X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=a2ee64f81cc603e6e4a03dbbfbbc00afeb863aa6;hp=13010c1a43f49571193d745a144ad92a4867bb9d;hb=699bae632f283746a3eee15c0950fcdbca8a355e;hpb=f2e94d6d35c14b274ed29fb67475acea5adc285f diff --git a/src/position.cpp b/src/position.cpp index 13010c1a..a2ee64f8 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,6 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file) + Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -34,6 +34,8 @@ using std::string; +namespace Stockfish { + namespace Zobrist { Key psq[PIECE_NB][SQUARE_NB]; @@ -249,6 +251,8 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th set_castling_right(c, rsq); } + set_state(st); + // 4. En passant square. // Ignore if square is invalid or not on side to move relative rank 6. bool enpassant = false; @@ -262,12 +266,24 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th // a) side to move have a pawn threatening epSquare // b) there is an enemy pawn in front of epSquare // c) there is no piece on epSquare or behind epSquare + // d) enemy pawn didn't block a check of its own color by moving forward enpassant = pawn_attacks_bb(~sideToMove, st->epSquare) & pieces(sideToMove, PAWN) && (pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove))) - && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove)))); + && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove)))) + && ( file_of(square(sideToMove)) == file_of(st->epSquare) + || !(blockers_for_king(sideToMove) & (st->epSquare + pawn_push(~sideToMove)))); } - if (!enpassant) + // It's necessary for st->previous to be intialized in this way because legality check relies on its existence + if (enpassant) { + st->previous = new StateInfo(); + remove_piece(st->epSquare - pawn_push(sideToMove)); + st->previous->checkersBB = attackers_to(square(~sideToMove)) & pieces(sideToMove); + st->previous->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), st->previous->pinners[BLACK]); + st->previous->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), st->previous->pinners[WHITE]); + put_piece(make_piece(~sideToMove, PAWN), st->epSquare - pawn_push(sideToMove)); + } + else st->epSquare = SQ_NONE; // 5-6. Halfmove clock and fullmove number @@ -279,7 +295,6 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th chess960 = isChess960; thisThread = th; - set_state(st); st->accumulator.state[WHITE] = Eval::NNUE::INIT; st->accumulator.state[BLACK] = Eval::NNUE::INIT; @@ -393,7 +408,7 @@ Position& Position::set(const string& code, Color c, StateInfo* si) { /// Position::fen() returns a FEN representation of the position. In case of /// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function. -const string Position::fen() const { +string Position::fen() const { int emptyCnt; std::ostringstream ss; @@ -500,23 +515,11 @@ bool Position::legal(Move m) const { assert(color_of(moved_piece(m)) == us); assert(piece_on(square(us)) == make_piece(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 (type_of(m) == ENPASSANT) - { - Square ksq = square(us); - Square capsq = to - pawn_push(us); - Bitboard occupied = (pieces() ^ from ^ capsq) | to; - - assert(to == ep_square()); - assert(moved_piece(m) == make_piece(us, PAWN)); - assert(piece_on(capsq) == make_piece(~us, PAWN)); - assert(piece_on(to) == NO_PIECE); - - return !(attacks_bb< ROOK>(ksq, occupied) & pieces(~us, QUEEN, ROOK)) - && !(attacks_bb(ksq, occupied) & pieces(~us, QUEEN, BISHOP)); - } + // st->previous->blockersForKing consider capsq as empty. + // If pinned, it has to move along the king ray. + if (type_of(m) == EN_PASSANT) + return !(st->previous->blockersForKing[sideToMove] & from) + || aligned(from, to, square(us)); // Castling moves generation does not check if the castling path is clear of // enemy attacks, it is delayed at a later time: now! @@ -531,11 +534,9 @@ bool Position::legal(Move m) const { if (attackers_to(s) & pieces(~us)) return false; - // In case of Chess960, verify that when moving the castling rook we do - // not discover some hidden checker. + // In case of Chess960, verify if the Rook blocks some checks // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1. - return !chess960 - || !(attacks_bb(to, pieces() ^ to_sq(m)) & pieces(~us, ROOK, QUEEN)); + return !chess960 || !(blockers_for_king(us) & to_sq(m)); } // If the moving piece is a king, check whether the destination square is @@ -545,8 +546,8 @@ bool Position::legal(Move m) const { // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - return !(blockers_for_king(us) & from) - || aligned(from, to, square(us)); + return !