X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=64b833857b9976080db3b587715e8319f5da8e39;hb=3141490374182551ed26f39ba4e3efb59589f057;hp=701a1c0f9b08615b051893f2e5d2c3ab91e199f5;hpb=d155cd88d1ca914c8a9d398c0164b5a92a5b9629;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index 701a1c0f..b9acc645 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -17,51 +17,98 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include -#include +#include #include +#include +#include -#include "mersenne.h" +#include "bitcount.h" #include "movegen.h" -#include "movepick.h" #include "position.h" #include "psqtab.h" -#include "ucioption.h" +#include "rkiss.h" +#include "thread.h" +#include "tt.h" - -//// -//// Variables -//// - -int Position::castleRightsMask[64]; +using std::string; +using std::cout; +using std::endl; Key Position::zobrist[2][8][64]; Key Position::zobEp[64]; Key Position::zobCastle[16]; -Key Position::zobMaterial[2][8][16]; Key Position::zobSideToMove; +Key Position::zobExclusion; + +Score Position::pieceSquareTable[16][64]; + +// Material values arrays, indexed by Piece +const Value PieceValueMidgame[17] = { + VALUE_ZERO, + PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame, + VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, + PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, + RookValueMidgame, QueenValueMidgame +}; + +const Value PieceValueEndgame[17] = { + VALUE_ZERO, + PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, + RookValueEndgame, QueenValueEndgame, + VALUE_ZERO, VALUE_ZERO, VALUE_ZERO, + PawnValueEndgame, KnightValueEndgame, BishopValueEndgame, + RookValueEndgame, QueenValueEndgame +}; + + +namespace { + + // Bonus for having the side to move (modified by Joona Kiiski) + const Score TempoValue = make_score(48, 22); + + // To convert a Piece to and from a FEN char + const string PieceToChar(".PNBRQK pnbrqk "); +} + + +/// CheckInfo c'tor -Value Position::MgPieceSquareTable[16][64]; -Value Position::EgPieceSquareTable[16][64]; +CheckInfo::CheckInfo(const Position& pos) { + Color them = flip(pos.side_to_move()); + Square ksq = pos.king_square(them); -//// -//// Functions -//// + pinned = pos.pinned_pieces(); + dcCandidates = pos.discovered_check_candidates(); -/// Constructors + checkSq[PAWN] = pos.attacks_from(ksq, them); + checkSq[KNIGHT] = pos.attacks_from(ksq); + checkSq[BISHOP] = pos.attacks_from(ksq); + checkSq[ROOK] = pos.attacks_from(ksq); + checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK]; + checkSq[KING] = EmptyBoardBB; +} + + +/// Position c'tors. Here we always create a copy of the original position +/// or the FEN string, we want the new born Position object do not depend +/// on any external data so we detach state pointer from the source one. + +Position::Position(const Position& pos, int th) { -Position::Position(const Position &pos) { - copy(pos); + memcpy(this, &pos, sizeof(Position)); + threadID = th; + nodes = 0; + + assert(is_ok()); } -Position::Position(const std::string &fen) { - from_fen(fen); +Position::Position(const string& fen, bool isChess960, int th) { + + from_fen(fen, isChess960); + threadID = th; } @@ -69,1751 +116,1464 @@ Position::Position(const std::string &fen) { /// string. This function is not very robust - make sure that input FENs are /// correct (this is assumed to be the responsibility of the GUI). -void Position::from_fen(const std::string &fen) { +void Position::from_fen(const string& fenStr, bool isChess960) { +/* + A FEN string defines a particular position using only the ASCII character set. + + A FEN string contains six fields. The separator between fields is a space. The fields are: + + 1) Piece placement (from white's perspective). Each rank is described, starting with rank 8 and ending + with rank 1; within each rank, the contents of each square are described from file A through file H. + Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken + from the standard English names. White pieces are designated using upper-case letters ("PNBRQK") + while Black take lowercase ("pnbrqk"). Blank squares are noted using digits 1 through 8 (the number + of blank squares), and "/" separate ranks. + + 2) Active color. "w" means white moves next, "b" means black. + + 3) Castling availability. If neither side can castle, this is "-". Otherwise, this has one or more + letters: "K" (White can castle kingside), "Q" (White can castle queenside), "k" (Black can castle + kingside), and/or "q" (Black can castle queenside). + + 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 + regardless of whether there is a pawn in position to make an en passant capture. + + 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 fifty-move rule. + + 6) Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move. +*/ - static const std::string pieceLetters = "KQRBNPkqrbnp"; - static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; + char col, row, token; + size_t p; + Square sq = SQ_A8; + std::istringstream fen(fenStr); clear(); + fen >> std::noskipws; - // Board - Rank rank = RANK_8; - File file = FILE_A; - size_t i = 0; - for ( ; fen[i] != ' '; i++) + // 1. Piece placement + while ((fen >> token) && !isspace(token)) { - if (isdigit(fen[i])) - { - // Skip the given number of files - file += (fen[i] - '1' + 1); - continue; - } - else if (fen[i] == '/') - { - file = FILE_A; - rank--; - continue; - } - size_t idx = pieceLetters.find(fen[i]); - if (idx == std::string::npos) + if (token == '/') + sq -= Square(16); // Jump back of 2 rows + + else if (isdigit(token)) + sq += Square(token - '0'); // Skip the given number of files + + else if ((p = PieceToChar.find(token)) != string::npos) { - std::cout << "Error in FEN at character " << i << std::endl; - return; + put_piece(Piece(p), sq); + sq++; } - Square square = make_square(file, rank); - put_piece(pieces[idx], square); - file++; } - // Side to move - i++; - if (fen[i] != 'w' && fen[i] != 'b') - { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - sideToMove = (fen[i] == 'w' ? WHITE : BLACK); + // 2. Active color + fen >> token; + sideToMove = (token == 'w' ? WHITE : BLACK); + fen >> token; - // Castling rights: - i++; - if (fen[i] != ' ') + // 3. Castling availability + while ((fen >> token) && !isspace(token)) + set_castling_rights(token); + + // 4. En passant square. Ignore if no pawn capture is possible + if ( ((fen >> col) && (col >= 'a' && col <= 'h')) + && ((fen >> row) && (row == '3' || row == '6'))) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } + st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); + Color them = flip(sideToMove); - i++; - while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) { - if(fen[i] == '-') { - i++; break; - } - else if(fen[i] == 'K') allow_oo(WHITE); - else if(fen[i] == 'Q') allow_ooo(WHITE); - else if(fen[i] == 'k') allow_oo(BLACK); - else if(fen[i] == 'q') allow_ooo(BLACK); - else if(fen[i] >= 'A' && fen[i] <= 'H') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B1; square <= SQ_G1; square++) - if(piece_on(square) == WK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'A') + FILE_A; - if(rookFile < initialKFile) { - allow_ooo(WHITE); - initialQRFile = rookFile; - } - else { - allow_oo(WHITE); - initialKRFile = rookFile; - } - } - else if(fen[i] >= 'a' && fen[i] <= 'h') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B8; square <= SQ_G8; square++) - if(piece_on(square) == BK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'a') + FILE_A; - if(rookFile < initialKFile) { - allow_ooo(BLACK); - initialQRFile = rookFile; - } - else { - allow_oo(BLACK); - initialKRFile = rookFile; - } - } - else { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - i++; + if (!