X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=7fcbe670711361d0ae0cd90e53059672a1f11079;hp=f6ad622f2017df066971264a3bd7887e6ef968e9;hb=05e70d674019e27f2c9a58839f6a9c17e16f9fcc;hpb=5dd9159106a9722ebb2db5ccfd9af0f8ecb22b99 diff --git a/src/position.cpp b/src/position.cpp index f6ad622f..7fcbe670 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 @@ -23,16 +23,22 @@ //// #include -#include +#include #include +#include +#include "bitcount.h" #include "mersenne.h" #include "movegen.h" #include "movepick.h" #include "position.h" #include "psqtab.h" +#include "san.h" +#include "tt.h" #include "ucioption.h" +using std::string; + //// //// Variables @@ -49,6 +55,7 @@ Key Position::zobSideToMove; Value Position::MgPieceSquareTable[16][64]; Value Position::EgPieceSquareTable[16][64]; +static bool RequestPending = false; //// //// Functions @@ -56,11 +63,11 @@ Value Position::EgPieceSquareTable[16][64]; /// Constructors -Position::Position(const Position &pos) { +Position::Position(const Position& pos) { copy(pos); } -Position::Position(const std::string &fen) { +Position::Position(const string& fen) { from_fen(fen); } @@ -69,9 +76,9 @@ 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(); @@ -95,7 +102,7 @@ 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; @@ -114,7 +121,7 @@ void Position::from_fen(const std::string &fen) { } sideToMove = (fen[i] == 'w' ? WHITE : BLACK); - // Castling rights: + // Castling rights i++; if (fen[i] != ' ') { @@ -124,8 +131,10 @@ void Position::from_fen(const std::string &fen) { i++; while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) { - if(fen[i] == '-') { - i++; break; + if (fen[i] == '-') + { + i++; + break; } else if(fen[i] == 'K') allow_oo(WHITE); else if(fen[i] == 'Q') allow_ooo(WHITE); @@ -183,10 +192,10 @@ 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++) @@ -201,23 +210,23 @@ 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--) @@ -235,15 +244,15 @@ const std::string Position::to_fen() const { fen += (char)skip + '0'; skip = 0; } - fen += pieceLetters[piece_on(sq)]; + fen += pieceLetters[piece_on(sq)]; } if (skip > 0) fen += (char)skip + '0'; fen += (rank > RANK_1 ? '/' : ' '); } - fen += (sideToMove == WHITE ? 'w' : 'b') + ' '; - if (castleRights != NO_CASTLES) + fen += (sideToMove == WHITE ? "w " : "b "); + if (st->castleRights != NO_CASTLES) { if (can_castle_kingside(WHITE)) fen += 'K'; if (can_castle_queenside(WHITE)) fen += 'Q'; @@ -263,119 +272,115 @@ const std::string Position::to_fen() const { /// Position::print() prints an ASCII representation of the position to -/// the standard output. - -void Position::print() const { - char pieceStrings[][8] = - {"| ? ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ", - "| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K=" - }; - - for(Rank rank = RANK_8; rank >= RANK_1; rank--) { - std::cout << "+---+---+---+---+---+---+---+---+\n"; - for(File file = FILE_A; file <= FILE_H; file++) { - Square sq = make_square(file, rank); - Piece piece = piece_on(sq); - if(piece == EMPTY) - std::cout << ((square_color(sq) == WHITE)? "| " : "| . "); - else - std::cout << pieceStrings[piece]; - } - std::cout << "|\n"; - } - std::cout << "+---+---+---+---+---+---+---+---+\n"; - std::cout << to_fen() << std::endl; - std::cout << key << std::endl; -} +/// the standard output. If a move is given then also the san is print. +void Position::print(Move m) const { -/// Position::copy() creates a copy of the input position. + static const string pieceLetters = " PNBRQK PNBRQK ."; -void Position::copy(const Position &pos) { + // Check for reentrancy, as example when called from inside + // MovePicker that is used also here in move_to_san() + if (RequestPending) + return; - memcpy(this, &pos, sizeof(Position)); -} + RequestPending = true; + std::cout << std::endl; + if (m != MOVE_NONE) + { + 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--) + { + std::cout << "+---+---+---+---+---+---+---+---+" << std::endl; + for (File file = FILE_A; file <= FILE_H; file++) + { + Square sq = make_square(file, rank); + Piece piece = piece_on(sq); + if (piece == EMPTY && square_color(sq) == WHITE) + piece = NO_PIECE; -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. -Bitboard Position::pinned_pieces(Color c) const { + char col = (color_of_piece_on(sq) == BLACK ? '=' : ' '); + std::cout << '|' << col << pieceLetters[piece] << col; + } + std::cout << '|' << std::endl; + } + std::cout << "+---+---+---+---+---+---+---+---+" << std::endl + << "Fen is: " << to_fen() << std::endl + << "Key is: " << st->key << std::endl; - Square ksq = king_square(c); - return hidden_checks(c, ksq) | hidden_checks(c, ksq); + RequestPending = false; } -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the given side which are candidates for giving a discovered -/// check. The code is almost the same as the function for finding pinned -/// pieces. +/// Position::copy() creates a copy of the input position. -Bitboard Position::discovered_check_candidates(Color c) const { +void Position::copy(const Position& pos) { - Square ksq = king_square(opposite_color(c)); - return hidden_checks(c, ksq) | hidden_checks(c, ksq); + memcpy(this, &pos, sizeof(Position)); + saveState(); // detach and copy state info } -/// Position:hidden_checks<>() returns a bitboard of all pinned (against the +/// 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 pinned pieces of opposite color -/// that are, indeed, the pieces candidate for a discovery check. -template -Bitboard Position::hidden_checks(Color c, Square ksq) const { +/// 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. - 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]; +template +Bitboard Position::hidden_checkers(Color c) const { - if (sliders && (!FindPinned || (sliders & ~checkersBB))) - { - // King blockers are candidate pinned pieces - Bitboard candidate_pinned = piece_attacks(ksq) & pieces_of_color(c); + Bitboard pinners, result = EmptyBoardBB; - // Pinners are sliders, not checkers, that give check when - // candidate pinned are removed. - Bitboard pinners = (FindPinned ? sliders & ~checkersBB : sliders); + // Pinned pieces protect our king, dicovery checks attack + // the enemy king. + Square ksq = king_square(FindPinned ? c : opposite_color(c)); - if (Piece == ROOK) - pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - else - pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); + // 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]); - // Finally for each pinner find the corresponding pinned piece (if same color of king) - // or discovery checker (if opposite color) among the candidates. - while (pinners) - { - s = pop_1st_bit(&pinners); - result |= (squares_between(s, ksq) & candidate_pinned); - } + if (FindPinned && pinners) + pinners &= ~st->checkersBB; + + while (pinners) + { + Square s = pop_1st_bit(&pinners); + Bitboard b = squares_between(s, ksq) & occupied_squares(); + + assert(b); + + if ( !