X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=7b01172f1cd0baf3bef24e93b74f9adc7a18b8bb;hp=57f731d4f257b9cd26deb0842042423bc7953ab0;hb=HEAD;hpb=a24f28be8567c2527b154ef981090368a2bd8f76 diff --git a/src/position.cpp b/src/position.cpp index 57f731d4..c45dd7b2 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) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + 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 @@ -18,144 +16,152 @@ along with this program. If not, see . */ +#include "position.h" + #include +#include #include -#include // For offsetof() -#include // For std::memset, std::memcmp +#include +#include +#include +#include #include +#include #include +#include +#include #include "bitboard.h" #include "misc.h" #include "movegen.h" -#include "position.h" +#include "nnue/nnue_common.h" +#include "syzygy/tbprobe.h" #include "thread.h" #include "tt.h" #include "uci.h" -#include "syzygy/tbprobe.h" using std::string; +namespace Stockfish { + namespace Zobrist { - Key psq[PIECE_NB][SQUARE_NB]; - Key enpassant[FILE_NB]; - Key castling[CASTLING_RIGHT_NB]; - Key side, noPawns; +Key psq[PIECE_NB][SQUARE_NB]; +Key enpassant[FILE_NB]; +Key castling[CASTLING_RIGHT_NB]; +Key side, noPawns; } 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 }; -} // namespace +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 -/// operator<<(Position) returns an ASCII representation of the position - +// Returns an ASCII representation of the position std::ostream& operator<<(std::ostream& os, const Position& pos) { - os << "\n +---+---+---+---+---+---+---+---+\n"; - - for (Rank r = RANK_8; r >= RANK_1; --r) - { - for (File f = FILE_A; f <= FILE_H; ++f) - os << " | " << PieceToChar[pos.piece_on(make_square(f, r))]; - - os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n"; - } - - 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: "; - - for (Bitboard b = pos.checkers(); b; ) - os << UCI::square(pop_lsb(&b)) << " "; - - if ( int(Tablebases::MaxCardinality) >= popcount(pos.pieces()) - && !pos.can_castle(ANY_CASTLING)) - { - StateInfo st; - Position p; - p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread()); - Tablebases::ProbeState s1, s2; - Tablebases::WDLScore wdl = Tablebases::probe_wdl(p, &s1); - int dtz = Tablebases::probe_dtz(p, &s2); - os << "\nTablebases WDL: " << std::setw(4) << wdl << " (" << s1 << ")" - << "\nTablebases DTZ: " << std::setw(4) << dtz << " (" << s2 << ")"; - } - - return os; + os << "\n +---+---+---+---+---+---+---+---+\n"; + + for (Rank r = RANK_8; r >= RANK_1; --r) + { + for (File f = FILE_A; f <= FILE_H; ++f) + os << " | " << PieceToChar[pos.piece_on(make_square(f, r))]; + + os << " | " << (1 + r) << "\n +---+---+---+---+---+---+---+---+\n"; + } + + 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: "; + + for (Bitboard b = pos.checkers(); b;) + os << UCI::square(pop_lsb(b)) << " "; + + if (int(Tablebases::MaxCardinality) >= popcount(pos.pieces()) && !pos.can_castle(ANY_CASTLING)) + { + StateInfo st; + ASSERT_ALIGNED(&st, Eval::NNUE::CacheLineSize); + + Position p; + p.set(pos.fen(), pos.is_chess960(), &st, pos.this_thread()); + Tablebases::ProbeState s1, s2; + Tablebases::WDLScore wdl = Tablebases::probe_wdl(p, &s1); + int dtz = Tablebases::probe_dtz(p, &s2); + os << "\nTablebases WDL: " << std::setw(4) << wdl << " (" << s1 << ")" + << "\nTablebases DTZ: " << std::setw(4) << dtz << " (" << s2 << ")"; + } + + return os; } -// 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 +// Implements Marcel van Kervinck's cuckoo algorithm to detect repetition of positions +// for 3-fold repetition draws. The algorithm uses two hash tables with Zobrist hashes +// to allow fast detection of recurring positions. For details see: +// 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; } 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]; +Key cuckoo[8192]; Move cuckooMove[8192]; -/// Position::init() initializes at startup the various arrays used to compute hash keys - +// Initializes at startup the various arrays used to compute hash keys void Position::init() { - PRNG rng(1070372); - - for (Piece pc : Pieces) - for (Square s = SQ_A1; s <= SQ_H8; ++s) - Zobrist::psq[pc][s] = rng.rand(); - - for (File f = FILE_A; f <= FILE_H; ++f) - Zobrist::enpassant[f] = rng.rand(); - - for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr) - 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); + PRNG rng(1070372); + + for (Piece pc : Pieces) + for (Square s = SQ_A1; s <= SQ_H8; ++s) + Zobrist::psq[pc][s] = rng.rand(); + + for (File f = FILE_A; f <= FILE_H; ++f) + Zobrist::enpassant[f] = rng.rand(); + + for (int cr = NO_CASTLING; cr <= ANY_CASTLING; ++cr) + 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)); + [[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) + 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); } -/// Position::set() initializes the position object with the given 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. - +// Initializes the position object with the given 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. Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Thread* th) { -/* + /* A FEN string defines a particular position using only the ASCII character set. A FEN string contains six fields separated by a space. The fields are: @@ -178,9 +184,9 @@ 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. 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. + 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 @@ -190,947 +196,959 @@ Position& Position::set(const string& fenStr, bool isChess960, StateInfo* si, Th incremented after Black's move. */ - unsigned char col, row, token; - size_t idx; - Square sq = SQ_A8; - std::istringstream ss(fenStr); - - std::memset(this, 0, sizeof(Position)); - std::memset(si, 0, sizeof(StateInfo)); - std::fill_n(&pieceList[0][0], sizeof(pieceList) / sizeof(Square), SQ_NONE); - st = si; - - ss >> std::noskipws; - - // 1. Piece placement - while ((ss >> token) && !isspace(token)) - { - if (isdigit(token)) - sq += (token - '0') * EAST; // Advance the given number of files - - else if (token == '/') - sq += 2 * SOUTH; - - else if ((idx = PieceToChar.find(token)) != string::npos) - { - put_piece(Piece(idx), sq); - ++sq; - } - } - - // 2. Active color - ss >> token; - sideToMove = (token == 'w' ? WHITE : BLACK); - ss >> token; - - // 3. Castling availability. Compatible with 3 