << std::endl;
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return;
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}
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i++;
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}
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while(fen[i] == ' ')
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i++;
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// En passant square
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if(i < int(fen.length()) - 2)
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if(fen[i] >= 'a' && fen[i] <= 'h' && (fen[i+1] == '3' || fen[i+1] == '6'))
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epSquare = square_from_string(fen.substr(i, 2));
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// Various initialisation
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for(Square sq = SQ_A1; sq <= SQ_H8; sq++)
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castleRightsMask[sq] = ALL_CASTLES;
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castleRightsMask[make_square(initialKFile, RANK_1)] ^=
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(WHITE_OO|WHITE_OOO);
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castleRightsMask[make_square(initialKFile, RANK_8)] ^=
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(BLACK_OO|BLACK_OOO);
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castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
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castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
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castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
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castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
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this->find_checkers();
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key = this->compute_key();
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pawnKey = this->compute_pawn_key();
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materialKey = this->compute_material_key();
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mgValue = this->compute_mg_value();
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egValue = this->compute_eg_value();
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npMaterial[WHITE] = this->compute_non_pawn_material(WHITE);
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npMaterial[BLACK] = this->compute_non_pawn_material(BLACK);
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}
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/// Position::to_fen() converts the position object to a FEN string. This is
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/// probably only useful for debugging.
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const std::string Position::to_fen() const {
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char pieceLetters[] = " PNBRQK pnbrqk";
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std::string result;
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int skip;
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for(Rank rank = RANK_8; rank >= RANK_1; rank--) {
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skip = 0;
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for(File file = FILE_A; file <= FILE_H; file++) {
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Square square = make_square(file, rank);
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if(this->square_is_occupied(square)) {
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if(skip > 0) result += (char)skip + '0';
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result += pieceLetters[this->piece_on(square)];
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skip = 0;
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}
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else skip++;
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}
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if(skip > 0) result += (char)skip + '0';
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result += (rank > RANK_1)? '/' : ' ';
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}
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result += (sideToMove == WHITE)? 'w' : 'b';
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result += ' ';
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if(castleRights == NO_CASTLES) result += '-';
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else {
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if(this->can_castle_kingside(WHITE)) result += 'K';
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if(this->can_castle_queenside(WHITE)) result += 'Q';
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if(this->can_castle_kingside(BLACK)) result += 'k';
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if(this->can_castle_queenside(BLACK)) result += 'q';
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}
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result += ' ';
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if(this->ep_square() == SQ_NONE) result += '-';
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else result += square_to_string(this->ep_square());
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return result;
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}
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/// Position::print() prints an ASCII representation of the position to
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/// the standard output.
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void Position::print() const {
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char pieceStrings[][8] =
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{"| ? ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ",
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"| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K="
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};
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for(Rank rank = RANK_8; rank >= RANK_1; rank--) {
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std::cout << "+---+---+---+---+---+---+---+---+\n";
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for(File file = FILE_A; file <= FILE_H; file++) {
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Square sq = make_square(file, rank);
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Piece piece = this->piece_on(sq);
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if(piece == EMPTY)
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std::cout << ((square_color(sq) == WHITE)? "| " : "| . ");
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else
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std::cout << pieceStrings[piece];
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}
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std::cout << "|\n";
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}
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std::cout << "+---+---+---+---+---+---+---+---+\n";
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std::cout << this->to_fen() << std::endl;
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std::cout << key << std::endl;
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}
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/// Position::copy() creates a copy of the input position.
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void Position::copy(const Position &pos) {
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memcpy(this, &pos, sizeof(Position));
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}
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/// Position:pinned_pieces() returns a bitboard of all pinned (against the
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/// king) pieces for the given color.
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Bitboard Position::pinned_pieces(Color c) const {
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Bitboard b1, b2, pinned, pinners, sliders;
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Square ksq = this->king_square(c), s;
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Color them = opposite_color(c);
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pinned = EmptyBoardBB;
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b1 = this->occupied_squares();
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sliders = this->rooks_and_queens(them) & ~this->checkers();
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if(sliders & RookPseudoAttacks[ksq]) {
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b2 = this->rook_attacks(ksq) & this->pieces_of_color(c);
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pinners = rook_attacks_bb(ksq, b1 ^ b2) & sliders;
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while(pinners) {
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s = pop_1st_bit(&pinners);
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pinned |= (squares_between(s, ksq) & b2);
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}
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}
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sliders = this->bishops_and_queens(them) & ~this->checkers();
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if(sliders & BishopPseudoAttacks[ksq]) {
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b2 = this->bishop_attacks(ksq) & this->pieces_of_color(c);
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pinners = bishop_attacks_bb(ksq, b1 ^ b2) & sliders;
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while(pinners) {
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s = pop_1st_bit(&pinners);
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pinned |= (squares_between(s, ksq) & b2);
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}
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}
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return pinned;
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}
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/// Position:discovered_check_candidates() returns a bitboard containing all
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/// pieces for the given side which are candidates for giving a discovered
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/// check. The code is almost the same as the function for finding pinned
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/// pieces.
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Bitboard Position::discovered_check_candidates(Color c) const {
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Bitboard b1, b2, dc, checkers, sliders;
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Square ksq = this->king_square(opposite_color(c)), s;
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dc = EmptyBoardBB;
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b1 = this->occupied_squares();
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sliders = this->rooks_and_queens(c);
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if(sliders & RookPseudoAttacks[ksq]) {
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b2 = this->rook_attacks(ksq) & this->pieces_of_color(c);
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checkers = rook_attacks_bb(ksq, b1 ^ b2) & sliders;
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while(checkers) {
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s = pop_1st_bit(&checkers);
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dc |= (squares_between(s, ksq) & b2);
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}
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}
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sliders = this->bishops_and_queens(c);
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if(sliders & BishopPseudoAttacks[ksq]) {
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b2 = this->bishop_attacks(ksq) & this->pieces_of_color(c);
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checkers = bishop_attacks_bb(ksq, b1 ^ b2) & sliders;
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while(checkers) {
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s = pop_1st_bit(&checkers);
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dc |= (squares_between(s, ksq) & b2);
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}
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}
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return dc;
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}
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/// Position::square_is_attacked() checks whether the given side attacks the
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/// given square.
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bool Position::square_is_attacked(Square s, Color c) const {
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return
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(this->pawn_attacks(opposite_color(c), s) & this->pawns(c)) ||
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(this->knight_attacks(s) & this->knights(c)) ||
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(this->king_attacks(s) & this->kings(c)) ||
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(this->rook_attacks(s) & this->rooks_and_queens(c)) ||
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(this->bishop_attacks(s) & this->bishops_and_queens(c));
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}
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/// Position::attacks_to() computes a bitboard containing all pieces which
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/// attacks a given square. There are two versions of this function: One
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/// which finds attackers of both colors, and one which only finds the
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/// attackers for one side.
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Bitboard Position::attacks_to(Square s) const {
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return
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(this->black_pawn_attacks(s) & this->pawns(WHITE)) |
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(this->white_pawn_attacks(s) & this->pawns(BLACK)) |
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(this->knight_attacks(s) & this->pieces_of_type(KNIGHT)) |
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(this->rook_attacks(s) & this->rooks_and_queens()) |
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(this->bishop_attacks(s) & this->bishops_and_queens()) |
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(this->king_attacks(s) & this->pieces_of_type(KING));
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}
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Bitboard Position::attacks_to(Square s, Color c) const {
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return this->attacks_to(s) & this->pieces_of_color(c);
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}
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/// Position::piece_attacks_square() tests whether the piece on square f
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/// attacks square t.
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bool Position::piece_attacks_square(Square f, Square t) const {
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assert(square_is_ok(f));
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assert(square_is_ok(t));
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switch(this->piece_on(f)) {
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case WP: return this->white_pawn_attacks_square(f, t);
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case BP: return this->black_pawn_attacks_square(f, t);
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case WN: case BN: return this->knight_attacks_square(f, t);
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case WB: case BB: return this->bishop_attacks_square(f, t);
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case WR: case BR: return this->rook_attacks_square(f, t);
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case WQ: case BQ: return this->queen_attacks_square(f, t);
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case WK: case BK: return this->king_attacks_square(f, t);
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default: return false;
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}
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return false;
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}
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/// Position::find_checkers() computes the checkersBB bitboard, which
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/// contains a nonzero bit for each checking piece (0, 1 or 2). It
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/// currently works by calling Position::attacks_to, which is probably
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/// inefficient. Consider rewriting this function to use the last move
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/// played, like in non-bitboard versions of Glaurung.
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void Position::find_checkers() {
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checkersBB = attacks_to(this->king_square(this->side_to_move()),
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opposite_color(this->side_to_move()));
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}
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/// Position::move_is_legal() tests whether a pseudo-legal move is legal.
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/// There are two versions of this function: One which takes only a
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/// move as input, and one which takes a move and a bitboard of pinned
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/// pieces. The latter function is faster, and should always be preferred
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/// when a pinned piece bitboard has already been computed.
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bool Position::move_is_legal(Move m) const {
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return this->move_is_legal(m, this->pinned_pieces(this->side_to_move()));
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}
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bool Position::move_is_legal(Move m, Bitboard pinned) const {
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Color us, them;
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Square ksq, from;
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assert(this->is_ok());
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assert(move_is_ok(m));
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assert(pinned == this->pinned_pieces(this->side_to_move()));
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// If we're in check, all pseudo-legal moves are legal, because our
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// check evasion generator only generates true legal moves.