(attacks_from(st->epSquare, them) & pieces(PAWN, sideToMove))) + st->epSquare = SQ_NONE; } - // Skip blanks - while (fen[i] == ' ') - i++; + // 5-6. Halfmove clock and fullmove number + fen >> std::skipws >> st->rule50 >> startPosPly; - // En passant square - if ( i < fen.length() - 2 - && (fen[i] >= 'a' && fen[i] <= 'h') - && (fen[i+1] == '3' || fen[i+1] == '6')) - epSquare = square_from_string(fen.substr(i, 2)); + // Convert from fullmove starting from 1 to ply starting from 0, + // handle also common incorrect FEN with fullmove = 0. + startPosPly = Max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK); - // Various initialisation - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - castleRightsMask[sq] = ALL_CASTLES; + // Various initialisations + chess960 = isChess960; + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove)); + + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); + st->value = compute_value(); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); + + assert(is_ok()); +} + + +/// Position::set_castle() is an helper function used to set +/// correct castling related flags. + +void Position::set_castle(int f, Square ksq, Square rsq) { + + st->castleRights |= f; + castleRightsMask[ksq] ^= f; + castleRightsMask[rsq] ^= f; + castleRookSquare[f] = rsq; +} + + +/// Position::set_castling_rights() sets castling parameters castling avaiability. +/// This function is 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 traditional castling tag will be replaced +/// by the file letter of the involved rook as for the Shredder-FEN. + +void Position::set_castling_rights(char token) { + + Color c = islower(token) ? BLACK : WHITE; + + Square sqA = relative_square(c, SQ_A1); + Square sqH = relative_square(c, SQ_H1); + Square rsq, ksq = king_square(c); + + token = char(toupper(token)); + + if (token == 'K') + for (rsq = sqH; piece_on(rsq) != make_piece(c, ROOK); rsq--) {} + + else if (token == 'Q') + for (rsq = sqA; piece_on(rsq) != make_piece(c, ROOK); rsq++) {} + + else if (token >= 'A' && token <= 'H') + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); + + else return; - castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO); - castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO); - castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO; - castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO; - castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO; - castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; - - find_checkers(); - - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); - mgValue = compute_mg_value(); - egValue = compute_eg_value(); - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + if (file_of(rsq) < file_of(ksq)) + set_castle(WHITE_OOO << c, ksq, rsq); + else + set_castle(WHITE_OO << c, ksq, rsq); } -/// Position::to_fen() converts the position object to a FEN string. This is -/// probably only useful for debugging. +/// Position::to_fen() returns a FEN representation of the position. In case +/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. -const std::string Position::to_fen() const { +const string Position::to_fen() const { - static const std::string pieceLetters = " PNBRQK pnbrqk"; - std::string fen; - int skip; + std::ostringstream fen; + Square sq; + int emptyCnt; for (Rank rank = RANK_8; rank >= RANK_1; rank--) { - skip = 0; + emptyCnt = 0; + for (File file = FILE_A; file <= FILE_H; file++) { - Square sq = make_square(file, rank); - if (!square_is_occupied(sq)) - { skip++; - continue; - } - if (skip > 0) + sq = make_square(file, rank); + + if (!square_is_empty(sq)) { - fen += (char)skip + '0'; - skip = 0; + if (emptyCnt) + { + fen << emptyCnt; + emptyCnt = 0; + } + fen << PieceToChar[piece_on(sq)]; } - fen += pieceLetters[piece_on(sq)]; + else + emptyCnt++; } - if (skip > 0) - fen += (char)skip + '0'; - fen += (rank > RANK_1 ? '/' : ' '); - } - fen += (sideToMove == WHITE ? 'w' : 'b') + ' '; - if (castleRights != NO_CASTLES) - { - if (can_castle_kingside(WHITE)) fen += 'K'; - if (can_castle_queenside(WHITE)) fen += 'Q'; - if (can_castle_kingside(BLACK)) fen += 'k'; - if (can_castle_queenside(BLACK)) fen += 'q'; - } else - fen += '-'; + if (emptyCnt) + fen << emptyCnt; - fen += ' '; - if (ep_square() != SQ_NONE) - fen += square_to_string(ep_square()); - else - fen += '-'; + if (rank > RANK_1) + fen << '/'; + } - return fen; -} + fen << (sideToMove == WHITE ? " w " : " b "); + if (st->castleRights != CASTLES_NONE) + { + if (can_castle(WHITE_OO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K'); -/// Position::print() prints an ASCII representation of the position to -/// the standard output. - -void Position::print() const { - char pieceStrings[][8] = - {"| ? ", "| P ", "| N ", "| B ", "| R ", "| Q ", "| K ", "| ? ", - "| ? ", "|=P=", "|=N=", "|=B=", "|=R=", "|=Q=", "|=K=" - }; - - for(Rank rank = RANK_8; rank >= RANK_1; rank--) { - std::cout << "+---+---+---+---+---+---+---+---+\n"; - for(File file = FILE_A; file <= FILE_H; file++) { - Square sq = make_square(file, rank); - Piece piece = piece_on(sq); - if(piece == EMPTY) - std::cout << ((square_color(sq) == WHITE)? "| " : "| . "); - else - std::cout << pieceStrings[piece]; - } - std::cout << "|\n"; - } - std::cout << "+---+---+---+---+---+---+---+---+\n"; - std::cout << to_fen() << std::endl; - std::cout << key << std::endl; -} + if (can_castle(WHITE_OOO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q'); + if (can_castle(BLACK_OO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k'); -/// Position::copy() creates a copy of the input position. + if (can_castle(BLACK_OOO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q'); + } else + fen << '-'; -void Position::copy(const Position &pos) { + fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square())) + << " " << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; - memcpy(this, &pos, sizeof(Position)); + return fen.str(); } -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. -Bitboard Position::pinned_pieces(Color c) const { +/// Position::print() prints an ASCII representation of the position to +/// the standard output. If a move is given then also the san is printed. - Square ksq = king_square(c); - return hidden_checks(c, ksq) | hidden_checks(c, ksq); -} +void Position::print(Move move) const { + const char* dottedLine = "\n+---+---+---+---+---+---+---+---+\n"; -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the given side which are candidates for giving a discovered -/// check. The code is almost the same as the function for finding pinned -/// pieces. + if (move) + { + Position p(*this, thread()); + string dd = (sideToMove == BLACK ? ".." : ""); + cout << "\nMove is: " << dd << move_to_san(p, move); + } + + for (Rank rank = RANK_8; rank >= RANK_1; rank--) + { + cout << dottedLine << '|'; + for (File file = FILE_A; file <= FILE_H; file++) + { + Square sq = make_square(file, rank); + Piece piece = piece_on(sq); -Bitboard Position::discovered_check_candidates(Color c) const { + if (piece == PIECE_NONE && color_of(sq) == DARK) + piece = PIECE_NONE_DARK_SQ; - Square ksq = king_square(opposite_color(c)); - return hidden_checks(c, ksq) | hidden_checks(c, ksq); + char c = (color_of(piece_on(sq)) == BLACK ? '=' : ' '); + cout << c << PieceToChar[piece] << c << '|'; + } + } + cout << dottedLine << "Fen is: " << to_fen() << "\nKey is: " << st->key << endl; } -/// Position:hidden_checks<>() returns a bitboard of all pinned (against the -/// king) pieces for the given color and for the given pinner type. Or, when -/// template parameter FindPinned is false, the pinned pieces of opposite color -/// that are, indeed, the pieces candidate for a discovery check. -template -Bitboard Position::hidden_checks(Color c, Square ksq) const { +/// Position:hidden_checkers<>() returns a bitboard of all pinned (against the +/// king) pieces for the given color. Or, when template parameter FindPinned is +/// false, the function return the pieces of the given color candidate for a +/// discovery check against the enemy king. - Square s; - Bitboard sliders, result = EmptyBoardBB; - - if (Piece == ROOK) // Resolved at compile time - sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]; - else - sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]; +template +Bitboard Position::hidden_checkers() const { - if (sliders && (!FindPinned || (sliders & ~checkersBB))) - { - // King blockers are candidate pinned pieces - Bitboard candidate_pinned = piece_attacks(ksq) & pieces_of_color(c); + // Pinned pieces protect our king, dicovery checks attack the enemy king + Bitboard b, result = EmptyBoardBB; + Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove); + Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove)); - // Pinners are sliders, not checkers, that give check when - // candidate pinned are removed. - Bitboard pinners = (FindPinned ? sliders & ~checkersBB : sliders); + // Pinners are sliders, that give check when candidate pinned is removed + pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq]) + | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]); - if (Piece == ROOK) - pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - else - pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); + while (pinners) + { + b = squares_between(ksq, pop_1st_bit(&pinners)) & occupied_squares(); - // Finally for each pinner find the corresponding pinned piece (if same color of king) - // or discovery checker (if opposite color) among the candidates. - while (pinners) - { - s = pop_1st_bit(&pinners); - result |= (squares_between(s, ksq) & candidate_pinned); - } + // Only one bit set and is an our piece? + if (b && !(b & (b - 1)) && (b & pieces(sideToMove))) + result |= b; } return result; } -/// Position::square_is_attacked() checks whether the given side attacks the -/// given square. +/// Position:pinned_pieces() returns a bitboard of all pinned (against the +/// king) pieces for the side to move. -bool Position::square_is_attacked(Square s, Color c) const { +Bitboard Position::pinned_pieces() const { - return (pawn_attacks(opposite_color(c), s) & pawns(c)) - || (piece_attacks(s) & knights(c)) - || (piece_attacks(s) & kings(c)) - || (piece_attacks(s) & rooks_and_queens(c)) - || (piece_attacks(s) & bishops_and_queens(c)); + return hidden_checkers(); } -/// Position::attacks_to() computes a bitboard containing all pieces which -/// attacks a given square. There are two versions of this function: One -/// which finds attackers of both colors, and one which only finds the -/// attackers for one side. +/// Position:discovered_check_candidates() returns a bitboard containing all +/// pieces for the side to move which are candidates for giving a discovered +/// check. -Bitboard Position::attacks_to(Square s) const { +Bitboard Position::discovered_check_candidates() const { - return (pawn_attacks(BLACK, s) & pawns(WHITE)) - | (pawn_attacks(WHITE, s) & pawns(BLACK)) - | (piece_attacks(s) & pieces_of_type(KNIGHT)) - | (piece_attacks(s) & rooks_and_queens()) - | (piece_attacks(s) & bishops_and_queens()) - | (piece_attacks(s) & pieces_of_type(KING)); + return hidden_checkers(); } -Bitboard Position::attacks_to(Square s, Color c) const { +/// Position::attackers_to() computes a bitboard containing all pieces which +/// attacks a given square. + +Bitboard Position::attackers_to(Square s) const { - return attacks_to(s) & pieces_of_color(c); + return (attacks_from(s, BLACK) & pieces(PAWN, WHITE)) + | (attacks_from(s, WHITE) & pieces(PAWN, BLACK)) + | (attacks_from(s) & pieces(KNIGHT)) + | (attacks_from(s) & pieces(ROOK, QUEEN)) + | (attacks_from(s) & pieces(BISHOP, QUEEN)) + | (attacks_from(s) & pieces(KING)); } +Bitboard Position::attackers_to(Square s, Bitboard occ) const { + + return (attacks_from(s, BLACK) & pieces(PAWN, WHITE)) + | (attacks_from(s, WHITE) & pieces(PAWN, BLACK)) + | (attacks_from(s) & pieces(KNIGHT)) + | (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN)) + | (bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN)) + | (attacks_from(s) & pieces(KING)); +} -/// Position::piece_attacks_square() tests whether the piece on square f -/// attacks square t. +/// Position::attacks_from() computes a bitboard of all attacks +/// of a given piece put in a given square. -bool Position::piece_attacks_square(Square f, Square t) const { +Bitboard Position::attacks_from(Piece p, Square s) const { - assert(square_is_ok(f)); - assert(square_is_ok(t)); + assert(square_is_ok(s)); - switch (piece_on(f)) + switch (p) { - case WP: return pawn_attacks_square(WHITE, f, t); - case BP: return pawn_attacks_square(BLACK, f, t); - case WN: case BN: return piece_attacks_square(f, t); - case WB: case BB: return piece_attacks_square(f, t); - case WR: case BR: return piece_attacks_square(f, t); - case WQ: case BQ: return piece_attacks_square(f, t); - case WK: case BK: return piece_attacks_square(f, t); - default: return false; + case WB: case BB: return attacks_from(s); + case WR: case BR: return attacks_from(s); + case WQ: case BQ: return attacks_from(s); + default: return StepAttacksBB[p][s]; } - return false; } +Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { -/// Position::move_attacks_square() tests whether a move from the current -/// position attacks a given square. Only attacks by the moving piece are -/// considered; the function does not handle X-ray attacks. - -bool Position::move_attacks_square(Move m, Square s) const { - - assert(move_is_ok(m)); assert(square_is_ok(s)); - Square f = move_from(m), t = move_to(m); - - assert(square_is_occupied(f)); - - switch (piece_on(f)) + switch (p) { - case WP: return pawn_attacks_square(WHITE, t, s); - case BP: return pawn_attacks_square(BLACK, t, s); - case WN: case BN: return piece_attacks_square(t, s); - case WB: case BB: return piece_attacks_square(t, s); - case WR: case BR: return piece_attacks_square(t, s); - case WQ: case BQ: return piece_attacks_square(t, s); - case WK: case BK: return piece_attacks_square(t, s); - default: assert(false); + case WB: case BB: return bishop_attacks_bb(s, occ); + case WR: case BR: return rook_attacks_bb(s, occ); + case WQ: case BQ: return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ); + default: return StepAttacksBB[p][s]; } - return false; } -/// Position::find_checkers() computes the checkersBB bitboard, which -/// contains a nonzero bit for each checking piece (0, 1 or 2). It -/// currently works by calling Position::attacks_to, which is probably -/// inefficient. Consider rewriting this function to use the last move -/// played, like in non-bitboard versions of Glaurung. +/// Position::move_attacks_square() tests whether a move from the current +/// position attacks a given square. -void Position::find_checkers() { +bool Position::move_attacks_square(Move m, Square s) const { - checkersBB = attacks_to(king_square(side_to_move()),opposite_color(side_to_move())); -} + assert(is_ok(m)); + assert(square_is_ok(s)); + Bitboard occ, xray; + Square f = move_from(m), t = move_to(m); -/// Position::move_is_legal() tests whether a pseudo-legal move is legal. -/// There are two versions of this function: One which takes only a -/// move as input, and one which takes a move and a bitboard of pinned -/// pieces. The latter function is faster, and should always be preferred -/// when a pinned piece bitboard has already been computed. + assert(!square_is_empty(f)); -bool Position::move_is_legal(Move m) const { + if (bit_is_set(attacks_from(piece_on(f), t), s)) + return true; - return move_is_legal(m, pinned_pieces(side_to_move())); + // Move the piece and scan for X-ray attacks behind it + occ = occupied_squares(); + do_move_bb(&occ, make_move_bb(f, t)); + xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN)) + |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))) + & pieces(color_of(piece_on(f))); + + // If we have attacks we need to verify that are caused by our move + // and are not already existent ones. + return xray && (xray ^ (xray & attacks_from(s))); } -bool Position::move_is_legal(Move m, Bitboard pinned) const { - - Color us, them; - Square ksq, from; - assert(is_ok()); - assert(move_is_ok(m)); - assert(pinned == pinned_pieces(side_to_move())); +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - if (is_check()) - return true; +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { - // Castling moves are checked for legality during move generation. - if (move_is_castle(m)) - return true; + assert(is_ok(m)); + assert(pinned == pinned_pieces()); - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - ksq = king_square(us); + Color us = side_to_move(); + Square from = move_from(m); - assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == king_of_color(us)); + assert(color_of(piece_on(from)) == us); + assert(piece_on(king_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 (move_is_ep(m)) + // 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 (is_enpassant(m)) { + Color them = flip(us); Square to = move_to(m); - Square capsq = make_square(square_file(to), square_rank(from)); + Square capsq = to + pawn_push(them); + Square ksq = king_square(us); Bitboard b = occupied_squares(); assert(to == ep_square()); - assert(piece_on(from) == pawn_of_color(us)); - assert(piece_on(capsq) == pawn_of_color(them)); - assert(piece_on(to) == EMPTY); + assert(piece_on(from) == make_piece(us, PAWN)); + assert(piece_on(capsq) == make_piece(them, PAWN)); + assert(piece_on(to) == PIECE_NONE); clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to); - return !(rook_attacks_bb(ksq, b) & rooks_and_queens(them)) - && !(bishop_attacks_bb(ksq, b) & bishops_and_queens(them)); + return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) + && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); } // If the moving piece is a king, check whether the destination - // square is attacked by the opponent. - if (from == ksq) - return !(square_is_attacked(move_to(m), them)); + // square is attacked by the opponent. Castling moves are checked + // for legality during move generation. + if (type_of(piece_on(from)) == KING) + return is_castle(m) || !(attackers_to(move_to(m)) & pieces(flip(us))); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. - if ( !bit_is_set(pinned, from) - || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))) - return true; - - return false; + return !pinned + || !bit_is_set(pinned, from) + || squares_aligned(from, move_to(m), king_square(us)); } -/// Position::move_is_check() tests whether a pseudo-legal move is a check. -/// There are two versions of this function: One which takes only a move as -/// input, and one which takes a move and a bitboard of discovered check -/// candidates. The latter function is faster, and should always be preferred -/// when a discovered check candidates bitboard has already been computed. +/// Position::move_is_legal() takes a random move and tests whether the move +/// is legal. This version is not very fast and should be used only +/// in non time-critical paths. + +bool Position::move_is_legal(const Move m) const { -bool Position::move_is_check(Move m) const { + for (MoveList ml(*this); !ml.end(); ++ml) + if (ml.move() == m) + return true; - Bitboard dc = discovered_check_candidates(side_to_move()); - return move_is_check(m, dc); + return false; } -bool Position::move_is_check(Move m, Bitboard dcCandidates) const { - Color us, them; - Square ksq, from, to; +/// Position::is_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. - assert(is_ok()); - assert(move_is_ok(m)); - assert(dcCandidates == discovered_check_candidates(side_to_move())); +bool Position::is_pseudo_legal(const Move m) const { - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - ksq = king_square(them); + Color us = sideToMove; + Color them = flip(sideToMove); + Square from = move_from(m); + Square to = move_to(m); + Piece pc = piece_on(from); + + // Use a slower but simpler function for uncommon cases + if (is_special(m)) + return move_is_legal(m); + + // Is not a promotion, so promotion piece must be empty + if (promotion_piece_type(m) - 2 != PIECE_TYPE_NONE) + 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 == PIECE_NONE || color_of(pc) != us) + return false; - assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == king_of_color(them)); + // The destination square cannot be occupied by a friendly piece + if (color_of(piece_on(to)) == us) + return false; - // Proceed according to the type of the moving piece - switch (type_of_piece_on(from)) + // Handle the special case of a pawn move + if (type_of(pc) == PAWN) { - case PAWN: - - if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check? - return true; - - if ( bit_is_set(dcCandidates, from) // Discovered check? - && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) - return true; - - if (move_promotion(m)) // Promotion with check? + // Move direction must be compatible with pawn color + int direction = to - from; + if ((us == WHITE) != (direction > 0)) + return false; + + // We have already handled promotion moves, so destination + // cannot be on the 8/1th rank. + if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1) + return false; + + // Proceed according to the square delta between the origin and + // destination squares. + switch (direction) { - Bitboard b = occupied_squares(); - clear_bit(&b, from); + case DELTA_NW: + case DELTA_NE: + case DELTA_SW: + case DELTA_SE: + // Capture. The destination square must be occupied by an enemy + // piece (en passant captures was handled earlier). + if (color_of(piece_on(to)) != them) + return false; - switch (move_promotion(m)) - { - case KNIGHT: - return bit_is_set(piece_attacks(to), ksq); - case BISHOP: - return bit_is_set(bishop_attacks_bb(to, b), ksq); - case ROOK: - return bit_is_set(rook_attacks_bb(to, b), ksq); - case QUEEN: - return bit_is_set(queen_attacks_bb(to, b), ksq); - default: - assert(false); - } + // From and to files must be one file apart, avoids a7h5 + if (abs(file_of(from) - file_of(to)) != 1) + return false; + break; + + case DELTA_N: + case DELTA_S: + // Pawn push. The destination square must be empty. + if (!square_is_empty(to)) + return false; + break; + + case DELTA_NN: + // Double white pawn push. The destination square must be on the fourth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( rank_of(to) != RANK_4 + || !square_is_empty(to) + || !square_is_empty(from + DELTA_N)) + return false; + break; + + case DELTA_SS: + // Double black pawn push. The destination square must be on the fifth + // rank, and both the destination square and the square between the + // source and destination squares must be empty. + if ( rank_of(to) != RANK_5 + || !square_is_empty(to) + || !square_is_empty(from + DELTA_S)) + return false; + break; + + default: + return false; } - // En passant capture with check? We have already handled the case - // of direct checks and ordinary discovered check, the only case we - // need to handle is the unusual case of a discovered check through the - // captured pawn. - else if (move_is_ep(m)) + } + else if (!bit_is_set(attacks_from(pc, from), to)) + return false; + + if (in_check()) + { + // In case of king moves under check we have to remove king so to catch + // as invalid moves like b1a1 when opposite queen is on c1. + if (type_of(piece_on(from)) == KING) { - Square capsq = make_square(square_file(to), square_rank(from)); Bitboard b = occupied_squares(); clear_bit(&b, from); - clear_bit(&b, capsq); - set_bit(&b, to); - return (rook_attacks_bb(ksq, b) & rooks_and_queens(us)) - ||(bishop_attacks_bb(ksq, b) & bishops_and_queens(us)); + if (attackers_to(move_to(m), b) & pieces(flip(us))) + return false; } - return false; + else + { + Bitboard target = checkers(); + Square checksq = pop_1st_bit(&target); - case KNIGHT: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + if (target) // double check ? In this case a king move is required + return false; - case BISHOP: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + // Our move must be a blocking evasion or a capture of the checking piece + target = squares_between(checksq, king_square(us)) | checkers(); + if (!bit_is_set(target, move_to(m))) + return