X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=2658c71a6e624eb2d431c357ed54b39623599abb;hp=42c1adff71591a270148adb43b37d2588cd2fe29;hb=2c097c81268e083f472bccfb47ecf56db3e3853e;hpb=ba4e215493de31263b9bd352af79d00193e545bf diff --git a/src/position.cpp b/src/position.cpp index 42c1adff..2658c71a 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,8 +1,6 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2004-2020 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 @@ -36,10 +34,6 @@ using std::string; -namespace PSQT { - extern Score psq[PIECE_NB][SQUARE_NB]; -} - namespace Zobrist { Key psq[PIECE_NB][SQUARE_NB]; @@ -52,38 +46,8 @@ namespace { const string PieceToChar(" PNBRQK pnbrqk"); -const 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 }; - -// min_attacker() is a helper function used by see_ge() to locate the least -// valuable attacker for the side to move, remove the attacker we just found -// from the bitboards and scan for new X-ray attacks behind it. - -template -PieceType min_attacker(const Bitboard* bb, Square to, Bitboard stmAttackers, - Bitboard& occupied, Bitboard& attackers) { - - Bitboard b = stmAttackers & bb[Pt]; - if (!b) - return min_attacker(bb, to, stmAttackers, occupied, attackers); - - occupied ^= b & ~(b - 1); - - if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) - attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); - - if (Pt == ROOK || Pt == QUEEN) - attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); - - attackers &= occupied; // After X-ray that may add already processed pieces - return (PieceType)Pt; -} - -template<> -PieceType min_attacker(const Bitboard*, Square, Bitboard, Bitboard&, Bitboard&) { - return KING; // No need to update bitboards: it is the last cycle -} - +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 }; } // namespace @@ -98,10 +62,11 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { for (File f = FILE_A; f <= FILE_H; ++f) os << " | " << PieceToChar[pos.piece_on(make_square(f, r))]; - os << " |\n +---+---+---+---+---+---+---+---+\n"; + os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n"; } - os << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase + os << " a b c d e f g h\n" + << "\nFen: " << pos.fen() << "\nKey: " << std::hex << std::uppercase << std::setfill('0') << std::setw(16) << pos.key() << std::setfill(' ') << std::dec << "\nCheckers: "; @@ -125,8 +90,20 @@ std::ostream& operator<<(std::ostream& os, const Position& pos) { } -/// Position::init() initializes at startup the various arrays used to compute -/// hash keys. +// 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 + +// First and second hash functions for indexing the cuckoo tables +inline int H1(Key h) { return h & 0x1fff; } +inline int H2(Key h) { return (h >> 16) & 0x1fff; } + +// Cuckoo tables with Zobrist hashes of valid reversible moves, and the moves themselves +Key cuckoo[8192]; +Move cuckooMove[8192]; + + +/// Position::init() initializes at startup the various arrays used to compute hash keys void Position::init() { @@ -140,18 +117,34 @@ void Position::init() { Zobrist::enpassant[f] = rng.rand(); for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr) - { - Zobrist::castling[cr] = 0; - Bitboard b = cr; - while (b) - { - Key k = Zobrist::castling[1ULL << pop_lsb(&b)]; - Zobrist::castling[cr] ^= k ? k : rng.rand(); - } - } + Zobrist::castling[cr] = rng.rand(); Zobrist::side = rng.rand(); Zobrist::noPawns = rng.rand(); + + // Prepare the cuckoo tables + std::memset(cuckoo, 0, sizeof(cuckoo)); + std::memset(cuckooMove, 0, sizeof(cuckooMove)); + 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) + if ((type_of(pc) != PAWN) && (attacks_bb(type_of(pc), s1, 0) & s2)) + { + Move move = make_move(s1, s2); + Key key = Zobrist::psq[pc][s1] ^ Zobrist::psq[pc][s2] ^ Zobrist::side; + int i = H1(key); + while (true) + { + std::swap(cuckoo[i], key); + std::swap(cuckooMove[i], move); + if (move == MOVE_NONE) // Arrived at empty slot? + break; + i = (i == H1(key)) ? H2(key) : H1(key); // Push victim to alternative slot + } + count++; + } + assert(count == 3668); } @@ -183,9 +176,9 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th 4) En passant target square (in algebraic notation). If there's no en passant target square, this is "-". If a pawn has just made a 2-square move, this - is the position "behind" the pawn. This is recorded only if there is a pawn - in position to make an en passant capture, and if there really is a pawn - that might have advanced two squares. + is the position "behind" the pawn. Following X-FEN standard, this is recorded only + if there is a pawn in position to make an en passant capture, and if there really + is a pawn that might have advanced two squares. 