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if(this->is_check()) return true;
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// Castling moves are checked for legality during move generation.
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if(move_is_castle(m)) return true;
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us = this->side_to_move();
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them = opposite_color(us);
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from = move_from(m);
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ksq = this->king_square(us);
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assert(this->color_of_piece_on(from) == us);
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assert(this->piece_on(ksq) == king_of_color(us));
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// En passant captures are a tricky special case. Because they are
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// rather uncommon, we do it simply by testing whether the king is attacked
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// after the move is made:
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if(move_is_ep(m)) {
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Square to = move_to(m);
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Square capsq = make_square(square_file(to), square_rank(from));
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Bitboard b = this->occupied_squares();
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assert(to == this->ep_square());
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assert(this->piece_on(from) == pawn_of_color(us));
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assert(this->piece_on(capsq) == pawn_of_color(them));
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assert(this->piece_on(to) == EMPTY);
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clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to);
|
|
return
|
|
(!(rook_attacks_bb(ksq, b) & this->rooks_and_queens(them)) &&
|
|
!(bishop_attacks_bb(ksq, b) & this->bishops_and_queens(them)));
|
|
}
|
|
|
|
// If the moving piece is a king, check whether the destination
|
|
// square is attacked by the opponent.
|
|
if(from == ksq) return !(this->square_is_attacked(move_to(m), them));
|
|
|
|
// A non-king move is legal if and only if it is not pinned or it
|
|
// is moving along the ray towards or away from the king.
|
|
if(!bit_is_set(pinned, from)) return true;
|
|
if(direction_between_squares(from, ksq) ==
|
|
direction_between_squares(move_to(m), ksq))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/// Position::move_is_check() tests whether a pseudo-legal move is a check.
|
|
/// There are two versions of this function: One which takes only a move as
|
|
/// input, and one which takes a move and a bitboard of discovered check
|
|
/// candidates. The latter function is faster, and should always be preferred
|
|
/// when a discovered check candidates bitboard has already been computed.
|
|
|
|
bool Position::move_is_check(Move m) const {
|
|
Bitboard dc = this->discovered_check_candidates(this->side_to_move());
|
|
return this->move_is_check(m, dc);
|
|
}
|
|
|
|
|
|
bool Position::move_is_check(Move m, Bitboard dcCandidates) const {
|
|
Color us, them;
|
|
Square ksq, from, to;
|
|
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
assert(dcCandidates ==
|
|
this->discovered_check_candidates(this->side_to_move()));
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
ksq = this->king_square(them);
|
|
assert(this->color_of_piece_on(from) == us);
|
|
assert(this->piece_on(ksq) == king_of_color(them));
|
|
|
|
// Proceed according to the type of the moving piece:
|
|
switch(this->type_of_piece_on(from)) {
|
|
case PAWN:
|
|
// Normal check?
|
|
if(bit_is_set(this->pawn_attacks(them, ksq), to))
|
|
return true;
|
|
// Discovered check?
|
|
else if(bit_is_set(dcCandidates, from) &&
|
|
direction_between_squares(from, ksq) !=
|
|
direction_between_squares(to, ksq))
|
|
return true;
|
|
// Promotion with check?
|
|
else if(move_promotion(m)) {
|
|
Bitboard b = this->occupied_squares();
|
|
clear_bit(&b, from);
|
|
|
|
switch(move_promotion(m)) {
|
|
case KNIGHT:
|
|
return this->knight_attacks_square(to, ksq);
|
|
case BISHOP:
|
|
return bit_is_set(bishop_attacks_bb(to, b), ksq);
|
|
case ROOK:
|
|
return bit_is_set(rook_attacks_bb(to, b), ksq);
|
|
case QUEEN:
|
|
return bit_is_set(queen_attacks_bb(to, b), ksq);
|
|
default:
|
|
assert(false);
|
|
}
|
|
}
|
|
// En passant capture with check? We have already handled the case
|
|
// of direct checks and ordinary discovered check, the only case we
|
|
// need to handle is the unusual case of a discovered check through the
|
|
// captured pawn.
|
|
else if(move_is_ep(m)) {
|
|
Square capsq = make_square(square_file(to), square_rank(from));
|
|
Bitboard b = this->occupied_squares();
|
|
|
|
clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to);
|
|
return
|
|
((rook_attacks_bb(ksq, b) & this->rooks_and_queens(us)) ||
|
|
(bishop_attacks_bb(ksq, b) & this->bishops_and_queens(us)));
|
|
}
|
|
return false;
|
|
|
|
case KNIGHT:
|
|
// Discovered check?
|
|
if(bit_is_set(dcCandidates, from))
|
|
return true;
|
|
// Normal check?
|
|
else
|
|
return bit_is_set(this->knight_attacks(ksq), to);
|
|
|
|
case BISHOP:
|
|
// Discovered check?
|
|
if(bit_is_set(dcCandidates, from))
|
|
return true;
|
|
// Normal check?
|
|
else
|
|
return bit_is_set(this->bishop_attacks(ksq), to);
|
|
|
|
case ROOK:
|
|
// Discovered check?
|
|
if(bit_is_set(dcCandidates, from))
|
|
return true;
|
|
// Normal check?
|
|
else
|
|
return bit_is_set(this->rook_attacks(ksq), to);
|
|
|
|
case QUEEN:
|
|
// Discovered checks are impossible!
|
|
assert(!bit_is_set(dcCandidates, from));
|
|
// Normal check?
|
|
return bit_is_set(this->queen_attacks(ksq), to);
|
|
|
|
case KING:
|
|
// Discovered check?
|
|
if(bit_is_set(dcCandidates, from) &&
|
|
direction_between_squares(from, ksq) !=
|
|
direction_between_squares(to, ksq))
|
|
return true;
|
|
// Castling with check?
|
|
if(move_is_castle(m)) {
|
|
Square kfrom, kto, rfrom, rto;
|
|
Bitboard b = this->occupied_squares();
|
|
|
|
kfrom = from;
|
|
rfrom = to;
|
|
if(rfrom > kfrom) {
|
|
kto = relative_square(us, SQ_G1);
|
|
rto = relative_square(us, SQ_F1);
|
|
}
|
|
else {
|
|
kto = relative_square(us, SQ_C1);
|
|
rto = relative_square(us, SQ_D1);
|
|
}
|
|
|
|
clear_bit(&b, kfrom); clear_bit(&b, rfrom);
|
|
set_bit(&b, rto); set_bit(&b, kto);
|
|
|
|
return bit_is_set(rook_attacks_bb(rto, b), ksq);
|
|
}
|
|
|
|
return false;
|
|
|
|
default:
|
|
assert(false);
|
|
return false;
|
|
}
|
|
|
|
assert(false);
|
|
return false;
|
|
}
|
|
|
|
|
|
/// Position::move_is_capture() tests whether a move from the current
|
|
/// position is a capture.
|
|
|
|
bool Position::move_is_capture(Move m) const {
|
|
return
|
|
this->color_of_piece_on(move_to(m)) == opposite_color(this->side_to_move())
|
|
|| move_is_ep(m);
|
|
}
|
|
|
|
|
|
/// Position::move_attacks_square() tests whether a move from the current
|
|
/// position attacks a given square. Only attacks by the moving piece are
|
|
/// considered; the function does not handle X-ray attacks.
|
|
|
|
bool Position::move_attacks_square(Move m, Square s) const {
|
|
assert(move_is_ok(m));
|
|
assert(square_is_ok(s));
|
|
|
|
Square f = move_from(m), t = move_to(m);
|
|
|
|
assert(this->square_is_occupied(f));
|
|
|
|
switch(this->piece_on(f)) {
|
|
case WP: return this->white_pawn_attacks_square(t, s);
|
|
case BP: return this->black_pawn_attacks_square(t, s);
|
|
case WN: case BN: return this->knight_attacks_square(t, s);
|
|
case WB: case BB: return this->bishop_attacks_square(t, s);
|
|
case WR: case BR: return this->rook_attacks_square(t, s);
|
|
case WQ: case BQ: return this->queen_attacks_square(t, s);
|
|
case WK: case BK: return this->king_attacks_square(t, s);
|
|
default: assert(false);
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
|
|
/// Position::backup() is called when making a move. All information
|
|
/// necessary to restore the position when the move is later unmade
|
|
/// is saved to an UndoInfo object. The function Position::restore
|
|
/// does the reverse operation: When one does a backup followed by
|
|
/// a restore with the same UndoInfo object, the position is restored
|
|
/// to the state before backup was called.
|
|
|
|
void Position::backup(UndoInfo &u) const {
|
|
u.castleRights = castleRights;
|
|
u.epSquare = epSquare;
|
|
u.checkersBB = checkersBB;
|
|
u.key = key;
|
|
u.pawnKey = pawnKey;
|
|
u.materialKey = materialKey;
|
|
u.rule50 = rule50;
|
|
u.lastMove = lastMove;
|
|
u.capture = NO_PIECE_TYPE;
|
|
u.mgValue = mgValue;
|
|
u.egValue = egValue;
|
|
}
|
|
|
|
|
|
/// Position::restore() is called when unmaking a move. It copies back
|
|
/// the information backed up during a previous call to Position::backup.