false; + } + } + + return true; +} + + +/// Position::move_gives_check() tests whether a pseudo-legal move gives a check + +bool Position::move_gives_check(Move m, const CheckInfo& ci) const { - case ROOK: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + assert(is_ok(m)); + assert(ci.dcCandidates == discovered_check_candidates()); + assert(color_of(piece_on(move_from(m))) == side_to_move()); - case QUEEN: - // Discovered checks are impossible! - assert(!bit_is_set(dcCandidates, from)); - return bit_is_set(piece_attacks(ksq), to); // Normal check? + Square from = move_from(m); + Square to = move_to(m); + PieceType pt = type_of(piece_on(from)); - case KING: - // Discovered check? - if ( bit_is_set(dcCandidates, from) - && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) + // Direct check ? + if (bit_is_set(ci.checkSq[pt], to)) + return true; + + // Discovery check ? + if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from)) + { + // For pawn and king moves we need to verify also direction + if ( (pt != PAWN && pt != KING) + || !squares_aligned(from, to, king_square(flip(side_to_move())))) return true; + } - // Castling with check? - if (move_is_castle(m)) - { - Square kfrom, kto, rfrom, rto; - Bitboard b = occupied_squares(); - kfrom = from; - rfrom = to; + // Can we skip the ugly special cases ? + if (!is_special(m)) + return false; - if (rfrom > kfrom) - { - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); - } else { - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); - } - clear_bit(&b, kfrom); - clear_bit(&b, rfrom); - set_bit(&b, rto); - set_bit(&b, kto); - return bit_is_set(rook_attacks_bb(rto, b), ksq); + Color us = side_to_move(); + Bitboard b = occupied_squares(); + Square ksq = king_square(flip(us)); + + // Promotion with check ? + if (is_promotion(m)) + { + clear_bit(&b, from); + + switch (promotion_piece_type(m)) + { + case KNIGHT: + return bit_is_set(attacks_from(to), ksq); + case BISHOP: + return bit_is_set(bishop_attacks_bb(to, b), ksq); + case ROOK: + return bit_is_set(rook_attacks_bb(to, b), ksq); + case QUEEN: + return bit_is_set(queen_attacks_bb(to, b), ksq); + default: + assert(false); } - return false; + } + + // En passant capture with check ? We have already handled the case + // of direct checks and ordinary discovered check, the only case we + // need to handle is the unusual case of a discovered check through + // the captured pawn. + if (is_enpassant(m)) + { + Square capsq = make_square(file_of(to), rank_of(from)); + clear_bit(&b, from); + clear_bit(&b, capsq); + set_bit(&b, to); + return (rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, us)) + ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us)); + } + + // Castling with check ? + if (is_castle(m)) + { + Square kfrom, kto, rfrom, rto; + kfrom = from; + rfrom = to; - default: - assert(false); + if (rfrom > kfrom) + { + kto = relative_square(us, SQ_G1); + rto = relative_square(us, SQ_F1); + } else { + kto = relative_square(us, SQ_C1); + rto = relative_square(us, SQ_D1); + } + clear_bit(&b, kfrom); + clear_bit(&b, rfrom); + set_bit(&b, rto); + set_bit(&b, kto); + return bit_is_set(rook_attacks_bb(rto, b), ksq); } - assert(false); + return false; } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. +/// 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. -bool Position::move_is_capture(Move m) const { +void Position::do_move(Move m, StateInfo& newSt) { - return color_of_piece_on(move_to(m)) == opposite_color(side_to_move()) - || move_is_ep(m); + CheckInfo ci(*this); + do_move(m, newSt, ci, move_gives_check(m, ci)); } +void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) { -/// Position::backup() is called when making a move. All information -/// necessary to restore the position when the move is later unmade -/// is saved to an UndoInfo object. The function Position::restore -/// does the reverse operation: When one does a backup followed by -/// a restore with the same UndoInfo object, the position is restored -/// to the state before backup was called. - -void Position::backup(UndoInfo &u) const { - u.castleRights = castleRights; - u.epSquare = epSquare; - u.checkersBB = checkersBB; - u.key = key; - u.pawnKey = pawnKey; - u.materialKey = materialKey; - u.rule50 = rule50; - u.lastMove = lastMove; - u.capture = NO_PIECE_TYPE; - u.mgValue = mgValue; - u.egValue = egValue; -} + assert(is_ok(m)); + assert(&newSt != st); + nodes++; + Key key = st->key; -/// Position::restore() is called when unmaking a move. It copies back -/// the information backed up during a previous call to Position::backup. - -void Position::restore(const UndoInfo &u) { - castleRights = u.castleRights; - epSquare = u.epSquare; - checkersBB = u.checkersBB; - key = u.key; - pawnKey = u.pawnKey; - materialKey = u.materialKey; - rule50 = u.rule50; - lastMove = u.lastMove; - mgValue = u.mgValue; - egValue = u.egValue; -} + // Copy some fields of old state to our new StateInfo object except the + // ones which are recalculated from scratch anyway, then switch our state + // pointer to point to the new, ready to be updated, state. + struct ReducedStateInfo { + Key pawnKey, materialKey; + Value npMaterial[2]; + int castleRights, rule50, pliesFromNull; + Score value; + Square epSquare; + }; + memcpy(&newSt, st, sizeof(ReducedStateInfo)); -/// Position::do_move() makes a move, and backs up all information necessary -/// to undo the move to an UndoInfo object. The move is assumed to be legal. -/// Pseudo-legal moves should be filtered out before this function is called. -/// There are two versions of this function, one which takes only the move and -/// the UndoInfo as input, and one which takes a third parameter, a bitboard of -/// discovered check candidates. The second version is faster, because knowing -/// the discovered check candidates makes it easier to update the checkersBB -/// member variable in the position object. + newSt.previous = st; + st = &newSt; -void Position::do_move(Move m, UndoInfo &u) { - do_move(m, u, discovered_check_candidates(side_to_move())); -} + // Update side to move + key ^= zobSideToMove; -void Position::do_move(Move m, UndoInfo &u, Bitboard dcCandidates) { - assert(is_ok()); - assert(move_is_ok(m)); + // Increment the 50 moves rule draw counter. Resetting it to zero in the + // case of non-reversible moves is taken care of later. + st->rule50++; + st->pliesFromNull++; + + if (is_castle(m)) + { + st->key = key; + do_castle_move(m); + return; + } - // Back up the necessary information to our UndoInfo object (except the - // captured piece, which is taken care of later: - backup(u); + Color us = side_to_move(); + Color them = flip(us); + Square from = move_from(m); + Square to = move_to(m); + bool ep = is_enpassant(m); + bool pm = is_promotion(m); - // Save the current key to the history[] array, in order to be able to - // detect repetition draws: - history[gamePly] = key; + Piece piece = piece_on(from); + PieceType pt = type_of(piece); + PieceType capture = ep ? PAWN : type_of(piece_on(to)); - // Increment the 50 moves rule draw counter. Resetting it to zero in the - // case of non-reversible moves is taken care of later. - rule50++; + assert(color_of(piece_on(from)) == us); + assert(color_of(piece_on(to)) == them || square_is_empty(to)); + assert(!