X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=9376aa91ad5b06fbf06ca3f27a0b9a79f78e8db6;hb=ea5616785e7cc35808d75897282109c51e823caa;hp=e73e1e5dc3a2dd99b119b35cb0549106f289e14b;hpb=f56af8e84db25c0d26fe762fbe171ec5518177bb;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index e73e1e5d..9376aa91 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,13 +1,14 @@ /* - Glaurung, a UCI chess playing engine. - Copyright (C) 2004-2008 Tord Romstad + Stockfish, a UCI chess playing engine derived from Glaurung 2.1 + Copyright (C) 2004-2008 Tord Romstad (Glaurung author) + Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad - Glaurung is free software: you can redistribute it and/or modify + Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. - Glaurung is distributed in the hope that it will be useful, + Stockfish is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. @@ -16,53 +17,100 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include +#include #include -#include +#include +#include -#include "mersenne.h" +#include "bitcount.h" #include "movegen.h" -#include "movepick.h" #include "position.h" #include "psqtab.h" -#include "ucioption.h" - +#include "rkiss.h" +#include "thread.h" +#include "tt.h" -//// -//// Variables -//// - -int Position::castleRightsMask[64]; +using std::string; +using std::cout; +using std::endl; Key Position::zobrist[2][8][64]; -Key Position::zobEp[64]; +Key Position::zobEp[8]; Key Position::zobCastle[16]; -Key Position::zobMaterial[2][8][16]; Key Position::zobSideToMove; +Key Position::zobExclusion; + +Score Position::pieceSquareTable[16][64]; -Value Position::MgPieceSquareTable[16][64]; -Value Position::EgPieceSquareTable[16][64]; +// Material values arrays, indexed by Piece +const Value PieceValueMidgame[17] = { + VALUE_ZERO, + PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame, + VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, + PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame +}; +const Value PieceValueEndgame[17] = { + VALUE_ZERO, + PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, + RookValueEndgame, QueenValueEndgame, + VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, + PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, + RookValueEndgame, QueenValueEndgame +}; -//// -//// Functions -//// -/// Constructors +namespace { -Position::Position() { } // Do we really need this one? + // Bonus for having the side to move (modified by Joona Kiiski) + const Score TempoValue = make_score(48, 22); -Position::Position(const Position &pos) { - this->copy(pos); + // To convert a Piece to and from a FEN char + const string PieceToChar(" PNBRQK pnbrqk ."); } -Position::Position(const std::string &fen) { - this->from_fen(fen); + +/// CheckInfo c'tor + +CheckInfo::CheckInfo(const Position& pos) { + + Color them = ~pos.side_to_move(); + ksq = pos.king_square(them); + + pinned = pos.pinned_pieces(); + dcCandidates = pos.discovered_check_candidates(); + + checkSq[PAWN] = pos.attacks_from(ksq, them); + checkSq[KNIGHT] = pos.attacks_from(ksq); + checkSq[BISHOP] = pos.attacks_from(ksq); + checkSq[ROOK] = pos.attacks_from(ksq); + checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK]; + checkSq[KING] = 0; +} + + +/// Position c'tors. Here we always create a copy of the original position +/// or the FEN string, we want the new born Position object do not depend +/// on any external data so we detach state pointer from the source one. + +void Position::copy(const Position& pos, int th) { + + memcpy(this, &pos, sizeof(Position)); + startState = *st; + st = &startState; + threadID = th; + nodes = 0; + + assert(pos_is_ok()); +} + +Position::Position(const string& fen, bool isChess960, int th) { + + from_fen(fen, isChess960); + threadID = th; } @@ -70,1756 +118,1293 @@ Position::Position(const std::string &fen) { /// string. This function is not very robust - make sure that input FENs are /// correct (this is assumed to be the responsibility of the GUI). -void Position::from_fen(const std::string &fen) { - File file; - Rank rank; - int i; +void Position::from_fen(const string& fenStr, bool isChess960) { +/* + A FEN string defines a particular position using only the ASCII character set. - this->clear(); + A FEN string contains six fields separated by a space. The fields are: - // Board - rank = RANK_8; - file = FILE_A; - for(i = 0; fen[i] != ' '; i++) { - if(isdigit(fen[i])) - // Skip the given number of files - file += (fen[i] - '1' + 1); - else { - Square square = make_square(file, rank); - switch(fen[i]) { - case 'K': this->put_piece(WK, square); file++; break; - case 'Q': this->put_piece(WQ, square); file++; break; - case 'R': this->put_piece(WR, square); file++; break; - case 'B': this->put_piece(WB, square); file++; break; - case 'N': this->put_piece(WN, square); file++; break; - case 'P': this->put_piece(WP, square); file++; break; - case 'k': this->put_piece(BK, square); file++; break; - case 'q': this->put_piece(BQ, square); file++; break; - case 'r': this->put_piece(BR, square); file++; break; - case 'b': this->put_piece(BB, square); file++; break; - case 'n': this->put_piece(BN, square); file++; break; - case 'p': this->put_piece(BP, square); file++; break; - case '/': file = FILE_A; rank--; break; - case ' ': break; - default: - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - } - } + 1) Piece placement (from white's perspective). Each rank is described, starting + with rank 8 and ending with rank 1; within each rank, the contents of each + square are described from file A through file H. Following the Standard + Algebraic Notation (SAN), each piece is identified by a single letter taken + from the standard English names. White pieces are designated using upper-case + letters ("PNBRQK") while Black take lowercase ("pnbrqk"). Blank squares are + noted using digits 1 through 8 (the number of blank squares), and "/" + separates ranks. - // Side to move - i++; - if(fen[i] == 'w') - sideToMove = WHITE; - else if(fen[i] == 'b') - sideToMove = BLACK; - else { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } + 2) Active color. "w" means white moves next, "b" means black. - // Castling rights: - i++; - if(fen[i] != ' ') { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } + 3) Castling availability. If neither side can castle, this is "-". Otherwise, + this has one or more letters: "K" (White can castle kingside), "Q" (White + can castle queenside), "k" (Black can castle kingside), and/or "q" (Black + can castle queenside). - i++; - while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) { - if(fen[i] == '-') { - i++; break; - } - else if(fen[i] == 'K') this->allow_oo(WHITE); - else if(fen[i] == 'Q') this->allow_ooo(WHITE); - else if(fen[i] == 'k') this->allow_oo(BLACK); - else if(fen[i] == 'q') this->allow_ooo(BLACK); - else if(fen[i] >= 'A' && fen[i] <= 'H') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B1; square <= SQ_G1; square++) - if(this->piece_on(square) == WK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'A') + FILE_A; - if(rookFile < initialKFile) { - this->allow_ooo(WHITE); - initialQRFile = rookFile; - } - else { - this->allow_oo(WHITE); - initialKRFile = rookFile; - } - } - else if(fen[i] >= 'a' && fen[i] <= 'h') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B8; square <= SQ_G8; square++) - if(this->piece_on(square) == BK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'a') + FILE_A; - if(rookFile < initialKFile) { - this->allow_ooo(BLACK); - initialQRFile = rookFile; - } - else { - this->allow_oo(BLACK); - initialKRFile = rookFile; - } - } - else { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - i++; - } + 4) En passant target square (in algebraic notation). If there's no en passant + target square, this is "-". If a pawn has just made a 2-square move, this + is the position "behind" the pawn. This is recorded regardless of whether + there is a pawn in position to make an en passant capture. - while(fen[i] == ' ') - i++; + 5) Halfmove clock. This is the number of halfmoves since the last pawn advance + or capture. This is used to determine if a draw can be claimed under the + fifty-move rule. - // En passant square - if(i < int(fen.length()) - 2) - if(fen[i] >= 'a' && fen[i] <= 'h' && (fen[i+1] == '3' || fen[i+1] == '6')) - epSquare = square_from_string(fen.substr(i, 2)); - - // Various initialisation - - 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; - - this->find_checkers(); - - key = this->compute_key(); - pawnKey = this->compute_pawn_key(); - materialKey = this->compute_material_key(); - mgValue = this->compute_mg_value(); - egValue = this->compute_eg_value(); - npMaterial[WHITE] = this->compute_non_pawn_material(WHITE); - npMaterial[BLACK] = this->compute_non_pawn_material(BLACK); -} + 6) Fullmove number. The number of the full move. It starts at 1, and is + incremented after Black's move. +*/ + char col, row, token; + size_t p; + Square sq = SQ_A8; + std::istringstream fen(fenStr); -/// Position::to_fen() converts the position object to a FEN string. This is -/// probably only useful for debugging. + clear(); + fen >> std::noskipws; -const std::string Position::to_fen() const { - char pieceLetters[] = " PNBRQK pnbrqk"; - std::string result; - int skip; + // 1. Piece placement + while ((fen >> token) && !isspace(token)) + { + if (isdigit(token)) + sq += Square(token - '0'); // Advance the given number of files - for(Rank rank = RANK_8; rank >= RANK_1; rank--) { - skip = 0; - for(File file = FILE_A; file <= FILE_H; file++) { - Square square = make_square(file, rank); - if(this->square_is_occupied(square)) { - if(skip > 0) result += (char)skip + '0'; - result += pieceLetters[this->piece_on(square)]; - skip = 0; + else if (token == '/') + sq = make_square(FILE_A, rank_of(sq) - Rank(2)); + + else if ((p = PieceToChar.find(token)) != string::npos) + { + put_piece(Piece(p), sq); + sq++; } - else skip++; - } - if(skip > 0) result += (char)skip + '0'; - result += (rank > RANK_1)? '/' : ' '; } - result += (sideToMove == WHITE)? 'w' : 'b'; - result += ' '; - if(castleRights == NO_CASTLES) result += '-'; - else { - if(this->can_castle_kingside(WHITE)) result += 'K'; - if(this->can_castle_queenside(WHITE)) result += 'Q'; - if(this->can_castle_kingside(BLACK)) result += 'k'; - if(this->can_castle_queenside(BLACK)) result += 'q'; - } + // 2. Active color + fen >> token; + sideToMove = (token == 'w' ? WHITE : BLACK); + fen >> token; - result += ' '; - if(this->ep_square() == SQ_NONE) result += '-'; - else result += square_to_string(this->ep_square()); + // 3. Castling availability. Compatible with 3 standards: Normal FEN standard, + // Shredder-FEN that uses the letters of the columns on which the rooks began + // the game instead of KQkq and also X-FEN standard that, in case of Chess960, + // if an inner rook is associated with the castling right, the castling tag is + // replaced by the file letter of the involved rook, as for the Shredder-FEN. + while ((fen >> token) && !isspace(token)) + { + Square rsq; + Color c = islower(token) ? BLACK : WHITE; - return result; -} + token = char(toupper(token)); + if (token == 'K') + for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {} + + else if (token == 'Q') + for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {} + + else if (token >= 'A' && token <= 'H') + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); -/// Position::print() prints an ASCII representation of the position to -/// the standard output. - -void Position::print() const { - char pieceStrings[][8] = - {"| ? ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ", - "| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K=" - }; - - for(Rank rank = RANK_8; rank >= RANK_1; rank--) { - std::cout << "+---+---+---+---+---+---+---+---+\n"; - for(File file = FILE_A; file <= FILE_H; file++) { - Square sq = make_square(file, rank); - Piece piece = this->piece_on(sq); - if(piece == EMPTY) - std::cout << ((square_color(sq) == WHITE)? "| " : "| . "); else - std::cout << pieceStrings[piece]; - } - std::cout << "|\n"; + continue; + + set_castle_right(c, rsq); } - std::cout << "+---+---+---+---+---+---+---+---+\n"; - std::cout << this->to_fen() << std::endl; - std::cout << key << std::endl; -} + // 4. En passant square. Ignore if no pawn capture is possible + if ( ((fen >> col) && (col >= 'a' && col <= 'h')) + && ((fen >> row) && (row == '3' || row == '6'))) + { + st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); -/// Position::copy() creates a copy of the input position. + if (!(attackers_to(st->epSquare) & pieces(PAWN, sideToMove))) + st->epSquare = SQ_NONE; + } -void Position::copy(const Position &pos) { - memcpy(this, &pos, sizeof(Position)); -} + // 5-6. Halfmove clock and fullmove number + fen >> std::skipws >> st->rule50 >> startPosPly; + // Convert from fullmove starting from 1 to ply starting from 0, + // handle also common incorrect FEN with fullmove = 0. + startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK); -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); + st->value = compute_value(); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); + chess960 = isChess960; -Bitboard Position::pinned_pieces(Color c) const { - Bitboard b1, b2, pinned, pinners, sliders; - Square ksq = this->king_square(c), s; - Color them = opposite_color(c); + assert(pos_is_ok()); +} - pinned = EmptyBoardBB; - b1 = this->occupied_squares(); - sliders = this->rooks_and_queens(them) & ~this->checkers(); - if(sliders & RookPseudoAttacks[ksq]) { - b2 = this->rook_attacks(ksq) & this->pieces_of_color(c); - pinners = rook_attacks_bb(ksq, b1 ^ b2) & sliders; - while(pinners) { - s = pop_1st_bit(&pinners); - pinned |= (squares_between(s, ksq) & b2); - } - } +/// Position::set_castle_right() is an helper function used to set castling +/// rights given the corresponding color and the rook starting square. - sliders = this->bishops_and_queens(them) & ~this->checkers(); - if(sliders & BishopPseudoAttacks[ksq]) { - b2 = this->bishop_attacks(ksq) & this->pieces_of_color(c); - pinners = bishop_attacks_bb(ksq, b1 ^ b2) & sliders; - while(pinners) { - s = pop_1st_bit(&pinners); - pinned |= (squares_between(s, ksq) & b2); - } - } +void Position::set_castle_right(Color c, Square rsq) { - return pinned; -} + int f = (rsq < king_square(c) ? WHITE_OOO : WHITE_OO) << c; -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the given side which are candidates for giving a discovered -/// check. The code is almost the same as the function for finding pinned -/// pieces. - -Bitboard Position::discovered_check_candidates(Color c) const { - Bitboard b1, b2, dc, checkers, sliders; - Square ksq = this->king_square(opposite_color(c)), s; - - dc = EmptyBoardBB; - b1 = this->occupied_squares(); - - sliders = this->rooks_and_queens(c); - if(sliders & RookPseudoAttacks[ksq]) { - b2 = this->rook_attacks(ksq) & this->pieces_of_color(c); - checkers = rook_attacks_bb(ksq, b1 ^ b2) & sliders; - while(checkers) { - s = pop_1st_bit(&checkers); - dc |= (squares_between(s, ksq) & b2); - } - } + st->castleRights |= f; + castleRightsMask[king_square(c)] |= f; + castleRightsMask[rsq] |= f; + castleRookSquare[f] = rsq; +} - sliders = this->bishops_and_queens(c); - if(sliders & BishopPseudoAttacks[ksq]) { - b2 = this->bishop_attacks(ksq) & this->pieces_of_color(c); - checkers = bishop_attacks_bb(ksq, b1 ^ b2) & sliders; - while(checkers) { - s = pop_1st_bit(&checkers); - dc |= (squares_between(s, ksq) & b2); - } - } - return dc; -} +/// Position::to_fen() returns a FEN representation of the position. In case +/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. +const string Position::to_fen() const { -/// Position::square_is_attacked() checks whether the given side attacks the -/// given square. + std::ostringstream fen; + Square sq; + int emptyCnt; -bool Position::square_is_attacked(Square s, Color c) const { - return - (this->pawn_attacks(opposite_color(c), s) & this->pawns(c)) || - (this->knight_attacks(s) & this->knights(c)) || - (this->king_attacks(s) & this->kings(c)) || - (this->rook_attacks(s) & this->rooks_and_queens(c)) || - (this->bishop_attacks(s) & this->bishops_and_queens(c)); -} + for (Rank rank = RANK_8; rank >= RANK_1; rank--) + { + emptyCnt = 0; + for (File file = FILE_A; file <= FILE_H; file++) + { + sq = make_square(file, rank); -/// Position::attacks_to() computes a bitboard containing all pieces which -/// attacks a given square. There are two versions of this function: One -/// which finds attackers of both colors, and one which only finds the -/// attackers for one side. + if (square_is_empty(sq)) + emptyCnt++; + else + { + if (emptyCnt > 0) + { + fen << emptyCnt; + emptyCnt = 0; + } + fen << PieceToChar[piece_on(sq)]; + } + } -Bitboard Position::attacks_to(Square s) const { - return - (this->black_pawn_attacks(s) & this->pawns(WHITE)) | - (this->white_pawn_attacks(s) & this->pawns(BLACK)) | - (this->knight_attacks(s) & this->pieces_of_type(KNIGHT)) | - (this->rook_attacks(s) & this->rooks_and_queens()) | - (this->bishop_attacks(s) & this->bishops_and_queens()) | - (this->king_attacks(s) & this->pieces_of_type(KING)); -} + if (emptyCnt > 0) + fen << emptyCnt; -Bitboard Position::attacks_to(Square s, Color c) const { - return this->attacks_to(s) & this->pieces_of_color(c); -} + if (rank > RANK_1) + fen << '/'; + } + fen << (sideToMove == WHITE ? " w " : " b "); -/// Position::piece_attacks_square() tests whether the piece on square f -/// attacks square t. + if (can_castle(WHITE_OO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K'); -bool Position::piece_attacks_square(Square f, Square t) const { - assert(square_is_ok(f)); - assert(square_is_ok(t)); + if (can_castle(WHITE_OOO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q'); - switch(this->piece_on(f)) { - case WP: return this->white_pawn_attacks_square(f, t); - case BP: return this->black_pawn_attacks_square(f, t); - case WN: case BN: return this->knight_attacks_square(f, t); - case WB: case BB: return this->bishop_attacks_square(f, t); - case WR: case BR: return this->rook_attacks_square(f, t); - case WQ: case BQ: return this->queen_attacks_square(f, t); - case WK: case BK: return this->king_attacks_square(f, t); - default: return false; - } + if (can_castle(BLACK_OO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k'); - return false; -} + if (can_castle(BLACK_OOO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q'); + if (st->castleRights == CASTLES_NONE) + fen << '-'; -/// Position::find_checkers() computes the checkersBB bitboard, which -/// contains a nonzero bit for each checking piece (0, 1 or 2). It -/// currently works by calling Position::attacks_to, which is probably -/// inefficient. Consider rewriting this function to use the last move -/// played, like in non-bitboard versions of Glaurung. + fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") + << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; -void Position::find_checkers() { - checkersBB = attacks_to(this->king_square(this->side_to_move()), - opposite_color(this->side_to_move())); + return fen.str(); } -/// Position::move_is_legal() tests whether a pseudo-legal move is legal. -/// 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 pinned -/// pieces. The latter function is faster, and should always be preferred -/// when a pinned piece bitboard has already been computed. +/// Position::print() prints an ASCII representation of the position to +/// the standard output. If a move is given then also the san is printed. -bool Position::move_is_legal(Move m) const { - return this->move_is_legal(m, this->pinned_pieces(this->side_to_move())); -} +void Position::print(Move move) const { + const char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n"; -bool Position::move_is_legal(Move m, Bitboard pinned) const { - Color us, them; - Square ksq, from; + if (move) + { + Position p(*this, thread()); + cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move); + } - assert(this->is_ok()); - assert(move_is_ok(m)); - assert(pinned == this->pinned_pieces(this->side_to_move())); + for (Rank rank = RANK_8; rank >= RANK_1; rank--) + { + cout << dottedLine << '|'; + for (File file = FILE_A; file <= FILE_H; file++) + { + Square sq = make_square(file, rank); + Piece piece = piece_on(sq); + char c = (color_of(piece) == BLACK ? '=' : ' '); - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - if(this->is_check()) return true; + if (piece == NO_PIECE && !opposite_colors(sq, SQ_A1)) + piece++; // Index the dot - // Castling moves are checked for legality during move generation. - if(move_is_castle(m)) return true; + cout << c << PieceToChar[piece] << c << '|'; + } + } + cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl; +} - us = this->side_to_move(); - them = opposite_color(us); - from = move_from(m); - ksq = this->king_square(us); +/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the +/// king) pieces for the given color. Or, when template parameter FindPinned is +/// false, the function return the pieces of the given color candidate for a +/// discovery check against the enemy king. +template +Bitboard Position::hidden_checkers() const { - assert(this->color_of_piece_on(from) == us); - assert(this->piece_on(ksq) == king_of_color(us)); + // Pinned pieces protect our king, dicovery checks attack the enemy king + Bitboard b, result = 0; + Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove); + Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove); - // En passant captures are a tricky special case. Because they are - // rather uncommon, we do it simply by testing whether the king is attacked - // after the move is made: - if(move_is_ep(m)) { - Square to = move_to(m); - Square capsq = make_square(square_file(to), square_rank(from)); - Bitboard b = this->occupied_squares(); + // Pinners are sliders, that give check when candidate pinned is removed + pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq]) + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]); - assert(to == this->ep_square()); - assert(this->piece_on(from) == pawn_of_color(us)); - assert(this->piece_on(capsq) == pawn_of_color(them)); - assert(this->piece_on(to) == EMPTY); + while (pinners) + { + b = squares_between(ksq, pop_1st_bit(&pinners)) & occupied_squares(); - 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))); + // Only one bit set and is an our piece? + if (b && !(b & (b - 1)) && (b & pieces(sideToMove))) + result |= b; } + return result; +} - // 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)); +// Explicit template instantiations +template Bitboard Position::hidden_checkers() const; +template Bitboard Position::hidden_checkers() const; - // 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::attackers_to() computes a bitboard of all pieces which attack a +/// given square. Slider attacks use occ bitboard as occupancy. + +Bitboard Position::attackers_to(Square s, Bitboard occ) const { + + return (attacks_from(s, BLACK) & pieces(PAWN, WHITE)) + | (attacks_from(s, WHITE) & pieces(PAWN, BLACK)) + | (attacks_from(s) & pieces(KNIGHT)) + | (attacks_bb(s, occ) & pieces(ROOK, QUEEN)) + | (attacks_bb(s, occ) & pieces(BISHOP, QUEEN)) + | (attacks_from(s) & pieces(KING)); } -/// 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. +/// Position::attacks_from() computes a bitboard of all attacks of a given piece +/// put in a given square. Slider attacks use occ bitboard as occupancy. + +Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { -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); + assert(square_is_ok(s)); + + switch (type_of(p)) + { + case BISHOP: return attacks_bb(s, occ); + case ROOK : return attacks_bb(s, occ); + case QUEEN : return attacks_bb(s, occ) | attacks_bb(s, occ); + default : return StepAttacksBB[p][s]; + } } -bool Position::move_is_check(Move m, Bitboard dcCandidates) const { - Color us, them; - Square ksq, from, to; +/// Position::move_attacks_square() tests whether a move from the current +/// position attacks a given square. - assert(this->is_ok()); - assert(move_is_ok(m)); - assert(dcCandidates == - this->discovered_check_candidates(this->side_to_move())); +bool Position::move_attacks_square(Move m, Square s) const { - us = this->side_to_move(); - them = opposite_color(us); + assert(is_ok(m)); + assert(square_is_ok(s)); - 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)); + Bitboard occ, xray; + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_moved(m); - // 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); + assert(!square_is_empty(from)); - case BISHOP: - // Discovered check? - if(bit_is_set(dcCandidates, from)) - return true; - // Normal check? - else - return bit_is_set(this->bishop_attacks(ksq), to); + // Update occupancy as if the piece is moving + occ = occupied_squares(); + occ ^= from; + occ ^= 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)) + // The piece moved in 'to' attacks the square 's' ? + if (attacks_from(piece, to, occ) & s) 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); - } + // Scan for possible X-ray attackers behind the moved piece + xray = (attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece))) + |(attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece))); - clear_bit(&b, kfrom); clear_bit(&b, rfrom); - set_bit(&b, rto); set_bit(&b, kto); + // Verify attackers are triggered by our move and not already existing + return xray && (xray ^ (xray & attacks_from(s))); +} - return bit_is_set(rook_attacks_bb(rto, b), ksq); - } - return false; +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal - default: - assert(false); - return false; - } +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { - assert(false); - return false; -} + assert(is_ok(m)); + assert(pinned == pinned_pieces()); + Color us = sideToMove; + Square from = from_sq(m); -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. + assert(color_of(piece_moved(m)) == us); + assert(piece_on(king_square(us)) == make_piece(us, KING)); -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); -} + // En passant captures are a tricky special case. Because they are rather + // uncommon, we do it simply by testing whether the king is attacked after + // the move is made. + if (is_enpassant(m)) + { + Color them = ~us; + Square to = to_sq(m); + Square capsq = to + pawn_push(them); + Square ksq = king_square(us); + Bitboard b = occupied_squares(); + assert(to == ep_square()); + assert(piece_moved(m) == make_piece(us, PAWN)); + assert(piece_on(capsq) == make_piece(them, PAWN)); + assert(piece_on(to) == NO_PIECE); -/// 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. + b ^= from; + b ^= capsq; + b |= to; -bool Position::move_attacks_square(Move m, Square s) const { - assert(move_is_ok(m)); - assert(square_is_ok(s)); + return !(attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) + && !(attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); + } + + // If the moving piece is a king, check whether the destination + // square is attacked by the opponent. Castling moves are checked + // for legality during move generation. + if (type_of(piece_on(from)) == KING) + return is_castle(m) || !(attackers_to(to_sq(m)) & pieces(~us)); + + // 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. + return !pinned + || !(pinned & from) + || squares_aligned(from, to_sq(m), king_square(us)); +} - Square f = move_from(m), t = move_to(m); - assert(this->square_is_occupied(f)); +/// Position::move_is_legal() takes a random move and tests whether the move +/// is legal. This version is not very fast and should be used only in non +/// time-critical paths. - 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); - } +bool Position::move_is_legal(const Move m) const { + + for (MoveList ml(*this); !ml.end(); ++ml) + if (ml.move() == m) + return true; return false; } +/// Position::is_pseudo_legal() takes a random move and tests whether the move +/// is pseudo legal. It is used to validate moves from TT that can be corrupted +/// due to SMP concurrent access or hash position key aliasing. -/// 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; -} +bool Position::is_pseudo_legal(const Move m) const { + Color us = sideToMove; + Color them = ~sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_moved(m); -/// 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; -} + // Use a slower but simpler function for uncommon cases + if (is_special(m)) + return move_is_legal(m); + // Is not a promotion, so promotion piece must be empty + if (promotion_piece_type(m) - 2 != NO_PIECE_TYPE) + return false; -/// 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. + // If the from square is not occupied by a piece belonging to the side to + // move, the move is obviously not legal. + if (pc == NO_PIECE || color_of(pc) != us) + return false; -void Position::do_move(Move m, UndoInfo &u) { - this->do_move(m, u, this->discovered_check_candidates(this->side_to_move())); -} + // The destination square cannot be occupied by a friendly piece + if (color_of(piece_on(to)) == us) + return false; -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; + // Handle the special case of a pawn move + if (type_of(pc) == PAWN) + { + // Move direction must be compatible with pawn color + int direction = to - from; + if ((us == WHITE) != (direction > 0)) + return false; - 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; + // We have already handled promotion moves, so destination + // cannot be on the 8/1th rank. + if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1) + return false; - 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; + // Proceed according to the square delta between the origin and + // destination squares. + switch (direction) + { + case DELTA_NW: + case DELTA_NE: + case DELTA_SW: + case DELTA_SE: + // Capture. The destination square must be occupied by an enemy + // piece (en passant captures was handled earlier). + if (color_of(piece_on(to)) != them) + return false; - 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)); + // From and to files must be one file apart, avoids a7h5 + if (abs(file_of(from) - file_of(to)) != 1) + return false; break; - case QUEEN: - if(bit_is_set(this->queen_attacks(ksq), to)) - set_bit(&checkersBB, to); + case DELTA_N: + case DELTA_S: + // Pawn push. The destination square must be empty. + if (!square_is_empty(to)) + return false; 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))); + case DELTA_NN: + // Double white pawn push. The destination square must be on the fourth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( rank_of(to) != RANK_4 + || !square_is_empty(to) + || !square_is_empty(from + DELTA_N)) + return false; break; - default: - assert(false); + case DELTA_SS: + // Double black pawn push. The destination square must be on the fifth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( rank_of(to) != RANK_5 + || !square_is_empty(to) + || !square_is_empty(from + DELTA_S)) + return false; break; - } + + default: + return false; + } } + else if (!(attacks_from(pc, from) & to)) + return false; - // Finish - key ^= zobSideToMove; - sideToMove = opposite_color(sideToMove); - gamePly++; + // Evasions generator already takes care to avoid some kind of illegal moves + // and pl_move_is_legal() relies on this. So we have to take care that the + // same kind of moves are filtered out here. + if (in_check()) + { + // In case of king moves under check we have to remove king so to catch + // as invalid moves like b1a1 when opposite queen is on c1. + if (type_of(pc) == KING) + { + Bitboard b = occupied_squares(); + b ^= from; + if (attackers_to(to, b) & pieces(~us)) + return false; + } + else + { + Bitboard target = checkers(); + Square checksq = pop_1st_bit(&target); - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + if (target) // double check ? In this case a king move is required + return false; - assert(this->is_ok()); -} + // Our move must be a blocking evasion or a capture of the checking piece + target = squares_between(checksq, king_square(us)) | checkers(); + if (!(target & to)) + return false; + } + } + return true; +} -/// 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; +/// Position::move_gives_check() tests whether a pseudo-legal move gives a check - assert(this->is_ok()); - assert(move_is_ok(m)); - assert(move_is_castle(m)); +bool Position::move_gives_check(Move m, const CheckInfo& ci) const { - us = this->side_to_move(); - them = opposite_color(us); + assert(is_ok(m)); + assert(ci.dcCandidates == discovered_check_candidates()); + assert(color_of(piece_moved(m)) == sideToMove); - // Find source squares for king and rook: - kfrom = move_from(m); - rfrom = move_to(m); // HACK: See comment at beginning of function. + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); - assert(this->piece_on(kfrom) == king_of_color(us)); - assert(this->piece_on(rfrom) == rook_of_color(us)); + // Direct check ? + if (ci.checkSq[pt] & to) + return true; - // 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); + // Discovery check ? + if (ci.dcCandidates && (ci.dcCandidates & from)) + { + // For pawn and king moves we need to verify also direction + if ( (pt != PAWN && pt != KING) + || !squares_aligned(from, to, king_square(~sideToMove))) + return true; } - // 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; + // Can we skip the ugly special cases ? + if (!is_special(m)) + return false; + + Color us = sideToMove; + Bitboard b = occupied_squares(); + Square ksq = king_square(~us); - // 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; + // Promotion with check ? + if (is_promotion(m)) + { + b ^= from; + return attacks_from(Piece(promotion_piece_type(m)), to, b) & ksq; } - // Update castling rights: - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[kfrom]; - key ^= zobCastle[castleRights]; + // 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. + if (is_enpassant(m)) + { + Square capsq = make_square(file_of(to), rank_of(from)); + b ^= from; + b ^= capsq; + b |= to; + return (attacks_bb(ksq, b) & pieces(ROOK, QUEEN, us)) + ||(attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us)); + } - // Reset rule 50 counter: - rule50 = 0; + // Castling with check ? + if (is_castle(m)) + { + Square kfrom, kto, rfrom, rto; + kfrom = from; + rfrom = to; - // Update checkers BB: - checkersBB = attacks_to(this->king_square(them), us); -} + 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); + } + b ^= kfrom; + b ^= rfrom; + b |= rto; + b |= kto; + return attacks_bb(rto, b) & ksq; + } + return false; +} -/// 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; +/// Position::do_move() makes a move, and saves all