X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=aeac23a33f4c2d631bb3367517d3e20c45911f61;hb=f0556dcbe3ba2fc804ab26d4552446602a75f064;hp=2b3be3f7767c267937514e18ed9ce46b92ee7b17;hpb=fbbd4adc3c01460faa3cc8f91771ab9b0ef718ca;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index 2b3be3f7..aeac23a3 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) 2004-2021 The Stockfish developers (see AUTHORS file) + Copyright (C) 2004-2023 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 @@ -22,6 +22,7 @@ #include // For std::memset, std::memcmp #include #include +#include #include "bitboard.h" #include "misc.h" @@ -46,7 +47,7 @@ namespace Zobrist { namespace { -const string PieceToChar(" PNBRQK pnbrqk"); +constexpr std::string_view PieceToChar(" PNBRQK pnbrqk"); constexpr Piece Pieces[] = { W_PAWN, W_KNIGHT, W_BISHOP, W_ROOK, W_QUEEN, W_KING, B_PAWN, B_KNIGHT, B_BISHOP, B_ROOK, B_QUEEN, B_KING }; @@ -96,7 +97,7 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { // Marcel van Kervinck's cuckoo algorithm for fast detection of "upcoming repetition" // situations. Description of the algorithm in the following paper: -// https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf +// http://web.archive.org/web/20201107002606/https://marcelk.net/2013-04-06/paper/upcoming-rep-v2.pdf // First and second hash functions for indexing the cuckoo tables inline int H1(Key h) { return h & 0x1fff; } @@ -129,7 +130,7 @@ void Position::init() { // Prepare the cuckoo tables std::memset(cuckoo, 0, sizeof(cuckoo)); std::memset(cuckooMove, 0, sizeof(cuckooMove)); - int count = 0; + [[maybe_unused]] int count = 0; for (Piece pc : Pieces) for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) for (Square s2 = Square(s1 + 1); s2 <= SQ_H8; ++s2) @@ -251,8 +252,6 @@ 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; @@ -266,24 +265,12 @@ 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)))) - && ( file_of(square(sideToMove)) == file_of(st->epSquare) - || !(blockers_for_king(sideToMove) & (st->epSquare + pawn_push(~sideToMove)))); + && !(pieces() & (st->epSquare | (st->epSquare + pawn_push(sideToMove)))); } - // 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 + if (!enpassant) st->epSquare = SQ_NONE; // 5-6. Halfmove clock and fullmove number @@ -295,8 +282,7 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th chess960 = isChess960; thisThread = th; - st->accumulator.state[WHITE] = Eval::NNUE::INIT; - st->accumulator.state[BLACK] = Eval::NNUE::INIT; + set_state(st); assert(pos_is_ok()); @@ -517,11 +503,23 @@ bool Position::legal(Move m) const { assert(color_of(moved_piece(m)) == us); assert(piece_on(square(us)) == make_piece(us, KING)); - // st->previous->blockersForKing consider capsq as empty. - // If pinned, it has to move along the king ray. + // 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) == EN_PASSANT) - return !(st->previous->blockersForKing[sideToMove] & from) - || aligned(from, to, square(us)); + { + 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)); + } // Castling moves generation does not check if the castling path is clear of // enemy attacks, it is delayed at a later time: now! @@ -571,8 +569,7 @@ bool Position::pseudo_legal(const Move m) const { : MoveList(*this).contains(m); // Is not a promotion, so promotion piece must be empty - if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE) - return false; + assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE); // If the 'from' square is not occupied by a piece belonging to the side to // move, the move is obviously not legal. @@ -654,15 +651,18 @@ bool Position::gives_check(Move m) const { case PROMOTION: return attacks_bb(promotion_type(m), to, pieces() ^ from) & square(~sideToMove); - // 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. + // 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 EN_PASSANT: - return st->previous->checkersBB - || ( rank_of(square(~sideToMove)) == rank_of(from) - && st->previous->blockersForKing[~sideToMove] & from); + { + Square capsq = make_square(file_of(to), rank_of(from)); + Bitboard b = (pieces() ^ from ^ capsq) | to; + return (attacks_bb< ROOK>(square(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK)) + | (attacks_bb(square(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP)); + } default: //CASTLING { // Castling is encoded as 'king captures the rook' @@ -702,8 +702,8 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { ++st->pliesFromNull; // Used by NNUE - st->accumulator.state[WHITE] = Eval::NNUE::EMPTY; - st->accumulator.state[BLACK] = Eval::NNUE::EMPTY; + st->accumulator.computed[WHITE] = false; + st->accumulator.computed[BLACK] = false; auto& dp = st->dirtyPiece; dp.dirty_num = 1; @@ -765,9 +765,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update board and piece lists remove_piece(capsq); - if (type_of(m) == EN_PASSANT) - board[capsq] = NO_PIECE; - // Update material hash key and prefetch access to materialTable k ^= Zobrist::psq[captured][capsq]; st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]]; @@ -988,7 +985,7 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ } -/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips +/// Position::do_null_move() is used to do a "null move": it flips /// the side to move without executing any move on the board. void Position::do_null_move(StateInfo& newSt) { @@ -1003,8 +1000,8 @@ void Position::do_null_move(StateInfo& newSt) { st->dirtyPiece.dirty_num = 0; st->dirtyPiece.piece[0] = NO_PIECE; // Avoid checks in UpdateAccumulator() - st->accumulator.state[WHITE] = Eval::NNUE::EMPTY; - st->accumulator.state[BLACK] = Eval::NNUE::EMPTY; + st->accumulator.computed[WHITE] = false; + st->accumulator.computed[BLACK] = false; if (st->epSquare != SQ_NONE) { @@ -1013,9 +1010,9 @@ void Position::do_null_move(StateInfo& newSt) { } st->key ^= Zobrist::side; + ++st->rule50; prefetch(TT.first_entry(key())); - ++st->rule50; st->pliesFromNull = 0; sideToMove = ~sideToMove; @@ -1027,6 +1024,9 @@ void Position::do_null_move(StateInfo& newSt) { assert(pos_is_ok()); } + +/// Position::undo_null_move() must be used to undo a "null move" + void Position::undo_null_move() { assert(!checkers()); @@ -1051,7 +1051,10 @@ Key Position::key_after(Move m) const { if (captured) k ^= Zobrist::psq[captured][to]; - return k ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from]; + k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from]; + + return (captured || type_of(pc) == PAWN) + ? k : adjust_key50(k); } @@ -1077,8 +1080,9 @@ bool Position::see_ge(Move m, Value threshold) const { if (swap <= 0) return true; + assert(color_of(piece_on(from)) == sideToMove); Bitboard occupied = pieces() ^ from ^ to; - Color stm = color_of(piece_on(from)); + Color stm = sideToMove; Bitboard attackers = attackers_to(to, occupied); Bitboard stmAttackers, bb; int res = 1; @@ -1092,13 +1096,15 @@ bool Position::see_ge(Move m, Value threshold) const { if (!(stmAttackers = attackers & pieces(stm))) break; - // Don't allow pinned pieces to attack (except the king) as long as - // there are pinners on their original square. + // Don't allow pinned pieces to attack as long as there are + // pinners on their original square. if (pinners(~stm) & occupied) + { stmAttackers &= ~blockers_for_king(stm); - if (!stmAttackers) - break; + if (!stmAttackers) + break; + } res ^= 1;