(b & (b - 1)) // Only one bit set? + && (b & pieces_of_color(c))) // Is an our piece? + result |= b; } return result; } -/// Position::square_is_attacked() checks whether the given side attacks the -/// given square. +/// Position:pinned_pieces() returns a bitboard of all pinned (against the +/// king) pieces for the given color. -bool Position::square_is_attacked(Square s, Color c) const { +Bitboard Position::pinned_pieces(Color c) const { - return (pawn_attacks(opposite_color(c), s) & pawns(c)) - || (piece_attacks(s) & knights(c)) - || (piece_attacks(s) & kings(c)) - || (piece_attacks(s) & rooks_and_queens(c)) - || (piece_attacks(s) & bishops_and_queens(c)); + 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 { @@ -387,21 +392,15 @@ Bitboard Position::attacks_to(Square s) const { | (piece_attacks(s) & pieces_of_type(KING)); } -Bitboard Position::attacks_to(Square s, Color c) const { - - return attacks_to(s) & pieces_of_color(c); -} - - /// Position::piece_attacks_square() tests whether the piece on square f /// attacks square t. -bool Position::piece_attacks_square(Square f, Square t) const { +bool Position::piece_attacks_square(Piece p, Square f, Square t) const { assert(square_is_ok(f)); assert(square_is_ok(t)); - switch (piece_on(f)) + switch (p) { case WP: return pawn_attacks_square(WHITE, f, t); case BP: return pawn_attacks_square(BLACK, f, t); @@ -410,15 +409,14 @@ bool Position::piece_attacks_square(Square f, Square t) const { case WR: case BR: return piece_attacks_square(f, t); case WQ: case BQ: return piece_attacks_square(f, t); case WK: case BK: return piece_attacks_square(f, t); - default: return false; + default: break; } return false; } /// Position::move_attacks_square() tests whether a move from the current -/// position attacks a given square. Only attacks by the moving piece are -/// considered; the function does not handle X-ray attacks. +/// position attacks a given square. bool Position::move_attacks_square(Move m, Square s) const { @@ -429,82 +427,76 @@ bool Position::move_attacks_square(Move m, Square s) const { assert(square_is_occupied(f)); - switch (piece_on(f)) - { - case WP: return pawn_attacks_square(WHITE, t, s); - case BP: return pawn_attacks_square(BLACK, t, s); - case WN: case BN: return piece_attacks_square(t, s); - case WB: case BB: return piece_attacks_square(t, s); - case WR: case BR: return piece_attacks_square(t, s); - case WQ: case BQ: return piece_attacks_square(t, s); - case WK: case BK: return piece_attacks_square(t, s); - default: assert(false); - } - return false; + if (piece_attacks_square(piece_on(f), t, s)) + return true; + + // Move the piece and scan for X-ray attacks behind it + Bitboard occ = occupied_squares(); + Color us = color_of_piece_on(f); + clear_bit(&occ, f); + set_bit(&occ, t); + Bitboard xray = ( (rook_attacks_bb(s, occ) & rooks_and_queens()) + |(bishop_attacks_bb(s, occ) & bishops_and_queens())) & pieces_of_color(us); + + // If we have attacks we need to verify that are caused by our move + // and are not already existent ones. + return xray && (xray ^ (xray & piece_attacks(s))); } /// 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 +/// inefficient. Consider rewriting this function to use the last move /// played, like in non-bitboard versions of Glaurung. void Position::find_checkers() { - checkersBB = attacks_to(king_square(side_to_move()),opposite_color(side_to_move())); + Color us = side_to_move(); + st->checkersBB = attacks_to(king_square(us), opposite_color(us)); } -/// Position::move_is_legal() tests whether a pseudo-legal move is legal. -/// There are two versions of this function: One which takes only a -/// move as input, and one which takes a move and a bitboard of pinned -/// pieces. The latter function is faster, and should always be preferred -/// when a pinned piece bitboard has already been computed. +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal -bool Position::move_is_legal(Move m) const { +bool Position::pl_move_is_legal(Move m) const { - return move_is_legal(m, pinned_pieces(side_to_move())); + // If we're in check, all pseudo-legal moves are legal, because our + // check evasion generator only generates true legal moves. + return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); } -bool Position::move_is_legal(Move m, Bitboard pinned) const { - - Color us, them; - Square ksq, from; +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())); - - // 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; + assert(!is_check()); // Castling moves are checked for legality during move generation. if (move_is_castle(m)) return true; - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - ksq = king_square(us); + Color us = side_to_move(); + Square from = move_from(m); + Square ksq = king_square(us); assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == king_of_color(us)); + assert(piece_on(ksq) == piece_of_color_and_type(us, KING)); // En passant captures are a tricky special case. Because they are // rather uncommon, we do it simply by testing whether the king is attacked // after the move is made if (move_is_ep(m)) { + Color them = opposite_color(us); Square to = move_to(m); Square capsq = make_square(square_file(to), square_rank(from)); Bitboard b = occupied_squares(); assert(to == ep_square()); - assert(piece_on(from) == pawn_of_color(us)); - assert(piece_on(capsq) == pawn_of_color(them)); + assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); + assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN)); assert(piece_on(to) == EMPTY); clear_bit(&b, from); @@ -518,23 +510,17 @@ bool Position::move_is_legal(Move m, Bitboard pinned) 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. - if ( !bit_is_set(pinned, from) - || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))) - return true; - - return false; + return ( !pinned + || !bit_is_set(pinned, from) + || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))); } -/// Position::move_is_check() tests whether a pseudo-legal move is a check. -/// There are two versions of this function: One which takes only a move as -/// input, and one which takes a move and a bitboard of discovered check -/// candidates. The latter function is faster, and should always be preferred -/// when a discovered check candidates bitboard has already been computed. +/// Position::move_is_check() tests whether a pseudo-legal move is a check bool Position::move_is_check(Move m) const { @@ -544,40 +530,38 @@ bool Position::move_is_check(Move m) const { bool Position::move_is_check(Move m, Bitboard dcCandidates) const { - Color us, them; - Square ksq, from, to; - assert(is_ok()); assert(move_is_ok(m)); assert(dcCandidates == discovered_check_candidates(side_to_move())); - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - ksq = king_square(them); + 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); assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == king_of_color(them)); + assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); // Proceed according to the type of the moving piece switch (type_of_piece_on(from)) { case PAWN: - + 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; - - if (move_promotion(m)) // Promotion with check? + + if (move_is_promotion(m)) // Promotion with check? { Bitboard b = occupied_squares(); clear_bit(&b, from); - switch (move_promotion(m)) + switch (move_promotion_piece(m)) { case KNIGHT: return bit_is_set(piece_attacks(to), ksq); @@ -607,22 +591,24 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { } return false; - case KNIGHT: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + // Test discovered check and normal check according to piece type + case KNIGHT: + 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? + assert(!bit_is_set(dcCandidates, from)); + 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? @@ -654,286 +640,306 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { } return false; - default: - assert(false); + default: // NO_PIECE_TYPE + break; } assert(false); return false; } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. +/// Position::update_checkers() udpates chekers info given the move. It is called +/// in do_move() and is faster then find_checkers(). -bool Position::move_is_capture(Move m) const { +template +inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, + Square to, Bitboard dcCandidates) { - return color_of_piece_on(move_to(m)) == opposite_color(side_to_move()) - || 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 { - - u.castleRights = castleRights; - u.epSquare = epSquare; - u.checkersBB = checkersBB; - u.key = key; - u.pawnKey = pawnKey; - u.materialKey = materialKey; - u.rule50 = rule50; - u.lastMove = lastMove; - u.capture = NO_PIECE_TYPE; - u.mgValue = mgValue; - u.egValue = egValue; -} + 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); -/// Position::restore() is called when unmaking a move. It copies back -/// the information backed up during a previous call to Position::backup. + else if ( Piece != KING + && !Slider + && bit_is_set(piece_attacks(ksq), to)) + set_bit(pCheckersBB, to); -void Position::restore(const UndoInfo& u) { + // Discovery checks + if (Piece != QUEEN && bit_is_set(dcCandidates, from)) + { + if (Piece != ROOK) + (*pCheckersBB) |= (piece_attacks(ksq) & rooks_and_queens(side_to_move())); - castleRights = u.castleRights; - epSquare = u.epSquare; - checkersBB = u.checkersBB; - key = u.key; - pawnKey = u.pawnKey; - materialKey = u.materialKey; - rule50 = u.rule50; - lastMove = u.lastMove; - // u.capture is restored in undo_move() - mgValue = u.mgValue; - egValue = u.egValue; + if (Piece != BISHOP) + (*pCheckersBB) |= (piece_attacks(ksq) & bishops_and_queens(side_to_move())); + } } -/// 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. -/// There are two versions of this function, one which takes only the move and -/// the UndoInfo as input, and one which takes a third parameter, a bitboard of -/// discovered check candidates. The second version is faster, because knowing -/// the discovered check candidates makes it easier to update the checkersBB -/// member variable in the position object. -void Position::do_move(Move m, UndoInfo& u) { +void Position::do_move(Move m, StateInfo& newSt) { - do_move(m, u, discovered_check_candidates(side_to_move())); + do_move(m, newSt, discovered_check_candidates(side_to_move())); } -void Position::do_move(Move m, UndoInfo& u, Bitboard dcCandidates) { +void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { assert(is_ok()); assert(move_is_ok(m)); - // Back up the necessary information to our UndoInfo object (except the - // captured piece, which is taken care of later. - backup(u); + // 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]; + }; + + 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++; + st->rule50++; + + // Update side to move + st->key ^= zobSideToMove; if (move_is_castle(m)) do_castle_move(m); - else if (move_promotion(m)) - do_promotion_move(m, u); - else if (move_is_ep(m)) - do_ep_move(m); else { Color us = side_to_move(); Color them = opposite_color(us); Square from = move_from(m); Square to = move_to(m); + bool ep = move_is_ep(m); + bool pm = move_is_promotion(m); - assert(color_of_piece_on(from) == us); - 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); + Piece piece = piece_on(from); + PieceType pt = type_of_piece(piece); - if (capture) - { - assert(capture != KING); - - // Remove captured piece - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); - - // Update hash key - key ^= zobrist[them][capture][to]; - - // If the captured piece was a pawn, update pawn hash key - if (capture == PAWN) - pawnKey ^= zobrist[them][PAWN][to]; - - // Update incremental scores - mgValue -= mg_pst(them, capture, to); - egValue -= eg_pst(them, capture, to); - - // Update material - if (capture != PAWN) - npMaterial[them] -= piece_value_midgame(capture); + assert(color_of_piece_on(from) == us); + assert(color_of_piece_on(to) == them || square_is_empty(to)); + assert(!