standards: Normal FEN standard, - // Shredder-FEN that uses the letters of the columns on which the rooks began - // the game instead of KQkq and also X-FEN standard that, in case of Chess960, - // if an inner rook is associated with the castling right, the castling tag is - // replaced by the file letter of the involved rook, as for the Shredder-FEN. - while ((ss >> token) && !isspace(token)) - { - Square rsq; - Color c = islower(token) ? BLACK : WHITE; - Piece rook = make_piece(c, ROOK); - - token = char(toupper(token)); - - if (token == 'K') - for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; --rsq) {} - - else if (token == 'Q') - for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; ++rsq) {} - - else if (token >= 'A' && token <= 'H') - rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); - - else - continue; - - set_castling_right(c, rsq); - } - - // 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 == (sideToMove == WHITE ? '6' : '3')))) - { - st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); - - // 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)))); - } - - if (!enpassant) - st->epSquare = SQ_NONE; - - // 5-6. Halfmove clock and fullmove number - ss >> std::skipws >> st->rule50 >> gamePly; - - // Convert from fullmove starting from 1 to gamePly starting from 0, - // handle also common incorrect FEN with fullmove = 0. - gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK); - - chess960 = isChess960; - thisThread = th; - set_state(st); - - return *this; -} + unsigned char col, row, token; + size_t idx; + Square sq = SQ_A8; + std::istringstream ss(fenStr); + std::memset(this, 0, sizeof(Position)); + std::memset(si, 0, sizeof(StateInfo)); + st = si; -/// Position::set_castling_right() is a helper function used to set castling -/// rights given the corresponding color and the rook starting square. + ss >> std::noskipws; -void Position::set_castling_right(Color c, Square rfrom) { + // 1. Piece placement + while ((ss >> token) && !isspace(token)) + { + if (isdigit(token)) + sq += (token - '0') * EAST; // Advance the given number of files - Square kfrom = square(c); - CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE: QUEEN_SIDE); + else if (token == '/') + sq += 2 * SOUTH; - st->castlingRights |= cr; - castlingRightsMask[kfrom] |= cr; - castlingRightsMask[rfrom] |= cr; - castlingRookSquare[cr] = rfrom; + else if ((idx = PieceToChar.find(token)) != string::npos) + { + put_piece(Piece(idx), sq); + ++sq; + } + } - Square kto = relative_square(c, cr & KING_SIDE ? SQ_G1 : SQ_C1); - Square rto = relative_square(c, cr & KING_SIDE ? SQ_F1 : SQ_D1); + // 2. Active color + ss >> token; + sideToMove = (token == 'w' ? WHITE : BLACK); + ss >> token; + + // 3. Castling availability. Compatible with 3 standards: Normal FEN standard, + // Shredder-FEN that uses the letters of the columns on which the rooks began + // the game instead of KQkq and also X-FEN standard that, in case of Chess960, + // if an inner rook is associated with the castling right, the castling tag is + // replaced by the file letter of the involved rook, as for the Shredder-FEN. + while ((ss >> token) && !isspace(token)) + { + Square rsq; + Color c = islower(token) ? BLACK : WHITE; + Piece rook = make_piece(c, ROOK); - castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto) | rto | kto) - & ~(kfrom | rfrom); -} + token = char(toupper(token)); + if (token == 'K') + for (rsq = relative_square(c, SQ_H1); piece_on(rsq) != rook; --rsq) + {} -/// Position::set_check_info() sets king attacks to detect if a move gives check + else if (token == 'Q') + for (rsq = relative_square(c, SQ_A1); piece_on(rsq) != rook; ++rsq) + {} -void Position::set_check_info(StateInfo* si) const { + else if (token >= 'A' && token <= 'H') + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); - si->blockersForKing[WHITE] = slider_blockers(pieces(BLACK), square(WHITE), si->pinners[BLACK]); - si->blockersForKing[BLACK] = slider_blockers(pieces(WHITE), square(BLACK), si->pinners[WHITE]); + else + continue; - Square ksq = square(~sideToMove); + set_castling_right(c, rsq); + } - 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; -} + // 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 == (sideToMove == WHITE ? '6' : '3')))) + { + st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); + + // 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)))); + } + if (!enpassant) + st->epSquare = SQ_NONE; -/// Position::set_state() computes the hash keys of the position, and other -/// data that once computed is updated incrementally as moves are made. -/// The function is only used when a new position is set up, and to verify -/// the correctness of the StateInfo data when running in debug mode. + // 5-6. Halfmove clock and fullmove number + ss >> std::skipws >> st->rule50 >> gamePly; -void Position::set_state(StateInfo* si) const { + // Convert from fullmove starting from 1 to gamePly starting from 0, + // handle also common incorrect FEN with fullmove = 0. + gamePly = std::max(2 * (gamePly - 1), 0) + (sideToMove == BLACK); - si->key = si->materialKey = 0; - si->pawnKey = Zobrist::noPawns; - si->nonPawnMaterial[WHITE] = si->nonPawnMaterial[BLACK] = VALUE_ZERO; - si->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); + chess960 = isChess960; + thisThread = th; + set_state(); - set_check_info(si); + assert(pos_is_ok()); - for (Bitboard b = pieces(); b; ) - { - Square s = pop_lsb(&b); - Piece pc = piece_on(s); - si->key ^= Zobrist::psq[pc][s]; + return *this; +} - 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]; - } +// Helper function used to set castling +// rights given the corresponding color and the rook starting square. +void Position::set_castling_right(Color c, Square rfrom) { - if (si->epSquare != SQ_NONE) - si->key ^= Zobrist::enpassant[file_of(si->epSquare)]; + Square kfrom = square(c); + CastlingRights cr = c & (kfrom < rfrom ? KING_SIDE : QUEEN_SIDE); - if (sideToMove == BLACK) - si->key ^= Zobrist::side; + st->castlingRights |= cr; + castlingRightsMask[kfrom] |= cr; + castlingRightsMask[rfrom] |= cr; + castlingRookSquare[cr] = rfrom; - si->key ^= Zobrist::castling[si->castlingRights]; + 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 (Piece pc : Pieces) - for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) - si->materialKey ^= Zobrist::psq[pc][cnt]; + castlingPath[cr] = (between_bb(rfrom, rto) | between_bb(kfrom, kto)) & ~(kfrom | rfrom); } -/// Position::set() is an overload to initialize the position object with -/// the given endgame code string like "KBPKN". It is mainly a helper to -/// get the material key out of an endgame code. +// Sets king attacks to detect if a move gives check +void Position::set_check_info() const { -Position& Position::set(const string& code, Color c, StateInfo* si) { + update_slider_blockers(WHITE); + update_slider_blockers(BLACK); - assert(code[0] == 'K'); + Square ksq = square(~sideToMove); - string sides[] = { code.substr(code.find('K', 1)), // Weak - code.substr(0, std::min(code.find('v'), code.find('K', 1))) }; // Strong + st->checkSquares[PAWN] = pawn_attacks_bb(~sideToMove, ksq); + st->checkSquares[KNIGHT] = attacks_bb(ksq); + st->checkSquares[BISHOP] = attacks_bb(ksq, pieces()); + st->checkSquares[ROOK] = attacks_bb(ksq, pieces()); + st->checkSquares[QUEEN] = st->checkSquares[BISHOP] | st->checkSquares[ROOK]; + st->checkSquares[KING] = 0; +} - 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); +// Computes the hash keys of the position, and other +// data that once computed is updated incrementally as moves are made. +// The function is only used when a new position is set up +void Position::set_state() const { - string fenStr = "8/" + sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/" - + sides[1] + char(8 - sides[1].length() + '0') + "/8 w - - 0 10"; + st->key = st->materialKey = 0; + st->pawnKey = Zobrist::noPawns; + st->nonPawnMaterial[WHITE] = st->nonPawnMaterial[BLACK] = VALUE_ZERO; + st->checkersBB = attackers_to(square(sideToMove)) & pieces(~sideToMove); - return set(fenStr, false, si, nullptr); + set_check_info(); + + for (Bitboard b = pieces(); b;) + { + Square s = pop_lsb(b); + Piece pc = piece_on(s); + st->key ^= Zobrist::psq[pc][s]; + + if (type_of(pc) == PAWN) + st->pawnKey ^= Zobrist::psq[pc][s]; + + else if (type_of(pc) != KING) + st->nonPawnMaterial[color_of(pc)] += PieceValue[pc]; + } + + if (st->epSquare != SQ_NONE) + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + + if (sideToMove == BLACK) + st->key ^= Zobrist::side; + + st->key ^= Zobrist::castling[st->castlingRights]; + + for (Piece pc : Pieces) + for (int cnt = 0; cnt < pieceCount[pc]; ++cnt) + st->materialKey ^= Zobrist::psq[pc][cnt]; } -/// 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. +// Overload to initialize the position object with the given endgame code string +// like "KBPKN". It's mainly a helper to get the material key out of an endgame code. +Position& Position::set(const string& code, Color c, StateInfo* si) { + + assert(code[0] == 'K'); + + string sides[] = {code.substr(code.find('K', 1)), // Weak + 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); -const string Position::fen() const { + std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower); - int emptyCnt; - std::ostringstream ss; + string fenStr = "8/" + sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/" + sides[1] + + char(8 - sides[1].length() + '0') + "/8 w - - 0 10"; - for (Rank r = RANK_8; r >= RANK_1; --r) - { - for (File f = FILE_A; f <= FILE_H; ++f) - { - for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f) - ++emptyCnt; + return set(fenStr, false, si, nullptr); +} - if (emptyCnt) - ss << emptyCnt; - if (f <= FILE_H) - ss << PieceToChar[piece_on(make_square(f, r))]; - } +// Returns a FEN representation of the position. In case of +// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function. +string Position::fen() const { - if (r > RANK_1) - ss << '/'; - } + int emptyCnt; + std::ostringstream ss; - ss << (sideToMove == WHITE ? " w " : " b "); + for (Rank r = RANK_8; r >= RANK_1; --r) + { + for (File f = FILE_A; f <= FILE_H; ++f) + { + for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f) + ++emptyCnt; - if (can_castle(WHITE_OO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO ))) : 'K'); + if (emptyCnt) + ss << emptyCnt; - if (can_castle(WHITE_OOO)) - ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OOO))) : 'Q'); + if (f <= FILE_H) + ss << PieceToChar[piece_on(make_square(f, r))]; + } - if (can_castle(BLACK_OO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OO ))) : 'k'); + if (r > RANK_1) + ss << '/'; + } - if (can_castle(BLACK_OOO)) - ss << (chess960 ? char('a' + file_of(castling_rook_square(BLACK_OOO))) : 'q'); + ss << (sideToMove == WHITE ? " w " : " b "); - if (!can_castle(ANY_CASTLING)) - ss << '-'; + if (can_castle(WHITE_OO)) + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OO))) : 'K'); - ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ") - << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2; + if (can_castle(WHITE_OOO)) + ss << (chess960 ? char('A' + file_of(castling_rook_square(WHITE_OOO))) : 'Q'); - return ss.str(); -} + if (can_castle(BLACK_OO)) + 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_OOO))) : 'q'); -/// Position::slider_blockers() returns a bitboard of all the pieces (both colors) -/// that are blocking attacks on the square 's' from 'sliders'. A piece blocks a -/// slider if removing that piece from the board would result in a position where -/// square 's' is attacked. For example, a king-attack blocking piece can be either -/// a pinned or a discovered check piece, according if its color is the opposite -/// or the same of the color of the slider. + if (!can_castle(ANY_CASTLING)) + ss << '-'; -Bitboard Position::slider_blockers(Bitboard sliders, Square s, Bitboard& pinners) const { + ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::square(ep_square()) + " ") << st->rule50 + << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2; - Bitboard blockers = 0; - pinners = 0; + return ss.str(); +} + +// Calculates st->blockersForKing[c] and st->pinners[~c], +// which store respectively the pieces preventing king of color c from being in check +// and the slider pieces of color ~c pinning pieces of color c to the king. +void Position::update_slider_blockers(Color c) const { + + Square ksq = square(c); - // 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; + st->blockersForKing[c] = 0; + st->pinners[~c] = 0; - while (snipers) - { - Square sniperSq = pop_lsb(&snipers); - Bitboard b = between_bb(s, sniperSq) & occupancy; + // Snipers are sliders that attack 's' when a piece and other snipers are removed + Bitboard snipers = ((attacks_bb(ksq) & pieces(QUEEN, ROOK)) + | (attacks_bb(ksq) & pieces(QUEEN, BISHOP))) + & pieces(~c); + Bitboard occupancy = pieces() ^ snipers; - if (b && !more_than_one(b)) + while (snipers) { - blockers |= b; - if (b & pieces(color_of(piece_on(s)))) - pinners |= sniperSq; + Square sniperSq = pop_lsb(snipers); + Bitboard b = between_bb(ksq, sniperSq) & occupancy; + + if (b && !more_than_one(b)) + { + st->blockersForKing[c] |= b; + if (b & pieces(c)) + st->pinners[~c] |= sniperSq; + } } - } - return blockers; } -/// Position::attackers_to() computes a bitboard of all pieces which attack a -/// given square. Slider attacks use the occupied bitboard to indicate occupancy. - +// Computes a bitboard of all pieces which attack a given square. +// Slider attacks use the occupied bitboard to indicate occupancy. Bitboard Position::attackers_to(Square s, Bitboard occupied) const { - 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_bb(s) & pieces(KING)); + return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN)) + | (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN)) + | (attacks_bb(s) & pieces(KNIGHT)) + | (attacks_bb(s, occupied) & pieces(ROOK, QUEEN)) + | (attacks_bb(s, occupied) & pieces(BISHOP, QUEEN)) + | (attacks_bb(s) & pieces(KING)); } -/// Position::legal() tests whether a pseudo-legal move is legal - +// Tests whether a pseudo-legal move is legal bool Position::legal(Move m) const { - assert(is_ok(m)); + assert(is_ok(m)); - Color us = sideToMove; - Square from = from_sq(m); - Square to = to_sq(m); + 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)); + 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; + // 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) + { + 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); + 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)) + return !(attacks_bb(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! - 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 !(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 !(blockers_for_king(us) & 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! + 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 if the Rook blocks some checks. + // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1. + return !chess960 || !(blockers_for_king(us) & to_sq(m)); + } + // 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 !(attackers_to(to, pieces() ^ from) & pieces(~us)); -/// Position::pseudo_legal() takes a random move and tests whether the move is -/// pseudo legal. It is used to validate moves from TT that can be corrupted -/// due to SMP concurrent access or hash position key aliasing. + // 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)); +} + +// Takes a random move and tests whether the move is +// pseudo-legal. It is used to validate moves from TT that can be corrupted +// due to SMP concurrent access or hash position key aliasing. bool Position::pseudo_legal(const Move m) const { - Color us = sideToMove; - Square from = from_sq(m); - Square to = to_sq(m); - Piece pc = moved_piece(m); - - // Use a slower but simpler function for uncommon cases - if (type_of(m) != NORMAL) - return MoveList(*this).contains(m); - - // Is not a promotion, so promotion piece must be empty - if (promotion_type(m) - KNIGHT != NO_PIECE_TYPE) - return false; - - // If the 'from' square is not occupied by a piece belonging to the side to - // move, the move is obviously not legal. - if (pc == NO_PIECE || color_of(pc) != us) - return false; - - // The destination square cannot be occupied by a friendly piece - if (pieces(us) & to) - return false; - - // Handle the special case of a pawn move - if (type_of(pc) == PAWN) - { - // We have already handled promotion moves, so destination - // cannot be on the 8th/1st rank. - if ((Rank8BB | Rank1BB) & to) - return false; - - 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 - && (relative_rank(us, from) == RANK_2) - && empty(to) - && empty(to - pawn_push(us)))) - return false; - } - else if (!(attacks_bb(type_of(pc), from, pieces()) & to)) - return false; - - // Evasions generator already takes care to avoid some kind of illegal moves - // and legal() relies on this. We therefore have to take care that the same - // kind of moves are filtered out here. - if (checkers()) - { - if (type_of(pc) != KING) - { - // Double check? In this case a king move is required - if (more_than_one(checkers())) - return false; - - // Our move must be a blocking evasion or a capture of the checking piece - if (!((between_bb(lsb(checkers()), square(us)) | checkers()) & to)) - return false; - } - // In case of king moves under check we have to remove king so as to catch - // invalid moves like b1a1 when opposite queen is on c1. - else if (attackers_to(to, pieces() ^ from) & pieces(~us)) - return false; - } - - return true; -} + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + 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 checkers() ? MoveList(*this).contains(m) + : MoveList(*this).contains(m); -/// Position::gives_check() tests whether a pseudo-legal move gives a check + // Is not a promotion, so the promotion piece must be empty + assert(promotion_type(m) - KNIGHT == NO_PIECE_TYPE); -bool Position::gives_check(Move m) const { + // If the 'from' square is not occupied by a piece belonging to the side to + // move, the move is obviously not legal. + if (pc == NO_PIECE || color_of(pc) != us) + return false; + + // The destination square cannot be occupied by a friendly piece + if (pieces(us) & to) + return false; + + // Handle the special case of a pawn move + if (type_of(pc) == PAWN) + { + // We have already handled promotion moves, so destination cannot be on the 8th/1st rank + if ((Rank8BB | Rank1BB) & to) + return false; + + 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 + && (relative_rank(us, from) == RANK_2) && empty(to) && empty(to - pawn_push(us)))) + return false; + } + else if (!(attacks_bb(type_of(pc), from, pieces()) & to)) + return false; + + // Evasions generator already takes care to avoid some kind of illegal moves + // and legal() relies on this. We therefore have to take care that the same + // kind of moves are filtered out here. + if (checkers()) + { + if (type_of(pc) != KING) + { + // Double check? In this case, a king move is required + if (more_than_one(checkers())) + return false; + + // Our move must be a blocking interposition or a capture of the checking piece + if (!