5) Halfmove clock. This is the number of halfmoves since the last pawn advance or capture. This is used to determine if a draw can be claimed under the @@ -211,13 +204,12 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th while ((ss >> token) && !isspace(token)) { if (isdigit(token)) - sq += Square(token - '0'); // Advance the given number of files + sq += (token - '0') * EAST; // Advance the given number of files else if (token == '/') - sq -= Square(16); + sq += 2 * SOUTH; - else if ((idx = PieceToChar.find(token)) != string::npos) - { + else if ((idx = PieceToChar.find(token)) != string::npos) { put_piece(Piece(idx), sq); ++sq; } @@ -256,17 +248,25 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th set_castling_right(c, rsq); } - // 4. En passant square. Ignore if no pawn capture is possible + // 4. En passant square. + // Ignore if square is invalid or not on side to move relative rank 6. + bool enpassant = false; + if ( ((ss >> col) && (col >= 'a' && col <= 'h')) - && ((ss >> row) && (row == '3' || row == '6'))) + && ((ss >> row) && (row == (sideToMove == WHITE ? '6' : '3')))) { st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); - if ( !(attackers_to(st->epSquare) & pieces(sideToMove, PAWN)) - || !(pieces(~sideToMove, PAWN) & (st->epSquare + pawn_push(~sideToMove)))) - st->epSquare = SQ_NONE; + // En passant square will be considered only if + // 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 + 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)))); } - else + + if (!enpassant) st->epSquare = SQ_NONE; // 5-6. Halfmove clock and fullmove number @@ -280,8 +280,6 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th thisThread = th; set_state(st); - assert(pos_is_ok()); - return *this; } @@ -292,24 +290,18 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th void Position::set_castling_right(Color c, Square rfrom) { Square kfrom = square(c); - CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; - CastlingRight cr = (c | cs); + CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE: QUEEN_SIDE); st->castlingRights |= cr; castlingRightsMask[kfrom] |= cr; castlingRightsMask[rfrom] |= cr; castlingRookSquare[cr] = rfrom; - Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); - Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); - - for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s) - if (s != kfrom && s != rfrom) - castlingPath[cr] |= s; + Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1); + Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1); - for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s) - if (s != kfrom && s != rfrom) - castlingPath[cr] |= s; + castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto) + & ~(kfrom | rfrom); } @@ -317,15 +309,15 @@ void Position::set_castling_right(Color c, Square rfrom) { void Position::set_check_info(StateInfo* si) const { - si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinnersForKing[WHITE]); - si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinnersForKing[BLACK]); + si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinners[BLACK]); + si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinners[WHITE]); Square ksq = square(~sideToMove); - si->checkSquares[PAWN] = attacks_from(ksq, ~sideToMove); - si->checkSquares[KNIGHT] = attacks_from(ksq); - si->checkSquares[BISHOP] = attacks_from(ksq); - si->checkSquares[ROOK] = attacks_from(ksq); + si->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq); + si->checkSquares[KNIGHT] = attacks_bb(ksq); + si->checkSquares[BISHOP] = attacks_bb(ksq, pieces()); + si->checkSquares[ROOK] = attacks_bb(ksq, pieces()); si->checkSquares[QUEEN] = si->checkSquares[BISHOP] | si->checkSquares[ROOK]; si->checkSquares[KING] = 