(ep || pm) || piece == piece_of_color_and_type(us, PAWN)); + assert(!pm || relative_rank(us, to) == RANK_8); - // Update material hash key - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + st->capture = ep ? PAWN : type_of_piece_on(to); - // Update piece count - pieceCount[them][capture]--; + if (st->capture) + do_capture_move(st->capture, them, to, ep); - // Update piece list - pieceList[them][capture][index[to]] = pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; + // Update hash key + st->key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; - // Remember the captured piece, in order to be able to undo the move correctly - u.capture = capture; + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; + } - // Reset rule 50 counter - rule50 = 0; + // 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]; } + // Prefetch TT access as soon as we know key is updated + TT.prefetch(st->key); + // 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[pt]), 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]; - - // 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); + // If the moving piece was a pawn do some special extra work + if (pt == PAWN) + { + // Reset rule 50 draw counter + st->rule50 = 0; - // If the moving piece was a king, update the king square - if (piece == KING) - kingSquare[us] = to; + // Update pawn hash key + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - // If the move was a double pawn push, set the en passant square. - // This code is a bit ugly right now, and should be cleaned up later. - // FIXME - if (epSquare != SQ_NONE) - { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; - } - if (piece == PAWN) - { + // Set en passant square, only if moved pawn can be captured if (abs(int(to) - int(from)) == 16) { - if( ( us == WHITE - && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK))) - || ( us == BLACK - && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE)))) + 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]; } } - // Reset rule 50 draw counter - rule50 = 0; - - // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; } + + // Update incremental scores + st->mgValue += pst_delta(piece, from, to); + st->egValue += pst_delta(piece, from, to); + + // If the moving piece was a king, update the king square + if (pt == KING) + kingSquare[us] = to; + // Update piece lists - pieceList[us][piece][index[from]] = to; + pieceList[us][pt][index[from]] = to; index[to] = index[from]; - // Update castle rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[from]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; + if (pm) + { + PieceType promotion = move_promotion_piece(m); + + assert(promotion >= KNIGHT && promotion <= QUEEN); - // Update checkers bitboard - checkersBB = EmptyBoardBB; - Square ksq = king_square(them); - switch (piece) + // Insert promoted piece instead of pawn + clear_bit(&(byTypeBB[PAWN]), to); + set_bit(&(byTypeBB[promotion]), to); + board[to] = piece_of_color_and_type(us, promotion); + + // Partially revert hash keys update + st->key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; + st->pawnKey ^= zobrist[us][PAWN][to]; + + // Update material key + st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; + st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; + + // Update piece counts + pieceCount[us][PAWN]--; + pieceCount[us][promotion]++; + + // Update piece lists + pieceList[us][PAWN][index[from]] = pieceList[us][PAWN][pieceCount[us][PAWN]]; + index[pieceList[us][PAWN][index[from]]] = index[from]; + pieceList[us][promotion][pieceCount[us][promotion] - 1] = to; + index[to] = pieceCount[us][promotion] - 1; + + // Partially revert and update incremental scores + st->mgValue -= pst(us, PAWN, to); + st->mgValue += pst(us, promotion, to); + st->egValue -= pst(us, PAWN, to); + st->egValue += pst(us, promotion, to); + + // Update material + st->npMaterial[us] += piece_value_midgame(promotion); + } + + // Update checkers bitboard, piece must be already moved + if (ep || pm) + st->checkersBB = attacks_to(king_square(them), us); + else { - case PAWN: - if (bit_is_set(pawn_attacks(them, ksq), to)) - set_bit(&checkersBB, to); - - if (bit_is_set(dcCandidates, from)) - checkersBB |= ( (piece_attacks(ksq) & rooks_and_queens(us)) - |(piece_attacks(ksq) & bishops_and_queens(us))); - break; - - case KNIGHT: - if (bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - - if (bit_is_set(dcCandidates, from)) - checkersBB |= ( (piece_attacks(ksq) & rooks_and_queens(us)) - |(piece_attacks(ksq) & bishops_and_queens(us))); - break; - - case BISHOP: - if (bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - - if (bit_is_set(dcCandidates, from)) - checkersBB |= (piece_attacks(ksq) & rooks_and_queens(us)); - break; - - case ROOK: - if (bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - - if (bit_is_set(dcCandidates, from)) - checkersBB |= (piece_attacks(ksq) & bishops_and_queens(us)); - break; - - case QUEEN: - if (bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - break; - - case KING: - if (bit_is_set(dcCandidates, from)) - checkersBB |= ( (piece_attacks(ksq) & rooks_and_queens(us)) - |(piece_attacks(ksq) & bishops_and_queens(us))); - break; - - default: - assert(false); - break; + st->checkersBB = EmptyBoardBB; // FIXME EP ? + Square ksq = king_square(them); + switch (pt) + { + 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; 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()); } +/// 