X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=1a8c7e00d6a0bc24af2e44c395a70fb9eb6c1d4b;hp=7709fdd22c201d3e55dc228d15d3c4c2b7839eee;hb=d3608c4e79a29110f4c4a369d7207c6dd8e01f34;hpb=0a003d3ba1e3082132606d06159693aaa805a138 diff --git a/src/position.cpp b/src/position.cpp index 7709fdd2..1a8c7e00 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,7 +1,7 @@ /* 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 + Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -19,6 +19,7 @@ #include #include +#include #include #include #include @@ -40,16 +41,16 @@ static const string PieceToChar(" PNBRQK pnbrqk"); CACHE_LINE_ALIGNMENT -Score pieceSquareTable[16][64]; // [piece][square] -Value PieceValue[2][18] = { // [Mg / Eg][piece / pieceType] +Score pieceSquareTable[PIECE_NB][SQUARE_NB]; +Value PieceValue[PHASE_NB][PIECE_NB] = { { VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, { VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; namespace Zobrist { -Key psq[2][8][64]; // [color][pieceType][square / piece count] -Key enpassant[8]; // [file] -Key castle[16]; // [castleRight] +Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; +Key enpassant[FILE_NB]; +Key castle[CASTLE_RIGHT_NB]; Key side; Key exclusion; @@ -86,10 +87,10 @@ void init() { for (PieceType pt = PAWN; pt <= KING; pt++) { - PieceValue[Mg][make_piece(BLACK, pt)] = PieceValue[Mg][pt]; - PieceValue[Eg][make_piece(BLACK, pt)] = PieceValue[Eg][pt]; + PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt]; + PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt]; - Score v = make_score(PieceValue[Mg][pt], PieceValue[Eg][pt]); + Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]); for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -102,6 +103,40 @@ void init() { } // namespace Zobrist +namespace { + +/// next_attacker() is an helper function used by see() to locate the least +/// valuable attacker for the side to move, remove the attacker we just found +/// from the 'occupied' bitboard and scan for new X-ray attacks behind it. + +template FORCE_INLINE +PieceType next_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers, + Bitboard& occupied, Bitboard& attackers) { + + if (stmAttackers & bb[Pt]) + { + Bitboard b = stmAttackers & bb[Pt]; + occupied ^= b & ~(b - 1); + + if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); + + if (Pt == ROOK || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); + + return (PieceType)Pt; + } + return next_attacker(bb, to, stmAttackers, occupied, attackers); +} + +template<> FORCE_INLINE +PieceType next_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { + return KING; // No need to update bitboards, it is the last cycle +} + +} // namespace + + /// CheckInfo c'tor CheckInfo::CheckInfo(const Position& pos) { @@ -138,11 +173,11 @@ Position& Position::operator=(const Position& pos) { } -/// Position::from_fen() initializes the position object with the given 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). +/// Position::set() initializes the position object with the given 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 string& fenStr, bool isChess960, Thread* th) { +void Position::set(const string& fenStr, bool isChess960, Thread* th) { /* A FEN string defines a particular position using only the ASCII character set. @@ -180,13 +215,13 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { char col, row, token; size_t p; Square sq = SQ_A8; - std::istringstream fen(fenStr); + std::istringstream ss(fenStr); clear(); - fen >> std::noskipws; + ss >> std::noskipws; // 1. Piece placement - while ((fen >> token) && !isspace(token)) + while ((ss >> token) && !isspace(token)) { if (isdigit(token)) sq += Square(token - '0'); // Advance the given number of files @@ -202,16 +237,16 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { } // 2. Active color - fen >> token; + ss >> token; sideToMove = (token == 'w' ? WHITE : BLACK); - fen >> token; + ss >> token; // 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)) + while ((ss >> token) && !isspace(token)) { Square rsq; Color c = islower(token) ? BLACK : WHITE; @@ -234,8 +269,8 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { } // 4. En passant square. Ignore if no pawn capture is possible - if ( ((fen >> col) && (col >= 'a' && col <= 'h')) - && ((fen >> row) && (row == '3' || row == '6'))) + if ( ((ss >> col) && (col >= 'a' && col <= 'h')) + && ((ss >> row) && (row == '3' || row == '6'))) { st->epSquare = File(col - 'a') | Rank(row - '1'); @@ -244,11 +279,11 @@ void Position::from_fen(const string& fenStr, bool isChess960, Thread* th) { } // 5-6. Halfmove clock and fullmove