(ep || pm) || piece == make_piece(us, PAWN)); + assert(!pm || relative_rank(us, to) == RANK_8); - if(move_is_castle(m)) - do_castle_move(m); - else if(move_promotion(m)) - do_promotion_move(m, u); - else if(move_is_ep(m)) - do_ep_move(m); - else { - Color us, them; - Square from, to; - PieceType piece, capture; + if (capture) + do_capture_move(key, capture, them, to, ep); - us = side_to_move(); - them = opposite_color(us); + // Update hash key + key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; - from = move_from(m); - to = move_to(m); + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; + } - assert(color_of_piece_on(from) == us); - assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY); + // Update castle rights if needed + if ( st->castleRights != CASTLES_NONE + && (castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES) + { + key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[from] & castleRightsMask[to]; + key ^= zobCastle[st->castleRights]; + } - piece = type_of_piece_on(from); - capture = type_of_piece_on(to); + // Prefetch TT access as soon as we know key is updated + prefetch((char*)TT.first_entry(key)); - if(capture) { - assert(capture != KING); + // Move the piece + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&byColorBB[us], move_bb); + do_move_bb(&byTypeBB[pt], move_bb); + do_move_bb(&byTypeBB[0], move_bb); // HACK: byTypeBB[0] == occupied squares - // Remove captured piece: - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); + board[to] = board[from]; + board[from] = PIECE_NONE; - // Update hash key: - key ^= zobrist[them][capture][to]; + // Update piece lists, note that index[from] is not updated and + // becomes stale. This works as long as index[] is accessed just + // by known occupied squares. + index[to] = index[from]; + pieceList[us][pt][index[to]] = to; - // If the captured piece was a pawn, update pawn hash key: - if(capture == PAWN) - pawnKey ^= zobrist[them][PAWN][to]; + // If the moving piece was a pawn do some special extra work + if (pt == PAWN) + { + // Reset rule 50 draw counter + st->rule50 = 0; - // Update incremental scores: - mgValue -= mg_pst(them, capture, to); - egValue -= eg_pst(them, capture, to); + // Update pawn hash key and prefetch in L1/L2 cache + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - // Update material: - if(capture != PAWN) - npMaterial[them] -= piece_value_midgame(capture); + // Set en passant square, only if moved pawn can be captured + if ((to ^ from) == 16) + { + if (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them)) + { + st->epSquare = Square((int(from) + int(to)) / 2); + key ^= zobEp[st->epSquare]; + } + } - // Update material hash key: - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + if (pm) // promotion ? + { + PieceType promotion = promotion_piece_type(m); + + assert(promotion >= KNIGHT && promotion <= QUEEN); + + // Insert promoted piece instead of pawn + clear_bit(&byTypeBB[PAWN], to); + set_bit(&byTypeBB[promotion], to); + board[to] = make_piece(us, promotion); + + // Update piece counts + pieceCount[us][promotion]++; + pieceCount[us][PAWN]--; + + // Update material key + st->materialKey ^= zobrist[us][PAWN][pieceCount[us][PAWN]]; + st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]-1]; + + // Update piece lists, move the last pawn at index[to] position + // and shrink the list. Add a new promotion piece to the list. + Square lastPawnSquare = pieceList[us][PAWN][pieceCount[us][PAWN]]; + index[lastPawnSquare] = index[to]; + pieceList[us][PAWN][index[lastPawnSquare]] = lastPawnSquare; + pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; + index[to] = pieceCount[us][promotion] - 1; + pieceList[us][promotion][index[to]] = to; + + // Partially revert hash keys update + key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; + st->pawnKey ^= zobrist[us][PAWN][to]; + + // Partially revert and update incremental scores + st->value -= pst(make_piece(us, PAWN), to); + st->value += pst(make_piece(us, promotion), to); + + // Update material + st->npMaterial[us] += PieceValueMidgame[promotion]; + } + } - // Update piece count: - pieceCount[them][capture]--; + // Prefetch pawn and material hash tables + Threads[threadID].pawnTable.prefetch(st->pawnKey); + Threads[threadID].materialTable.prefetch(st->materialKey); - // Update piece list: - pieceList[them][capture][index[to]] = - pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; + // Update incremental scores + st->value += pst_delta(piece, from, to); - // Remember the captured piece, in order to be able to undo the move - // correctly: - u.capture = capture; + // Set capture piece + st->capturedType = capture; - // Reset rule 50 counter: - rule50 = 0; - } + // Update the key with the final value + st->key = key; - // Move the piece: - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[piece]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[piece]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = board[from]; - board[from] = EMPTY; - - // Update hash key: - key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; - - // Update incremental scores: - mgValue -= mg_pst(us, piece, from); - mgValue += mg_pst(us, piece, to); - egValue -= eg_pst(us, piece, from); - egValue += eg_pst(us, piece, to); - - // If the moving piece was a king, update the king square: - if(piece == KING) - kingSquare[us] = to; - - // If the move was a double pawn push, set the en passant square. - // This code is a bit ugly right now, and should be cleaned up later. - // FIXME - if(epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; - } - if(piece == PAWN) { - if(abs(int(to) - int(from)) == 16) { - if((us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & - pawns(BLACK))) || - (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & - pawns(WHITE)))) { - epSquare = Square((int(from) + int(to)) / 2); - key ^= zobEp[epSquare]; - } + // Update checkers bitboard, piece must be already moved + st->checkersBB = EmptyBoardBB; + + if (moveIsCheck) + { + if (ep | pm) + st->checkersBB = attackers_to(king_square(them)) & pieces(us); + else + { + // Direct checks + if (bit_is_set(ci.checkSq[pt], to)) + st->checkersBB = SetMaskBB[to]; + + // Discovery checks + if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from)) + { + if (pt != ROOK) + st->checkersBB |= (attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us)); + + if (pt != BISHOP) + st->checkersBB |= (attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us)); + } } - // Reset rule 50 draw counter. - rule50 = 0; - // Update pawn hash key: - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - } + } - // Update piece lists: - pieceList[us][piece][index[from]] = to; - index[to] = index[from]; - - // Update castle rights: - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[from]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; - - // Update checkers bitboard: - checkersBB = EmptyBoardBB; - Square ksq = king_square(them); - - switch(piece) { - - case PAWN: - if(bit_is_set(pawn_attacks(them, ksq), to)) - set_bit(&checkersBB, to); - if(bit_is_set(dcCandidates, from)) - checkersBB |= - ((piece_attacks(ksq) & rooks_and_queens(us)) | - (piece_attacks(ksq) & bishops_and_queens(us))); - break; + // Finish + sideToMove = flip(sideToMove); + st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); - case KNIGHT: - if(bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - if(bit_is_set(dcCandidates, from)) - checkersBB |= - ((piece_attacks(ksq) & rooks_and_queens(us)) | - (piece_attacks(ksq) & bishops_and_queens(us))); - break; + assert(is_ok()); +} - case BISHOP: - if(bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - if(bit_is_set(dcCandidates, from)) - checkersBB |= - (piece_attacks(ksq) & rooks_and_queens(us)); - break; - case ROOK: - if(bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - if(bit_is_set(dcCandidates, from)) - checkersBB |= - (piece_attacks(ksq) & bishops_and_queens(us)); - break; +/// Position::do_capture_move() is a private method used to update captured +/// piece info. It is called from the main Position::do_move function. - case QUEEN: - if(bit_is_set(piece_attacks(ksq), to)) - set_bit(&checkersBB, to); - break; +void Position::do_capture_move(Key& key, PieceType capture, Color them, Square to, bool ep) { - case KING: - if(bit_is_set(dcCandidates, from)) - checkersBB |= - ((piece_attacks(ksq) & rooks_and_queens(us)) | - (piece_attacks(ksq) & bishops_and_queens(us))); - break; + assert(capture != KING); - default: - assert(false); - break; + Square capsq = to; + + // If the captured piece was a pawn, update pawn hash key, + // otherwise