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(PieceType capture, Color them, Square to, bool ep) { + + assert(capture != KING); + + Square capsq = to; + + if (ep) + { + capsq = (them == BLACK)? (to - DELTA_N) : (to - DELTA_S); + + assert(to == st->epSquare); + assert(relative_rank(opposite_color(them), 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)); + + board[capsq] = EMPTY; + } + + // Remove captured piece + clear_bit(&(byColorBB[them]), capsq); + clear_bit(&(byTypeBB[capture]), capsq); + clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares + + // Update hash key + st->key ^= zobrist[them][capture][capsq]; + + // If the captured piece was a pawn, update pawn hash key + if (capture == PAWN) + st->pawnKey ^= zobrist[them][PAWN][capsq]; + + // Update incremental scores + st->mgValue -= pst(them, capture, capsq); + st->egValue -= pst(them, capture, capsq); + + // Update material + if (capture != PAWN) + st->npMaterial[them] -= piece_value_midgame(capture); + + // Update material hash key + st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + + // Update piece count + pieceCount[them][capture]--; + + // Update piece list + pieceList[them][capture][index[capsq]] = pieceList[them][capture][pieceCount[them][capture]]; + index[pieceList[them][capture][index[capsq]]] = index[capsq]; + + // Reset rule 50 counter + st->rule50 = 0; +} + + /// Position::do_castle_move() is a private method used to make a castling -/// move. It is called from the main Position::do_move function. Note that +/// move. It is called from the main Position::do_move function. Note that /// castling moves are encoded as "king captures friendly rook" moves, for /// instance white short castling in a non-Chess960 game is encoded as e1h1. @@ -951,8 +957,8 @@ void Position::do_castle_move(Move m) { Square rfrom = move_to(m); // HACK: See comment at beginning of function Square kto, rto; - assert(piece_on(kfrom) == king_of_color(us)); - assert(piece_on(rfrom) == rook_of_color(us)); + assert(piece_on(kfrom) == piece_of_color_and_type(us, KING)); + assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK)); // Find destination squares for king and rook if (rfrom > kfrom) // O-O @@ -964,26 +970,23 @@ void Position::do_castle_move(Move m) { rto = relative_square(us, SQ_D1); } - // Remove pieces from source squares - clear_bit(&(byColorBB[us]), kfrom); - clear_bit(&(byTypeBB[KING]), kfrom); - clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rfrom); - clear_bit(&(byTypeBB[ROOK]), rfrom); - clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on destination squares - set_bit(&(byColorBB[us]), kto); - set_bit(&(byTypeBB[KING]), kto); - set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rto); - set_bit(&(byTypeBB[ROOK]), rto); - set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares + // Move the pieces + Bitboard kmove_bb = make_move_bb(kfrom, kto); + do_move_bb(&(byColorBB[us]), kmove_bb); + do_move_bb(&(byTypeBB[KING]), kmove_bb); + do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares + + Bitboard rmove_bb = make_move_bb(rfrom, rto); + do_move_bb(&(byColorBB[us]), rmove_bb); + do_move_bb(&(byTypeBB[ROOK]), rmove_bb); + do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares // Update board array + Piece king = piece_of_color_and_type(us, KING); + Piece rook = piece_of_color_and_type(us, ROOK); board[kfrom] = board[rfrom] = EMPTY; - board[kto] = king_of_color(us); - board[rto] = rook_of_color(us); + board[kto] = king; + board[rto] = rook; // Update king square kingSquare[us] = kto; @@ -996,252 +999,39 @@ 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_delta(king, kfrom, kto); + st->egValue += pst_delta(king, kfrom, kto); + st->mgValue += pst_delta(rook, rfrom, rto); + st->egValue += pst_delta(rook, rfrom, 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). +/// 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. -void Position::do_promotion_move(Move m, UndoInfo &u) { - - Color us, them; - Square from, to; - PieceType capture, promotion; - - assert(is_ok()); - assert(move_is_ok(m)); - assert(move_promotion(m)); - - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == pawn_of_color(us)); - assert(color_of_piece_on(to) == them || square_is_empty(to)); - - capture = type_of_piece_on(to); - - if (capture) - { - assert(capture != KING); - - // Remove captured piece - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); - - // Update hash key - key ^= zobrist[them][capture][to]; - - // Update incremental scores - mgValue -= mg_pst(them, capture, to); - egValue -= eg_pst(them, capture, to); - - // Update material. Because our move is a promotion, we know that the - // captured piece is not a pawn. - assert(capture != PAWN); - npMaterial[them] -= piece_value_midgame(capture); - - // Update material hash key - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; - - // Update piece count - pieceCount[them][capture]--; - - // Update piece list - pieceList[them][capture][index[to]] = pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; - - // Remember the captured piece, in order to be able to undo the move correctly - u.capture = capture; - } - - // Remove pawn - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = EMPTY; - - // Insert promoted piece - promotion = move_promotion(m); - assert(promotion >= KNIGHT && promotion <= QUEEN); - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[promotion]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(us, promotion); - - // Update hash key - key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; - - // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from]; - - // Update material key - materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; - materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; - - // Update piece counts - pieceCount[us][PAWN]--; - pieceCount[us][promotion]++; - - // Update piece lists - pieceList[us][PAWN][index[from]] = pieceList[us][PAWN][pieceCount[us][PAWN]]; - index[pieceList[us][PAWN][index[from]]] = index[from]; - pieceList[us][promotion][pieceCount[us][promotion] - 1] = to; - index[to] = pieceCount[us][promotion] - 