|
|
|
|
void Position::restore(const UndoInfo &u) {
|
|
castleRights = u.castleRights;
|
|
epSquare = u.epSquare;
|
|
checkersBB = u.checkersBB;
|
|
key = u.key;
|
|
pawnKey = u.pawnKey;
|
|
materialKey = u.materialKey;
|
|
rule50 = u.rule50;
|
|
lastMove = u.lastMove;
|
|
mgValue = u.mgValue;
|
|
egValue = u.egValue;
|
|
}
|
|
|
|
|
|
/// Position::do_move() makes a move, and backs up all information necessary
|
|
/// to undo the move to an UndoInfo object. The move is assumed to be legal.
|
|
/// Pseudo-legal moves should be filtered out before this function is called.
|
|
/// There are two versions of this function, one which takes only the move and
|
|
/// the UndoInfo as input, and one which takes a third parameter, a bitboard of
|
|
/// discovered check candidates. The second version is faster, because knowing
|
|
/// the discovered check candidates makes it easier to update the checkersBB
|
|
/// member variable in the position object.
|
|
|
|
void Position::do_move(Move m, UndoInfo &u) {
|
|
this->do_move(m, u, this->discovered_check_candidates(this->side_to_move()));
|
|
}
|
|
|
|
void Position::do_move(Move m, UndoInfo &u, Bitboard dcCandidates) {
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
|
|
// Back up the necessary information to our UndoInfo object (except the
|
|
// captured piece, which is taken care of later:
|
|
this->backup(u);
|
|
|
|
// Save the current key to the history[] array, in order to be able to
|
|
// detect repetition draws:
|
|
history[gamePly] = key;
|
|
|
|
// Increment the 50 moves rule draw counter. Resetting it to zero in the
|
|
// case of non-reversible moves is taken care of later.
|
|
rule50++;
|
|
|
|
if(move_is_castle(m))
|
|
this->do_castle_move(m);
|
|
else if(move_promotion(m))
|
|
this->do_promotion_move(m, u);
|
|
else if(move_is_ep(m))
|
|
this->do_ep_move(m);
|
|
else {
|
|
Color us, them;
|
|
Square from, to;
|
|
PieceType piece, capture;
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
|
|
assert(this->color_of_piece_on(from) == us);
|
|
assert(this->color_of_piece_on(to) == them || this->piece_on(to) == EMPTY);
|
|
|
|
piece = this->type_of_piece_on(from);
|
|
capture = this->type_of_piece_on(to);
|
|
|
|
if(capture) {
|
|
assert(capture != KING);
|
|
|
|
// Remove captured piece:
|
|
clear_bit(&(byColorBB[them]), to);
|
|
clear_bit(&(byTypeBB[capture]), to);
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[them][capture][to];
|
|
|
|
// If the captured piece was a pawn, update pawn hash key:
|
|
if(capture == PAWN)
|
|
pawnKey ^= zobrist[them][PAWN][to];
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(them, capture, to);
|
|
egValue -= this->eg_pst(them, capture, to);
|
|
|
|
// Update material:
|
|
if(capture != PAWN)
|
|
npMaterial[them] -= piece_value_midgame(capture);
|
|
|
|
// Update material hash key:
|
|
materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][capture]--;
|
|
|
|
// Update piece list:
|
|
pieceList[them][capture][index[to]] =
|
|
pieceList[them][capture][pieceCount[them][capture]];
|
|
index[pieceList[them][capture][index[to]]] = index[to];
|
|
|
|
// Remember the captured piece, in order to be able to undo the move
|
|
// correctly:
|
|
u.capture = capture;
|
|
|
|
// Reset rule 50 counter:
|
|
rule50 = 0;
|
|
}
|
|
|
|
// Move the piece:
|
|
clear_bit(&(byColorBB[us]), from);
|
|
clear_bit(&(byTypeBB[piece]), from);
|
|
clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
|
|
set_bit(&(byColorBB[us]), to);
|
|
set_bit(&(byTypeBB[piece]), to);
|
|
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
board[to] = board[from];
|
|
board[from] = EMPTY;
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to];
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(us, piece, from);
|
|
mgValue += this->mg_pst(us, piece, to);
|
|
egValue -= this->eg_pst(us, piece, from);
|
|
egValue += this->eg_pst(us, piece, to);
|
|
|
|
// If the moving piece was a king, update the king square:
|
|
if(piece == KING)
|
|
kingSquare[us] = to;
|
|
|
|
// If the move was a double pawn push, set the en passant square.
|
|
// This code is a bit ugly right now, and should be cleaned up later.
|
|
// FIXME
|
|
if(epSquare != SQ_NONE) {
|
|
key ^= zobEp[epSquare];
|
|
epSquare = SQ_NONE;
|
|
}
|
|
if(piece == PAWN) {
|
|
if(abs(int(to) - int(from)) == 16) {
|
|
if((us == WHITE && (this->white_pawn_attacks(from + DELTA_N) &
|
|
this->pawns(BLACK))) ||
|
|
(us == BLACK && (this->black_pawn_attacks(from + DELTA_S) &
|
|
this->pawns(WHITE)))) {
|
|
epSquare = Square((int(from) + int(to)) / 2);
|
|
key ^= zobEp[epSquare];
|
|
}
|
|
}
|
|
// Reset rule 50 draw counter.
|
|
rule50 = 0;
|
|
// Update pawn hash key:
|
|
pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
|
|
}
|
|
|
|
// Update piece lists:
|
|
pieceList[us][piece][index[from]] = to;
|
|
index[to] = index[from];
|
|
|
|
// Update castle rights:
|
|
key ^= zobCastle[castleRights];
|
|
castleRights &= castleRightsMask[from];
|
|
castleRights &= castleRightsMask[to];
|
|
key ^= zobCastle[castleRights];
|
|
|
|
// Update checkers bitboard:
|
|
checkersBB = EmptyBoardBB;
|
|
Square ksq = this->king_square(them);
|
|
|
|
switch(piece) {
|
|
|
|
case PAWN:
|
|
if(bit_is_set(this->pawn_attacks(them, ksq), to))
|
|
set_bit(&checkersBB, to);
|
|
if(bit_is_set(dcCandidates, from))
|
|
checkersBB |=
|
|
((this->rook_attacks(ksq) & this->rooks_and_queens(us)) |
|
|
(this->bishop_attacks(ksq) & this->bishops_and_queens(us)));
|
|
break;
|
|
|
|
case KNIGHT:
|
|
if(bit_is_set(this->knight_attacks(ksq), to))
|
|
set_bit(&checkersBB, to);
|
|
if(bit_is_set(dcCandidates, from))
|
|
checkersBB |=
|
|
((this->rook_attacks(ksq) & this->rooks_and_queens(us)) |
|
|
(this->bishop_attacks(ksq) & this->bishops_and_queens(us)));
|
|
break;
|
|
|
|
case BISHOP:
|
|
if(bit_is_set(this->bishop_attacks(ksq), to))
|
|
set_bit(&checkersBB, to);
|
|
if(bit_is_set(dcCandidates, from))
|
|
checkersBB |=
|
|
(this->rook_attacks(ksq) & this->rooks_and_queens(us));
|
|
break;
|
|
|
|
case ROOK:
|
|
if(bit_is_set(this->rook_attacks(ksq), to))
|
|
set_bit(&checkersBB, to);
|
|
if(bit_is_set(dcCandidates, from))
|
|
checkersBB |=
|
|
(this->bishop_attacks(ksq) & this->bishops_and_queens(us));
|
|
break;
|
|
|
|
case QUEEN:
|
|
if(bit_is_set(this->queen_attacks(ksq), to))
|
|
set_bit(&checkersBB, to);
|
|
break;
|
|
|
|
case KING:
|
|
if(bit_is_set(dcCandidates, from))
|
|
checkersBB |=
|
|
((this->rook_attacks(ksq) & this->rooks_and_queens(us)) |
|
|
(this->bishop_attacks(ksq) & this->bishops_and_queens(us)));
|
|
break;
|
|
|
|
default:
|
|
assert(false);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Finish
|
|
key ^= zobSideToMove;
|
|
sideToMove = opposite_color(sideToMove);
|
|
gamePly++;
|
|
|
|
mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
|
|
egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
|
|
|
|
assert(this->is_ok());
|
|
}
|
|
|
|
|
|
/// Position::do_castle_move() is a private method used to make a castling
|
|
/// move. It is called from the main Position::do_move function. Note that
|
|
/// castling moves are encoded as "king captures friendly rook" moves, for
|
|
/// instance white short castling in a non-Chess960 game is encoded as e1h1.
|
|
|
|
void Position::do_castle_move(Move m) {
|
|
Color us, them;
|
|
Square kfrom, kto, rfrom, rto;
|
|
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
assert(move_is_castle(m));
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
// Find source squares for king and rook:
|
|
kfrom = move_from(m);
|
|
rfrom = move_to(m); // HACK: See comment at beginning of function.
