X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=c17c5c5757e550680ee9929e144dcbf5bf3f2216;hp=2fc73b660d912898b9563f87a127ff682bf6d5e3;hb=190f88e5324ffd048c5234e78b41748432dc7579;hpb=95cfc0e3069e2bd573e37c42785a1d7b287295c2 diff --git a/src/position.cpp b/src/position.cpp index 2fc73b66..c17c5c57 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 Marco Costalba + Copyright (C) 2008-2009 Marco Costalba Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -23,9 +23,11 @@ //// #include -#include +#include #include +#include +#include "bitcount.h" #include "mersenne.h" #include "movegen.h" #include "movepick.h" @@ -34,13 +36,13 @@ #include "san.h" #include "ucioption.h" +using std::string; + //// //// Variables //// -extern SearchStack EmptySearchStack; - int Position::castleRightsMask[64]; Key Position::zobrist[2][8][64]; @@ -64,7 +66,7 @@ Position::Position(const Position& pos) { copy(pos); } -Position::Position(const std::string& fen) { +Position::Position(const string& fen) { from_fen(fen); } @@ -73,9 +75,9 @@ 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) { +void Position::from_fen(const string& fen) { - static const std::string pieceLetters = "KQRBNPkqrbnp"; + static const string pieceLetters = "KQRBNPkqrbnp"; static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; clear(); @@ -99,7 +101,7 @@ void Position::from_fen(const std::string& fen) { continue; } size_t idx = pieceLetters.find(fen[i]); - if (idx == std::string::npos) + if (idx == string::npos) { std::cout << "Error in FEN at character " << i << std::endl; return; @@ -189,10 +191,10 @@ void Position::from_fen(const std::string& fen) { i++; // En passant square - if ( i < fen.length() - 2 + if ( i <= fen.length() - 2 && (fen[i] >= 'a' && fen[i] <= 'h') && (fen[i+1] == '3' || fen[i+1] == '6')) - epSquare = square_from_string(fen.substr(i, 2)); + st->epSquare = square_from_string(fen.substr(i, 2)); // Various initialisation for (Square sq = SQ_A1; sq <= SQ_H8; sq++) @@ -207,23 +209,23 @@ void Position::from_fen(const std::string& fen) { find_checkers(); - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); - mgValue = compute_mg_value(); - egValue = compute_eg_value(); - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); + st->mgValue = compute_value(); + st->egValue = compute_value(); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); } /// Position::to_fen() converts the position object to a FEN string. This is /// probably only useful for debugging. -const std::string Position::to_fen() const { +const string Position::to_fen() const { - static const std::string pieceLetters = " PNBRQK pnbrqk"; - std::string fen; + static const string pieceLetters = " PNBRQK pnbrqk"; + string fen; int skip; for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -249,7 +251,7 @@ const std::string Position::to_fen() const { fen += (rank > RANK_1 ? '/' : ' '); } fen += (sideToMove == WHITE ? "w " : "b "); - if (castleRights != NO_CASTLES) + if (st->castleRights != NO_CASTLES) { if (can_castle_kingside(WHITE)) fen += 'K'; if (can_castle_queenside(WHITE)) fen += 'Q'; @@ -273,7 +275,7 @@ const std::string Position::to_fen() const { void Position::print(Move m) const { - static const std::string pieceLetters = " PNBRQK PNBRQK ."; + static const string pieceLetters = " PNBRQK PNBRQK ."; // Check for reentrancy, as example when called from inside // MovePicker that is used also here in move_to_san() @@ -285,7 +287,7 @@ void Position::print(Move m) const { std::cout << std::endl; if (m != MOVE_NONE) { - std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); + string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl; } for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -305,7 +307,7 @@ void Position::print(Move m) const { } std::cout << "+---+---+---+---+---+---+---+---+" << std::endl << "Fen is: " << to_fen() << std::endl - << "Key is: " << key << std::endl; + << "Key is: " << st->key << std::endl; RequestPending = false; } @@ -313,95 +315,71 @@ void Position::print(Move m) const { /// Position::copy() creates a copy of the input position. -void Position::copy(const Position &pos) { +void Position::copy(const Position& pos) { memcpy(this, &pos, sizeof(Position)); + saveState(); // detach and copy state info } -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. -Bitboard Position::pinned_pieces(Color c) const { +/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the +/// king) pieces for the given color and for the given pinner type. Or, when +/// template parameter FindPinned is false, the pieces of the given color +/// candidate for a discovery check against the enemy king. +/// Note that checkersBB bitboard must be already updated. - if (pinned[c] != ~EmptyBoardBB) - return pinned[c]; +template +Bitboard Position::hidden_checkers(Color c) const { - Bitboard p1, p2; - Square ksq = king_square(c); - pinned[c] = hidden_checks(c, ksq, p1) | hidden_checks(c, ksq, p2); - pinners[c] = p1 | p2; - return pinned[c]; -} + Bitboard pinners, result = EmptyBoardBB; -Bitboard Position::pinned_pieces(Color c, Bitboard& p) const { + // Pinned pieces protect our king, dicovery checks attack + // the enemy king. + Square ksq = king_square(FindPinned ? c : opposite_color(c)); - if (pinned[c] == ~EmptyBoardBB) - pinned_pieces(c); + // Pinners are sliders, not checkers, that give check when + // candidate pinned is removed. + pinners = (rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]) + | (bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]); - p = pinners[c]; - return pinned[c]; -} + if (FindPinned && pinners) + pinners &= ~st->checkersBB; -Bitboard Position::discovered_check_candidates(Color c) const { + while (pinners) + { + Square s = pop_1st_bit(&pinners); + Bitboard b = squares_between(s, ksq) & occupied_squares(); - if (dcCandidates[c] != ~EmptyBoardBB) - return dcCandidates[c]; + assert(b); - Bitboard dummy; - Square ksq = king_square(opposite_color(c)); - dcCandidates[c] = hidden_checks(c, ksq, dummy) | hidden_checks(c, ksq, dummy); - return dcCandidates[c]; + if ( !