information necessary +/// to a StateInfo object. The move is assumed to be legal. Pseudo-legal +/// moves should be filtered out before this function is called. - assert(this->is_ok()); - assert(move_is_ok(m)); - assert(move_promotion(m)); +void Position::do_move(Move m, StateInfo& newSt) { - us = this->side_to_move(); - them = opposite_color(us); + CheckInfo ci(*this); + do_move(m, newSt, ci, move_gives_check(m, ci)); +} - from = move_from(m); - to = move_to(m); +void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) { - assert(relative_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)); + assert(is_ok(m)); + assert(&newSt != st); - capture = this->type_of_piece_on(to); + nodes++; + Key k = st->key; - if(capture) { - assert(capture != KING); + // Copy some fields of old state to our new StateInfo object except the ones + // which are recalculated from scratch anyway, then switch our state pointer + // to point to the new, ready to be updated, state. + struct ReducedStateInfo { + Key pawnKey, materialKey; + Value npMaterial[2]; + int castleRights, rule50, pliesFromNull; + Score value; + Square epSquare; + }; - // Remove captured piece: - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); + memcpy(&newSt, st, sizeof(ReducedStateInfo)); - // Update hash key: - key ^= zobrist[them][capture][to]; + newSt.previous = st; + st = &newSt; - // Update incremental scores: - mgValue -= this->mg_pst(them, capture, to); - egValue -= this->eg_pst(them, capture, to); + // Update side to move + k ^= zobSideToMove; - // 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); + // Increment the 50 moves rule draw counter. Resetting it to zero in the + // case of a capture or a pawn move is taken care of later. + st->rule50++; + st->pliesFromNull++; - // Update material hash key: - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + if (is_castle(m)) + { + st->key = k; + do_castle_move(m); + return; + } - // Update piece count: - pieceCount[them][capture]--; + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_on(from); + PieceType pt = type_of(piece); + PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to)); + + assert(color_of(piece) == us); + assert(color_of(piece_on(to)) != us); + assert(capture != KING); + + if (capture) + { + Square capsq = to; + + // If the captured piece is a pawn, update pawn hash key, otherwise + // update non-pawn material. + if (capture == PAWN) + { + if (is_enpassant(m)) + { + capsq += pawn_push(them); + + assert(pt == PAWN); + assert(to == st->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(to) == NO_PIECE); + assert(piece_on(capsq) == make_piece(them, PAWN)); + + board[capsq] = NO_PIECE; + } + + st->pawnKey ^= zobrist[them][PAWN][capsq]; + } + else + st->npMaterial[them] -= PieceValueMidgame[capture]; + + // Remove the captured piece + byColorBB[them] ^= capsq; + byTypeBB[capture] ^= capsq; + occupied ^= capsq; + + // Update piece list, move the last piece at index[capsq] position and + // shrink the list. + // + // WARNING: This is a not revresible operation. When we will reinsert the + // captured piece in undo_move() we will put it at the end of the list and + // not in its original place, it means index[] and pieceList[] are not + // guaranteed to be invariant to a do_move() + undo_move() sequence. + Square lastSquare = pieceList[them][capture][--pieceCount[them][capture]]; + index[lastSquare] = index[capsq]; + pieceList[them][capture][index[lastSquare]] = lastSquare; + pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; + + // Update hash keys + k ^= zobrist[them][capture][capsq]; + st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]]; + + // Update incremental scores + st->value -= pst(make_piece(them, capture), capsq); + + // Reset rule 50 counter + st->rule50 = 0; + } - // Update piece list: - pieceList[them][capture][index[to]] = - pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; + // Update hash key + k ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; - // Remember the captured piece, in order to be able to undo the move - // correctly: - u.capture = capture; + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + k ^= zobEp[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; } - // 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 if needed + if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to])) + { + int cr = castleRightsMask[from] | castleRightsMask[to]; + k ^= zobCastle[st->castleRights & cr]; + st->castleRights &= ~cr; } - // Update castle rights: - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; + // Prefetch TT access as soon as we know key is updated + prefetch((char*)TT.first_entry(k)); - // Reset rule 50 counter: - rule50 = 0; + // Move the piece + Bitboard from_to_bb = SquareBB[from] | SquareBB[to]; + byColorBB[us] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + occupied ^= from_to_bb; - // Update checkers BB: - checkersBB = attacks_to(this->king_square(them), us); -} + board[to] = board[from]; + board[from] = NO_PIECE; + // Update piece lists, index[from] is not updated and becomes stale. This + // works as long as index[] is accessed just by known occupied squares. + index[to] = index[from]; + pieceList[us][pt][index[to]] = to; + + // If the moving piece is a pawn do some special extra work + if (pt == PAWN) + { + // Set en-passant square, only if moved pawn can be captured + if ( (to ^ from) == 16 + && (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them))) + { + st->epSquare = Square((from + to) / 2); + k ^= zobEp[file_of(st->epSquare)]; + } -/// 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(relative_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; + if (is_promotion(m)) + { + PieceType promotion = promotion_piece_type(m); + + assert(relative_rank(us, to) == RANK_8); + assert(promotion >= KNIGHT && promotion <= QUEEN); + + // Replace the pawn with the promoted piece + byTypeBB[PAWN] ^= to; + byTypeBB[promotion] |= to; + board[to] = make_piece(us, promotion); + + // Update piece lists, move the last pawn at index[to] position + // and shrink the list. Add a new promotion piece to the list. + Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]]; + index[lastSquare] = index[to]; + pieceList[us][PAWN][index[lastSquare]] = lastSquare; + pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; + index[to] = pieceCount[us][promotion]; + pieceList[us][promotion][index[to]] = to; + + // Update hash keys + k ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; + st->pawnKey ^= zobrist[us][PAWN][to]; + st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++] + ^ zobrist[us][PAWN][pieceCount[us][PAWN]]; + + // Update incremental score + st->value += pst(make_piece(us, promotion), to) + - pst(make_piece(us, PAWN), to); + + // Update material + st->npMaterial[us] += PieceValueMidgame[promotion]; + } - // Update material hash key: - materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; + // Update pawn hash key + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - // Update piece count: - pieceCount[them][PAWN]--; + // Reset rule 50 draw counter + st->rule50 = 0; + } - // 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); -} + // Prefetch pawn and material hash tables + Threads[threadID].pawnTable.prefetch(st->pawnKey); + Threads[threadID].materialTable.prefetch(st->materialKey); + + // Update incremental scores + st->value += pst_delta(piece, from, to); + + // Set capture piece + st->capturedType = capture; + // Update the key with the final value + st->key = k; -/// 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; + // Update checkers bitboard, piece must be already moved + st->checkersBB = 0; + + if (moveIsCheck) + { + if (is_special(m)) + st->checkersBB = attackers_to(king_square(them)) & pieces(us); + else + { + // Direct checks + if (ci.checkSq[pt] & to) + st->checkersBB |= to; + + // Discovery checks + if (ci.dcCandidates && (ci.dcCandidates & from)) + { + if (pt != ROOK) + st->checkersBB |= attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us); + + if (pt != BISHOP) + st->checkersBB |= attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us); + } + } } - assert(this->is_ok()); -} + // Finish + sideToMove = ~sideToMove; + st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); + assert(pos_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; +/// 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. - assert(move_is_ok(m)); - assert(move_is_castle(m)); +void Position::undo_move(Move 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); + assert(is_ok(m)); - // Find source squares for king and rook: - kfrom = move_from(m); - rfrom = move_to(m); // HACK: See