(between_bb(square(us), lsb(checkers())) & to)) + return false; + } + // In case of king moves under check we have to remove the king so as to catch + // invalid moves like b1a1 when opposite queen is on c1. + else if (attackers_to(to, pieces() ^ from) & pieces(~us)) + return false; + } - assert(is_ok(m)); - assert(color_of(moved_piece(m)) == sideToMove); - - Square from = from_sq(m); - Square to = to_sq(m); - - // Is there a direct check? - if (check_squares(type_of(piece_on(from))) & to) - return true; - - // Is there a discovered check? - if ( (blockers_for_king(~sideToMove) & from) - && !aligned(from, to, square(~sideToMove))) - return true; - - switch (type_of(m)) - { - case NORMAL: - return false; - - 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; - - return (attacks_bb< ROOK>(square(~sideToMove), b) & pieces(sideToMove, QUEEN, ROOK)) - | (attacks_bb(square(~sideToMove), b) & pieces(sideToMove, QUEEN, BISHOP)); - } - case 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); - - return (attacks_bb(rto) & square(~sideToMove)) - && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & square(~sideToMove)); - } - default: - assert(false); - return false; - } + return true; } -/// 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. +// Tests whether a pseudo-legal move gives a check +bool Position::gives_check(Move m) const { + + assert(is_ok(m)); + assert(color_of(moved_piece(m)) == sideToMove); -void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { + Square from = from_sq(m); + Square to = to_sq(m); + + // Is there a direct check? + if (check_squares(type_of(piece_on(from))) & to) + return true; - assert(is_ok(m)); - assert(&newSt != st); - - thisThread->nodes.fetch_add(1, std::memory_order_relaxed); - Key k = st->key ^ Zobrist::side; - - // Copy some fields of the old state to our new StateInfo object except the - // ones which are going to be recalculated from scratch anyway and then switch - // our state pointer to point to the new (ready to be updated) state. - std::memcpy(&newSt, st, offsetof(StateInfo, key)); - newSt.previous = st; - st = &newSt; - - // Increment ply counters. In particular, rule50 will be reset to zero later on - // in case of a capture or a pawn move. - ++gamePly; - ++st->rule50; - ++st->pliesFromNull; - - Color us = sideToMove; - Color them = ~us; - 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); - - assert(color_of(pc) == us); - assert(captured == NO_PIECE || color_of(captured) == (type_of(m) != CASTLING ? them : us)); - assert(type_of(captured) != KING); - - if (type_of(m) == CASTLING) - { - assert(pc == make_piece(us, KING)); - assert(captured == make_piece(us, ROOK)); - - Square rfrom, rto; - do_castling(us, from, to, rfrom, rto); - - k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto]; - captured = NO_PIECE; - } - - if (captured) - { - Square capsq = to; - - // If the captured piece is a pawn, update pawn hash key, otherwise - // update non-pawn material. - if (type_of(captured) == PAWN) - { - if (type_of(m) == ENPASSANT) - { - capsq -= pawn_push(us); - - assert(pc == make_piece(us, PAWN)); - assert(to == st->epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == NO_PIECE); - assert(piece_on(capsq) == make_piece(them, PAWN)); - } - - st->pawnKey ^= Zobrist::psq[captured][capsq]; - } - else - st->nonPawnMaterial[them] -= PieceValue[MG][captured]; - - // Update board and piece lists - 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]); - - // Reset rule 50 counter - st->rule50 = 0; - } - - // Update hash key - k ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - - // Reset en passant square - if (st->epSquare != SQ_NONE) - { - k ^= Zobrist::enpassant[file_of(st->epSquare)]; - st->epSquare = SQ_NONE; - } - - // Update castling rights if needed - if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) - { - 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(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 - && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN))) - { - st->epSquare = to - pawn_push(us); - k ^= Zobrist::enpassant[file_of(st->epSquare)]; - } - - else if (type_of(m) == PROMOTION) - { - Piece promotion = make_piece(us, promotion_type(m)); - - assert(relative_rank(us, to) == RANK_8); - assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN); - - remove_piece(to); - put_piece(promotion, to); - - // 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 material - st->nonPawnMaterial[us] += PieceValue[MG][promotion]; - } - - // Update pawn hash key - st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; - - // Reset rule 50 draw counter - st->rule50 = 0; - } - - // Set capture piece - st->capturedPiece = captured; - - // Update the key with the final value - st->key = k; - - // Calculate checkers bitboard (if move gives check) - st->checkersBB = givesCheck ? attackers_to(square(them)) & pieces(us) : 0; - - sideToMove = ~sideToMove; - - // 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()); + // Is there a discovered check? + if (blockers_for_king(~sideToMove) & from) + return !aligned(from, to, square(~sideToMove)) || type_of(m) == CASTLING; + + switch (type_of(m)) + { + case NORMAL : + return false; + + 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 EN_PASSANT : { + Square capsq = make_square(file_of(to), rank_of(from)); + Bitboard b = (pieces() ^ from ^ capsq) | to; + + return (attacks_bb(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' + Square rto = relative_square(sideToMove, to > from ? SQ_F1 : SQ_D1); + + return check_squares(ROOK) & rto; + } + } } -/// 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. +// Makes a move, and saves all information necessary +// to a StateInfo object. The move is assumed to be legal. Pseudo-legal +// moves should be filtered out before this function is called. +void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) { + + assert(is_ok(m)); + assert(&newSt != st); + + thisThread->nodes.fetch_add(1, std::memory_order_relaxed); + Key k = st->key ^ Zobrist::side; + + // Copy some fields of the old state to our new StateInfo object except the + // ones which are going to be recalculated from scratch anyway and then switch + // our state pointer to point to the new (ready to be updated) state. + std::memcpy(&newSt, st, offsetof(StateInfo, key)); + newSt.previous = st; + st = &newSt; + + // Increment ply counters. In particular, rule50 