(b & (b - 1)) // Only one bit set? + && (b & pieces_of_color(c))) // Is an our piece? + result |= b; + } + return result; } -/// Position:hidden_checks<>() returns a bitboard of all pinned (against the -/// king) pieces for the given color and for the given pinner type. Or, when -/// template parameter FindPinned is false, the pinned pieces of opposite color -/// that are, indeed, the pieces candidate for a discovery check. -template -Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const { - - Square s; - Bitboard sliders, result = EmptyBoardBB; - if (Piece == ROOK) // Resolved at compile time - sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]; - else - sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]; +/// Position:pinned_pieces() returns a bitboard of all pinned (against the +/// king) pieces for the given color. - if (sliders && (!FindPinned || (sliders & ~checkersBB))) - { - // King blockers are candidate pinned pieces - Bitboard candidate_pinned = piece_attacks(ksq) & pieces_of_color(c); - - // Pinners are sliders, not checkers, that give check when - // candidate pinned are removed. - pinners = (FindPinned ? sliders & ~checkersBB : sliders); - - if (Piece == ROOK) - pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - else - pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - - // Finally for each pinner find the corresponding pinned piece (if same color of king) - // or discovery checker (if opposite color) among the candidates. - Bitboard p = pinners; - while (p) - { - s = pop_1st_bit(&p); - result |= (squares_between(s, ksq) & candidate_pinned); - } - } - else - pinners = EmptyBoardBB; +Bitboard Position::pinned_pieces(Color c) const { - return result; + return hidden_checkers(c); } +/// Position:discovered_check_candidates() returns a bitboard containing all +/// pieces for the given side which are candidates for giving a discovered +/// check. + +Bitboard Position::discovered_check_candidates(Color c) const { + + return hidden_checkers(c); +} + /// 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. +/// attacks a given square. Bitboard Position::attacks_to(Square s) const { @@ -466,7 +444,7 @@ bool Position::move_attacks_square(Move m, Square s) const { /// Position::find_checkers() computes the checkersBB bitboard, which -/// contains a nonzero bit for each checking piece (0, 1 or 2). It +/// 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. @@ -474,7 +452,7 @@ bool Position::move_attacks_square(Move m, Square s) const { void Position::find_checkers() { Color us = side_to_move(); - checkersBB = attacks_to(king_square(us), opposite_color(us)); + st->checkersBB = attacks_to(king_square(us), opposite_color(us)); } @@ -482,20 +460,23 @@ void Position::find_checkers() { bool Position::pl_move_is_legal(Move m) const { - assert(is_ok()); - assert(move_is_ok(m)); - // If we're in check, all pseudo-legal moves are legal, because our // check evasion generator only generates true legal moves. - if (is_check()) - return true; + return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); +} + +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { + + assert(is_ok()); + assert(move_is_ok(m)); + assert(pinned == pinned_pieces(side_to_move())); + assert(!is_check()); // Castling moves are checked for legality during move generation. if (move_is_castle(m)) return true; Color us = side_to_move(); - Color them = opposite_color(us); Square from = move_from(m); Square ksq = king_square(us); @@ -507,6 +488,7 @@ bool Position::pl_move_is_legal(Move m) const { // after the move is made if (move_is_ep(m)) { + Color them = opposite_color(us); Square to = move_to(m); Square capsq = make_square(square_file(to), square_rank(from)); Bitboard b = occupied_squares(); @@ -527,11 +509,12 @@ bool Position::pl_move_is_legal(Move m) const { // If the moving piece is a king, check whether the destination // square is attacked by the opponent. if (from == ksq) - return !(square_is_attacked(move_to(m), them)); + return !(square_is_attacked(move_to(m), opposite_color(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 ( !bit_is_set(pinned_pieces(us), from) + return ( !pinned + || !bit_is_set(pinned, from) || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))); } @@ -540,15 +523,21 @@ bool Position::pl_move_is_legal(Move m) const { bool Position::move_is_check(Move m) const { + Bitboard dc = discovered_check_candidates(side_to_move()); + return move_is_check(m, dc); +} + +bool Position::move_is_check(Move m, Bitboard dcCandidates) const { + assert(is_ok()); assert(move_is_ok(m)); + assert(dcCandidates == discovered_check_candidates(side_to_move())); Color us = side_to_move(); Color them = opposite_color(us); Square from = move_from(m); Square to = move_to(m); Square ksq = king_square(them); - Bitboard dcCandidates = discovered_check_candidates(us); assert(color_of_piece_on(from) == us); assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); @@ -561,7 +550,8 @@ bool Position::move_is_check(Move m) const { if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check? return true; - if ( bit_is_set(dcCandidates, from) // Discovered check? + if ( dcCandidates // Discovered check? + && bit_is_set(dcCandidates, from) && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) return true; @@ -600,22 +590,24 @@ bool Position::move_is_check(Move m) const { } return false; + // Test discovered check and normal check