update non-pawn material. + if (capture == PAWN) + { + if (ep) // en passant ? + { + capsq = to + pawn_push(them); + + assert(to == st->epSquare); + assert(relative_rank(flip(them), to) == RANK_6); + assert(piece_on(to) == PIECE_NONE); + assert(piece_on(capsq) == make_piece(them, PAWN)); + + board[capsq] = PIECE_NONE; + } + st->pawnKey ^= zobrist[them][PAWN][capsq]; } - } + else + st->npMaterial[them] -= PieceValueMidgame[capture]; - // Finish - key ^= zobSideToMove; - sideToMove = opposite_color(sideToMove); - gamePly++; + // Remove captured piece + clear_bit(&byColorBB[them], capsq); + clear_bit(&byTypeBB[capture], capsq); + clear_bit(&byTypeBB[0], capsq); - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + // Update hash key + key ^= zobrist[them][capture][capsq]; - assert(is_ok()); + // Update incremental scores + st->value -= pst(make_piece(them, capture), capsq); + + // Update piece count + pieceCount[them][capture]--; + + // Update material hash key + st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]]; + + // Update piece list, move the last piece at index[capsq] position + // + // WARNING: This is a not perfectly revresible operation. When we + // will reinsert the captured piece in undo_move() we will put it + // at the end of the list and not in its original place, it means + // index[] and pieceList[] are not guaranteed to be invariant to a + // do_move() + undo_move() sequence. + Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]]; + index[lastPieceSquare] = index[capsq]; + pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare; + pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; + + // Reset rule 50 counter + st->rule50 = 0; } /// Position::do_castle_move() is a private method used to make a castling -/// move. It is called from the main Position::do_move function. Note that +/// move. It is called from the main Position::do_move function. Note that /// castling moves are encoded as "king captures friendly rook" moves, for /// instance white short castling in a non-Chess960 game is encoded as e1h1. void Position::do_castle_move(Move m) { - Color us, them; - Square kfrom, kto, rfrom, rto; - assert(is_ok()); - assert(move_is_ok(m)); - assert(move_is_castle(m)); + assert(is_ok(m)); + assert(is_castle(m)); - us = side_to_move(); - them = opposite_color(us); + Color us = side_to_move(); + Color them = flip(us); - // Find source squares for king and rook: - kfrom = move_from(m); - rfrom = move_to(m); // HACK: See comment at beginning of function. + // Find source squares for king and rook + Square kfrom = move_from(m); + Square rfrom = move_to(m); + Square kto, rto; - assert(piece_on(kfrom) == king_of_color(us)); - assert(piece_on(rfrom) == rook_of_color(us)); + assert(piece_on(kfrom) == make_piece(us, KING)); + assert(piece_on(rfrom) == make_piece(us, ROOK)); - // Find destination squares for king and rook: - if(rfrom > kfrom) { // O-O - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); + // Find destination squares for king and rook + if (rfrom > kfrom) // O-O + { + kto = relative_square(us, SQ_G1); + rto = relative_square(us, SQ_F1); } - else { // O-O-O - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); + else // O-O-O + { + kto = relative_square(us, SQ_C1); + rto = relative_square(us, SQ_D1); } - // Remove pieces from source squares: - clear_bit(&(byColorBB[us]), kfrom); - clear_bit(&(byTypeBB[KING]), kfrom); - clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rfrom); - clear_bit(&(byTypeBB[ROOK]), rfrom); - clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on destination squares: - set_bit(&(byColorBB[us]), kto); - set_bit(&(byTypeBB[KING]), kto); - set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rto); - set_bit(&(byTypeBB[ROOK]), rto); - set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares - - // Update board array: - board[kfrom] = board[rfrom] = EMPTY; - board[kto] = king_of_color(us); - board[rto] = rook_of_color(us); - - // Update king square: - kingSquare[us] = kto; - - // Update piece lists: + // Remove pieces from source squares + clear_bit(&byColorBB[us], kfrom); + clear_bit(&byTypeBB[KING], kfrom); + clear_bit(&byTypeBB[0], kfrom); + clear_bit(&byColorBB[us], rfrom); + clear_bit(&byTypeBB[ROOK], rfrom); + clear_bit(&byTypeBB[0], rfrom); + + // Put pieces on destination squares + set_bit(&byColorBB[us], kto); + set_bit(&byTypeBB[KING], kto); + set_bit(&byTypeBB[0], kto); + set_bit(&byColorBB[us], rto); + set_bit(&byTypeBB[ROOK], rto); + set_bit(&byTypeBB[0], rto); + + // Update board + Piece king = make_piece(us, KING); + Piece rook = make_piece(us, ROOK); + board[kfrom] = board[rfrom] = PIECE_NONE; + board[kto] = king; + board[rto] = rook; + + // Update piece lists pieceList[us][KING][index[kfrom]] = kto; pieceList[us][ROOK][index[rfrom]] = rto; - int tmp = index[rfrom]; + int tmp = index[rfrom]; // In Chess960 could be kto == rfrom index[kto] = index[kfrom]; index[rto] = tmp; - // Update incremental scores: - mgValue -= mg_pst(us, KING, kfrom); - mgValue += mg_pst(us, KING, kto); - egValue -= eg_pst(us, KING, kfrom); - egValue += eg_pst(us, KING, kto); - mgValue -= mg_pst(us, ROOK, rfrom); - mgValue += mg_pst(us, ROOK, rto); - egValue -= eg_pst(us, ROOK, rfrom); - egValue += eg_pst(us, ROOK, rto); - - // Update hash key: - key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; - - // Clear en passant square: - if(epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; - } - - // Update castling rights: - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[kfrom]; - key ^= zobCastle[castleRights]; - - // Reset rule 50 counter: - rule50 = 0; - - // Update checkers BB: - checkersBB = attacks_to(king_square(them), us); -} - - -/// Position::do_promotion_move() is a private method used to make a promotion -/// move. It is called from the main Position::do_move function. The -/// UndoInfo object, which has been initialized in Position::do_move, is -/// used to store the captured piece (if any). - -void Position::do_promotion_move(Move m, UndoInfo &u) { - Color us, them; - Square from, to; - PieceType capture, promotion; - - assert(is_ok()); - assert(move_is_ok(m)); - assert(move_promotion(m)); + // Reset capture field + st->capturedType = PIECE_TYPE_NONE; - us = side_to_move(); - them = opposite_color(us); + // Update incremental scores + st->value += pst_delta(king, kfrom, kto); + st->value += pst_delta(rook, rfrom, rto); - from = move_from(m); - to = move_to(m); + // Update hash key + st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; + st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == pawn_of_color(us)); - assert(color_of_piece_on(to) == them || square_is_empty(to)); + // Clear en passant square + if (st->epSquare != SQ_NONE) + { + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; + } - capture = type_of_piece_on(to); + // Update castling rights + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[kfrom]; + st->key ^= zobCastle[st->castleRights]; - if(capture) { - assert(capture != KING); + // Reset rule 50 counter + st->rule50 = 0; - // Remove captured piece: - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); + // Update checkers BB + st->checkersBB = attackers_to(king_square(them)) & pieces(us); - // Update hash key: - key ^= zobrist[them][capture][to]; + // Finish + sideToMove = flip(sideToMove); + st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); - // Update incremental scores: - mgValue -= mg_pst(them, capture, to); - egValue -= eg_pst(them, capture, to); + assert(is_ok()); +} - // Update material. Because our move is a promotion, we know that the - // captured piece is not a pawn. - assert(capture != PAWN); - npMaterial[them] -= piece_value_midgame(capture); - // Update material hash key: - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; +/// 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. - // Update piece count: - pieceCount[them][capture]--; +void Position::undo_move(Move m) { - // Update piece