number - fen >> std::skipws >> st->rule50 >> startPosPly; + ss >> std::skipws >> st->rule50 >> gamePly; // 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); + gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK); st->key = compute_key(); st->pawnKey = compute_pawn_key(); @@ -291,71 +326,64 @@ void Position::set_castle_right(Color c, Square rfrom) { } -/// Position::to_fen() returns a FEN representation of the position. In case +/// Position::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 { +const string Position::fen() const { - std::ostringstream fen; - Square sq; - int emptyCnt; + std::ostringstream ss; for (Rank rank = RANK_8; rank >= RANK_1; rank--) { - emptyCnt = 0; - for (File file = FILE_A; file <= FILE_H; file++) { - sq = file | rank; + Square sq = file | rank; if (is_empty(sq)) - emptyCnt++; - else { - if (emptyCnt > 0) - { - fen << emptyCnt; - emptyCnt = 0; - } - fen << PieceToChar[piece_on(sq)]; + int emptyCnt = 1; + + for ( ; file < FILE_H && is_empty(sq++); file++) + emptyCnt++; + + ss << emptyCnt; } + else + ss << PieceToChar[piece_on(sq)]; } - if (emptyCnt > 0) - fen << emptyCnt; - if (rank > RANK_1) - fen << '/'; + ss << '/'; } - fen << (sideToMove == WHITE ? " w " : " b "); + ss << (sideToMove == WHITE ? " w " : " b "); if (can_castle(WHITE_OO)) - fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE))))) : 'K'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K'); if (can_castle(WHITE_OOO)) - fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE))))) : 'Q'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q'); if (can_castle(BLACK_OO)) - fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE))) : 'k'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k'); if (can_castle(BLACK_OOO)) - fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE))) : 'q'); + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q'); if (st->castleRights == CASTLES_NONE) - fen << '-'; + ss << '-'; - fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") - << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; + ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") + << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2; - return fen.str(); + return ss.str(); } -/// Position::print() prints an ASCII representation of the position to -/// the standard output. If a move is given then also the san is printed. +/// Position::pretty() returns an ASCII representation of the position to be +/// printed to the standard output together with the move's san notation. -void Position::print(Move move) const { +const string Position::pretty(Move move) const { const string dottedLine = "\n+---+---+---+---+---+---+---+---+"; const string twoRows = dottedLine + "\n| | . | | . | | . | | . |" @@ -363,19 +391,27 @@ void Position::print(Move move) const { string brd = twoRows + twoRows + twoRows + twoRows + dottedLine; - sync_cout; + std::ostringstream ss; if (move) - { - Position p(*this); - cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move); - } + ss << "\nMove: " << (sideToMove == BLACK ? ".." : "") + << move_to_san(*const_cast(this), move); for (Square sq = SQ_A1; sq <= SQ_H8; sq++) if (piece_on(sq) != NO_PIECE) brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)]; - cout << brd << "\nFen is: " << to_fen() << "\nKey is: " << st->key << sync_endl; + ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: "; + + for (Bitboard b = checkers(); b; ) + ss << square_to_string(pop_lsb(&b)) << " "; + + ss << "\nLegal moves: "; + for (MoveList it(*this); *it; ++it) + ss << move_to_san(*const_cast(this), *it) << " "; + + return ss.str(); } @@ -441,37 +477,6 @@ Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { } -/// Position::move_attacks_square() tests whether a move from the current -/// position attacks a given square. - -bool Position::move_attacks_square(Move m, Square s) const { - - assert(is_ok(m)); - assert(is_ok(s)); - - Bitboard occ, xray; - Square from = from_sq(m); - Square to = to_sq(m); - Piece piece = piece_moved(m); - - assert(!is_empty(from)); - - // Update occupancy as if the piece is moving - occ = pieces() ^ from ^ to; - - // The piece moved in 'to' attacks the square 's' ? - if (attacks_from(piece, to, occ) & s) - return true; - - // Scan for possible X-ray attackers behind the moved piece - xray = (attacks_bb< ROOK>(s, occ) & pieces(color_of(piece), QUEEN, ROOK)) - | (attacks_bb(s, occ) & pieces(color_of(piece), QUEEN, BISHOP)); - - // Verify attackers are triggered by our move and not already existing - return xray && (xray ^ (xray & attacks_from(s))); -} - - /// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { @@ -519,20 +524,6 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { } -/// 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. - -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. @@ -540,14 +531,13 @@ bool Position::move_is_legal(const Move m) const { 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); // Use a slower but simpler function for uncommon cases if (type_of(m) != NORMAL) - return move_is_legal(m); + return MoveList(*this).contains(m); // Is not a promotion, so promotion piece must be empty if (promotion_type(m) - 2 != NO_PIECE_TYPE) @@ -559,7 +549,7 @@ bool Position::is_pseudo_legal(const Move m) const { return false; // The destination square cannot be occupied by a friendly piece - if (color_of(piece_on(to)) == us) + if (piece_on(to) != NO_PIECE && color_of(piece_on(to)) == us) return false; // Handle the special case of a pawn move @@ -585,7 +575,7 @@ bool Position::is_pseudo_legal(const Move m) const { 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) + if (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us) return false; // From and to files must be one file apart, avoids a7h5 @@ -630,18 +620,16 @@ bool Position::is_pseudo_legal(const Move m) const { // 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()) + if (checkers()) { if (type_of(pc) != KING) { - Bitboard b = checkers(); - Square checksq = pop_lsb(&b); - - if (b) // double check ? In this case a king move is required + // Double check? In this case a king move is required + if (more_than_one(checkers())) return false; // Our move must be a blocking evasion or a capture of the checking piece - if (!((between_bb(checksq, king_square(us)) | checkers()) & to)) + if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to)) return false; } // In case of king moves under check we have to remove king so to catch @@ -686,15 +674,16 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { Color us = sideToMove; Square ksq = king_square(~us); - // Promotion with check ? - if (type_of(m) == PROMOTION) + switch (type_of(m)) + { + case PROMOTION: return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq; // 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 (type_of(m) == ENPASSANT) + case ENPASSANT: { Square capsq = file_of(to) | rank_of(from); Bitboard b = (pieces() ^ from ^ capsq) | to; @@ -702,9 +691,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK)) | (attacks_bb(ksq, b) & pieces(us, QUEEN, BISHOP)); } - - // Castling with check ? - if (type_of(m) == CASTLE) + case CASTLE: { Square kfrom = from; Square rfrom = to; // 'King captures the rook' notation @@ -714,8 +701,10 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { return attacks_bb(rto, b) & ksq; } - - return false; + default: + assert(false); + return false; + } } @@ -738,9 +727,9 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI Key k = st->key; // 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. - memcpy(&newSt, st, sizeof(ReducedStateInfo)); + // which are going to be recalculated from scratch anyway, then switch our state + // pointer to point to the new, ready to be updated, state. + memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t)); newSt.previous = st; st = &newSt; @@ -748,18 +737,12 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // Update side to move k ^= Zobrist::side; - // 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. + // Increment ply counters.In particular rule50 will be later reset it to zero + // in case of a capture or a pawn move. + gamePly++; st->rule50++; st->pliesFromNull++; - if (type_of(m) == CASTLE) - { - st->key = k; - do_castle_move(m); - return; - } - Color us = sideToMove; Color them = ~us; Square from = from_sq(m); @@ -769,9 +752,25 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); assert(color_of(piece) == us); - assert(color_of(piece_on(to)) != us); + assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE); assert(capture != KING); + if (type_of(m) == CASTLE) + { + assert(piece == make_piece(us, KING)); + + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; + + do_castle(from, to, rfrom, rto); + + st->psqScore += psq_delta(make_piece(us, ROOK), rfrom, rto); + k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; + } + if (capture) { Square capsq = to; @@ -796,7 +795,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; } else - st->npMaterial[them] -= PieceValue[Mg][capture]; + st->npMaterial[them] -= PieceValue[MG][capture]; // Remove the captured piece byTypeBB[ALL_PIECES] ^= capsq; @@ -806,7 +805,7 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI // 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 + // WARNING: This is a not reversible 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. @@ -815,9 +814,10 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI pieceList[them][capture][index[lastSquare]] = lastSquare; pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; - // Update hash keys + // Update material hash key and prefetch access to materialTable k ^= Zobrist::psq[them][capture][capsq]; st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]]; + prefetch((char*)thisThread->materialTable[st->materialKey]); // Update incremental scores st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq]; @@ -844,22 +844,25 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->castleRights &= ~cr; } - // Prefetch TT access as soon as we know key is updated + // Prefetch TT access as soon as we know the new hash key prefetch((char*)TT.first_entry(k)); - // Move the piece - Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; - byTypeBB[ALL_PIECES] ^= from_to_bb; - byTypeBB[pt] ^= from_to_bb; - byColorBB[us] ^= from_to_bb; - - 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; + // Move the piece. The tricky Chess960 castle is handled earlier + if (type_of(m) != CASTLE) + { + Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; + byTypeBB[ALL_PIECES] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + byColorBB[us] ^= from_to_bb; + + board[from] = NO_PIECE; + board[to] = 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) @@ -904,20 +907,17 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI - pieceSquareTable[make_piece(us, PAWN)][to]; // Update material - st->npMaterial[us] += PieceValue[Mg][promotion]; + st->npMaterial[us] += PieceValue[MG][promotion]; } - // Update pawn hash key + // Update pawn hash key and prefetch access to pawnsTable st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to]; + prefetch((char*)thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter st->rule50 = 0; } - // Prefetch pawn and material hash tables - prefetch((char*)thisThread->pawnTable.entries[st->pawnKey]); - prefetch((char*)thisThread->materialTable.entries[st->materialKey]); - // Update incremental scores st->psqScore += psq_delta(piece, from, to); @@ -967,22 +967,14 @@ void Position::undo_move(Move m) { sideToMove = ~sideToMove; - if (type_of(m) == CASTLE) - { - do_castle_move(m); - return; - } - 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 pt = type_of(piece_on(to)); PieceType capture = st->capturedType; - assert(is_empty(from)); - assert(color_of(piece) == us); + assert(is_empty(from) || type_of(m) == CASTLE); assert(capture != KING); if (type_of(m) == PROMOTION) @@ -1010,19 +1002,32 @@ void Position::undo_move(Move m) { pt = PAWN; } - // Put the piece back at the source square - Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; - byTypeBB[ALL_PIECES] ^= from_to_bb; - byTypeBB[pt] ^= from_to_bb; - byColorBB[us] ^= from_to_bb; - - board[from] = board[to]; - board[to] = NO_PIECE; - - // 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; + if (type_of(m) == CASTLE) + { + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; + pt = KING; + do_castle(to, from, rto, rfrom); + } + else + { + // Put the piece back at the source square + Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; + byTypeBB[ALL_PIECES] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + byColorBB[us] ^= from_to_bb; + + board[to] = NO_PIECE; + board[from] = make_piece(us, pt); + + // 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; + } if (capture) { @@ -1052,49 +1057,18 @@ void Position::undo_move(Move m) { // Finally point our state pointer back to the previous state st = st->previous; + gamePly--; assert(pos_is_ok()); } -/// 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) { +/// Position::do_castle() is a helper used to do/undo a castling move. This +/// is a bit tricky, especially in Chess960. - assert(is_ok(m)); - assert(type_of(m) == CASTLE); - - Square kto, kfrom, rfrom, rto, kAfter, rAfter; +void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) { Color us = sideToMove; - Square kBefore = from_sq(m); - Square rBefore = to_sq(m); - - // 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); - } - - 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)); - - // Move the pieces, with some care; in chess960 could be kto == rfrom Bitboard k_from_to_bb = SquareBB[kfrom] ^ SquareBB[kto]; Bitboard r_from_to_bb = SquareBB[rfrom] ^ SquareBB[rto]; byTypeBB[KING] ^= k_from_to_bb; @@ -1102,105 +1076,63 @@ void Position::do_castle_move(Move m) { byTypeBB[ALL_PIECES] ^= k_from_to_bb ^ r_from_to_bb; byColorBB[us] ^= k_from_to_bb ^ r_from_to_bb; - // Update