according to piece type case KNIGHT: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || bit_is_set(piece_attacks(ksq), to); case BISHOP: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case ROOK: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)); case QUEEN: // Discovered checks are impossible! assert(!bit_is_set(dcCandidates, from)); - return bit_is_set(piece_attacks(ksq), to); // Normal check? + return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)) + || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to))); case KING: // Discovered check? @@ -655,83 +647,29 @@ bool Position::move_is_check(Move m) const { } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. Move must not be MOVE_NONE. - -bool Position::move_is_capture(Move m) const { - - assert(m != MOVE_NONE); - - return ( !square_is_empty(move_to(m)) - && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m))) - ) - || move_is_ep(m); -} - - -/// 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 { - - for (Color c = WHITE; c <= BLACK; c++) - { - u.pinners[c] = pinners[c]; - u.pinned[c] = pinned[c]; - u.dcCandidates[c] = dcCandidates[c]; - } - u.checkersBB = checkersBB; - u.key = key; - u.pawnKey = pawnKey; - u.materialKey = materialKey; - u.castleRights = castleRights; - u.rule50 = rule50; - u.epSquare = epSquare; - u.lastMove = lastMove; - u.mgValue = mgValue; - u.egValue = egValue; - u.capture = NO_PIECE_TYPE; -} - - -/// 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) { - - for (Color c = WHITE; c <= BLACK; c++) - { - pinners[c] = u.pinners[c]; - pinned[c] = u.pinned[c]; - dcCandidates[c] = u.dcCandidates[c]; - } - checkersBB = u.checkersBB; - key = u.key; - pawnKey = u.pawnKey; - materialKey = u.materialKey; - castleRights = u.castleRights; - rule50 = u.rule50; - epSquare = u.epSquare; - lastMove = u.lastMove; - mgValue = u.mgValue; - egValue = u.egValue; - // u.capture is restored in undo_move() -} - - -/// Position::update_checkers() is a private method to udpate chekers info +/// Position::update_checkers() udpates chekers info given the move. It is called +/// in do_move() and is faster then find_checkers(). template inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, Square to, Bitboard dcCandidates) { - if (Piece != KING && bit_is_set(piece_attacks(ksq), to)) + const bool Bishop = (Piece == QUEEN || Piece == BISHOP); + const bool Rook = (Piece == QUEEN || Piece == ROOK); + const bool Slider = Bishop || Rook; + + // Direct checks + if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to)) + || (Rook && bit_is_set(RookPseudoAttacks[ksq], to))) + && bit_is_set(piece_attacks(ksq), to)) // slow, try to early skip set_bit(pCheckersBB, to); + else if ( Piece != KING + && !Slider + && bit_is_set(piece_attacks(ksq), to)) + set_bit(pCheckersBB, to); + + // Discovery checks if (Piece != QUEEN && bit_is_set(dcCandidates, from)) { if (Piece != ROOK) @@ -743,39 +681,48 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square } -/// 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. +/// 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. -void Position::do_move(Move m, UndoInfo& u) { +void Position::do_move(Move m, StateInfo& newSt) { + + do_move(m, newSt, discovered_check_candidates(side_to_move())); +} + +void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { assert(is_ok()); assert(move_is_ok(m)); - // Get now the current (pre-move) dc candidates that we will use - // in update_checkers(). - Bitboard oldDcCandidates = discovered_check_candidates(side_to_move()); + // 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 key, pawnKey, materialKey; + int castleRights, rule50; + Square epSquare; + Value mgValue, egValue; + Value npMaterial[2]; + }; - // Back up the necessary information to our UndoInfo object (except the - // captured piece, which is taken care of later. - backup(u); + memcpy(&newSt, st, sizeof(ReducedStateInfo)); + newSt.capture = NO_PIECE_TYPE; + newSt.previous = st; + st = &newSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. - history[gamePly] = key; + history[gamePly] = st->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++; - - // Reset pinned bitboard and its friends - for (Color c = WHITE; c <= BLACK; c++) - pinners[c] = pinned[c] = dcCandidates[c] = ~EmptyBoardBB; + st->rule50++; if (move_is_castle(m)) do_castle_move(m); else if (move_promotion(m)) - do_promotion_move(m, u); + do_promotion_move(m); else if (move_is_ep(m)) do_ep_move(m); else @@ -789,52 +736,49 @@ void Position::do_move(Move m, UndoInfo& u) { assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY); PieceType piece = type_of_piece_on(from); - PieceType capture = type_of_piece_on(to); - if (capture) - { - u.capture = capture; - do_capture_move(m, capture, them, to); - } + st->capture = type_of_piece_on(to); + + if (st->capture) + do_capture_move(st->capture, them, to); // 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 + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares + board[to] = board[from]; board[from] = EMPTY; // Update hash key - key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; + st->key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; // Update incremental scores - mgValue -= mg_pst(us, piece, from); - mgValue += mg_pst(us, piece, to); - egValue -= eg_pst(us, piece, from); - egValue += eg_pst(us, piece, to); + st->mgValue -= pst(us, piece, from); + st->mgValue += pst(us, piece, to); + st->egValue -= pst(us, piece, from); + st->egValue += pst(us, piece, to); // If the moving piece was a king, update the king square if (piece == KING) kingSquare[us] = to; // Reset en passant square - if (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // If the moving piece was a pawn do some special extra