|
|
|
|
assert(this->piece_on(kfrom) == king_of_color(us));
|
|
assert(this->piece_on(rfrom) == rook_of_color(us));
|
|
|
|
// Find destination squares for king and rook:
|
|
if(rfrom > kfrom) { // O-O
|
|
kto = relative_square(us, SQ_G1);
|
|
rto = relative_square(us, SQ_F1);
|
|
}
|
|
else { // O-O-O
|
|
kto = relative_square(us, SQ_C1);
|
|
rto = relative_square(us, SQ_D1);
|
|
}
|
|
|
|
// Remove pieces from source squares:
|
|
clear_bit(&(byColorBB[us]), kfrom);
|
|
clear_bit(&(byTypeBB[KING]), kfrom);
|
|
clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares
|
|
clear_bit(&(byColorBB[us]), rfrom);
|
|
clear_bit(&(byTypeBB[ROOK]), rfrom);
|
|
clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Put pieces on destination squares:
|
|
set_bit(&(byColorBB[us]), kto);
|
|
set_bit(&(byTypeBB[KING]), kto);
|
|
set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares
|
|
set_bit(&(byColorBB[us]), rto);
|
|
set_bit(&(byTypeBB[ROOK]), rto);
|
|
set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Update board array:
|
|
board[kfrom] = board[rfrom] = EMPTY;
|
|
board[kto] = king_of_color(us);
|
|
board[rto] = rook_of_color(us);
|
|
|
|
// Update king square:
|
|
kingSquare[us] = kto;
|
|
|
|
// Update piece lists:
|
|
pieceList[us][KING][index[kfrom]] = kto;
|
|
pieceList[us][ROOK][index[rfrom]] = rto;
|
|
int tmp = index[rfrom];
|
|
index[kto] = index[kfrom];
|
|
index[rto] = tmp;
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(us, KING, kfrom);
|
|
mgValue += this->mg_pst(us, KING, kto);
|
|
egValue -= this->eg_pst(us, KING, kfrom);
|
|
egValue += this->eg_pst(us, KING, kto);
|
|
mgValue -= this->mg_pst(us, ROOK, rfrom);
|
|
mgValue += this->mg_pst(us, ROOK, rto);
|
|
egValue -= this->eg_pst(us, ROOK, rfrom);
|
|
egValue += this->eg_pst(us, ROOK, rto);
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto];
|
|
key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto];
|
|
|
|
// Clear en passant square:
|
|
if(epSquare != SQ_NONE) {
|
|
key ^= zobEp[epSquare];
|
|
epSquare = SQ_NONE;
|
|
}
|
|
|
|
// Update castling rights:
|
|
key ^= zobCastle[castleRights];
|
|
castleRights &= castleRightsMask[kfrom];
|
|
key ^= zobCastle[castleRights];
|
|
|
|
// Reset rule 50 counter:
|
|
rule50 = 0;
|
|
|
|
// Update checkers BB:
|
|
checkersBB = attacks_to(this->king_square(them), us);
|
|
}
|
|
|
|
|
|
/// Position::do_promotion_move() is a private method used to make a promotion
|
|
/// move. It is called from the main Position::do_move function. The
|
|
/// UndoInfo object, which has been initialized in Position::do_move, is
|
|
/// used to store the captured piece (if any).
|
|
|
|
void Position::do_promotion_move(Move m, UndoInfo &u) {
|
|
Color us, them;
|
|
Square from, to;
|
|
PieceType capture, promotion;
|
|
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
assert(move_promotion(m));
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
|
|
assert(pawn_rank(us, to) == RANK_8);
|
|
assert(this->piece_on(from) == pawn_of_color(us));
|
|
assert(this->color_of_piece_on(to) == them || this->square_is_empty(to));
|
|
|
|
capture = this->type_of_piece_on(to);
|
|
|
|
if(capture) {
|
|
assert(capture != KING);
|
|
|
|
// Remove captured piece:
|
|
clear_bit(&(byColorBB[them]), to);
|
|
clear_bit(&(byTypeBB[capture]), to);
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[them][capture][to];
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(them, capture, to);
|
|
egValue -= this->eg_pst(them, capture, to);
|
|
|
|
// Update material. Because our move is a promotion, we know that the
|
|
// captured piece is not a pawn.
|
|
assert(capture != PAWN);
|
|
npMaterial[them] -= piece_value_midgame(capture);
|
|
|
|
// Update material hash key:
|
|
materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][capture]--;
|
|
|
|
// Update piece list:
|
|
pieceList[them][capture][index[to]] =
|
|
pieceList[them][capture][pieceCount[them][capture]];
|
|
index[pieceList[them][capture][index[to]]] = index[to];
|
|
|
|
// Remember the captured piece, in order to be able to undo the move
|
|
// correctly:
|
|
u.capture = capture;
|
|
}
|
|
|
|
// Remove pawn:
|
|
clear_bit(&(byColorBB[us]), from);
|
|
clear_bit(&(byTypeBB[PAWN]), from);
|
|
clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
|
|
board[from] = EMPTY;
|
|
|
|
// Insert promoted piece:
|
|
promotion = move_promotion(m);
|
|
assert(promotion >= KNIGHT && promotion <= QUEEN);
|
|
set_bit(&(byColorBB[us]), to);
|
|
set_bit(&(byTypeBB[promotion]), to);
|
|
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
board[to] = piece_of_color_and_type(us, promotion);
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to];
|
|
|
|
// Update pawn hash key:
|
|
pawnKey ^= zobrist[us][PAWN][from];
|
|
|
|
// Update material key:
|
|
materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]];
|
|
materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1];
|
|
|
|
// Update piece counts:
|
|
pieceCount[us][PAWN]--;
|
|
pieceCount[us][promotion]++;
|
|
|
|
// Update piece lists:
|
|
pieceList[us][PAWN][index[from]] =
|
|
pieceList[us][PAWN][pieceCount[us][PAWN]];
|
|
index[pieceList[us][PAWN][index[from]]] = index[from];
|
|
pieceList[us][promotion][pieceCount[us][promotion] - 1] = to;
|
|
index[to] = pieceCount[us][promotion] - 1;
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(us, PAWN, from);
|
|
mgValue += this->mg_pst(us, promotion, to);
|
|
egValue -= this->eg_pst(us, PAWN, from);
|
|
egValue += this->eg_pst(us, promotion, to);
|
|
|
|
// Update material:
|
|
npMaterial[us] += piece_value_midgame(promotion);
|
|
|
|
// Clear the en passant square:
|
|
if(epSquare != SQ_NONE) {
|
|
key ^= zobEp[epSquare];
|
|
epSquare = SQ_NONE;
|
|
}
|
|
|
|
// Update castle rights:
|
|
key ^= zobCastle[castleRights];
|
|
castleRights &= castleRightsMask[to];
|
|
key ^= zobCastle[castleRights];
|
|
|
|
// Reset rule 50 counter:
|
|
rule50 = 0;
|
|
|
|
// Update checkers BB:
|
|
checkersBB = attacks_to(this->king_square(them), us);
|
|
}
|
|
|
|
|
|
/// Position::do_ep_move() is a private method used to make an en passant
|
|
/// capture. It is called from the main Position::do_move function. Because
|
|
/// the captured piece is always a pawn, we don't need to pass an UndoInfo
|
|
/// object in which to store the captured piece.
|
|
|
|
void Position::do_ep_move(Move m) {
|
|
Color us, them;
|
|
Square from, to, capsq;
|
|
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
assert(move_is_ep(m));
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
// Find from, to and capture squares:
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
|
|
|
|
assert(to == epSquare);
|
|
assert(pawn_rank(us, to) == RANK_6);
|
|
assert(this->piece_on(to) == EMPTY);
|
|
assert(this->piece_on(from) == pawn_of_color(us));
|
|
assert(this->piece_on(capsq) == pawn_of_color(them));
|
|
|
|
// Remove captured piece:
|
|
clear_bit(&(byColorBB[them]), capsq);
|
|
clear_bit(&(byTypeBB[PAWN]), capsq);
|
|
clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares
|
|
board[capsq] = EMPTY;
|
|
|
|
// Remove moving piece from source square:
|
|
clear_bit(&(byColorBB[us]), from);
|
|
clear_bit(&(byTypeBB[PAWN]), from);
|
|
clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Put moving piece on destination square:
|
|
set_bit(&(byColorBB[us]), to);
|
|
set_bit(&(byTypeBB[PAWN]), to);
|
|
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
board[to] = board[from];
|
|
board[from] = EMPTY;
|
|
|
|
// Update material hash key:
|
|
materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][PAWN]--;
|
|
|
|
// Update piece list:
|
|
pieceList[us][PAWN][index[from]] = to;
|
|
index[to] = index[from];
|
|
pieceList[them][PAWN][index[capsq]] =
|
|
pieceList[them][PAWN][pieceCount[them][PAWN]];
|
|
index[pieceList[them][PAWN][index[capsq]]] = index[capsq];
|
|
|
|
// Update hash key:
|
|
key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
|
|
key ^= zobrist[them][PAWN][capsq];
|
|
key ^= zobEp[epSquare];
|
|
|
|
// Update pawn hash key:
|
|
pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to];
|
|
pawnKey ^= zobrist[them][PAWN][capsq];
|
|
|
|
// Update incremental scores:
|
|
mgValue -= this->mg_pst(them, PAWN, capsq);
|
|
mgValue -= this->mg_pst(us, PAWN, from);
|
|
mgValue += this->mg_pst(us, PAWN, to);
|
|
egValue -= this->eg_pst(them, PAWN, capsq);
|
|
egValue -= this->eg_pst(us, PAWN, from);
|
|
egValue += this->eg_pst(us, PAWN, to);
|
|
|
|
// Reset en passant square:
|
|
epSquare = SQ_NONE;
|
|
|
|
// Reset rule 50 counter:
|
|
rule50 = 0;
|
|
|
|
// Update checkers BB:
|
|
checkersBB = attacks_to(this->king_square(them), us);
|
|
}
|
|
|
|
|
|
/// Position::undo_move() unmakes a move. When it returns, the position should
|
|
/// be restored to exactly the same state as before the move was made. It is
|
|
/// important that Position::undo_move is called with the same move and UndoInfo
|
|
/// object as the earlier call to Position::do_move.