0; } @@ -341,7 +333,6 @@ void Position::set_state(StateInfo* si) const { si->key = si->materialKey = 0; si->pawnKey = Zobrist::noPawns; si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; - si->psq = SCORE_ZERO; si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); set_check_info(si); @@ -351,7 +342,12 @@ void Position::set_state(StateInfo* si) const { Square s = pop_lsb(&b); Piece pc = piece_on(s); si->key ^= Zobrist::psq[pc][s]; - si->psq += PSQT::psq[pc][s]; + + if (type_of(pc) == PAWN) + si->pawnKey ^= Zobrist::psq[pc][s]; + + else if (type_of(pc) != KING) + si->nonPawnMaterial[color_of(pc)] += PieceValue[MG][pc]; } if (si->epSquare != SQ_NONE) @@ -362,20 +358,9 @@ void Position::set_state(StateInfo* si) const { si->key ^= Zobrist::castling[si->castlingRights]; - for (Bitboard b = pieces(PAWN); b; ) - { - Square s = pop_lsb(&b); - si->pawnKey ^= Zobrist::psq[piece_on(s)][s]; - } - for (Piece pc : Pieces) - { - if (type_of(pc) != PAWN && type_of(pc) != KING) - si->nonPawnMaterial[color_of(pc)] += pieceCount[pc] * PieceValue[MG][pc]; - for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) si->materialKey ^= Zobrist::psq[pc][cnt]; - } } @@ -385,11 +370,13 @@ void Position::set_state(StateInfo* si) const { Position& Position::set(const string& code, Color c, StateInfo* si) { - assert(code.length() > 0 && code.length() < 8); assert(code[0] == 'K'); string sides[] = { code.substr(code.find('K', 1)), // Weak - code.substr(0, code.find('K', 1)) }; // Strong + code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong + + assert(sides[0].length() > 0 && sides[0].length() < 8); + assert(sides[1].length() > 0 && sides[1].length() < 8); std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); @@ -429,18 +416,18 @@ const string Position::fen() const { ss << (sideToMove == WHITE ? " w " : " b "); if (can_castle(WHITE_OO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | KING_SIDE))) : 'K'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO ))) : 'K'); if (can_castle(WHITE_OOO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE))) : 'Q'); + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OOO))) : 'Q'); if (can_castle(BLACK_OO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | KING_SIDE))) : 'k'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OO ))) : 'k'); if (can_castle(BLACK_OOO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE))) : 'q'); + ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OOO))) : 'q'); - if (!can_castle(WHITE) && !can_castle(BLACK)) + if (!can_castle(ANY_CASTLING)) ss << '-'; ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ") @@ -459,26 +446,27 @@ const string Position::fen() const { Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const { - Bitboard result = 0; + Bitboard blockers = 0; pinners = 0; - // Snipers are sliders that attack 's' when a piece is removed - Bitboard snipers = ( (PseudoAttacks[ ROOK][s] & pieces(QUEEN, ROOK)) - | (PseudoAttacks[BISHOP][s] & pieces(QUEEN, BISHOP))) & sliders; + // Snipers are sliders that attack 's' when a piece and other snipers are removed + Bitboard snipers = ( (attacks_bb< ROOK>(s) & pieces(QUEEN, ROOK)) + | (attacks_bb(s) & pieces(QUEEN, BISHOP))) & sliders; + Bitboard occupancy = pieces() ^ snipers; while (snipers) { Square sniperSq = pop_lsb(&snipers); - Bitboard b = between_bb(s, sniperSq) & pieces(); + Bitboard b = between_bb(s, sniperSq) & occupancy; - if (!more_than_one(b)) + if (b && !more_than_one(b)) { - result |= b; + blockers |= b; if (b & pieces(color_of(piece_on(s)))) pinners |= sniperSq; } } - return result; + return blockers; } @@ -487,12 +475,12 @@ Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners Bitboard Position::attackers_to(Square s, Bitboard occupied) const { - return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) - | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) - | (attacks_from(s) & pieces(KNIGHT)) + return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN)) + | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN)) + | (attacks_bb(s) & pieces(KNIGHT)) | (attacks_bb< ROOK>(s, occupied) & pieces( ROOK, QUEEN)) | (attacks_bb(s, occupied) & pieces(BISHOP, QUEEN)) - | (attacks_from(s) & pieces(KING)); + | (attacks_bb(s) & pieces(KING)); } @@ -504,6 +492,7 @@ bool Position::legal(Move m) const { Color us = sideToMove; Square from = from_sq(m); + Square to = to_sq(m); assert(color_of(moved_piece(m)) == us); assert(piece_on(square(us)) == make_piece(us, KING)); @@ -514,7 +503,6 @@ bool Position::legal(Move m) const { if (type_of(m) == ENPASSANT) { Square ksq = square(us); - Square to = to_sq(m); Square capsq = to - pawn_push(us); Bitboard occupied = (pieces() ^ from ^ capsq) | to; @@ -527,16 +515,35 @@ bool Position::legal(Move m) const { && !(attacks_bb(ksq, occupied) & pieces(~us, QUEEN, BISHOP)); } - // If the moving piece is a king, check whether the destination - // square is attacked by the opponent. Castling moves are checked - // for legality during move generation. + // Castling moves generation does not check if the castling path is clear of + // enemy attacks, it is delayed at a later time: now! + if (type_of(m) == CASTLING) + { + // After castling, the rook and king final positions are the same in + // Chess960 as they would be in standard chess. + to = relative_square(us, to > from ? SQ_G1 : SQ_C1); + Direction step = to > from ? WEST : EAST; + + for (Square s = to; s != from; s += step) + 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. + // 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)); + } + + // If the moving piece is a king, check whether the destination square is + // attacked by the opponent. if (type_of(piece_on(from)) == KING) - return type_of(m) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us)); + return !(attackers_to(to) & pieces(~us)); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - return !(pinned_pieces(us) & from) - || aligned(from, to_sq(m), square(us)); + return !(blockers_for_king(us) & from) + || aligned(from, to, square(us)); } @@ -573,18 +580,18 @@ bool Position::pseudo_legal(const Move m) const { { // We have already handled promotion moves, so destination // cannot be on the 8th/1st rank. - if (rank_of(to) == relative_rank(us, RANK_8)) + if ((Rank8BB | Rank1BB) & to) return false; - if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture + if ( !(pawn_attacks_bb(us, from) & pieces(~us) & to) // Not a capture && !((from + pawn_push(us) == to) && empty(to)) // Not a single push && !( (from + 2 * pawn_push(us) == to) // Not a double push - && (rank_of(from) == relative_rank(us, RANK_2)) + && (relative_rank(us, from) == RANK_2) && empty(to) && empty(to - pawn_push(us)))) return false; } - else if (!(attacks_from(type_of(pc), from) & to)) + else if (!(attacks_bb(type_of(pc), from, pieces()) & to)) return false; // Evasions generator already takes care to avoid some kind of illegal moves @@ -623,11 +630,11 @@ bool Position::gives_check(Move m) const { Square to = to_sq(m); // Is there a direct check? - if (st->checkSquares[type_of(piece_on(from))] & to) + if (check_squares(type_of(piece_on(from))) & to) return true; // Is there a discovered check? - if ( (discovered_check_candidates() & from) + if ( (blockers_for_king(~sideToMove) & from) && !aligned(from, to, square(~sideToMove))) return true; @@ -654,11 +661,11 @@ bool Position::gives_check(Move m) const { case CASTLING: { Square kfrom = from; - Square rfrom = to; // Castling is encoded as 'King captures the rook' + 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); - return (PseudoAttacks[ROOK][rto] & square(~sideToMove)) + return (attacks_bb(rto) & square(~sideToMove)) && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square(~sideToMove)); } default: @@ -693,6 +700,11 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { ++st->rule50; ++st->pliesFromNull; + // Used by NNUE + st->accumulator.computed_accumulation = false; + auto& dp = st->dirtyPiece; + dp.dirty_num = 1; + Color us = sideToMove; Color them = ~us; Square from = from_sq(m); @@ -712,7 +724,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { Square rfrom, rto; do_castling(us, from, to, rfrom, rto); - st->psq += PSQT::psq[captured][rto] - PSQT::psq[captured][rfrom]; k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto]; captured = NO_PIECE; } @@ -734,8 +745,6 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(relative_rank(us, to) == RANK_6); assert(piece_on(to) == NO_PIECE); assert(piece_on(capsq) == make_piece(them, PAWN)); - - board[capsq] = NO_PIECE; // Not done by remove_piece() } st->pawnKey ^= Zobrist::psq[captured][capsq]; @@ -743,17 +752,25 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { else st->nonPawnMaterial[them] -= PieceValue[MG][captured]; + if (Eval::useNNUE) + { + dp.dirty_num = 2; // 1 piece moved, 1 piece captured + dp.piece[1] = captured; + dp.from[1] = capsq; + dp.to[1] = SQ_NONE; + } + // Update board and piece lists - remove_piece(captured, capsq); + remove_piece(capsq); + + if (type_of(m) == ENPASSANT) + 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]]; prefetch(thisThread->materialTable[st->materialKey]); - // Update incremental scores - st->psq -= PSQT::psq[captured][capsq]; - // Reset rule 50 counter st->rule50 = 0; } @@ -771,23 +788,32 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update castling rights if needed if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) { - int cr = castlingRightsMask[from] | castlingRightsMask[to]; - k ^= Zobrist::castling[st->castlingRights & cr]; - st->castlingRights &= ~cr; + k ^= Zobrist::castling[st->castlingRights]; + st->castlingRights &= ~(castlingRightsMask[from] | castlingRightsMask[to]); + k ^= Zobrist::castling[st->castlingRights]; } // Move the piece. The tricky Chess960 castling is handled earlier if (type_of(m) != CASTLING) - move_piece(pc, from, to); + { + if (Eval::useNNUE) + { + dp.piece[0] = pc; + dp.from[0] = from; + dp.to[0] = to; + } + + move_piece(from, to); + } // 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 if ( (int(to) ^ int(from)) == 16 - && (attacks_from(to - pawn_push(us), us) & pieces(them, PAWN))) + && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN))) { - st->epSquare = (from + to) / 2; + st->epSquare = to - pawn_push(us); k ^= Zobrist::enpassant[file_of(st->epSquare)]; } @@ -798,33 +824,36 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { assert(relative_rank(us, to) == RANK_8); assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN); - remove_piece(pc, to); + remove_piece(to); put_piece(promotion, to); + if (Eval::useNNUE) + { + // Promoting pawn to SQ_NONE, promoted piece from SQ_NONE + dp.to[0] = SQ_NONE; + dp.piece[dp.dirty_num] = promotion; + dp.from[dp.dirty_num] = SQ_NONE; + dp.to[dp.dirty_num] = to; + dp.dirty_num++; + } + // Update hash keys k ^= Zobrist::psq[pc][to] ^ Zobrist::psq[promotion][to]; st->pawnKey ^= Zobrist::psq[pc][to]; st->materialKey ^= Zobrist::psq[promotion][pieceCount[promotion]-1] ^ Zobrist::psq[pc][pieceCount[pc]]; - // Update incremental score - st->psq += PSQT::psq[promotion][to] - PSQT::psq[pc][to]; - // Update material st->nonPawnMaterial[us] += PieceValue[MG][promotion]; } - // Update pawn hash key and prefetch access to pawnsTable + // Update pawn hash key st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - prefetch2(thisThread->pawnsTable[st->pawnKey]); // Reset rule 50 draw counter st->rule50 = 0; } - // Update incremental scores - st->psq += PSQT::psq[pc][to] - PSQT::psq[pc][from]; - // Set capture piece st->capturedPiece = captured; @@ -839,6 +868,25 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { // Update king attacks used for fast check detection set_check_info(st); + // Calculate the repetition info. It is the ply distance from the previous + // occurrence of the same position, negative in the 3-fold case, or zero + // if the position was not repeated. + st->repetition = 0; + int end = std::min(st->rule50, st->pliesFromNull); + if (end >= 4) + { + StateInfo* stp = st->previous->previous; + for (int i = 4; i <= end; i += 2) + { + stp = stp->previous->previous; + if (stp->key == st->key) + { + st->repetition = stp->repetition ? -i : i; + break; + } + } + } + assert(pos_is_ok()); } @@ -866,7 +914,7 @@ void Position::undo_move(Move m) { assert(type_of(pc) == promotion_type(m)); assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN); - remove_piece(pc, to); + remove_piece(to); pc = make_piece(us, PAWN); put_piece(pc, to); } @@ -878,7 +926,7 @@ void