1; - - // Update incremental scores - mgValue -= mg_pst(us, PAWN, from); - mgValue += mg_pst(us, promotion, to); - egValue -= eg_pst(us, PAWN, from); - egValue += eg_pst(us, promotion, to); - - // Update material - npMaterial[us] += piece_value_midgame(promotion); - - // Clear the en passant square - if (epSquare != SQ_NONE) - { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; - } - - // Update castle rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; - - // Reset rule 50 counter - rule50 = 0; - - // Update checkers BB - checkersBB = attacks_to(king_square(them), us); -} - - -/// Position::do_ep_move() is a private method used to make an en passant -/// capture. It is called from the main Position::do_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object in which to store the captured piece. - -void Position::do_ep_move(Move m) { - - Color us, them; - Square from, to, capsq; - - assert(is_ok()); - assert(move_is_ok(m)); - assert(move_is_ep(m)); - - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == EMPTY); - assert(piece_on(from) == pawn_of_color(us)); - assert(piece_on(capsq) == pawn_of_color(them)); - - // Remove captured piece - clear_bit(&(byColorBB[them]), capsq); - clear_bit(&(byTypeBB[PAWN]), capsq); - clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares - board[capsq] = EMPTY; - - // Remove moving piece from source square - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - - // Put moving piece on destination square - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[PAWN]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = board[from]; - board[from] = EMPTY; - - // Update material hash key - materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; - - // Update piece count - pieceCount[them][PAWN]--; - - // Update piece list - pieceList[us][PAWN][index[from]] = to; - index[to] = index[from]; - pieceList[them][PAWN][index[capsq]] = pieceList[them][PAWN][pieceCount[them][PAWN]]; - index[pieceList[them][PAWN][index[capsq]]] = index[capsq]; - - // Update hash key - key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - key ^= zobrist[them][PAWN][capsq]; - key ^= zobEp[epSquare]; - - // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - pawnKey ^= zobrist[them][PAWN][capsq]; - - // Update incremental scores - mgValue -= 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); - - // Reset en passant square - epSquare = SQ_NONE; - - // Reset rule 50 counter - rule50 = 0; - - // Update checkers BB - 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. - -void Position::undo_move(Move m, const UndoInfo &u) { +void Position::undo_move(Move m) { assert(is_ok()); assert(move_is_ok(m)); @@ -1249,41 +1039,57 @@ 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); - else if (move_is_ep(m)) - undo_ep_move(m); else { - Color us, them; - Square from, to; - PieceType piece, capture; + Color us = side_to_move(); + Color them = opposite_color(us); + Square from = move_from(m); + Square to = move_to(m); + bool ep = move_is_ep(m); + bool pm = move_is_promotion(m); - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); + PieceType piece = type_of_piece_on(to); - assert(piece_on(from) == EMPTY); + assert(square_is_empty(from)); assert(color_of_piece_on(to) == us); + assert(!pm || relative_rank(us, to) == RANK_8); + assert(!ep || to == st->previous->epSquare); + assert(!ep || relative_rank(us, to) == RANK_6); + assert(!ep || piece_on(to) == piece_of_color_and_type(us, PAWN)); + + if (pm) + { + PieceType promotion = move_promotion_piece(m); + + assert(piece_on(to) == piece_of_color_and_type(us, promotion)); + assert(promotion >= KNIGHT && promotion <= QUEEN); + + // Replace promoted piece with a pawn + clear_bit(&(byTypeBB[promotion]), to); + set_bit(&(byTypeBB[PAWN]), to); + + // Update piece list replacing promotion piece with a pawn + pieceList[us][promotion][index[to]] = pieceList[us][promotion][pieceCount[us][promotion] - 1]; + index[pieceList[us][promotion][index[to]]] = index[to]; + pieceList[us][PAWN][pieceCount[us][PAWN]] = to; + index[to] = pieceCount[us][PAWN]; + + // Update piece counts + pieceCount[us][promotion]--; + pieceCount[us][PAWN]++; + + piece = PAWN; + } // Put the piece back at the source square - 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 + Bitboard move_bb = make_move_bb(to, from); + 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 + board[to] = EMPTY; // If the moving piece was a king, update the king square if (piece == KING) @@ -1293,32 +1099,34 @@ 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); + Square capsq = to; + + if (ep) + capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - // Replace the captured piece - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); - set_bit(&(byTypeBB[0]), to); - board[to] = piece_of_color_and_type(them, capture); + assert(st->capture != KING); + assert(!ep || square_is_empty(capsq)); - // Update material - if (capture != PAWN) - npMaterial[them] += piece_value_midgame(capture); + // Restore the captured piece + set_bit(&(byColorBB[them]), capsq); + set_bit(&(byTypeBB[st->capture]), capsq); + set_bit(&(byTypeBB[0]), capsq); + board[capsq] = 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]] = capsq; + index[capsq] = pieceCount[them][st->capture]; // Update piece count - pieceCount[them][capture]++; - } else - board[to] = EMPTY; + pieceCount[them][st->capture]++; + } } + // Finally point our state pointer back to the previous state + st = st->previous; + assert(is_ok()); } @@ -1337,7 +1145,6 @@ void Position::undo_castle_move(Move m) { // Position::undo_move. In particular, the side to move has been switched, // so the code below is correct. Color us = side_to_move(); - Color them = opposite_color(us); // Find source squares for king and rook Square kfrom = move_from(m); @@ -1354,29 +1161,24 @@ void Position::undo_castle_move(Move m) { rto = relative_square(us, SQ_D1); } - assert(piece_on(kto) == king_of_color(us)); - assert(piece_on(rto) == rook_of_color(us)); - - // Remove pieces from destination squares - clear_bit(&(byColorBB[us]), kto); - clear_bit(&(byTypeBB[KING]), kto); - clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rto); - clear_bit(&(byTypeBB[ROOK]), rto); - clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on source squares - set_bit(&(byColorBB[us]), kfrom); - set_bit(&(byTypeBB[KING]), kfrom); - set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rfrom); - set_bit(&(byTypeBB[ROOK]), rfrom); - set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares + assert(piece_on(kto) == piece_of_color_and_type(us, KING)); + assert(piece_on(rto) == piece_of_color_and_type(us, ROOK)); + + // Put the pieces back at the source square + Bitboard kmove_bb = make_move_bb(kto, kfrom); + do_move_bb(&(byColorBB[us]), kmove_bb); + do_move_bb(&(byTypeBB[KING]), kmove_bb); + do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares + + Bitboard rmove_bb = make_move_bb(rto, rfrom); + do_move_bb(&(byColorBB[us]), rmove_bb); + do_move_bb(&(byTypeBB[ROOK]), rmove_bb); + do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares // Update board board[rto] = board[kto] = EMPTY; - board[rfrom] = rook_of_color(us); - board[kfrom] = king_of_color(us); + board[rfrom] = piece_of_color_and_type(us, ROOK); + board[kfrom] = piece_of_color_and_type(us, KING); // Update king square kingSquare[us] = kfrom; @@ -1390,171 +1192,42 @@ 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). - -void Position::undo_promotion_move(Move m, const UndoInfo &u) { - - Color us, them; - Square from, to; - PieceType capture, promotion; - - assert(move_is_ok(m)); - assert(move_promotion(m)); - - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == EMPTY); - - // Remove promoted piece - promotion = move_promotion(m); - assert(piece_on(to)==piece_of_color_and_type(us, promotion)); - assert(promotion >= KNIGHT && promotion <= QUEEN); - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[promotion]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - - // Insert pawn at source square - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = pawn_of_color(us); - - // Update material - npMaterial[us] -= piece_value_midgame(promotion); - - // Update piece list - pieceList[us][PAWN][pieceCount[us][PAWN]] = from; - index[from] = pieceCount[us][PAWN]; - pieceList[us][promotion][index[to]] = - pieceList[us][promotion][pieceCount[us][promotion] - 1]; - index[pieceList[us][promotion][index[to]]] = index[to]; - - // Update piece counts - pieceCount[us][promotion]--; - pieceCount[us][PAWN]++; - - capture = u.capture; - - if (capture) - { - assert(capture != KING); - - // Insert captured piece: - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(them, capture); - - // Update material. Because the move is a promotion move, we know - // that the captured piece cannot be a pawn. - assert(capture != PAWN); - npMaterial[them] += piece_value_midgame(capture); - - // Update piece list - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; - - // Update piece count - pieceCount[them][capture]++; - } else - board[to] = EMPTY; -} - - -/// Position::undo_ep_move() is a private method used to unmake an en passant -/// capture. It is called from the main Position::undo_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object from which to retrieve the captured piece. - -void Position::undo_ep_move(Move m) { - - assert(move_is_ok(m)); - assert(move_is_ep(m)); - - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); - Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == ep_square()); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == pawn_of_color(us)); - assert(piece_on(from) == EMPTY); - assert(piece_on(capsq) == EMPTY); - - // Replace captured piece - set_bit(&(byColorBB[them]), capsq); - set_bit(&(byTypeBB[PAWN]), capsq); - set_bit(&(byTypeBB[0]), capsq); - board[capsq] = pawn_of_color(them); - - // Remove moving piece from destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[PAWN]), to); - clear_bit(&(byTypeBB[0]), to); - board[to] = EMPTY; - - // Replace moving piece at source square - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); - board[from] = pawn_of_color(us); - - // Update piece list: - pieceList[us][PAWN][index[to]] = from; - index[from] = index[to]; - pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; - index[capsq] = pieceCount[them][PAWN]; - - // Update piece count: - pieceCount[them][PAWN]++; -} - - /// Position::do_null_move makes() a "null move": It switches the side to move /// and updates the hash key without executing any move on the board. -void Position::do_null_move(UndoInfo &u) { +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->key ^= zobSideToMove; + TT.prefetch(st->key); + sideToMove = opposite_color(sideToMove); + st->epSquare = SQ_NONE; + st->rule50++; gamePly++; - 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()); } @@ -1562,35 +1235,38 @@ 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 two versions of -/// this function: One which takes a move as input, and one which takes a -/// 'from' and a 'to' square. The function does not yet understand promotions -/// or en passant captures. +/// 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. + +int Position::see(Square to) const { + + assert(square_is_ok(to)); + return see(SQ_NONE, to); +} int Position::see(Move m) const { @@ -1598,20 +1274,40 @@ int Position::see(Move m) const { return see(move_from(m), move_to(m)); } +int Position::see_sign(Move m) const { + + assert(move_is_ok(m)); + + Square from = move_from(m); + Square to = move_to(m); + + // Early return if SEE cannot be negative because capturing piece value + // is not bigger then captured one. + if ( midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to) + && type_of_piece_on(from) != KING) + return 1; + + return see(from, to); +} + int Position::see(Square from, Square to) const { - // Approximate material values, with pawn = 1 + // Material values static const int seeValues[18] = { - 0, 1, 3, 3, 5, 10, 100, 0, 0, 1, 3, 3, 5, 10, 100, 0, 0, 0 + 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0, + 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0, + 0, 0 }; - Bitboard attackers, occ, b; + Bitboard