|
|
|
|
void Position::undo_move(Move m, const UndoInfo &u) {
|
|
assert(this->is_ok());
|
|
assert(move_is_ok(m));
|
|
|
|
gamePly--;
|
|
sideToMove = opposite_color(sideToMove);
|
|
|
|
// Restore information from our UndoInfo object (except the captured piece,
|
|
// which is taken care of later):
|
|
this->restore(u);
|
|
|
|
if(move_is_castle(m))
|
|
this->undo_castle_move(m);
|
|
else if(move_promotion(m))
|
|
this->undo_promotion_move(m, u);
|
|
else if(move_is_ep(m))
|
|
this->undo_ep_move(m);
|
|
else {
|
|
Color us, them;
|
|
Square from, to;
|
|
PieceType piece, capture;
|
|
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
|
|
assert(this->piece_on(from) == EMPTY);
|
|
assert(color_of_piece_on(to) == us);
|
|
|
|
// Put the piece back at the source square:
|
|
piece = this->type_of_piece_on(to);
|
|
set_bit(&(byColorBB[us]), from);
|
|
set_bit(&(byTypeBB[piece]), from);
|
|
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
|
|
board[from] = piece_of_color_and_type(us, piece);
|
|
|
|
// Clear the destination square
|
|
clear_bit(&(byColorBB[us]), to);
|
|
clear_bit(&(byTypeBB[piece]), to);
|
|
clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// If the moving piece was a king, update the king square:
|
|
if(piece == KING)
|
|
kingSquare[us] = from;
|
|
|
|
// Update piece list:
|
|
pieceList[us][piece][index[to]] = from;
|
|
index[from] = index[to];
|
|
|
|
capture = u.capture;
|
|
|
|
if(capture) {
|
|
assert(capture != KING);
|
|
// Replace the captured piece:
|
|
set_bit(&(byColorBB[them]), to);
|
|
set_bit(&(byTypeBB[capture]), to);
|
|
set_bit(&(byTypeBB[0]), to);
|
|
board[to] = piece_of_color_and_type(them, capture);
|
|
|
|
// Update material:
|
|
if(capture != PAWN)
|
|
npMaterial[them] += piece_value_midgame(capture);
|
|
|
|
// Update piece list:
|
|
pieceList[them][capture][pieceCount[them][capture]] = to;
|
|
index[to] = pieceCount[them][capture];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][capture]++;
|
|
}
|
|
else
|
|
board[to] = EMPTY;
|
|
}
|
|
|
|
assert(this->is_ok());
|
|
}
|
|
|
|
|
|
/// Position::undo_castle_move() is a private method used to unmake a castling
|
|
/// move. It is called from the main Position::undo_move function. Note that
|
|
/// castling moves are encoded as "king captures friendly rook" moves, for
|
|
/// instance white short castling in a non-Chess960 game is encoded as e1h1.
|
|
|
|
void Position::undo_castle_move(Move m) {
|
|
Color us, them;
|
|
Square kfrom, kto, rfrom, rto;
|
|
|
|
assert(move_is_ok(m));
|
|
assert(move_is_castle(m));
|
|
|
|
// When we have arrived here, some work has already been done by
|
|
// Position::undo_move. In particular, the side to move has been switched,
|
|
// so the code below is correct.
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
// Find source squares for king and rook:
|
|
kfrom = move_from(m);
|
|
rfrom = move_to(m); // HACK: See comment at beginning of function.
|
|
|
|
// Find destination squares for king and rook:
|
|
if(rfrom > kfrom) { // O-O
|
|
kto = relative_square(us, SQ_G1);
|
|
rto = relative_square(us, SQ_F1);
|
|
}
|
|
else { // O-O-O
|
|
kto = relative_square(us, SQ_C1);
|
|
rto = relative_square(us, SQ_D1);
|
|
}
|
|
|
|
assert(this->piece_on(kto) == king_of_color(us));
|
|
assert(this->piece_on(rto) == rook_of_color(us));
|
|
|
|
// Remove pieces from destination squares:
|
|
clear_bit(&(byColorBB[us]), kto);
|
|
clear_bit(&(byTypeBB[KING]), kto);
|
|
clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares
|
|
clear_bit(&(byColorBB[us]), rto);
|
|
clear_bit(&(byTypeBB[ROOK]), rto);
|
|
clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Put pieces on source squares:
|
|
set_bit(&(byColorBB[us]), kfrom);
|
|
set_bit(&(byTypeBB[KING]), kfrom);
|
|
set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares
|
|
set_bit(&(byColorBB[us]), rfrom);
|
|
set_bit(&(byTypeBB[ROOK]), rfrom);
|
|
set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Update board:
|
|
board[rto] = board[kto] = EMPTY;
|
|
board[rfrom] = rook_of_color(us);
|
|
board[kfrom] = king_of_color(us);
|
|
|
|
// Update king square:
|
|
kingSquare[us] = kfrom;
|
|
|
|
// Update piece lists:
|
|
pieceList[us][KING][index[kto]] = kfrom;
|
|
pieceList[us][ROOK][index[rto]] = rfrom;
|
|
int tmp = index[rto]; // Necessary because we may have rto == kfrom in FRC.
|
|
index[kfrom] = index[kto];
|
|
index[rfrom] = tmp;
|
|
}
|
|
|
|
|
|
/// Position::undo_promotion_move() is a private method used to unmake a
|
|
/// promotion move. It is called from the main Position::do_move
|
|
/// function. The UndoInfo object, which has been initialized in
|
|
/// Position::do_move, is used to put back the captured piece (if any).
|
|
|
|
void Position::undo_promotion_move(Move m, const UndoInfo &u) {
|
|
Color us, them;
|
|
Square from, to;
|
|
PieceType capture, promotion;
|
|
|
|
assert(move_is_ok(m));
|
|
assert(move_promotion(m));
|
|
|
|
// When we have arrived here, some work has already been done by
|
|
// Position::undo_move. In particular, the side to move has been switched,
|
|
// so the code below is correct.
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
|
|
assert(pawn_rank(us, to) == RANK_8);
|
|
assert(this->piece_on(from) == EMPTY);
|
|
|
|
// Remove promoted piece:
|
|
promotion = move_promotion(m);
|
|
assert(this->piece_on(to)==piece_of_color_and_type(us, promotion));
|
|
assert(promotion >= KNIGHT && promotion <= QUEEN);
|
|
clear_bit(&(byColorBB[us]), to);
|
|
clear_bit(&(byTypeBB[promotion]), to);
|
|
clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
|
|
// Insert pawn at source square:
|
|
set_bit(&(byColorBB[us]), from);
|
|
set_bit(&(byTypeBB[PAWN]), from);
|
|
set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares
|
|
board[from] = pawn_of_color(us);
|
|
|
|
// Update material:
|
|
npMaterial[us] -= piece_value_midgame(promotion);
|
|
|
|
// Update piece list:
|
|
pieceList[us][PAWN][pieceCount[us][PAWN]] = from;
|
|
index[from] = pieceCount[us][PAWN];
|
|
pieceList[us][promotion][index[to]] =
|
|
pieceList[us][promotion][pieceCount[us][promotion] - 1];
|
|
index[pieceList[us][promotion][index[to]]] = index[to];
|
|
|
|
// Update piece counts:
|
|
pieceCount[us][promotion]--;
|
|
pieceCount[us][PAWN]++;
|
|
|
|
capture = u.capture;
|
|
if(capture) {
|
|
assert(capture != KING);
|
|
|
|
// Insert captured piece:
|
|
set_bit(&(byColorBB[them]), to);
|
|
set_bit(&(byTypeBB[capture]), to);
|
|
set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares
|
|
board[to] = piece_of_color_and_type(them, capture);
|
|
|
|
// Update material. Because the move is a promotion move, we know
|
|
// that the captured piece cannot be a pawn.
|
|
assert(capture != PAWN);
|
|
npMaterial[them] += piece_value_midgame(capture);
|
|
|
|
// Update piece list:
|
|
pieceList[them][capture][pieceCount[them][capture]] = to;
|
|
index[to] = pieceCount[them][capture];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][capture]++;
|
|
}
|
|
else
|
|
board[to] = EMPTY;
|
|
}
|
|
|
|
|
|
/// Position::undo_ep_move() is a private method used to unmake an en passant
|
|
/// capture. It is called from the main Position::undo_move function. Because
|
|
/// the captured piece is always a pawn, we don't need to pass an UndoInfo
|
|
/// object from which to retrieve the captured piece.
|
|
|
|
void Position::undo_ep_move(Move m) {
|
|
Color us, them;
|
|
Square from, to, capsq;
|
|
|
|
assert(move_is_ok(m));
|
|
assert(move_is_ep(m));
|
|
|
|
// When we have arrived here, some work has already been done by
|
|
// Position::undo_move. In particular, the side to move has been switched,
|
|
// so the code below is correct.