Position::undo_move(Move m) { } else { - move_piece(pc, to, from); // Put the piece back at the source square + move_piece(to, from); // Put the piece back at the source square if (st->capturedPiece) { @@ -917,16 +965,28 @@ void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Squ rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + if (Do && Eval::useNNUE) + { + auto& dp = st->dirtyPiece; + dp.piece[0] = make_piece(us, KING); + dp.from[0] = from; + dp.to[0] = to; + dp.piece[1] = make_piece(us, ROOK); + dp.from[1] = rfrom; + dp.to[1] = rto; + dp.dirty_num = 2; + } + // Remove both pieces first since squares could overlap in Chess960 - remove_piece(make_piece(us, KING), Do ? from : to); - remove_piece(make_piece(us, ROOK), Do ? rfrom : rto); - board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us + remove_piece(Do ? from : to); + remove_piece(Do ? rfrom : rto); + board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do this for us put_piece(make_piece(us, KING), Do ? to : from); put_piece(make_piece(us, ROOK), Do ? rto : rfrom); } -/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips +/// Position::do(undo)_null_move() is used to do(undo) a "null move": it flips /// the side to move without executing any move on the board. void Position::do_null_move(StateInfo& newSt) { @@ -934,7 +994,13 @@ void Position::do_null_move(StateInfo& newSt) { assert(!checkers()); assert(&newSt != st); - std::memcpy(&newSt, st, sizeof(StateInfo)); + if (Eval::useNNUE) + { + std::memcpy(&newSt, st, sizeof(StateInfo)); + } + else + std::memcpy(&newSt, st, offsetof(StateInfo, accumulator)); + newSt.previous = st; st = &newSt; @@ -954,6 +1020,8 @@ void Position::do_null_move(StateInfo& newSt) { set_check_info(st); + st->repetition = 0; + assert(pos_is_ok()); } @@ -998,56 +1066,94 @@ bool Position::see_ge(Move m, Value threshold) const { return VALUE_ZERO >= threshold; Square from = from_sq(m), to = to_sq(m); - PieceType nextVictim = type_of(piece_on(from)); - Color stm = ~color_of(piece_on(from)); // First consider opponent's move - Value balance; // Values of the pieces taken by us minus opponent's ones - Bitboard occupied, stmAttackers; - balance = PieceValue[MG][piece_on(to)]; - - if (balance < threshold) + int swap = PieceValue[MG][piece_on(to)] - threshold; + if (swap < 0) return false; - balance -= PieceValue[MG][nextVictim]; - - if (balance >= threshold) // Always true if nextVictim == KING + swap = PieceValue[MG][piece_on(from)] - swap; + if (swap <= 0) return true; - bool relativeStm = true; // True if the opponent is to move - occupied = pieces() ^ from ^ to; - - // Find all attackers to the destination square, with the moving piece removed, - // but possibly an X-ray attacker added behind it. - Bitboard attackers = attackers_to(to, occupied) & occupied; + Bitboard occupied = pieces() ^ from ^ to; + Color stm = color_of(piece_on(from)); + Bitboard attackers = attackers_to(to, occupied); + Bitboard stmAttackers, bb; + int res = 1; while (true) { - stmAttackers = attackers & pieces(stm); + stm = ~stm; + attackers &= occupied; - // Don't allow pinned pieces to attack pieces except the king as long all - // pinners are on their original square. - if (!(st->pinnersForKing[stm] & ~occupied)) - stmAttackers &= ~st->blockersForKing[stm]; + // If stm has no more attackers then give up: stm loses + 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. + if (pinners(~stm) & occupied) + stmAttackers &= ~blockers_for_king(stm); if (!stmAttackers) - return relativeStm; + break; - // Locate and remove the next least valuable attacker - nextVictim = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); + res ^= 1; - if (nextVictim == KING) - return relativeStm == bool(attackers & pieces(~stm)); + // Locate and remove the next least valuable attacker, and add to + // the bitboard 'attackers' any X-ray attackers behind it. + if ((bb = stmAttackers & pieces(PAWN))) + { + if ((swap = PawnValueMg - swap) < res) + break; - balance += relativeStm ? PieceValue[MG][nextVictim] - : -PieceValue[MG][nextVictim]; + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } - relativeStm = !relativeStm; + else if ((bb = stmAttackers & pieces(KNIGHT))) + { + if ((swap = KnightValueMg - swap) < res) + break; - if (relativeStm == (balance >= threshold)) - return relativeStm; + occupied ^= lsb(bb); + } - stm = ~stm; + else if ((bb = stmAttackers & pieces(BISHOP))) + { + if ((swap = BishopValueMg - swap) < res) + break; + + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } + + else if ((bb = stmAttackers & pieces(ROOK))) + { + if ((swap = RookValueMg - swap) < res) + break; + + occupied ^= lsb(bb); + attackers |= attacks_bb(to, occupied) & pieces(ROOK, QUEEN); + } + + else if ((bb = stmAttackers & pieces(QUEEN))) + { + if ((swap = QueenValueMg - swap) < res) + break; + + occupied ^= lsb(bb); + attackers |= (attacks_bb(to, occupied) & pieces(BISHOP, QUEEN)) + | (attacks_bb(to, occupied) & pieces(ROOK , QUEEN)); + } + + else // KING + // If we "capture" with the king but opponent still has attackers, + // reverse the result. + return (attackers & ~pieces(stm)) ? res ^ 1 : res; } + + return bool(res); } @@ -1059,25 +1165,75 @@ bool Position::is_draw(int ply) const { if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; + // Return a draw score if a position repeats once earlier but strictly + // after the root, or repeats twice before or at the root. + return st->repetition && st->repetition < ply; +} + + +// Position::has_repeated() tests whether there has been at least one repetition +// of positions since the last capture or pawn move. + +bool Position::has_repeated() const { + + StateInfo* stc = st; + int end = std::min(st->rule50, st->pliesFromNull); + while (end-- >= 4) + { + if (stc->repetition) + return true; + + stc = stc->previous; + } + return false; +} + + +/// Position::has_game_cycle() tests if the position has a move which draws by repetition, +/// or an earlier position has a move that directly reaches the current position. + +bool Position::has_game_cycle(int ply) const { + + int j; + int end = std::min(st->rule50, st->pliesFromNull); - if (end < 4) + if (end < 3) return false; - StateInfo* stp = st->previous->previous; - int cnt = 0; + Key originalKey = st->key; + StateInfo* stp = st->previous; - for (int i = 4; i <= end; i += 2) + for (int i = 3; i <= end; i += 2) { stp = stp->previous->previous; - // Return a draw score if a position repeats once earlier but strictly - // after the root, or repeats twice before or at the root. - if ( stp->key == st->key - && ++cnt + (ply > i) == 2) - return true; - } + Key moveKey = originalKey ^ stp->key; + if ( (j = H1(moveKey), cuckoo[j] == moveKey) + || (j = H2(moveKey), cuckoo[j] == moveKey)) + { + Move move = cuckooMove[j]; + Square s1 = from_sq(move); + Square s2 = to_sq(move); + if (!(between_bb(s1, s2) & pieces())) + { + if (ply > i) + return true; + + // For nodes before or at the root, check that the move is a + // repetition rather than a move to the current position. + // In the cuckoo table, both moves Rc1c5 and Rc5c1 are stored in + // the same location, so we have to select which square to check. + if (color_of(piece_on(empty(s1) ? s2 : s1)) != side_to_move()) + continue; + + // For repetitions before or at the root, require one more + if (stp->repetition) + return true; + } + } + } return false; } @@ -1123,7 +1279,7 @@ void Position::flip() { bool Position::pos_is_ok() const { - const bool Fast = true; // Quick (default) or full check? + constexpr bool Fast = true; // Quick (default) or full check? if ( (sideToMove != WHITE && sideToMove != BLACK) || piece_on(square(WHITE)) != W_KING @@ -1172,15 +1328,15 @@ bool Position::pos_is_ok() const { assert(0 && "pos_is_ok: Index"); } - for (Color c = WHITE; c <= BLACK; ++c) - for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) + for (Color c : { WHITE, BLACK }) + for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE}) { - if (!can_castle(c | s)) + if (!can_castle(cr)) continue; - if ( piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK) - || castlingRightsMask[castlingRookSquare[c | s]] != (c | s) - || (castlingRightsMask[square(c)] & (c | s)) != (c | s)) + if ( piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK) + || castlingRightsMask[castlingRookSquare[cr]] != cr + || (castlingRightsMask[square(c)] & cr) != cr) assert(0 && "pos_is_ok: Castling"); }