will be reset to zero later on + // in case of a capture or a pawn move. + ++gamePly; + ++st->rule50; + ++st->pliesFromNull; + + // Used by NNUE + st->accumulator.computed[WHITE] = false; + st->accumulator.computed[BLACK] = false; + auto& dp = st->dirtyPiece; + dp.dirty_num = 1; + + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_on(from); + 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)); + assert(type_of(captured) != KING); + + if (type_of(m) == CASTLING) + { + assert(pc == make_piece(us, KING)); + assert(captured == make_piece(us, ROOK)); + + Square rfrom, rto; + do_castling(us, from, to, rfrom, rto); + + k ^= Zobrist::psq[captured][rfrom] ^ Zobrist::psq[captured][rto]; + captured = NO_PIECE; + } + + if (captured) + { + Square capsq = to; + + // If the captured piece is a pawn, update pawn hash key, otherwise + // update non-pawn material. + if (type_of(captured) == PAWN) + { + if (type_of(m) == EN_PASSANT) + { + capsq -= pawn_push(us); + + assert(pc == make_piece(us, PAWN)); + assert(to == st->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(to) == NO_PIECE); + assert(piece_on(capsq) == make_piece(them, PAWN)); + } + + st->pawnKey ^= Zobrist::psq[captured][capsq]; + } + else + st->nonPawnMaterial[them] -= PieceValue[captured]; + + 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(capsq); + + // Update material hash key and prefetch access to materialTable + k ^= Zobrist::psq[captured][capsq]; + st->materialKey ^= Zobrist::psq[captured][pieceCount[captured]]; + + // Reset rule 50 counter + st->rule50 = 0; + } + + // Update hash key + k ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; + + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + k ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } + + // Update castling rights if needed + if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) + { + 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) + { + 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 + && (pawn_attacks_bb(us, to - pawn_push(us)) & pieces(them, PAWN))) + { + st->epSquare = to - pawn_push(us); + k ^= Zobrist::enpassant[file_of(st->epSquare)]; + } + + else if (type_of(m) == PROMOTION) + { + Piece promotion = make_piece(us, promotion_type(m)); + + assert(relative_rank(us, to) == RANK_8); + assert(type_of(promotion) >= KNIGHT && type_of(promotion) <= QUEEN); + + remove_piece(to); + put_piece(promotion, to); + + // 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 material + st->nonPawnMaterial[us] += PieceValue[promotion]; + } + + // Update pawn hash key + st->pawnKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to]; + + // Reset rule 50 draw counter + st->rule50 = 0; + } + + // Set capture piece + st->capturedPiece = captured; + + // Update the key with the final value + st->key = k; + + // Calculate checkers bitboard (if move gives check) + st->checkersBB = givesCheck ? attackers_to(square(them)) & pieces(us) : 0; + + sideToMove = ~sideToMove; + + // Update king attacks used for fast check detection + set_check_info(); + + // 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()); +} + +// Unmakes a move. When it returns, the position should +// be restored to exactly the same state as before the move was made. void Position::undo_move(Move m) { - assert(is_ok(m)); - - sideToMove = ~sideToMove; - - Color us = sideToMove; - Square from = from_sq(m); - Square to = to_sq(m); - Piece pc = piece_on(to); - - assert(empty(from) || type_of(m) == CASTLING); - assert(type_of(st->capturedPiece) != KING); - - if (type_of(m) == PROMOTION) - { - assert(relative_rank(us, to) == RANK_8); - assert(type_of(pc) == promotion_type(m)); - assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN); - - remove_piece(to); - pc = make_piece(us, PAWN); - put_piece(pc, to); - } - - if (type_of(m) == CASTLING) - { - Square rfrom, rto; - do_castling(us, from, to, rfrom, rto); - } - else - { - move_piece(to, from); // Put the piece back at the source square - - if (st->capturedPiece) - { - Square capsq = to; - - if (type_of(m) == ENPASSANT) - { - capsq -= pawn_push(us); - - assert(type_of(pc) == PAWN); - assert(to == st->previous->epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(capsq) == NO_PIECE); - assert(st->capturedPiece == make_piece(~us, PAWN)); - } - - put_piece(st->capturedPiece, capsq); // Restore the captured piece - } - } - - // Finally point our state pointer back to the previous state - st = st->previous; - --gamePly; - - assert(pos_is_ok()); + assert(is_ok(m)); + + sideToMove = ~sideToMove; + + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_on(to); + + assert(empty(from) || type_of(m) == CASTLING); + assert(type_of(st->capturedPiece) != KING); + + if (type_of(m) == PROMOTION) + { + assert(relative_rank(us, to) == RANK_8); + assert(type_of(pc) == promotion_type(m)); + assert(type_of(pc) >= KNIGHT && type_of(pc) <= QUEEN); + + remove_piece(to); + pc = make_piece(us, PAWN); + put_piece(pc, to); + } + + if (type_of(m) == CASTLING) + { + Square rfrom, rto; + do_castling(us, from, to, rfrom, rto); + } + else + { + move_piece(to, from); // Put the piece back at the source square + + if (st->capturedPiece) + { + Square capsq = to; + + if (type_of(m) == EN_PASSANT) + { + capsq -= pawn_push(us); + + assert(type_of(pc) == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + assert(st->capturedPiece == make_piece(~us, PAWN)); + } + + put_piece(st->capturedPiece, capsq); // Restore the captured piece + } + } + + // Finally point our state pointer back to the previous state + st = st->previous; + --gamePly; + + assert(pos_is_ok()); } -/// Position::do_castling() is a helper used to do/undo a castling move. This -/// is a bit tricky in Chess960 where from/to squares can overlap. +// Helper used to do/undo a castling move. This is a bit +// tricky in Chess960 where from/to squares can overlap. template void Position::do_castling(Color us, Square from, Square& to, Square& rfrom, Square& rto) { - bool kingSide = to > from; - rfrom = to; // Castling is encoded as "king captures friendly rook" - rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); - to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); - - // Remove both pieces first since squares could overlap in Chess960 - 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); -} + bool kingSide = to > from; + rfrom = to; // Castling is encoded as "king captures friendly