|
|
us = this->side_to_move();
|
|
them = opposite_color(us);
|
|
|
|
// Find from, to and captures squares:
|
|
from = move_from(m);
|
|
to = move_to(m);
|
|
capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S);
|
|
|
|
assert(to == this->ep_square());
|
|
assert(pawn_rank(us, to) == RANK_6);
|
|
assert(this->piece_on(to) == pawn_of_color(us));
|
|
assert(this->piece_on(from) == EMPTY);
|
|
assert(this->piece_on(capsq) == EMPTY);
|
|
|
|
// Replace captured piece:
|
|
set_bit(&(byColorBB[them]), capsq);
|
|
set_bit(&(byTypeBB[PAWN]), capsq);
|
|
set_bit(&(byTypeBB[0]), capsq);
|
|
board[capsq] = pawn_of_color(them);
|
|
|
|
// Remove moving piece from destination square:
|
|
clear_bit(&(byColorBB[us]), to);
|
|
clear_bit(&(byTypeBB[PAWN]), to);
|
|
clear_bit(&(byTypeBB[0]), to);
|
|
board[to] = EMPTY;
|
|
|
|
// Replace moving piece at source square:
|
|
set_bit(&(byColorBB[us]), from);
|
|
set_bit(&(byTypeBB[PAWN]), from);
|
|
set_bit(&(byTypeBB[0]), from);
|
|
board[from] = pawn_of_color(us);
|
|
|
|
// Update piece list:
|
|
pieceList[us][PAWN][index[to]] = from;
|
|
index[from] = index[to];
|
|
pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq;
|
|
index[capsq] = pieceCount[them][PAWN];
|
|
|
|
// Update piece count:
|
|
pieceCount[them][PAWN]++;
|
|
}
|
|
|
|
|
|
/// Position::do_null_move makes() a "null move": It switches the side to move
|
|
/// and updates the hash key without executing any move on the board.
|
|
|
|
void Position::do_null_move(UndoInfo &u) {
|
|
assert(this->is_ok());
|
|
assert(!this->is_check());
|
|
|
|
// Back up the information necessary to undo the null move to the supplied
|
|
// UndoInfo object. In the case of a null move, the only thing we need to
|
|
// remember is the last move made and the en passant square.
|
|
u.lastMove = lastMove;
|
|
u.epSquare = epSquare;
|
|
|
|
// Save the current key to the history[] array, in order to be able to
|
|
// detect repetition draws:
|
|
history[gamePly] = key;
|
|
|
|
// Update the necessary information.
|
|
sideToMove = opposite_color(sideToMove);
|
|
if(epSquare != SQ_NONE)
|
|
key ^= zobEp[epSquare];
|
|
epSquare = SQ_NONE;
|
|
rule50++;
|
|
gamePly++;
|
|
key ^= zobSideToMove;
|
|
|
|
mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
|
|
egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
|
|
|
|
assert(this->is_ok());
|
|
}
|
|
|
|
|
|
/// Position::undo_null_move() unmakes a "null move".
|
|
|
|
void Position::undo_null_move(const UndoInfo &u) {
|
|
assert(this->is_ok());
|
|
assert(!this->is_check());
|
|
|
|
// Restore information from the supplied UndoInfo object:
|
|
lastMove = u.lastMove;
|
|
epSquare = u.epSquare;
|
|
if(epSquare != SQ_NONE)
|
|
key ^= zobEp[epSquare];
|
|
|
|
// Update the necessary information.
|
|
sideToMove = opposite_color(sideToMove);
|
|
rule50--;
|
|
gamePly--;
|
|
key ^= zobSideToMove;
|
|
|
|
mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame;
|
|
egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame;
|
|
|
|
assert(this->is_ok());
|
|
}
|
|
|
|
|
|
/// Position::see() is a static exchange evaluator: It tries to estimate the
|
|
/// material gain or loss resulting from a move. There are two versions of
|
|
/// this function: One which takes a move as input, and one which takes a
|
|
/// 'from' and a 'to' square. The function does not yet understand promotions
|
|
/// or en passant captures.
|
|
|
|
int Position::see(Square from, Square to) const {
|
|
// Approximate material values, with pawn = 1:
|
|
static const int seeValues[18] = {
|
|
0, 1, 3, 3, 5, 10, 100, 0, 0, 1, 3, 3, 5, 10, 100, 0, 0, 0
|
|
};
|
|
Color us, them;
|
|
Piece piece, capture;
|
|
Bitboard attackers, occ, b;
|
|
|
|
assert(square_is_ok(from));
|
|
assert(square_is_ok(to));
|
|
|
|
// Initialize colors:
|
|
us = this->color_of_piece_on(from);
|
|
them = opposite_color(us);
|
|
|
|
// Initialize pieces:
|
|
piece = this->piece_on(from);
|
|
capture = this->piece_on(to);
|
|
|
|
// Find all attackers to the destination square, with the moving piece
|
|
// removed, but possibly an X-ray attacker added behind it:
|
|
occ = this->occupied_squares();
|
|
clear_bit(&occ, from);
|
|
attackers =
|
|
(rook_attacks_bb(to, occ) & this->rooks_and_queens()) |
|
|
(bishop_attacks_bb(to, occ) & this->bishops_and_queens()) |
|
|
(this->knight_attacks(to) & this->knights()) |
|
|
(this->king_attacks(to) & this->kings()) |
|
|
(this->white_pawn_attacks(to) & this->pawns(BLACK)) |
|
|
(this->black_pawn_attacks(to) & this->pawns(WHITE));
|
|
attackers &= occ;
|
|
|
|
// If the opponent has no attackers, we are finished:
|
|
if((attackers & this->pieces_of_color(them)) == EmptyBoardBB)
|
|
return seeValues[capture];
|
|
|
|
// The destination square is defended, which makes things rather more
|
|
// difficult to compute. We proceed by building up a "swap list" containing
|
|
// the material gain or loss at each stop in a sequence of captures to the
|
|
// destianation square, where the sides alternately capture, and always
|
|
// capture with the least valuable piece. After each capture, we look for
|
|
// new X-ray attacks from behind the capturing piece.
|
|
int lastCapturingPieceValue = seeValues[piece];
|
|
int swapList[32], n = 1;
|
|
Color c = them;
|
|
PieceType pt;
|
|
|
|
swapList[0] = seeValues[capture];
|
|
|
|
do {
|
|
// Locate the least valuable attacker for the side to move. The loop
|
|
// below looks like it is potentially infinite, but it isn't. We know
|
|
// that the side to move still has at least one attacker left.
|
|
for(pt = PAWN; !(attackers&this->pieces_of_color_and_type(c, pt)); pt++)
|
|
assert(pt < KING);
|
|
|
|
// Remove the attacker we just found from the 'attackers' bitboard,
|
|
// and scan for new X-ray attacks behind the attacker:
|
|
b = attackers & this->pieces_of_color_and_type(c, pt);
|
|
occ ^= (b & -b);
|
|
attackers |=
|
|
(rook_attacks_bb(to, occ) & this->rooks_and_queens()) |
|
|
(bishop_attacks_bb(to, occ) & this->bishops_and_queens());
|
|
attackers &= occ;
|
|
|
|
// Add the new entry to the swap list:
|
|
assert(n < 32);
|
|
swapList[n] = -swapList[n - 1] + lastCapturingPieceValue;
|
|
n++;
|
|
|
|
// Remember the value of the capturing piece, and change the side to move
|
|
// before beginning the next iteration:
|
|
lastCapturingPieceValue = seeValues[pt];
|
|
c = opposite_color(c);
|
|
|
|
// Stop after a king capture:
|
|
if(pt == KING && (attackers & this->pieces_of_color(c))) {
|
|
assert(n < 32);
|
|
swapList[n++] = 100;
|
|
break;
|
|
}
|
|
} while(attackers & this->pieces_of_color(c));
|
|
|
|
// Having built the swap list, we negamax through it to find the best
|
|
// achievable score from the point of view of the side to move:
|
|
while(--n) swapList[n-1] = Min(-swapList[n], swapList[n-1]);
|
|
|
|
return swapList[0];
|
|
}
|
|
|
|
|
|
int Position::see(Move m) const {
|
|
assert(move_is_ok(m));
|
|
return this->see(move_from(m), move_to(m));
|
|
}
|
|
|
|
|
|
/// Position::clear() erases the position object to a pristine state, with an
|
|
/// empty board, white to move, and no castling rights.
|
|
|
|
void Position::clear() {
|
|
int i, j;
|
|
|
|
for(i = 0; i < 64; i++) {
|
|
board[i] = EMPTY;
|
|
index[i] = 0;
|
|
}
|
|
|
|
for(i = 0; i < 2; i++)
|
|
byColorBB[i] = EmptyBoardBB;
|
|
|
|
for(i = 0; i < 7; i++) {
|
|
byTypeBB[i] = EmptyBoardBB;
|
|
pieceCount[0][i] = pieceCount[1][i] = 0;
|
|
for(j = 0; j < 8; j++)
|
|
pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE;
|
|
}
|
|
|
|
checkersBB = EmptyBoardBB;
|
|
|
|
lastMove = MOVE_NONE;
|
|
|
|
sideToMove = WHITE;
|
|
castleRights = NO_CASTLES;
|
|
initialKFile = FILE_E;
|
|
initialKRFile = FILE_H;
|
|
initialQRFile = FILE_A;
|
|
epSquare = SQ_NONE;
|
|
rule50 = 0;
|
|
gamePly = 0;
|
|
}
|
|
|
|
|
|
/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the
|
|
/// UCI interface code, whenever a non-reversible move is made in a
|
|
/// 'position fen <fen> moves m1 m2 ...' command. This makes it possible
|
|
/// for the program to handle games of arbitrary length, as long as the GUI
|
|
/// handles draws by the 50 move rule correctly.
|
|
|
|
void Position::reset_game_ply() {
|
|
gamePly = 0;
|
|
}
|
|
|
|
|
|
/// Position::put_piece() puts a piece on the given square of the board,
|
|
/// updating the board array, bitboards, and piece counts.