work if (piece == PAWN) { // Reset rule 50 draw counter - rule50 = 0; + st->rule50 = 0; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; // Set en passant square, only if moved pawn can be captured if (abs(int(to) - int(from)) == 16) @@ -842,8 +786,8 @@ void Position::do_move(Move m, UndoInfo& u) { if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK))) || (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE)))) { - epSquare = Square((int(from) + int(to)) / 2); - key ^= zobEp[epSquare]; + st->epSquare = Square((int(from) + int(to)) / 2); + st->key ^= zobEp[st->epSquare]; } } } @@ -852,34 +796,37 @@ void Position::do_move(Move m, UndoInfo& u) { 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 castle rights, try to shortcut a common case + if ((castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES) + { + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[from]; + st->castleRights &= castleRightsMask[to]; + st->key ^= zobCastle[st->castleRights]; + } // Update checkers bitboard, piece must be already moved - checkersBB = EmptyBoardBB; + st->checkersBB = EmptyBoardBB; Square ksq = king_square(them); switch (piece) { - case PAWN: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case KNIGHT: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case BISHOP: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case ROOK: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case QUEEN: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case KING: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; + case PAWN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case KNIGHT: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case BISHOP: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case ROOK: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case QUEEN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; + case KING: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; default: assert(false); break; } } // Finish - key ^= zobSideToMove; + st->key ^= zobSideToMove; sideToMove = opposite_color(sideToMove); gamePly++; - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -888,33 +835,32 @@ void Position::do_move(Move m, UndoInfo& u) { /// Position::do_capture_move() is a private method used to update captured /// piece info. It is called from the main Position::do_move function. -void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) { +void Position::do_capture_move(PieceType capture, Color them, Square to) { assert(capture != KING); // Remove captured piece clear_bit(&(byColorBB[them]), to); clear_bit(&(byTypeBB[capture]), to); + clear_bit(&(byTypeBB[0]), to); // Update hash key - key ^= zobrist[them][capture][to]; + st->key ^= zobrist[them][capture][to]; // If the captured piece was a pawn, update pawn hash key if (capture == PAWN) - pawnKey ^= zobrist[them][PAWN][to]; + st->pawnKey ^= zobrist[them][PAWN][to]; // Update incremental scores - mgValue -= mg_pst(them, capture, to); - egValue -= eg_pst(them, capture, to); - - assert(!move_promotion(m) || capture != PAWN); + st->mgValue -= pst(them, capture, to); + st->egValue -= pst(them, capture, to); // Update material if (capture != PAWN) - npMaterial[them] -= piece_value_midgame(capture); + st->npMaterial[them] -= piece_value_midgame(capture); // Update material hash key - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; // Update piece count pieceCount[them][capture]--; @@ -924,7 +870,7 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) index[pieceList[them][capture][index[to]]] = index[to]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; } @@ -992,49 +938,47 @@ void Position::do_castle_move(Move m) { index[rto] = tmp; // Update incremental scores - mgValue -= mg_pst(us, KING, kfrom); - mgValue += mg_pst(us, KING, kto); - egValue -= eg_pst(us, KING, kfrom); - egValue += eg_pst(us, KING, kto); - mgValue -= mg_pst(us, ROOK, rfrom); - mgValue += mg_pst(us, ROOK, rto); - egValue -= eg_pst(us, ROOK, rfrom); - egValue += eg_pst(us, ROOK, rto); + st->mgValue -= pst(us, KING, kfrom); + st->mgValue += pst(us, KING, kto); + st->egValue -= pst(us, KING, kfrom); + st->egValue += pst(us, KING, kto); + st->mgValue -= pst(us, ROOK, rfrom); + st->mgValue += pst(us, ROOK, rto); + st->egValue -= pst(us, ROOK, rfrom); + st->egValue += 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]; + st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; + st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; // Clear en passant square - if (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // Update castling rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[kfrom]; - key ^= zobCastle[castleRights]; + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[kfrom]; + st->key ^= zobCastle[st->castleRights]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); } /// Position::do_promotion_move() is a private method used to make a promotion -/// move. It is called from the main Position::do_move function. The -/// UndoInfo object, which has been initialized in Position::do_move, is -/// used to store the captured piece (if any). +/// move. It is called from the main Position::do_move function. -void Position::do_promotion_move(Move m, UndoInfo &u) { +void Position::do_promotion_move(Move m) { Color us, them; Square from, to; - PieceType capture, promotion; + PieceType promotion; assert(is_ok()); assert(move_is_ok(m)); @@ -1049,13 +993,10 @@ void Position::do_promotion_move(Move m, UndoInfo &u) { assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); assert(color_of_piece_on(to) == them || square_is_empty(to)); - capture = type_of_piece_on(to); + st->capture = type_of_piece_on(to); - if (capture) - { - u.capture = capture; - do_capture_move(m, capture, them, to); - } + if (st->capture) + do_capture_move(st->capture, them, to); // Remove pawn clear_bit(&(byColorBB[us]), from); @@ -1072,14 +1013,14 @@ void Position::do_promotion_move(Move m, UndoInfo &u) { board[to] = piece_of_color_and_type(us, promotion); // Update hash key - key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; + st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from]; + st->pawnKey ^= zobrist[us][PAWN][from]; // Update material key - materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; - materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; + st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; + st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; // Update piece counts pieceCount[us][PAWN]--; @@ -1092,38 +1033,36 @@ void Position::do_promotion_move(Move m, UndoInfo &u) { index[to] = pieceCount[us][promotion] - 1; // Update incremental scores - mgValue -= mg_pst(us, PAWN, from); - mgValue += mg_pst(us, promotion, to); - egValue -= eg_pst(us, PAWN, from); - egValue += eg_pst(us, promotion, to); + st->mgValue -= pst(us, PAWN, from); + st->mgValue += pst(us, promotion, to); + st->egValue -= pst(us, PAWN, from); + st->egValue += pst(us, promotion, to); // Update material - npMaterial[us] += piece_value_midgame(promotion); + st->npMaterial[us] += piece_value_midgame(promotion); // Clear the en passant square - if (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // Update castle rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[to]; + st->key ^= zobCastle[st->castleRights]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); } /// Position::do_ep_move() is a private method used to make an en passant -/// capture. It is called from the main Position::do_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object in which to store the captured piece. +/// capture. It is called from the main Position::do_move function. void Position::do_ep_move(Move m) { @@ -1140,32 +1079,28 @@ void Position::do_ep_move(Move m) { to = move_to(m); capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - assert(to == epSquare); + assert(to == st->epSquare); assert(relative_rank(us, to) == RANK_6); assert(piece_on(to) == EMPTY); assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN)); - // Remove captured piece + // Remove captured pawn 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 + // Move capturing pawn + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[PAWN]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares board[to] = board[from]; board[from] = EMPTY; // Update material hash key - materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; + st->materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; // Update piece count pieceCount[them][PAWN]--; @@ -1177,39 +1112,37 @@ void Position::do_ep_move(Move m) { 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]; + st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + st->key ^= zobrist[them][PAWN][capsq]; + st->key ^= zobEp[st->epSquare]; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - pawnKey ^= zobrist[them][PAWN][capsq]; + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + st->pawnKey ^= zobrist[them][PAWN][capsq]; // Update incremental scores - mgValue -= mg_pst(them, PAWN, capsq); - mgValue -= mg_pst(us, PAWN, from); - mgValue += mg_pst(us, PAWN, to); - egValue -= eg_pst(them, PAWN, capsq); - egValue -= eg_pst(us, PAWN, from); - egValue += eg_pst(us, PAWN, to); + st->mgValue -= pst(them, PAWN, capsq); + st->mgValue -= pst(us, PAWN, from); + st->mgValue += pst(us, PAWN, to); + st->egValue -= pst(them, PAWN, capsq); + st->egValue -= pst(us, PAWN, from); + st->egValue += pst(us, PAWN, to); // Reset en passant square - epSquare = SQ_NONE; + st->epSquare = SQ_NONE; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); } /// Position::undo_move() unmakes a move. When it returns, the position should -/// be restored to exactly the same state as before the move was made. It is -/// important that Position::undo_move is called with the same move and UndoInfo -/// object as the earlier call to Position::do_move. +/// be restored to exactly the same state as before the move was made. -void Position::undo_move(Move m, const UndoInfo &u) { +void Position::undo_move(Move m) { assert(is_ok()); assert(move_is_ok(m)); @@ -1217,21 +1150,17 @@ void Position::undo_move(Move m, const UndoInfo &u) { gamePly--; sideToMove = opposite_color(sideToMove); - // Restore information from our UndoInfo object (except the captured piece, - // which is taken care of later) - restore(u); - if (move_is_castle(m)) undo_castle_move(m); else if (move_promotion(m)) - undo_promotion_move(m, u); + undo_promotion_move(m); else if (move_is_ep(m)) undo_ep_move(m); else { Color us, them; Square from, to; - PieceType piece, capture; + PieceType piece; us = side_to_move(); them = opposite_color(us); @@ -1242,17 +1171,13 @@ void Position::undo_move(Move m, const UndoInfo &u) { assert(color_of_piece_on(to) == us); // Put the piece back at the source square + Bitboard move_bb = make_move_bb(to, from); piece = 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 + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[piece]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // 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; @@ -1261,32 +1186,29 @@ void Position::undo_move(Move m, const UndoInfo &u) { pieceList[us][piece][index[to]] = from; index[from] = index[to]; - capture = u.capture; - - if (capture) + if (st->capture) { - assert(capture != KING); + assert(st->capture != KING); - // Replace the captured piece + // Restore the captured piece set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); + set_bit(&(byTypeBB[st->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); + board[to] = piece_of_color_and_type(them, st->capture); // Update