(blockers_for_king(us) & from) + || aligned(from, to, square(us)); } @@ -562,8 +563,10 @@ bool Position::pseudo_legal(const Move m) const { Piece pc = moved_piece(m); // Use a slower but simpler function for uncommon cases + // yet we skip the legality check of MoveList(). if (type_of(m) != NORMAL) - return MoveList(*this).contains(m); + return checkers() ? MoveList< EVASIONS>(*this).contains(m) + : MoveList(*this).contains(m); // Is not a promotion, so promotion piece must be empty if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE) @@ -649,31 +652,24 @@ bool Position::gives_check(Move m) const { case PROMOTION: return attacks_bb(promotion_type(m), to, pieces() ^ from) & square(~sideToMove); - // En passant capture with check? We have already handled the case - // of direct checks and ordinary discovered check, so the only case we - // need to handle is the unusual case of a discovered check through - // the captured pawn. - case ENPASSANT: - { - Square capsq = make_square(file_of(to), rank_of(from)); - Bitboard b = (pieces() ^ from ^ capsq) | to; + // The double-pushed pawn blocked a check? En Passant will remove the blocker. + // The only discovery check that wasn't handle is through capsq and fromsq + // So the King must be in the same rank as fromsq to consider this possibility. + // st->previous->blockersForKing consider capsq as empty. + case EN_PASSANT: + return st->previous->checkersBB + || ( rank_of(square(~sideToMove)) == rank_of(from) + && st->previous->blockersForKing[~sideToMove] & from); - return (attacks_bb< ROOK>(square(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK)) - | (attacks_bb(square(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP)); - } - case CASTLING: + default: //CASTLING { - Square kfrom = from; - Square rfrom = to; // Castling is encoded as 'king captures the rook' - Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); - Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); + // Castling is encoded as 'king captures the rook' + Square ksq = square(~sideToMove); + Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1); - return (attacks_bb(rto) & square(~sideToMove)) - && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square(~sideToMove)); + return (attacks_bb(rto) & ksq) + && (attacks_bb(rto, pieces() ^ from ^ to) & ksq); } - default: - assert(false); - return false; } } @@ -714,7 +710,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { Square from = from_sq(m); Square to = to_sq(m); Piece pc = piece_on(from); - Piece captured = type_of(m) == ENPASSANT ? make_piece(them, PAWN) : piece_on(to); + Piece captured = type_of(m) == EN_PASSANT ? make_piece(them, PAWN) : piece_on(to); assert(color_of(pc) == us); assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us)); @@ -740,7 +736,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // update non-pawn material. if (type_of(captured) == PAWN) { - if (type_of(m) == ENPASSANT) + if (type_of(m) == EN_PASSANT) { capsq -= pawn_push(us); @@ -767,7 +763,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update board and piece lists remove_piece(capsq); - if (type_of(m) == ENPASSANT) + if (type_of(m) == EN_PASSANT) board[capsq] = NO_PIECE; // Update material hash key and prefetch access to materialTable @@ -813,7 +809,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // If the moving piece is a pawn do some special extra work if (type_of(pc) == PAWN) { - // Set en-passant square if the moved pawn can be captured + // Set en passant square if the moved pawn can be captured if ( (int(to) ^ int(from)) == 16 && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN))) { @@ -936,7 +932,7 @@ void Position::undo_move(Move m) { { Square capsq = to; - if (type_of(m) == ENPASSANT) + if (type_of(m) == EN_PASSANT) { capsq -= pawn_push(us); @@ -1015,7 +1011,7 @@ void Position::do_null_move(StateInfo& newSt) { } st->key ^= Zobrist::side; - prefetch(TT.first_entry(st->key)); + prefetch(TT.first_entry(key())); ++st->rule50; st->pliesFromNull = 0; @@ -1040,7 +1036,7 @@ void Position::undo_null_move() { /// Position::key_after() computes the new hash key after the given move. Needed /// for speculative prefetch. It doesn't recognize special moves like castling, -/// en-passant and promotions. +/// en passant and promotions. Key Position::key_after(Move m) const { @@ -1065,7 +1061,7 @@ bool Position::see_ge(Move m, Value threshold) const { assert(is_ok(m)); - // Only deal with normal moves, assume others pass a simple see + // Only deal with normal moves, assume others pass a simple SEE if (type_of(m) != NORMAL) return VALUE_ZERO >= threshold; @@ -1342,3 +1338,5 @@ bool Position::pos_is_ok() const { return true; } + +} // namespace Stockfish