board - Piece king = make_piece(us, KING); - Piece rook = make_piece(us, ROOK); + // Could be from == to, so first set NO_PIECE then KING and ROOK board[kfrom] = board[rfrom] = NO_PIECE; - board[kto] = king; - board[rto] = rook; + board[kto] = make_piece(us, KING); + board[rto] = make_piece(us, ROOK); + + // Could be kfrom == rto, so use a 'tmp' variable + int tmp = index[kfrom]; + index[rto] = index[rfrom]; + index[kto] = tmp; + pieceList[us][KING][index[kto]] = kto; + pieceList[us][ROOK][index[rto]] = rto; +} - // 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; - if (Do) - { - // Reset capture field - st->capturedType = NO_PIECE_TYPE; +/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips +/// the side to move without executing any move on the board. - // Update incremental scores - st->psqScore += psq_delta(king, kfrom, kto); - st->psqScore += psq_delta(rook, rfrom, rto); +void Position::do_null_move(StateInfo& newSt) { - // Update hash key - st->key ^= Zobrist::psq[us][KING][kfrom] ^ Zobrist::psq[us][KING][kto]; - st->key ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; + assert(!checkers()); - // Clear en passant square - if (st->epSquare != SQ_NONE) - { - st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; - st->epSquare = SQ_NONE; - } + memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here - // Update castling rights - st->key ^= Zobrist::castle[st->castleRights & castleRightsMask[kfrom]]; - st->castleRights &= ~castleRightsMask[kfrom]; - - // Update checkers BB - st->checkersBB = attackers_to(king_square(~us)) & pieces(us); + newSt.previous = st; + st = &newSt; - sideToMove = ~sideToMove; + if (st->epSquare != SQ_NONE) + { + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; } - else - // Undo: point our state pointer back to the previous state - st = st->previous; - - assert(pos_is_ok()); -} - -/// 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) { + st->key ^= Zobrist::side; + prefetch((char*)TT.first_entry(st->key)); - assert(!in_check()); - - // 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->psqScore = src->psqScore; - dst->rule50 = src->rule50; - dst->pliesFromNull = src->pliesFromNull; + st->rule50++; + st->pliesFromNull = 0; sideToMove = ~sideToMove; - if (Do) - { - if (st->epSquare != SQ_NONE) - st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + assert(pos_is_ok()); +} - st->key ^= Zobrist::side; - prefetch((char*)TT.first_entry(st->key)); +void Position::undo_null_move() { - st->epSquare = SQ_NONE; - st->rule50++; - st->pliesFromNull = 0; - } + assert(!checkers()); - assert(pos_is_ok()); + st = st->previous; + sideToMove = ~sideToMove; } -// Explicit template instantiations -template void Position::do_null_move(StateInfo& backupSt); -template void Position::do_null_move(StateInfo& backupSt); - /// 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. +/// material gain or loss resulting from a move. Parameter 'asymmThreshold' takes +/// tempi into account. If the side who initiated the capturing sequence does the +/// last capture, he loses a tempo and if the result is below 'asymmThreshold' +/// the capturing sequence is considered bad. int Position::see_sign(Move m) const { @@ -1209,56 +1141,54 @@ int Position::see_sign(Move m) const { // 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 (PieceValue[Mg][piece_on(to_sq(m))] >= PieceValue[Mg][piece_moved(m)]) + if (PieceValue[MG][piece_on(to_sq(m))] >= PieceValue[MG][piece_moved(m)]) return 1; return see(m); } -int Position::see(Move m) const { +int Position::see(Move m, int asymmThreshold) const { Square from, to; - Bitboard occ, attackers, stmAttackers, b; + Bitboard occupied, attackers, stmAttackers; int swapList[32], slIndex = 1; - PieceType capturedType, pt; + PieceType captured; 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 (type_of(m) == CASTLE) - return 0; - from = from_sq(m); to = to_sq(m); - capturedType = type_of(piece_on(to)); - occ = pieces(); + captured = type_of(piece_on(to)); + occupied = pieces() ^ from; // Handle en passant moves if (type_of(m) == ENPASSANT) { Square capQq = to - pawn_push(sideToMove); - assert(!capturedType); + assert(!captured); assert(type_of(piece_on(capQq)) == PAWN); // Remove the captured pawn - occ ^= capQq; - capturedType = PAWN; + occupied ^= capQq; + captured = PAWN; } + else if (type_of(m) == CASTLE) + // Castle moves are implemented as king capturing the rook so cannot be + // handled correctly. Simply return 0 that is always the correct value + // unless the rook is ends up under attack. + return 0; // 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); + attackers = attackers_to(to, occupied); // If the opponent has no attackers we are finished stm = ~color_of(piece_on(from)); stmAttackers = attackers & pieces(stm); if (!stmAttackers) - return PieceValue[Mg][capturedType]; + return PieceValue[MG][captured]; // The destination square is defended, which makes things rather more // difficult to compute. We proceed by building up a "swap list" containing @@ -1266,44 +1196,43 @@ int Position::see(Move m) const { // 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] = PieceValue[Mg][capturedType]; - capturedType = type_of(piece_on(from)); + swapList[0] = PieceValue[MG][captured]; + captured = 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; (b = stmAttackers & pieces(pt)) == 0; pt++) - assert(pt < KING); - - // Remove the attacker we just found from the 'occupied' bitboard, - // and scan for new X-ray attacks behind the attacker. - 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 + assert(slIndex < 32); // Add the new entry to the swap list - assert(slIndex < 32); - swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[Mg][capturedType]; + swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; slIndex++; - // Remember the value of the capturing piece, and change the side to - // move before beginning the next iteration. - capturedType = pt; + // Locate and remove from 'occupied' the next least valuable attacker + captured = next_attacker(byTypeBB, to, stmAttackers, occupied, attackers); + + attackers &= occupied; // Remove the just found attacker stm = ~stm; stmAttackers = attackers & pieces(stm); - // Stop before processing a king capture - if (capturedType == KING && stmAttackers) + if (captured == KING) { - assert(slIndex < 32); - swapList[slIndex++] = QueenValueMg * 16; + // Stop before processing a king capture + if (stmAttackers) + swapList[slIndex++] = QueenValueMg * 16; + break; } + } while (stmAttackers); + // If we are doing asymmetric SEE evaluation and the same side does the first + // and the last capture, he loses a tempo and gain must be at least worth + // 'asymmThreshold', otherwise we replace the score with a very low value, + // before negamaxing. + if (asymmThreshold) + for (int i = 0; i < slIndex; i += 2) + if (swapList[i] < asymmThreshold) + swapList[i] = - QueenValueMg * 16; + // 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) @@ -1325,9 +1254,6 @@ void Position::clear() { for (int i = 0; i < 8; i++) for (int j = 0; j < 16; j++) pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - board[sq] = NO_PIECE; } @@ -1441,7 +1367,7 @@ Value Position::compute_non_pawn_material(Color c) const { Value value = VALUE_ZERO; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) - value += piece_count(c, pt) * PieceValue[Mg][pt]; + value += piece_count(c, pt) * PieceValue[MG][pt]; return value; } @@ -1450,7 +1376,6 @@ Value Position::compute_non_pawn_material(Color c) const { /// Position::is_draw() tests whether the position is drawn by material, /// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. -template bool Position::is_draw() const { // Draw by material? @@ -1459,37 +1384,30 @@ bool Position::is_draw() const { return true; // Draw by the 50 moves rule? - if (st->rule50 > 99 && (!in_check() || MoveList(*this).size())) + if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; // Draw by repetition? - if (!SkipRepetition) - { - int i = 4, e = std::min(st->rule50, st->pliesFromNull); + int i = 4, e = std::min(st->rule50, st->pliesFromNull); - if (i <= e) - { - StateInfo* stp = st->previous->previous; + if (i <= e) + { + StateInfo* stp = st->previous->previous; - do { - stp = stp->previous->previous; + do { + stp = stp->previous->previous; - if (stp->key == st->key) - return true; + if (stp->key == st->key) + return true; - i +=2; + i += 2; - } while (i <= e); - } + } while (i <= e); } return false; } -// Explicit template instantiations -template bool Position::is_draw() const; -template bool Position::is_draw() const; - /// Position::flip() flips position with the white and black sides reversed. This /// is only useful for debugging especially for finding evaluation symmetry bugs. @@ -1504,7 +1422,7 @@ void Position::flip() { thisThread = pos.this_thread(); nodes = pos.nodes_searched(); chess960 = pos.is_chess960(); - startPosPly = pos.startpos_ply_counter(); + gamePly = pos.game_ply(); for (Square s = SQ_A1; s <= SQ_H8; s++) if (!pos.is_empty(s)) @@ -1571,7 +1489,7 @@ bool Position::pos_is_ok(int* failedStep) const { if ((*step)++, debugKingCount) { - int kingCount[2] = {}; + int kingCount[COLOR_NB] = {}; for (Square s = SQ_A1; s <= SQ_H8; s++) if (type_of(piece_on(s)) == KING)