piece list - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; + pieceList[them][st->capture][pieceCount[them][st->capture]] = to; + index[to] = pieceCount[them][st->capture]; // Update piece count - pieceCount[them][capture]++; + pieceCount[them][st->capture]++; } else board[to] = EMPTY; } + // Finally point our state pointer back to the previous state + st = st->previous; + assert(is_ok()); } @@ -1359,14 +1281,13 @@ void Position::undo_castle_move(Move m) { /// 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). +/// function. -void Position::undo_promotion_move(Move m, const UndoInfo &u) { +void Position::undo_promotion_move(Move m) { Color us, them; Square from, to; - PieceType capture, promotion; + PieceType promotion; assert(move_is_ok(m)); assert(move_promotion(m)); @@ -1396,9 +1317,6 @@ void Position::undo_promotion_move(Move m, const UndoInfo &u) { set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares board[from] = piece_of_color_and_type(us, PAWN); - // Update material - npMaterial[us] -= piece_value_midgame(promotion); - // Update piece list pieceList[us][PAWN][pieceCount[us][PAWN]] = from; index[from] = pieceCount[us][PAWN]; @@ -1410,38 +1328,29 @@ void Position::undo_promotion_move(Move m, const UndoInfo &u) { pieceCount[us][promotion]--; pieceCount[us][PAWN]++; - capture = u.capture; - - if (capture) + if (st->capture) { - assert(capture != KING); + assert(st->capture != KING); // Insert captured piece: set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); + set_bit(&(byTypeBB[st->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); + board[to] = piece_of_color_and_type(them, st->capture); // Update piece list - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; + pieceList[them][st->capture][pieceCount[them][st->capture]] = to; + index[to] = pieceCount[them][st->capture]; // Update piece count - pieceCount[them][capture]++; + pieceCount[them][st->capture]++; } else board[to] = EMPTY; } /// Position::undo_ep_move() is a private method used to unmake an en passant -/// capture. It is called from the main Position::undo_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object from which to retrieve the captured piece. +/// capture. It is called from the main Position::undo_move function. void Position::undo_ep_move(Move m) { @@ -1457,37 +1366,33 @@ void Position::undo_ep_move(Move m) { Square to = move_to(m); Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - assert(to == ep_square()); + assert(to == st->previous->epSquare); assert(relative_rank(us, to) == RANK_6); assert(piece_on(to) == piece_of_color_and_type(us, PAWN)); assert(piece_on(from) == EMPTY); assert(piece_on(capsq) == EMPTY); - // Replace captured piece + // Restore captured pawn set_bit(&(byColorBB[them]), capsq); set_bit(&(byTypeBB[PAWN]), capsq); set_bit(&(byTypeBB[0]), capsq); board[capsq] = piece_of_color_and_type(them, PAWN); - // Remove moving piece from destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[PAWN]), to); - clear_bit(&(byTypeBB[0]), to); + // Move capturing pawn back to source square + Bitboard move_bb = make_move_bb(to, from); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[PAWN]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); 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] = piece_of_color_and_type(us, PAWN); - // Update piece list: + // Update piece list pieceList[us][PAWN][index[to]] = from; index[from] = index[to]; pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; index[capsq] = pieceCount[them][PAWN]; - // Update piece count: + // Update piece count pieceCount[them][PAWN]++; } @@ -1495,33 +1400,38 @@ void Position::undo_ep_move(Move m) { /// Position::do_null_move makes() a "null move": It switches the side to move /// and updates the hash key without executing any move on the board. -void Position::do_null_move(UndoInfo& u) { +void Position::do_null_move(StateInfo& backupSt) { assert(is_ok()); assert(!is_check()); // Back up the information necessary to undo the null move to the supplied - // UndoInfo object. In the case of a null move, the only thing we need to - // remember is the last move made and the en passant square. - u.lastMove = lastMove; - u.epSquare = epSquare; + // StateInfo object. + // Note that differently from normal case here backupSt is actually used as + // a backup storage not as a new state to be used. + backupSt.epSquare = st->epSquare; + backupSt.key = st->key; + backupSt.mgValue = st->mgValue; + backupSt.egValue = st->egValue; + backupSt.previous = st->previous; + st->previous = &backupSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. - history[gamePly] = key; + history[gamePly] = st->key; // Update the necessary information sideToMove = opposite_color(sideToMove); - if (epSquare != SQ_NONE) - key ^= zobEp[epSquare]; + if (st->epSquare != SQ_NONE) + st->key ^= zobEp[st->epSquare]; - epSquare = SQ_NONE; - rule50++; + st->epSquare = SQ_NONE; + st->rule50++; gamePly++; - key ^= zobSideToMove; + st->key ^= zobSideToMove; - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -1529,32 +1439,29 @@ void Position::do_null_move(UndoInfo& u) { /// Position::undo_null_move() unmakes a "null move". -void Position::undo_null_move(const UndoInfo &u) { +void Position::undo_null_move() { assert(is_ok()); assert(!is_check()); - // Restore information from the supplied UndoInfo object: - lastMove = u.lastMove; - epSquare = u.epSquare; - if (epSquare != SQ_NONE) - key ^= zobEp[epSquare]; + // Restore information from the our backup StateInfo object + st->epSquare = st->previous->epSquare; + st->key = st->previous->key; + st->mgValue = st->previous->mgValue; + st->egValue = st->previous->egValue; + st->previous = st->previous->previous; - // Update the necessary information. + // Update the necessary information sideToMove = opposite_color(sideToMove); - rule50--; + st->rule50--; gamePly--; - key ^= zobSideToMove; - - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } /// 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 +/// 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. @@ -1582,7 +1489,7 @@ int Position::see(Square from, Square to) const { 0, 0 }; - Bitboard attackers, occ, b; + Bitboard attackers, stmAttackers, occ, b; assert(square_is_ok(from) || from == SQ_NONE); assert(square_is_ok(to)); @@ -1600,13 +1507,12 @@ int Position::see(Square from, Square to) const { occ = occupied_squares(); // Handle en passant moves - if (epSquare == to && type_of_piece_on(from) == PAWN) + if (st->epSquare == to && type_of_piece_on(from) == PAWN) { assert(capture == EMPTY); Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S); capture = piece_on(capQq); - assert(type_of_piece_on(capQq) == PAWN); // Remove the captured pawn @@ -1641,7 +1547,8 @@ int Position::see(Square from, Square to) const { } // If the opponent has no attackers we are finished - if ((attackers & pieces_of_color(them)) == EmptyBoardBB) + stmAttackers = attackers & pieces_of_color(them); + if (!stmAttackers) return seeValues[capture]; attackers &= occ; // Remove the moving piece @@ -1660,16 +1567,16 @@ int Position::see(Square from, Square to) const { swapList[0] = seeValues[capture]; do { - // Locate the least valuable attacker for the side to move. The loop + // 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 & pieces_of_color_and_type(c, pt)); pt++) + for (pt = PAWN; !(stmAttackers & pieces_of_type(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 & pieces_of_color_and_type(c, pt); - occ ^= (b & -b); + b = stmAttackers & pieces_of_type(pt); + occ ^= (b & (~b + 1)); attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens()) | (bishop_attacks_bb(to, occ) & bishops_and_queens()); @@ -1684,15 +1591,16 @@ int Position::see(Square from, Square to) const { // before beginning the next iteration lastCapturingPieceValue = seeValues[pt]; c = opposite_color(c); + stmAttackers = attackers & pieces_of_color(c); // Stop after a king capture - if (pt == KING && (attackers & pieces_of_color(c))) + if (pt == KING && stmAttackers) { assert(n < 32); - swapList[n++] = 100; + swapList[n++] = QueenValueMidgame*10; break; } - } while (attackers & pieces_of_color(c)); + } while (stmAttackers); // 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 @@ -1703,19 +1611,33 @@ int Position::see(Square from, Square to) const { } +/// Position::saveState() copies the content of the current state +/// inside startState and makes st point to it. This is needed +/// when the st pointee could become stale, as example because +/// the caller is about to going out of scope. + +void Position::saveState() { + + startState = *st; + st = &startState; + st->previous = NULL; // as a safe guard +} + + /// Position::clear() erases the position object to a pristine state, with an /// empty board, white to move, and no castling rights. void Position::clear() { + st = &startState; + memset(st, 0, sizeof(StateInfo)); + st->epSquare = SQ_NONE; + + memset(index, 0, sizeof(int) * 64); + memset(byColorBB, 0, sizeof(Bitboard) * 2); + for (int i = 0; i < 64; i++) - { board[i] = EMPTY; - index[i] = 0; - } - - for (int i = 0; i < 2; i++) - byColorBB[i] = EmptyBoardBB; for (int i = 0; i < 7; i++) { @@ -1725,20 +1647,11 @@ void Position::clear() { pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; } - checkersBB = EmptyBoardBB; - for (Color c = WHITE; c <= BLACK; c++) - pinners[c] = pinned[c] = dcCandidates[c] = ~EmptyBoardBB; - - lastMove = MOVE_NONE; - sideToMove = WHITE; - castleRights = NO_CASTLES; + gamePly = 0; initialKFile = FILE_E; initialKRFile = FILE_H; initialQRFile = FILE_A; - epSquare = SQ_NONE; - rule50 = 0; - gamePly = 0; } @@ -1782,7 +1695,7 @@ void Position::put_piece(Piece p, Square s) { void Position::allow_oo(Color c) { - castleRights |= (1 + int(c)); + st->castleRights |= (1 + int(c)); } @@ -1791,7 +1704,7 @@ void Position::allow_oo(Color c) { void Position::allow_ooo(Color c) { - castleRights |= (4 + 4*int(c)); + st->castleRights |= (4 + 4*int(c)); } @@ -1811,7 +1724,7 @@ Key Position::compute_key() const { if (ep_square() != SQ_NONE) result ^= zobEp[ep_square()]; - result ^= zobCastle[castleRights]; + result ^= zobCastle[st->castleRights]; if (side_to_move() == BLACK) result ^= zobSideToMove; @@ -1864,13 +1777,12 @@ Key Position::compute_material_key() const { } -/// Position::compute_mg_value() and Position::compute_eg_value() compute the -/// incremental scores for the middle game and the endgame. These functions -/// are used to initialize the incremental scores when a new position is set -/// up, and to verify that the scores are correctly updated by do_move -/// and undo_move when the program is running in debug mode. - -Value Position::compute_mg_value() const { +/// 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. +template +Value Position::compute_value() const { Value result = Value(0); Bitboard b; @@ -1884,31 +1796,12 @@ Value Position::compute_mg_value() const { { s = pop_1st_bit(&b); assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += mg_pst(c, pt, s); + result += pst(c, pt, s); } } - result += (side_to_move() == WHITE)? TempoValueMidgame / 2 : -TempoValueMidgame / 2; - return result; -} - -Value Position::compute_eg_value() const { - Value result = Value(0); - Bitboard b; - Square s; - - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - { - b = pieces_of_color_and_type(c, pt); - while(b) - { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += eg_pst(c, pt, s); - } - } - result += (side_to_move() == WHITE)? TempoValueEndgame / 2 : -TempoValueEndgame / 2; + const Value TempoValue = (Phase == MidGame ? TempoValueMidgame : TempoValueEndgame); + result += (side_to_move() == WHITE)? TempoValue / 2 : -TempoValue / 2; return result; } @@ -1921,15 +1814,14 @@ Value Position::compute_eg_value() const { Value Position::compute_non_pawn_material(Color c) const { Value result = Value(0); - Square s; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) { Bitboard b = pieces_of_color_and_type(c, pt); - while(b) + while (b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); + assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt)); + pop_1st_bit(&b); result += piece_value_midgame(pt); } } @@ -1937,21 +1829,6 @@ Value Position::compute_non_pawn_material(Color c) const { } -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. Note that this function is currently very -/// slow, and shouldn't be used frequently inside the search. - -bool Position::is_mate() const { - - if (is_check()) - { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0)); - return mp.get_next_move() == MOVE_NONE; - } - return false; -} - - /// Position::is_draw() tests whether the position is drawn by material, /// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. @@ -1964,60 +1841,72 @@ bool Position::is_draw() const { return true; // Draw by the 50 moves rule? - if (rule50 > 100 || (rule50 == 100 && !is_check())) + if (st->rule50 > 100 || (st->rule50 == 100 && !is_check())) return true; // Draw by repetition? - for (int i = 2; i < Min(gamePly, rule50); i += 2) - if (history[gamePly - i] == key) + for (int i = 2; i < Min(gamePly, st->rule50); i += 2) + if (history[gamePly - i] == st->key) return true; return false; } +/// Position::is_mate() returns true or false depending on whether the +/// side to move is checkmated. + +bool Position::is_mate() const { + + MoveStack moves[256]; + + return is_check() && !generate_evasions(*this, moves, pinned_pieces(sideToMove)); +} + + /// 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. +/// from the current position. bool Position::has_mate_threat(Color c) { - UndoInfo u1, u2; + StateInfo st1, st2; Color stm = side_to_move(); - // The following lines are useless and silly, but prevents gcc from - // emitting a stupid warning stating that u1.lastMove and u1.epSquare might - // be used uninitialized. - u1.lastMove = lastMove; - u1.epSquare = epSquare; - if (is_check()) return false; // If the input color is not equal to the side to move, do a null move if (c != stm) - do_null_move(u1); + do_null_move(st1); MoveStack mlist[120]; int count; bool result = false; + Bitboard dc = discovered_check_candidates(sideToMove); + Bitboard pinned = pinned_pieces(sideToMove); - // Generate legal moves - count = generate_legal_moves(*this, mlist); + // Generate pseudo-legal non-capture and capture check moves + count = generate_non_capture_checks(*this, mlist, dc); + count += generate_captures(*this, mlist + count); // Loop through the moves, and see if one of them is mate for (int i = 0; i < count; i++) { - do_move(mlist[i].move, u2); + Move move = mlist[i].move; + + if (!pl_move_is_legal(move, pinned)) + continue; + + do_move(move, st2); if (is_mate()) result = true; - undo_move(mlist[i].move, u2); + undo_move(move); } // Undo null move, if necessary if (c != stm) - undo_null_move(u1); + undo_null_move(); return result; } @@ -2082,7 +1971,7 @@ void Position::init_piece_square_tables() { /// 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) { +void Position::flipped_copy(const Position& pos) { assert(pos.is_ok()); @@ -2117,24 +2006,24 @@ void Position::flipped_copy(const Position &pos) { castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; // En passant square - if (pos.epSquare != SQ_NONE) - epSquare = flip_square(pos.epSquare); + if (pos.st->epSquare != SQ_NONE) + st->epSquare = flip_square(pos.st->epSquare); // Checkers find_checkers(); // Hash keys - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); // Incremental scores - mgValue = compute_mg_value(); - egValue = compute_eg_value(); + st->mgValue = compute_value(); + st->egValue = compute_value(); // Material - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); assert(is_ok()); } @@ -2207,7 +2096,7 @@ bool Position::is_ok(int* failedStep) const { // Is there more than 2 checkers? if (failedStep) (*failedStep)++; - if (debugCheckerCount && count_1s(checkersBB) > 2) + if (debugCheckerCount && count_1s(st->checkersBB) > 2) return false; // Bitboards OK? @@ -2242,27 +2131,27 @@ bool Position::is_ok(int* failedStep) const { // Hash key OK? if (failedStep) (*failedStep)++; - if (debugKey && key != compute_key()) + if (debugKey && st->key != compute_key()) return false; // Pawn hash key OK? if (failedStep) (*failedStep)++; - if (debugPawnKey && pawnKey != compute_pawn_key()) + if (debugPawnKey && st->pawnKey != compute_pawn_key()) return false; // Material hash key OK? if (failedStep) (*failedStep)++; - if (debugMaterialKey && materialKey != compute_material_key()) + if (debugMaterialKey && st->materialKey != compute_material_key()) return false; // Incremental eval OK? if (failedStep) (*failedStep)++; if (debugIncrementalEval) { - if (mgValue != compute_mg_value()) + if (st->mgValue != compute_value()) return false; - if (egValue != compute_eg_value()) + if (st->egValue != compute_value()) return false; } @@ -2270,10 +2159,10 @@ bool Position::is_ok(int* failedStep) const { if (failedStep) (*failedStep)++; if (debugNonPawnMaterial) { - if (npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) return false; - if (npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; }