|
|
|
|
void Position::put_piece(Piece p, Square s) {
|
|
Color c = color_of_piece(p);
|
|
PieceType pt = type_of_piece(p);
|
|
|
|
board[s] = p;
|
|
index[s] = pieceCount[c][pt];
|
|
pieceList[c][pt][index[s]] = s;
|
|
|
|
set_bit(&(byTypeBB[pt]), s);
|
|
set_bit(&(byColorBB[c]), s);
|
|
set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares.
|
|
|
|
pieceCount[c][pt]++;
|
|
|
|
if(pt == KING)
|
|
kingSquare[c] = s;
|
|
}
|
|
|
|
|
|
/// Position::allow_oo() gives the given side the right to castle kingside.
|
|
/// Used when setting castling rights during parsing of FEN strings.
|
|
|
|
void Position::allow_oo(Color c) {
|
|
castleRights |= (1 + int(c));
|
|
}
|
|
|
|
|
|
/// Position::allow_ooo() gives the given side the right to castle queenside.
|
|
/// Used when setting castling rights during parsing of FEN strings.
|
|
|
|
void Position::allow_ooo(Color c) {
|
|
castleRights |= (4 + 4*int(c));
|
|
}
|
|
|
|
|
|
/// Position::compute_key() computes the hash key of the position. The hash
|
|
/// key is usually updated incrementally as moves are made and unmade, the
|
|
/// compute_key() function is only used when a new position is set up, and
|
|
/// to verify the correctness of the hash key when running in debug mode.
|
|
|
|
Key Position::compute_key() const {
|
|
Key result = Key(0ULL);
|
|
|
|
for(Square s = SQ_A1; s <= SQ_H8; s++)
|
|
if(this->square_is_occupied(s))
|
|
result ^=
|
|
zobrist[this->color_of_piece_on(s)][this->type_of_piece_on(s)][s];
|
|
|
|
if(this->ep_square() != SQ_NONE)
|
|
result ^= zobEp[this->ep_square()];
|
|
result ^= zobCastle[castleRights];
|
|
if(this->side_to_move() == BLACK) result ^= zobSideToMove;
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::compute_pawn_key() computes the hash key of the position. The
|
|
/// hash key is usually updated incrementally as moves are made and unmade,
|
|
/// the compute_pawn_key() function is only used when a new position is set
|
|
/// up, and to verify the correctness of the pawn hash key when running in
|
|
/// debug mode.
|
|
|
|
Key Position::compute_pawn_key() const {
|
|
Key result = Key(0ULL);
|
|
Bitboard b;
|
|
Square s;
|
|
|
|
for(Color c = WHITE; c <= BLACK; c++) {
|
|
b = this->pawns(c);
|
|
while(b) {
|
|
s = pop_1st_bit(&b);
|
|
result ^= zobrist[c][PAWN][s];
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::compute_material_key() computes the hash key of the position.
|
|
/// The hash key is usually updated incrementally as moves are made and unmade,
|
|
/// the compute_material_key() function is only used when a new position is set
|
|
/// up, and to verify the correctness of the material hash key when running in
|
|
/// debug mode.
|
|
|
|
Key Position::compute_material_key() const {
|
|
Key result = Key(0ULL);
|
|
for(Color c = WHITE; c <= BLACK; c++)
|
|
for(PieceType pt = PAWN; pt <= QUEEN; pt++) {
|
|
int count = this->piece_count(c, pt);
|
|
for(int i = 0; i <= count; i++)
|
|
result ^= zobMaterial[c][pt][i];
|
|
}
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::compute_mg_value() and Position::compute_eg_value() compute the
|
|
/// incremental scores for the middle game and the endgame. These functions
|
|
/// are used to initialize the incremental scores when a new position is set
|
|
/// up, and to verify that the scores are correctly updated by do_move
|
|
/// and undo_move when the program is running in debug mode.
|
|
|
|
Value Position::compute_mg_value() const {
|
|
Value result = Value(0);
|
|
Bitboard b;
|
|
Square s;
|
|
|
|
for(Color c = WHITE; c <= BLACK; c++)
|
|
for(PieceType pt = PAWN; pt <= KING; pt++) {
|
|
b = this->pieces_of_color_and_type(c, pt);
|
|
while(b) {
|
|
s = pop_1st_bit(&b);
|
|
assert(this->piece_on(s) == piece_of_color_and_type(c, pt));
|
|
result += this->mg_pst(c, pt, s);
|
|
}
|
|
}
|
|
result += (this->side_to_move() == WHITE)?
|
|
(TempoValueMidgame / 2) : -(TempoValueMidgame / 2);
|
|
return result;
|
|
}
|
|
|
|
Value Position::compute_eg_value() const {
|
|
Value result = Value(0);
|
|
Bitboard b;
|
|
Square s;
|
|
|
|
for(Color c = WHITE; c <= BLACK; c++)
|
|
for(PieceType pt = PAWN; pt <= KING; pt++) {
|
|
b = this->pieces_of_color_and_type(c, pt);
|
|
while(b) {
|
|
s = pop_1st_bit(&b);
|
|
assert(this->piece_on(s) == piece_of_color_and_type(c, pt));
|
|
result += this->eg_pst(c, pt, s);
|
|
}
|
|
}
|
|
result += (this->side_to_move() == WHITE)?
|
|
(TempoValueEndgame / 2) : -(TempoValueEndgame / 2);
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::compute_non_pawn_material() computes the total non-pawn middle
|
|
/// game material score for the given side. Material scores are updated
|
|
/// incrementally during the search, this function is only used while
|
|
/// initializing a new Position object.
|
|
|
|
Value Position::compute_non_pawn_material(Color c) const {
|
|
Value result = Value(0);
|
|
Square s;
|
|
|
|
for(PieceType pt = KNIGHT; pt <= QUEEN; pt++) {
|
|
Bitboard b = this->pieces_of_color_and_type(c, pt);
|
|
while(b) {
|
|
s = pop_1st_bit(&b);
|
|
assert(this->piece_on(s) == piece_of_color_and_type(c, pt));
|
|
result += piece_value_midgame(pt);
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::is_mate() returns true or false depending on whether the
|
|
/// side to move is checkmated. Note that this function is currently very
|
|
/// slow, and shouldn't be used frequently inside the search.
|
|
|
|
bool Position::is_mate() {
|
|
if(this->is_check()) {
|
|
MovePicker mp = MovePicker(*this, false, MOVE_NONE, MOVE_NONE, MOVE_NONE,
|
|
MOVE_NONE, Depth(0));
|
|
return mp.get_next_move() == MOVE_NONE;
|
|
}
|
|
else
|
|
return false;
|
|
}
|
|
|
|
|
|
/// Position::is_draw() tests whether the position is drawn by material,
|
|
/// repetition, or the 50 moves rule. It does not detect stalemates, this
|
|
/// must be done by the search.
|
|
|
|
bool Position::is_draw() const {
|
|
// Draw by material?
|
|
if(!this->pawns() &&
|
|
this->non_pawn_material(WHITE) + this->non_pawn_material(BLACK)
|
|
<= BishopValueMidgame)
|
|
return true;
|
|
|
|
// Draw by the 50 moves rule?
|
|
if(rule50 > 100 || (rule50 == 100 && !this->is_check()))
|
|
return true;
|
|
|
|
// Draw by repetition?
|
|
for(int i = 2; i < Min(gamePly, rule50); i += 2)
|
|
if(history[gamePly - i] == key)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/// Position::has_mate_threat() tests whether a given color has a mate in one
|
|
/// from the current position. This function is quite slow, but it doesn't
|
|
/// matter, because it is currently only called from PV nodes, which are rare.
|
|
|
|
bool Position::has_mate_threat(Color c) {
|
|
UndoInfo u1, u2;
|
|
Color stm = this->side_to_move();
|
|
|
|
// The following lines are useless and silly, but prevents gcc from
|
|
// emitting a stupid warning stating that u1.lastMove and u1.epSquare might
|
|
// be used uninitialized.
|
|
u1.lastMove = lastMove;
|
|
u1.epSquare = epSquare;
|
|
|
|
if(this->is_check())
|
|
return false;
|
|
|
|
// If the input color is not equal to the side to move, do a null move
|
|
if(c != stm) this->do_null_move(u1);
|
|
|
|
MoveStack mlist[120];
|
|
int count;
|
|
bool result = false;
|
|
|
|
// Generate legal moves
|
|
count = generate_legal_moves(*this, mlist);
|
|
|
|
// Loop through the moves, and see if one of them is mate.
|
|
for(int i = 0; i < count; i++) {
|
|
this->do_move(mlist[i].move, u2);
|
|
if(this->is_mate()) result = true;
|
|
this->undo_move(mlist[i].move, u2);
|
|
}
|
|
|
|
// Undo null move, if necessary
|
|
if(c != stm) this->undo_null_move(u1);
|
|
|
|
return result;
|
|
}
|
|
|
|
|
|
/// Position::init_zobrist() is a static member function which initializes the
|
|
/// various arrays used to compute hash keys.
|
|
|
|
void Position::init_zobrist() {
|
|
|
|
for(int i = 0; i < 2; i++)
|
|
for(int j = 0; j < 8; j++)
|
|
for(int k = 0; k < 64; k++)
|
|
zobrist[i][j][k] = Key(genrand_int64());
|
|
|
|
for(int i = 0; i < 64; i++)
|
|
zobEp[i] = Key(genrand_int64());
|
|
|
|
for(int i = 0; i < 16; i++)
|
|
zobCastle[i] = genrand_int64();
|
|
|
|
zobSideToMove = genrand_int64();
|
|
|
|
for(int i = 0; i < 2; i++)
|
|
for(int j = 0; j < 8; j++)
|
|
for(int k = 0; k < 16; k++)
|
|
zobMaterial[i][j][k] = (k > 0)? Key(genrand_int64()) : Key(0LL);
|
|
|
|
for(int i = 0; i < 16; i++)
|
|
zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL);
|
|
}
|
|
|
|
|
|
/// Position::init_piece_square_tables() initializes the piece square tables.