comment at beginning of function. + sideToMove = ~sideToMove; - // Find destination squares for king and rook: - if(rfrom > kfrom) { // O-O - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); + if (is_castle(m)) + { + do_castle_move(m); + return; } - else { // O-O-O - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); + + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_on(to); + PieceType pt = type_of(piece); + PieceType capture = st->capturedType; + + assert(square_is_empty(from)); + assert(color_of(piece) == us); + assert(capture != KING); + + if (is_promotion(m)) + { + PieceType promotion = promotion_piece_type(m); + + assert(promotion == pt); + assert(relative_rank(us, to) == RANK_8); + assert(promotion >= KNIGHT && promotion <= QUEEN); + + // Replace the promoted piece with the pawn + byTypeBB[promotion] ^= to; + byTypeBB[PAWN] |= to; + board[to] = make_piece(us, PAWN); + + // Update piece lists, move the last promoted piece at index[to] position + // and shrink the list. Add a new pawn to the list. + Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]]; + index[lastSquare] = index[to]; + pieceList[us][promotion][index[lastSquare]] = lastSquare; + pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; + index[to] = pieceCount[us][PAWN]++; + pieceList[us][PAWN][index[to]] = to; + + pt = PAWN; } - 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; -} + // Put the piece back at the source square + Bitboard from_to_bb = SquareBB[from] | SquareBB[to]; + byColorBB[us] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + occupied ^= from_to_bb; + board[from] = board[to]; + board[to] = NO_PIECE; -/// 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). + // Update piece lists, index[to] is not updated and becomes stale. This + // works as long as index[] is accessed just by known occupied squares. + index[from] = index[to]; + pieceList[us][pt][index[from]] = from; -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(relative_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; -} + if (capture) + { + Square capsq = to; + if (is_enpassant(m)) + { + capsq -= pawn_push(us); -/// 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(relative_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]; + assert(pt == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + } - // Update piece count: - pieceCount[them][PAWN]++; -} + // Restore the captured piece + byColorBB[them] |= capsq; + byTypeBB[capture] |= capsq; + occupied |= capsq; + board[capsq] = make_piece(them, capture); -/// 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. + // Update piece list, add a new captured piece in capsq square + index[capsq] = pieceCount[them][capture]++; + pieceList[them][capture][index[capsq]] = capsq; + } -void Position::do_null_move(UndoInfo &u) { - assert(this->is_ok()); - assert(!this->is_check()); + // Finally point our state pointer back to the previous state + st = st->previous; - // 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()); + assert(pos_is_ok()); } -/// Position::undo_null_move() unmakes a "null move". +/// Position::do_castle_move() is a private method used to do/undo a castling +/// move. 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. +template +void Position::do_castle_move(Move m) { + + assert(is_ok(m)); + assert(is_castle(m)); -void Position::undo_null_move(const UndoInfo &u) { - assert(this->is_ok()); - assert(!this->is_check()); + Square kto, kfrom, rfrom, rto, kAfter, rAfter; - // Restore information from the supplied UndoInfo object: - lastMove = u.lastMove; - epSquare = u.epSquare; - if(epSquare != SQ_NONE) - key ^= zobEp[epSquare]; + Color us = sideToMove; + Square kBefore = from_sq(m); + Square rBefore = to_sq(m); - // Update the necessary information. - sideToMove = opposite_color(sideToMove); - rule50--; - gamePly--; - key ^= zobSideToMove; + // Find after-castle squares for king and rook + if (rBefore > kBefore) // O-O + { + kAfter = relative_square(us, SQ_G1); + rAfter = relative_square(us, SQ_F1); + } + else // O-O-O + { + kAfter = relative_square(us, SQ_C1); + rAfter = relative_square(us, SQ_D1); + } - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + kfrom = Do ? kBefore : kAfter; + rfrom = Do ? rBefore : rAfter; + + kto = Do ? kAfter : kBefore; + rto = Do ? rAfter : rBefore; + + assert(piece_on(kfrom) == make_piece(us, KING)); + assert(piece_on(rfrom) == make_piece(us, ROOK)); + + // Remove pieces from source squares + byColorBB[us] ^= kfrom; + byTypeBB[KING] ^= kfrom; + occupied ^= kfrom; + byColorBB[us] ^= rfrom; + byTypeBB[ROOK] ^= rfrom; + occupied ^= rfrom; + + // Put pieces on destination squares + byColorBB[us] |= kto; + byTypeBB[KING] |= kto; + occupied |= kto; + byColorBB[us] |= rto; + byTypeBB[ROOK] |= rto; + occupied |= rto; + + // Update board + Piece king = make_piece(us, KING); + Piece rook = make_piece(us, ROOK); + board[kfrom] = board[rfrom] = NO_PIECE; + board[kto] = king; + board[rto] = rook; + + // Update piece lists + pieceList[us][KING][index[kfrom]] = kto; + pieceList[us][ROOK][index[rfrom]] = rto; + int tmp = index[rfrom]; // In Chess960 could be kto == rfrom + index[kto] = index[kfrom]; + index[rto] = tmp; - assert(this->is_ok()); -} + if (Do) + { + // Reset capture field + st->capturedType = NO_PIECE_TYPE; + // Update incremental scores + st->value += pst_delta(king, kfrom, kto); + st->value += pst_delta(rook, rfrom, rto); -/// 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. + // Update hash key + st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; + st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; -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; + // Clear en passant square + if (st->epSquare != SQ_NONE) + { + st->key ^= zobEp[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } - assert(square_is_ok(from)); - assert(square_is_ok(to)); + // Update castling rights + st->key ^= zobCastle[st->castleRights & castleRightsMask[kfrom]]; + st->castleRights &= ~castleRightsMask[kfrom]; - // Initialize colors: - us = this->color_of_piece_on(from); - them = opposite_color(us); + // Update checkers BB + st->checkersBB = attackers_to(king_square(~us)) & pieces(us); - // Initialize pieces: - piece = this->piece_on(from); - capture = this->piece_on(to); + // Finish + sideToMove = ~sideToMove; + st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); + } + else + // Undo: point our state pointer back to the previous state + st = st->previous; - // 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]; + assert(pos_is_ok()); +} - // 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]; +/// Position::do_null_move() is used to do/undo a "null move": It flips the side +/// to move and updates the hash key without executing any move on the board. +template +void Position::do_null_move(StateInfo& backupSt) { - 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)); + assert(!in_check()); - // 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]); + // Back up the information necessary to undo the null move to the supplied + // StateInfo object. Note that differently from normal case here backupSt + // is actually used as a backup storage not as the new state. This reduces + // the number of fields to be copied. + StateInfo* src = Do ? st : &backupSt; + StateInfo* dst = Do ? &backupSt : st; + + dst->key = src->key; + dst->epSquare = src->epSquare; + dst->value = src->value; + dst->rule50 = src->rule50; + dst->pliesFromNull = src->pliesFromNull; + + sideToMove = ~sideToMove; + + if (Do) + { + if (st->epSquare != SQ_NONE) + st->key ^= zobEp[file_of(st->epSquare)]; + + st->key ^= zobSideToMove; + prefetch((char*)TT.first_entry(st->key)); + + st->epSquare = SQ_NONE; + st->rule50++; + st->pliesFromNull = 0; + st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue; + } - return swapList[0]; + assert(pos_is_ok()); } +// Explicit template instantiations +template void Position::do_null_move(StateInfo& backupSt); +template void Position::do_null_move(StateInfo& backupSt); -int Position::see(Move m) const { - assert(move_is_ok(m)); - return this->see(move_from(m), move_to(m)); -} +/// Position::see() is a static exchange evaluator: It tries to estimate the +/// material gain or loss resulting from a move. There are three versions of +/// this function: One which takes a destination square as input, one takes a +/// move, and one which takes a 'from' and a 'to' square. The function does +/// not yet understand promotions captures. -/// Position::clear() erases the position object to a pristine state, with an -/// empty board, white to move, and no castling rights. +int Position::see_sign(Move m) const { -void Position::clear() { - int