attackers, stmAttackers, occ, b; - assert(square_is_ok(from)); + assert(square_is_ok(from) || from == SQ_NONE); assert(square_is_ok(to)); // Initialize colors - Color us = color_of_piece_on(from); + Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to))); Color them = opposite_color(us); // Initialize pieces @@ -1621,24 +1317,58 @@ int Position::see(Square from, Square to) const { // Find all attackers to the destination square, with the moving piece // removed, but possibly an X-ray attacker added behind it. occ = occupied_squares(); - clear_bit(&occ, from); - attackers = (rook_attacks_bb(to, occ) & rooks_and_queens()) - | (bishop_attacks_bb(to, occ) & bishops_and_queens()) - | (piece_attacks(to) & knights()) - | (piece_attacks(to) & kings()) - | (pawn_attacks(WHITE, to) & pawns(BLACK)) - | (pawn_attacks(BLACK, to) & pawns(WHITE)); - - attackers &= occ; // Re-add removed piece - - // If the opponent has no attackers, we are finished - if ((attackers & pieces_of_color(them)) == EmptyBoardBB) + + // Handle en passant moves + 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 + clear_bit(&occ, capQq); + } + + while (true) + { + clear_bit(&occ, from); + attackers = (rook_attacks_bb(to, occ) & rooks_and_queens()) + | (bishop_attacks_bb(to, occ) & bishops_and_queens()) + | (piece_attacks(to) & knights()) + | (piece_attacks(to) & kings()) + | (pawn_attacks(WHITE, to) & pawns(BLACK)) + | (pawn_attacks(BLACK, to) & pawns(WHITE)); + + if (from != SQ_NONE) + break; + + // If we don't have any attacker we are finished + if ((attackers & pieces_of_color(us)) == EmptyBoardBB) + return 0; + + // Locate the least valuable attacker to the destination square + // and use it to initialize from square. + PieceType pt; + for (pt = PAWN; !(attackers & pieces_of_color_and_type(us, pt)); pt++) + assert(pt < KING); + + from = first_1(attackers & pieces_of_color_and_type(us, pt)); + piece = piece_on(from); + } + + // If the opponent has no attackers we are finished + stmAttackers = attackers & pieces_of_color(them); + if (!stmAttackers) return seeValues[capture]; + attackers &= occ; // Remove the moving piece + // The destination square is defended, which makes things rather more // difficult to compute. We proceed by building up a "swap list" containing // the material gain or loss at each stop in a sequence of captures to the - // destianation square, where the sides alternately capture, and always + // 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. int lastCapturingPieceValue = seeValues[piece]; @@ -1649,16 +1379,16 @@ 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()); @@ -1673,15 +1403,16 @@ 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 @@ -1692,19 +1423,33 @@ 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++) { @@ -1714,22 +1459,15 @@ void Position::clear() { pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; } - checkersBB = 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; } -/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the +/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the /// UCI interface code, whenever a non-reversible move is made in a /// 'position fen moves m1 m2 ...' command. This makes it possible /// for the program to handle games of arbitrary length, as long as the GUI @@ -1769,7 +1507,7 @@ void Position::put_piece(Piece p, Square s) { void Position::allow_oo(Color c) { - castleRights |= (1 + int(c)); + st->castleRights |= (1 + int(c)); } @@ -1778,7 +1516,7 @@ void Position::allow_oo(Color c) { void Position::allow_ooo(Color c) { - castleRights |= (4 + 4*int(c)); + st->castleRights |= (4 + 4*int(c)); } @@ -1798,7 +1536,7 @@ 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; @@ -1806,7 +1544,7 @@ Key Position::compute_key() const { } -/// Position::compute_pawn_key() computes the hash key of the position. The +/// Position::compute_pawn_key() computes the hash key of the position. The /// hash key is usually updated incrementally as moves are made and unmade, /// the compute_pawn_key() function is only used when a new position is set /// up, and to verify the correctness of the pawn hash key when running in @@ -1851,13 +1589,12 @@ 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; @@ -1871,52 +1608,32 @@ 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; } /// Position::compute_non_pawn_material() computes the total non-pawn middle -/// game material score for the given side. Material scores are updated +/// game material score for the given side. Material scores are updated /// incrementally during the search, this function is only used while /// initializing a new Position object. Value Position::compute_non_pawn_material(Color c) const { Value result = Value(0); - Square s; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) { Bitboard b = 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); } } @@ -1924,24 +1641,8 @@ 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() { - - if (is_check()) - { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, MOVE_NONE, - MOVE_NONE, MOVE_NONE, 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 +/// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. bool Position::is_draw() const { @@ -1952,60 +1653,72 @@ 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; } @@ -2067,10 +1780,10 @@ void Position::init_piece_square_tables() { /// Position::flipped_copy() makes a copy of the input position, but with -/// the white and black sides reversed. This is only useful for debugging, +/// 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()); @@ -2105,24 +1818,24 @@ 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()); } @@ -2178,7 +1891,7 @@ bool Position::is_ok(int* failedStep) const { if (type_of_piece_on(s) == KING) kingCount[color_of_piece_on(s)]++; - if(kingCount[0] != 1 || kingCount[1] != 1) + if (kingCount[0] != 1 || kingCount[1] != 1) return false; } @@ -2195,7 +1908,7 @@ 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? @@ -2230,27 +1943,27 @@ 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; } @@ -2258,10 +1971,10 @@ 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; }