|
|
/// This is a two-step operation: First, the white halves of the tables are
|
|
/// copied from the MgPST[][] and EgPST[][] arrays, with a small random number
|
|
/// added to each entry if the "Randomness" UCI parameter is non-zero.
|
|
/// Second, the black halves of the tables are initialized by mirroring
|
|
/// and changing the sign of the corresponding white scores.
|
|
|
|
void Position::init_piece_square_tables() {
|
|
int r = get_option_value_int("Randomness"), i;
|
|
for(Square s = SQ_A1; s <= SQ_H8; s++) {
|
|
for(Piece p = WP; p <= WK; p++) {
|
|
i = (r == 0)? 0 : (genrand_int32() % (r*2) - r);
|
|
MgPieceSquareTable[p][s] = Value(MgPST[p][s] + i);
|
|
EgPieceSquareTable[p][s] = Value(EgPST[p][s] + i);
|
|
}
|
|
}
|
|
for(Square s = SQ_A1; s <= SQ_H8; s++)
|
|
for(Piece p = BP; p <= BK; p++) {
|
|
MgPieceSquareTable[p][s] = -MgPieceSquareTable[p-8][flip_square(s)];
|
|
EgPieceSquareTable[p][s] = -EgPieceSquareTable[p-8][flip_square(s)];
|
|
}
|
|
}
|
|
|
|
|
|
/// Position::flipped_copy() makes a copy of the input position, but with
|
|
/// the white and black sides reversed. This is only useful for debugging,
|
|
/// especially for finding evaluation symmetry bugs.
|
|
|
|
void Position::flipped_copy(const Position &pos) {
|
|
assert(pos.is_ok());
|
|
|
|
this->clear();
|
|
|
|
// Board
|
|
for(Square s = SQ_A1; s <= SQ_H8; s++)
|
|
if(!pos.square_is_empty(s))
|
|
this->put_piece(Piece(int(pos.piece_on(s)) ^ 8), flip_square(s));
|
|
|
|
// Side to move
|
|
sideToMove = opposite_color(pos.side_to_move());
|
|
|
|
// Castling rights
|
|
if(pos.can_castle_kingside(WHITE)) this->allow_oo(BLACK);
|
|
if(pos.can_castle_queenside(WHITE)) this->allow_ooo(BLACK);
|
|
if(pos.can_castle_kingside(BLACK)) this->allow_oo(WHITE);
|
|
if(pos.can_castle_queenside(BLACK)) this->allow_ooo(WHITE);
|
|
|
|
initialKFile = pos.initialKFile;
|
|
initialKRFile = pos.initialKRFile;
|
|
initialQRFile = pos.initialQRFile;
|
|
|
|
for(Square sq = SQ_A1; sq <= SQ_H8; sq++)
|
|
castleRightsMask[sq] = ALL_CASTLES;
|
|
castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO);
|
|
castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO);
|
|
castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO;
|
|
castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO;
|
|
castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO;
|
|
castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO;
|
|
|
|
// En passant square
|
|
if(pos.epSquare != SQ_NONE)
|
|
epSquare = flip_square(pos.epSquare);
|
|
|
|
// Checkers
|
|
this->find_checkers();
|
|
|
|
// Hash keys
|
|
key = this->compute_key();
|
|
pawnKey = this->compute_pawn_key();
|
|
materialKey = this->compute_material_key();
|
|
|
|
// Incremental scores
|
|
mgValue = this->compute_mg_value();
|
|
egValue = this->compute_eg_value();
|
|
|
|
// Material
|
|
npMaterial[WHITE] = this->compute_non_pawn_material(WHITE);
|
|
npMaterial[BLACK] = this->compute_non_pawn_material(BLACK);
|
|
|
|
assert(this->is_ok());
|
|
}
|
|
|
|
|
|
/// Position::is_ok() performs some consitency checks for the position object.
|
|
/// This is meant to be helpful when debugging.
|
|
|
|
bool Position::is_ok() const {
|
|
|
|
// What features of the position should be verified?
|
|
static const bool debugBitboards = false;
|
|
static const bool debugKingCount = false;
|
|
static const bool debugKingCapture = false;
|
|
static const bool debugCheckerCount = false;
|
|
static const bool debugKey = false;
|
|
static const bool debugMaterialKey = false;
|
|
static const bool debugPawnKey = false;
|
|
static const bool debugIncrementalEval = false;
|
|
static const bool debugNonPawnMaterial = false;
|
|
static const bool debugPieceCounts = false;
|
|
static const bool debugPieceList = false;
|
|
|
|
// Side to move OK?
|
|
if(!color_is_ok(this->side_to_move()))
|
|
return false;
|
|
|
|
// Are the king squares in the position correct?
|
|
if(this->piece_on(this->king_square(WHITE)) != WK)
|
|
return false;
|
|
if(this->piece_on(this->king_square(BLACK)) != BK)
|
|
return false;
|
|
|
|
// Castle files OK?
|
|
if(!file_is_ok(initialKRFile))
|
|
return false;
|
|
if(!file_is_ok(initialQRFile))
|
|
return false;
|
|
|
|
// Do both sides have exactly one king?
|
|
if(debugKingCount) {
|
|
int kingCount[2] = {0, 0};
|
|
for(Square s = SQ_A1; s <= SQ_H8; s++)
|
|
if(this->type_of_piece_on(s) == KING)
|
|
kingCount[this->color_of_piece_on(s)]++;
|
|
if(kingCount[0] != 1 || kingCount[1] != 1)
|
|
return false;
|
|
}
|
|
|
|
// Can the side to move capture the opponent's king?
|
|
if(debugKingCapture) {
|
|
Color us = this->side_to_move();
|
|
Color them = opposite_color(us);
|
|
Square ksq = this->king_square(them);
|
|
if(this->square_is_attacked(ksq, us))
|
|
return false;
|
|
}
|
|
|
|
// Is there more than 2 checkers?
|
|
if(debugCheckerCount && count_1s(checkersBB) > 2)
|
|
return false;
|
|
|
|
// Bitboards OK?
|
|
if(debugBitboards) {
|
|
// The intersection of the white and black pieces must be empty:
|
|
if((this->pieces_of_color(WHITE) & this->pieces_of_color(BLACK))
|
|
!= EmptyBoardBB)
|
|
return false;
|
|
|
|
// The union of the white and black pieces must be equal to all
|
|
// occupied squares:
|
|
if((this->pieces_of_color(WHITE) | this->pieces_of_color(BLACK))
|
|
!= this->occupied_squares())
|
|
return false;
|
|
|
|
// Separate piece type bitboards must have empty intersections:
|
|
for(PieceType p1 = PAWN; p1 <= KING; p1++)
|
|
for(PieceType p2 = PAWN; p2 <= KING; p2++)
|
|
if(p1 != p2 && (this->pieces_of_type(p1) & this->pieces_of_type(p2)))
|
|
return false;
|
|
}
|
|
|
|
// En passant square OK?
|
|
if(this->ep_square() != SQ_NONE) {
|
|
// The en passant square must be on rank 6, from the point of view of the
|
|
// side to move.
|
|
if(pawn_rank(this->side_to_move(), this->ep_square()) != RANK_6)
|
|
return false;
|
|
}
|
|
|
|
// Hash key OK?
|
|
if(debugKey && key != this->compute_key())
|
|
return false;
|
|
|
|
// Pawn hash key OK?
|
|
if(debugPawnKey && pawnKey != this->compute_pawn_key())
|
|
return false;
|
|
|
|
// Material hash key OK?
|
|
if(debugMaterialKey && materialKey != this->compute_material_key())
|
|
return false;
|
|
|
|
// Incremental eval OK?
|
|
if(debugIncrementalEval) {
|
|
if(mgValue != this->compute_mg_value())
|
|
return false;
|
|
if(egValue != this->compute_eg_value())
|
|
return false;
|
|
}
|
|
|
|
// Non-pawn material OK?
|
|
if(debugNonPawnMaterial) {
|
|
if(npMaterial[WHITE] != compute_non_pawn_material(WHITE))
|
|
return false;
|
|
if(npMaterial[BLACK] != compute_non_pawn_material(BLACK))
|
|
return false;
|
|
}
|
|
|
|
// Piece counts OK?
|
|
if(debugPieceCounts)
|
|
for(Color c = WHITE; c <= BLACK; c++)
|
|
for(PieceType pt = PAWN; pt <= KING; pt++)
|
|
if(pieceCount[c][pt] != count_1s(this->pieces_of_color_and_type(c, pt)))
|
|
return false;
|
|
|
|
if(debugPieceList) {
|
|
for(Color c = WHITE; c <= BLACK; c++)
|
|
for(PieceType pt = PAWN; pt <= KING; pt++)
|
|
for(int i = 0; i < pieceCount[c][pt]; i++) {
|
|
if(this->piece_on(this->piece_list(c, pt, i)) !=
|
|
piece_of_color_and_type(c, pt))
|
|
return false;
|
|
if(index[this->piece_list(c, pt, i)] != i)
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|