i, j; + assert(is_ok(m)); - for(i = 0; i < 64; i++) { - board[i] = EMPTY; - index[i] = 0; - } + // Early return if SEE cannot be negative because captured piece value + // is not less then capturing one. Note that king moves always return + // here because king midgame value is set to 0. + if (PieceValueMidgame[piece_on(to_sq(m))] >= PieceValueMidgame[piece_moved(m)]) + return 1; + + return see(m); +} - for(i = 0; i < 2; i++) - byColorBB[i] = EmptyBoardBB; +int Position::see(Move m) const { - 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; + Square from, to; + Bitboard occ, attackers, stmAttackers, b; + int swapList[32], slIndex = 1; + PieceType capturedType, pt; + Color stm; + + assert(is_ok(m)); + + // As castle moves are implemented as capturing the rook, they have + // SEE == RookValueMidgame most of the times (unless the rook is under + // attack). + if (is_castle(m)) + return 0; + + from = from_sq(m); + to = to_sq(m); + capturedType = type_of(piece_on(to)); + occ = occupied_squares(); + + // Handle en passant moves + if (is_enpassant(m)) + { + Square capQq = to - pawn_push(sideToMove); + + assert(!capturedType); + assert(type_of(piece_on(capQq)) == PAWN); + + // Remove the captured pawn + occ ^= capQq; + capturedType = PAWN; } - checkersBB = EmptyBoardBB; + // Find all attackers to the destination square, with the moving piece + // removed, but possibly an X-ray attacker added behind it. + occ ^= from; + attackers = attackers_to(to, occ); - lastMove = MOVE_NONE; + // If the opponent has no attackers we are finished + stm = ~color_of(piece_on(from)); + stmAttackers = attackers & pieces(stm); + if (!stmAttackers) + return PieceValueMidgame[capturedType]; - sideToMove = WHITE; - castleRights = NO_CASTLES; - initialKFile = FILE_E; - initialKRFile = FILE_H; - initialQRFile = FILE_A; - epSquare = SQ_NONE; - rule50 = 0; - gamePly = 0; -} + // 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 + // destination 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. + swapList[0] = PieceValueMidgame[capturedType]; + capturedType = type_of(piece_on(from)); + 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; !(stmAttackers & pieces(pt)); pt++) + assert(pt < KING); + + // Remove the attacker we just found from the 'occupied' bitboard, + // and scan for new X-ray attacks behind the attacker. + b = stmAttackers & pieces(pt); + occ ^= (b & (~b + 1)); + attackers |= (attacks_bb(to, occ) & pieces(ROOK, QUEEN)) + | (attacks_bb(to, occ) & pieces(BISHOP, QUEEN)); + + attackers &= occ; // Cut out pieces we've already done + + // Add the new entry to the swap list + assert(slIndex < 32); + swapList[slIndex] = -swapList[slIndex - 1] + PieceValueMidgame[capturedType]; + slIndex++; + + // Remember the value of the capturing piece, and change the side to + // move before beginning the next iteration. + capturedType = pt; + stm = ~stm; + stmAttackers = attackers & pieces(stm); + + // Stop before processing a king capture + if (capturedType == KING && stmAttackers) + { + assert(slIndex < 32); + swapList[slIndex++] = QueenValueMidgame*10; + break; + } + } while (stmAttackers); -/// 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 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. + // 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 (--slIndex) + swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]); -void Position::reset_game_ply() { - gamePly = 0; + return swapList[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); +/// Position::clear() erases the position object to a pristine state, with an +/// empty board, white to move, and no castling rights. - board[s] = p; - index[s] = pieceCount[c][pt]; - pieceList[c][pt][index[s]] = s; +void Position::clear() { - set_bit(&(byTypeBB[pt]), s); - set_bit(&(byColorBB[c]), s); - set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares. + memset(this, 0, sizeof(Position)); + startState.epSquare = SQ_NONE; + st = &startState; - pieceCount[c][pt]++; + for (int i = 0; i < 8; i++) + for (int j = 0; j < 16; j++) + pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - if(pt == KING) - kingSquare[c] = s; + for (Square sq = SQ_A1; sq <= SQ_H8; sq++) + board[sq] = NO_PIECE; } -/// Position::allow_oo() gives the given side the right to castle kingside. -/// Used when setting castling rights during parsing of FEN strings. +/// Position::put_piece() puts a piece on the given square of the board, +/// updating the board array, pieces list, bitboards, and piece counts. -void Position::allow_oo(Color c) { - castleRights |= (1 + int(c)); -} +void Position::put_piece(Piece p, Square s) { + Color c = color_of(p); + PieceType pt = type_of(p); -/// Position::allow_ooo() gives the given side the right to castle queenside. -/// Used when setting castling rights during parsing of FEN strings. + board[s] = p; + index[s] = pieceCount[c][pt]++; + pieceList[c][pt][index[s]] = s; -void Position::allow_ooo(Color c) { - castleRights |= (4 + 4*int(c)); + byTypeBB[pt] |= s; + byColorBB[c] |= s; + occupied |= s; } -/// Position::compute_key() computes the hash key of the position. The hash +/// 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]; + Key result = zobCastle[st->castleRights]; + + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (!square_is_empty(s)) + result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s]; + + if (ep_square() != SQ_NONE) + result ^= zobEp[file_of(ep_square())]; - if(this->ep_square() != SQ_NONE) - result ^= zobEp[this->ep_square()]; - result ^= zobCastle[castleRights]; - if(this->side_to_move() == BLACK) result ^= zobSideToMove; + if (sideToMove == BLACK) + result ^= zobSideToMove; return result; } -/// Position::compute_pawn_key() computes the hash key of the position. The +/// 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]; - } + Key result = 0; + + for (Color c = WHITE; c <= BLACK; c++) + { + b = pieces(PAWN, c); + while (b) + result ^= zobrist[c][PAWN][pop_1st_bit(&b)]; } return result; } @@ -1832,406 +1417,357 @@ Key Position::compute_pawn_key() const { /// 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; -} + Key result = 0; -/// 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. + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= QUEEN; pt++) + for (int i = 0; i < piece_count(c, pt); i++) + result ^= zobrist[c][pt][i]; -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); + +/// Position::compute_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. +Score Position::compute_value() const { + 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); + Score result = SCORE_ZERO; + + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + { + b = pieces(pt, c); + while (b) + result += pst(make_piece(c, pt), pop_1st_bit(&b)); } - } - result += (this->side_to_move() == WHITE)? - (TempoValueEndgame / 2) : -(TempoValueEndgame / 2); + + result += (sideToMove == WHITE ? TempoValue / 2 : -TempoValue / 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 +/// game material value for the given side. Material values 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; -} + Value result = VALUE_ZERO; -/// 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. + for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) + result += piece_count(c, pt) * PieceValueMidgame[pt]; -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; + return result; } /// Position::is_draw() tests whether the position is drawn by material, -/// repetition, or the 50 moves rule. It does not detect stalemates, this +/// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. - +template bool Position::is_draw() const { + // Draw by material? - if(!this->pawns() && - this->non_pawn_material(WHITE) + this->non_pawn_material(BLACK) - <= BishopValueMidgame) - return true; + if ( !pieces(PAWN) + && (non_pawn_material(WHITE) + 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) + if (st->rule50 > 99 && (!in_check() || MoveList(*this).size())) 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; + // Draw by repetition? + if (!SkipRepetition) + { + int i = 4, e = std::min(st->rule50, st->pliesFromNull); - if(this->is_check()) - return false; + if (i <= e) + { + StateInfo* stp = st->previous->previous; - // If the input color is not equal to the side to move, do a null move - if(c != stm) this->do_null_move(u1); + do { + stp = stp->previous->previous; - MoveStack mlist[120]; - int count; - bool result = false; + if (stp->key == st->key) + return true; - // Generate legal moves - count = generate_legal_moves(*this, mlist); + i +=2; - // 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); + } while (i <= e); + } } - // Undo null move, if necessary - if(c != stm) this->undo_null_move(u1); - - return result; + return false; } +// Explicit template instantiations +template bool Position::is_draw() const; +template bool Position::is_draw() const; -/// Position::init_zobrist() is a static member function which initializes the -/// various arrays used to compute hash keys. -void Position::init_zobrist() { +/// Position::init() is a static member function which initializes at startup +/// the various arrays used to compute hash keys and the piece square tables. +/// The latter is a two-step operation: First, the white halves of the tables +/// are copied from PSQT[] tables. Second, the black halves of the tables are +/// initialized by flipping and changing the sign of the white scores. - 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()); +void Position::init() { - for(int i = 0; i < 64; i++) - zobEp[i] = Key(genrand_int64()); + RKISS rk; - for(int i = 0; i < 16; i++) - zobCastle[i] = genrand_int64(); + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + for (Square s = SQ_A1; s <= SQ_H8; s++) + zobrist[c][pt][s] = rk.rand(); - zobSideToMove = genrand_int64(); + for (File f = FILE_A; f <= FILE_H; f++) + zobEp[f] = rk.rand(); - 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 cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++) + { + Bitboard b = cr; + while (b) + { + Key k = zobCastle[1 << pop_1st_bit(&b)]; + zobCastle[cr] ^= k ? k : rk.rand(); + } + } - for(int i = 0; i < 16; i++) - zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL); -} + zobSideToMove = rk.rand(); + zobExclusion = rk.rand(); + for (Piece p = W_PAWN; p <= W_KING; p++) + { + Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]); -/// 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++) + { + pieceSquareTable[p][s] = ps + PSQT[p][s]; + pieceSquareTable[p+8][~s] = -pieceSquareTable[p][s]; + } } - 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. +/// Position::flip_me() flips position 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()); +void Position::flip_me() { - this->clear(); + // Make a copy of current position before to start changing + const Position pos(*this, threadID); + + clear(); + threadID = pos.thread(); // 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)); + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (!pos.square_is_empty(s)) + put_piece(Piece(pos.piece_on(s) ^ 8), ~s); // Side to move - sideToMove = opposite_color(pos.side_to_move()); + sideToMove = ~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; + if (pos.can_castle(WHITE_OO)) + set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OO)); + if (pos.can_castle(WHITE_OOO)) + set_castle_right(BLACK, ~pos.castle_rook_square(WHITE_OOO)); + if (pos.can_castle(BLACK_OO)) + set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OO)); + if (pos.can_castle(BLACK_OOO)) + set_castle_right(WHITE, ~pos.castle_rook_square(BLACK_OOO)); // En passant square - if(pos.epSquare != SQ_NONE) - epSquare = flip_square(pos.epSquare); + if (pos.st->epSquare != SQ_NONE) + st->epSquare = ~pos.st->epSquare; // Checkers - this->find_checkers(); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); // Hash keys - key = this->compute_key(); - pawnKey = this->compute_pawn_key(); - materialKey = this->compute_material_key(); + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); // Incremental scores - mgValue = this->compute_mg_value(); - egValue = this->compute_eg_value(); + st->value = compute_value(); // Material - npMaterial[WHITE] = this->compute_non_pawn_material(WHITE); - npMaterial[BLACK] = this->compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); - assert(this->is_ok()); + assert(pos_is_ok()); } -/// Position::is_ok() performs some consitency checks for the position object. +/// Position::pos_is_ok() performs some consitency checks for the position object. /// This is meant to be helpful when debugging. -bool Position::is_ok() const { +bool Position::pos_is_ok(int* failedStep) 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; + const bool debugAll = false; + + const bool debugBitboards = debugAll || false; + const bool debugKingCount = debugAll || false; + const bool debugKingCapture = debugAll || false; + const bool debugCheckerCount = debugAll || false; + const bool debugKey = debugAll || false; + const bool debugMaterialKey = debugAll || false; + const bool debugPawnKey = debugAll || false; + const bool debugIncrementalEval = debugAll || false; + const bool debugNonPawnMaterial = debugAll || false; + const bool debugPieceCounts = debugAll || false; + const bool debugPieceList = debugAll || false; + const bool debugCastleSquares = debugAll || false; + + if (failedStep) *failedStep = 1; // Side to move OK? - if(!color_is_ok(this->side_to_move())) - return false; + if (sideToMove != WHITE && sideToMove != BLACK) + 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; + if (failedStep) (*failedStep)++; + if (piece_on(king_square(WHITE)) != W_KING) + return false; - // Castle files OK? - if(!file_is_ok(initialKRFile)) - return false; - if(!file_is_ok(initialQRFile)) - return false; + if (failedStep) (*failedStep)++; + if (piece_on(king_square(BLACK)) != B_KING) + 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; + if (failedStep) (*failedStep)++; + if (debugKingCount) + { + int kingCount[2] = {0, 0}; + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (type_of(piece_on(s)) == KING) + kingCount[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; + if (failedStep) (*failedStep)++; + if (debugKingCapture) + { + Color us = sideToMove; + Color them = ~us; + Square ksq = king_square(them); + if (attackers_to(ksq) & pieces(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) + if (failedStep) (*failedStep)++; + if (debugCheckerCount && popcount(st->checkersBB) > 2) 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; + // Bitboards OK? + if (failedStep) (*failedStep)++; + if (debugBitboards) + { + // The intersection of the white and black pieces must be empty + if (pieces(WHITE) & pieces(BLACK)) + 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))) + // The union of the white and black pieces must be equal to all + // occupied squares + if ((pieces(WHITE) | pieces(BLACK)) != 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 && (pieces(p1) & pieces(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(relative_rank(this->side_to_move(), this->ep_square()) != RANK_6) - return false; + if (failedStep) (*failedStep)++; + if (ep_square() != SQ_NONE) + { + // The en passant square must be on rank 6, from the point of view of the + // side to move. + if (relative_rank(sideToMove, ep_square()) != RANK_6) + return false; } // Hash key OK? - if(debugKey && key != this->compute_key()) - return false; + if (failedStep) (*failedStep)++; + if (debugKey && st->key != compute_key()) + return false; // Pawn hash key OK? - if(debugPawnKey && pawnKey != this->compute_pawn_key()) - return false; + if (failedStep) (*failedStep)++; + if (debugPawnKey && st->pawnKey != compute_pawn_key()) + return false; // Material hash key OK? - if(debugMaterialKey && materialKey != this->compute_material_key()) - return false; + if (failedStep) (*failedStep)++; + if (debugMaterialKey && st->materialKey != compute_material_key()) + return false; // Incremental eval OK? - if(debugIncrementalEval) { - if(mgValue != this->compute_mg_value()) - return false; - if(egValue != this->compute_eg_value()) + if (failedStep) (*failedStep)++; + if (debugIncrementalEval && st->value != compute_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))) + if (failedStep) (*failedStep)++; + if (debugNonPawnMaterial) + { + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) 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; - } + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + return false; } + // Piece counts OK? + if (failedStep) (*failedStep)++; + if (debugPieceCounts) + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + if (pieceCount[c][pt] != popcount(pieces(pt, c))) + return false; + + if (failedStep) (*failedStep)++; + 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 (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt)) + return false; + + if (index[piece_list(c, pt)[i]] != i) + return false; + } + + if (failedStep) (*failedStep)++; + if (debugCastleSquares) + for (CastleRight f = WHITE_OO; f <= BLACK_OOO; f = CastleRight(f << 1)) + { + if (!can_castle(f)) + continue; + + Piece rook = (f & (WHITE_OO | WHITE_OOO) ? W_ROOK : B_ROOK); + + if ( piece_on(castleRookSquare[f]) != rook + || castleRightsMask[castleRookSquare[f]] != f) + return false; + } + + if (failedStep) *failedStep = 0; return true; }