rook" + rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + if (Do) + { + 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(Do ? from : to); + remove_piece(Do ? rfrom : rto); + board[Do ? from : to] = board[Do ? rfrom : rto] = + NO_PIECE; // remove_piece does not 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 -/// the side to move without executing any move on the board. +// 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) { - assert(!checkers()); - assert(&newSt != st); + assert(!checkers()); + assert(&newSt != st); + + std::memcpy(&newSt, st, offsetof(StateInfo, accumulator)); + + newSt.previous = st; + st = &newSt; - std::memcpy(&newSt, st, sizeof(StateInfo)); - newSt.previous = st; - st = &newSt; + st->dirtyPiece.dirty_num = 0; + st->dirtyPiece.piece[0] = NO_PIECE; // Avoid checks in UpdateAccumulator() + st->accumulator.computed[WHITE] = false; + st->accumulator.computed[BLACK] = false; - if (st->epSquare != SQ_NONE) - { - st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; - st->epSquare = SQ_NONE; - } + if (st->epSquare != SQ_NONE) + { + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } - st->key ^= Zobrist::side; - prefetch(TT.first_entry(st->key)); + st->key ^= Zobrist::side; + ++st->rule50; + prefetch(TT.first_entry(key())); - ++st->rule50; - st->pliesFromNull = 0; + st->pliesFromNull = 0; - sideToMove = ~sideToMove; + sideToMove = ~sideToMove; - set_check_info(st); + set_check_info(); - st->repetition = 0; + st->repetition = 0; - assert(pos_is_ok()); + assert(pos_is_ok()); } + +// Must be used to undo a "null move" void Position::undo_null_move() { - assert(!checkers()); + assert(!checkers()); - st = st->previous; - sideToMove = ~sideToMove; + st = st->previous; + sideToMove = ~sideToMove; } -/// 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. - +// 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. Key Position::key_after(Move m) const { - Square from = from_sq(m); - Square to = to_sq(m); - Piece pc = piece_on(from); - Piece captured = piece_on(to); - Key k = st->key ^ Zobrist::side; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_on(from); + Piece captured = piece_on(to); + Key k = st->key ^ Zobrist::side; - if (captured) - k ^= Zobrist::psq[captured][to]; + 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); +} -/// Position::see_ge (Static Exchange Evaluation Greater or Equal) tests if the -/// SEE value of move is greater or equal to the given threshold. We'll use an -/// algorithm similar to alpha-beta pruning with a null window. +// Tests if the SEE (Static Exchange Evaluation) +// value of move is greater or equal to the given threshold. We'll use an +// algorithm similar to alpha-beta pruning with a null window. bool Position::see_ge(Move m, Value threshold) const { - assert(is_ok(m)); - - // Only deal with normal moves, assume others pass a simple see - if (type_of(m) != NORMAL) - return VALUE_ZERO >= threshold; - - Square from = from_sq(m), to = to_sq(m); - - int swap = PieceValue[MG][piece_on(to)] - threshold; - if (swap < 0) - return false; - - swap = PieceValue[MG][piece_on(from)] - swap; - if (swap <= 0) - return true; - - 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) - { - stm = ~stm; - attackers &= occupied; - - // 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 (st->pinners[~stm] & occupied) - stmAttackers &= ~st->blockersForKing[stm]; - - if (!stmAttackers) - break; - - res ^= 1; - - // 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; - - occupied ^= lsb(bb); - attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); - } - - else if ((bb = stmAttackers & pieces(KNIGHT))) - { - if ((swap = KnightValueMg - swap) < res) - break; - - occupied ^= lsb(bb); - } - - 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); -} + assert(is_ok(m)); + + // Only deal with normal moves, assume others pass a simple SEE + if (type_of(m) != NORMAL) + return VALUE_ZERO >= threshold; + + Square from = from_sq(m), to = to_sq(m); + int swap = PieceValue[piece_on(to)] - threshold; + if (swap < 0) + return false; -/// Position::is_draw() tests whether the position is drawn by 50-move rule -/// or by repetition. It does not detect stalemates. + swap = PieceValue[piece_on(from)] - swap; + if (swap <= 0) + return true; + assert(color_of(piece_on(from)) == sideToMove); + Bitboard occupied = pieces() ^ from ^ to; // xoring to is important for pinned piece logic + Color stm = sideToMove; + Bitboard attackers = attackers_to(to, occupied); + Bitboard stmAttackers, bb; + int res = 1; + + while (true) + { + stm = ~stm; + attackers &= occupied; + + // If stm has no more attackers then give up: stm loses + if (!(stmAttackers = attackers & pieces(stm))) + break; + + // 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; + } + + res ^= 1; + + // 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 = PawnValue - swap) < res) + break; + occupied ^= least_significant_square_bb(bb); + + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } + + else if ((bb = stmAttackers & pieces(KNIGHT))) + { + if ((swap = KnightValue - swap) < res) + break; + occupied ^= least_significant_square_bb(bb); + } + + else if ((bb = stmAttackers & pieces(BISHOP))) + { + if ((swap = BishopValue - swap) < res) + break; + occupied ^= least_significant_square_bb(bb); + + attackers |= attacks_bb(to, occupied) & pieces(BISHOP, QUEEN); + } + + else if ((bb = stmAttackers & pieces(ROOK))) + { + if ((swap = RookValue - swap) < res) + break; + occupied ^= least_significant_square_bb(bb); + + attackers |= attacks_bb(to, occupied) & pieces(ROOK, QUEEN); + } + + else if ((bb = stmAttackers & pieces(QUEEN))) + { + if ((swap = QueenValue - swap) < res) + break; + occupied ^= least_significant_square_bb(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 the opponent still has attackers, + // reverse the result. + return (attackers & ~pieces(stm)) ? res ^ 1 : res; + } + + return bool(res); +} + +// Tests whether the position is drawn by 50-move rule +// or by repetition. It does not detect stalemates. bool Position::is_draw(int ply) const { - if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) - return true; + 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; + // 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 +// 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); + int end = std::min(st->rule50, st->pliesFromNull); while (end-- >= 4) { if (stc->repetition) @@ -1142,156 +1160,137 @@ bool Position::has_repeated() const { } -/// 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. - +// 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 j; - int end = std::min(st->rule50, st->pliesFromNull); + int end = std::min(st->rule50, st->pliesFromNull); - if (end < 3) - return false; + if (end < 3) + return false; - Key originalKey = st->key; - StateInfo* stp = st->previous; - - for (int i = 3; i <= end; i += 2) - { - stp = stp->previous->previous; - - 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; -} + Key originalKey = st->key; + StateInfo* stp = st->previous; + for (int i = 3; i <= end; i += 2) + { + stp = stp->previous->previous; + + 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) ^ 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; +} -/// Position::flip() flips position with the white and black sides reversed. This -/// is only useful for debugging e.g. for finding evaluation symmetry bugs. +// Flips position with the white and black sides reversed. This +// is only useful for debugging e.g. for finding evaluation symmetry bugs. void Position::flip() { - string f, token; - std::stringstream ss(fen()); + string f, token; + std::stringstream ss(fen()); - for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement - { - std::getline(ss, token, r > RANK_1 ? '/' : ' '); - f.insert(0, token + (f.empty() ? " " : "/")); - } + for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement + { + std::getline(ss, token, r > RANK_1 ? '/' : ' '); + f.insert(0, token + (f.empty() ? " " : "/")); + } - ss >> token; // Active color - f += (token == "w" ? "B " : "W "); // Will be lowercased later + ss >> token; // Active color + f += (token == "w" ? "B " : "W "); // Will be lowercased later - ss >> token; // Castling availability - f += token + " "; + ss >> token; // Castling availability + f += token + " "; - std::transform(f.begin(), f.end(), f.begin(), - [](char c) { return char(islower(c) ? toupper(c) : tolower(c)); }); + std::transform(f.begin(), f.end(), f.begin(), + [](char c) { return char(islower(c) ? toupper(c) : tolower(c)); }); - ss >> token; // En passant square - f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3")); + ss >> token; // En passant square + f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3")); - std::getline(ss, token); // Half and full moves - f += token; + std::getline(ss, token); // Half and full moves + f += token; - set(f, is_chess960(), st, this_thread()); + set(f, is_chess960(), st, this_thread()); - assert(pos_is_ok()); + assert(pos_is_ok()); } -/// Position::pos_is_ok() performs some consistency checks for the -/// position object and raises an asserts if something wrong is detected. -/// This is meant to be helpful when debugging. - +// Performs some consistency checks for the position object +// and raise an assert if something wrong is detected. +// This is meant to be helpful when debugging. bool Position::pos_is_ok() const { - constexpr bool Fast = true; // Quick (default) or full check? - - if ( (sideToMove != WHITE && sideToMove != BLACK) - || piece_on(square(WHITE)) != W_KING - || piece_on(square(BLACK)) != B_KING - || ( ep_square() != SQ_NONE - && relative_rank(sideToMove, ep_square()) != RANK_6)) - assert(0 && "pos_is_ok: Default"); - - if (Fast) - return true; - - if ( pieceCount[W_KING] != 1 - || pieceCount[B_KING] != 1 - || attackers_to(square(~sideToMove)) & pieces(sideToMove)) - assert(0 && "pos_is_ok: Kings"); - - if ( (pieces(PAWN) & (Rank1BB | Rank8BB)) - || pieceCount[W_PAWN] > 8 - || pieceCount[B_PAWN] > 8) - assert(0 && "pos_is_ok: Pawns"); - - if ( (pieces(WHITE) & pieces(BLACK)) - || (pieces(WHITE) | pieces(BLACK)) != pieces() - || popcount(pieces(WHITE)) > 16 - || popcount(pieces(BLACK)) > 16) - assert(0 && "pos_is_ok: Bitboards"); - - for (PieceType p1 = PAWN; p1 <= KING; ++p1) - for (PieceType p2 = PAWN; p2 <= KING; ++p2) - if (p1 != p2 && (pieces(p1) & pieces(p2))) - assert(0 && "pos_is_ok: Bitboards"); - - StateInfo si = *st; - set_state(&si); - if (std::memcmp(&si, st, sizeof(StateInfo))) - assert(0 && "pos_is_ok: State"); - - for (Piece pc : Pieces) - { - if ( pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc))) - || pieceCount[pc] != std::count(board, board + SQUARE_NB, pc)) - assert(0 && "pos_is_ok: Pieces"); - - for (int i = 0; i < pieceCount[pc]; ++i) - if (board[pieceList[pc][i]] != pc || index[pieceList[pc][i]] != i) - assert(0 && "pos_is_ok: Index"); - } - - for (Color c : { WHITE, BLACK }) - for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE}) - { - if (!can_castle(cr)) - continue; - - if ( piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK) - || castlingRightsMask[castlingRookSquare[cr]] != cr - || (castlingRightsMask[square(c)] & cr) != cr) - assert(0 && "pos_is_ok: Castling"); - } - - return true; + constexpr bool Fast = true; // Quick (default) or full check? + + if ((sideToMove != WHITE && sideToMove != BLACK) || piece_on(square(WHITE)) != W_KING + || piece_on(square(BLACK)) != B_KING + || (ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6)) + assert(0 && "pos_is_ok: Default"); + + if (Fast) + return true; + + if (pieceCount[W_KING] != 1 || pieceCount[B_KING] != 1 + || attackers_to(square(~sideToMove)) & pieces(sideToMove)) + assert(0 && "pos_is_ok: Kings"); + + if ((pieces(PAWN) & (Rank1BB | Rank8BB)) || pieceCount[W_PAWN] > 8 || pieceCount[B_PAWN] > 8) + assert(0 && "pos_is_ok: Pawns"); + + if ((pieces(WHITE) & pieces(BLACK)) || (pieces(WHITE) | pieces(BLACK)) != pieces() + || popcount(pieces(WHITE)) > 16 || popcount(pieces(BLACK)) > 16) + assert(0 && "pos_is_ok: Bitboards"); + + for (PieceType p1 = PAWN; p1 <= KING; ++p1) + for (PieceType p2 = PAWN; p2 <= KING; ++p2) + if (p1 != p2 && (pieces(p1) & pieces(p2))) + assert(0 && "pos_is_ok: Bitboards"); + + + for (Piece pc : Pieces) + if (pieceCount[pc] != popcount(pieces(color_of(pc), type_of(pc))) + || pieceCount[pc] != std::count(board, board + SQUARE_NB, pc)) + assert(0 && "pos_is_ok: Pieces"); + + for (Color c : {WHITE, BLACK}) + for (CastlingRights cr : {c & KING_SIDE, c & QUEEN_SIDE}) + { + if (!can_castle(cr)) + continue; + + if (piece_on(castlingRookSquare[cr]) != make_piece(c, ROOK) + || castlingRightsMask[castlingRookSquare[cr]] != cr + || (castlingRightsMask[square(c)] & cr) != cr) + assert(0 && "pos_is_ok: Castling"); + } + + return true; } + +} // namespace Stockfish