list: - pieceList[them][capture][index[to]] = - pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; + assert(is_ok(m)); - // Remember the captured piece, in order to be able to undo the move - // correctly: - u.capture = capture; - } + sideToMove = flip(sideToMove); - // Remove pawn: - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = EMPTY; - - // Insert promoted piece: - promotion = move_promotion(m); - assert(promotion >= KNIGHT && promotion <= QUEEN); - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[promotion]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(us, promotion); - - // Update hash key: - key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; - - // Update pawn hash key: - pawnKey ^= zobrist[us][PAWN][from]; - - // Update material key: - materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; - materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; - - // Update piece counts: - pieceCount[us][PAWN]--; - pieceCount[us][promotion]++; - - // Update piece lists: - pieceList[us][PAWN][index[from]] = - pieceList[us][PAWN][pieceCount[us][PAWN]]; - index[pieceList[us][PAWN][index[from]]] = index[from]; - pieceList[us][promotion][pieceCount[us][promotion] - 1] = to; - index[to] = pieceCount[us][promotion] - 1; - - // Update incremental scores: - mgValue -= mg_pst(us, PAWN, from); - mgValue += mg_pst(us, promotion, to); - egValue -= eg_pst(us, PAWN, from); - egValue += eg_pst(us, promotion, to); - - // Update material: - npMaterial[us] += piece_value_midgame(promotion); - - // Clear the en passant square: - if(epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + if (is_castle(m)) + { + undo_castle_move(m); + return; } - // Update castle rights: - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; - - // Reset rule 50 counter: - rule50 = 0; + Color us = side_to_move(); + Color them = flip(us); + Square from = move_from(m); + Square to = move_to(m); + bool ep = is_enpassant(m); + bool pm = is_promotion(m); - // Update checkers BB: - checkersBB = attacks_to(king_square(them), us); -} + PieceType pt = type_of(piece_on(to)); + assert(square_is_empty(from)); + assert(color_of(piece_on(to)) == us); + assert(!pm || relative_rank(us, to) == RANK_8); + assert(!ep || to == st->previous->epSquare); + assert(!ep || relative_rank(us, to) == RANK_6); + assert(!ep || piece_on(to) == make_piece(us, PAWN)); -/// Position::do_ep_move() is a private method used to make an en passant -/// capture. It is called from the main Position::do_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object in which to store the captured piece. + if (pm) // promotion ? + { + PieceType promotion = promotion_piece_type(m); + pt = PAWN; + + assert(promotion >= KNIGHT && promotion <= QUEEN); + assert(piece_on(to) == make_piece(us, promotion)); + + // Replace promoted piece with a pawn + clear_bit(&byTypeBB[promotion], to); + set_bit(&byTypeBB[PAWN], to); + + // Update piece counts + pieceCount[us][promotion]--; + pieceCount[us][PAWN]++; + + // Update piece list replacing promotion piece with a pawn + Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]]; + index[lastPromotionSquare] = index[to]; + pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare; + pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; + index[to] = pieceCount[us][PAWN] - 1; + pieceList[us][PAWN][index[to]] = to; + } -void Position::do_ep_move(Move m) { - Color us, them; - Square from, to, capsq; + // Put the piece back at the source square + Bitboard move_bb = make_move_bb(to, from); + do_move_bb(&byColorBB[us], move_bb); + do_move_bb(&byTypeBB[pt], move_bb); + do_move_bb(&byTypeBB[0], move_bb); // HACK: byTypeBB[0] == occupied squares - assert(is_ok()); - assert(move_is_ok(m)); - assert(move_is_ep(m)); + board[from] = make_piece(us, pt); + board[to] = PIECE_NONE; - us = side_to_move(); - them = opposite_color(us); + // Update piece list + index[from] = index[to]; + pieceList[us][pt][index[from]] = from; - // Find from, to and capture squares: - from = move_from(m); - to = move_to(m); - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == EMPTY); - assert(piece_on(from) == pawn_of_color(us)); - assert(piece_on(capsq) == pawn_of_color(them)); - - // Remove captured piece: - clear_bit(&(byColorBB[them]), capsq); - clear_bit(&(byTypeBB[PAWN]), capsq); - clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares - board[capsq] = EMPTY; - - // Remove moving piece from source square: - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - - // Put moving piece on destination square: - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[PAWN]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = board[from]; - board[from] = EMPTY; + if (st->capturedType) + { + Square capsq = to; - // Update material hash key: - materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; + if (ep) + capsq = to - pawn_push(us); - // Update piece count: - pieceCount[them][PAWN]--; + assert(st->capturedType != KING); + assert(!ep || square_is_empty(capsq)); - // Update piece list: - pieceList[us][PAWN][index[from]] = to; - index[to] = index[from]; - pieceList[them][PAWN][index[capsq]] = - pieceList[them][PAWN][pieceCount[them][PAWN]]; - index[pieceList[them][PAWN][index[capsq]]] = index[capsq]; - - // Update hash key: - key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - key ^= zobrist[them][PAWN][capsq]; - key ^= zobEp[epSquare]; - - // Update pawn hash key: - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - pawnKey ^= zobrist[them][PAWN][capsq]; - - // Update incremental scores: - mgValue -= mg_pst(them, PAWN, capsq); - mgValue -= mg_pst(us, PAWN, from); - mgValue += mg_pst(us, PAWN, to); - egValue -= eg_pst(them, PAWN, capsq); - egValue -= eg_pst(us, PAWN, from); - egValue += eg_pst(us, PAWN, to); - - // Reset en passant square: - epSquare = SQ_NONE; - - // Reset rule 50 counter: - rule50 = 0; - - // Update checkers BB: - checkersBB = attacks_to(king_square(them), us); -} + // Restore the captured piece + set_bit(&byColorBB[them], capsq); + set_bit(&byTypeBB[st->capturedType], capsq); + set_bit(&byTypeBB[0], capsq); + board[capsq] = make_piece(them, st->capturedType); -/// Position::undo_move() unmakes a move. When it returns, the position should -/// be restored to exactly the same state as before the move was made. It is -/// important that Position::undo_move is called with the same move and UndoInfo -/// object as the earlier call to Position::do_move. + // Update piece count + pieceCount[them][st->capturedType]++; -void Position::undo_move(Move m, const UndoInfo &u) { - assert(is_ok()); - assert(move_is_ok(m)); - - gamePly--; - sideToMove = opposite_color(sideToMove); - - // Restore information from our UndoInfo object (except the captured piece, - // which is taken care of later): - restore(u); - - if(move_is_castle(m)) - undo_castle_move(m); - else if(move_promotion(m)) - undo_promotion_move(m, u); - else if(move_is_ep(m)) - undo_ep_move(m); - else { - Color us, them; - Square from, to; - PieceType piece, capture; - - us = side_to_move(); - them = opposite_color(us); - - from = move_from(m); - to = move_to(m); - - assert(piece_on(from) == EMPTY); - assert(color_of_piece_on(to) == us); - - // Put the piece back at the source square: - piece = type_of_piece_on(to); - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[piece]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = piece_of_color_and_type(us, piece); - - // Clear the destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[piece]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - - // If the moving piece was a king, update the king square: - if(piece == KING) - kingSquare[us] = from; - - // Update piece list: - pieceList[us][piece][index[to]] = from; - index[from] = index[to]; - - capture = u.capture; - - if(capture) { - assert(capture != KING); - // Replace the captured piece: - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); - set_bit(&(byTypeBB[0]), to); - board[to] = piece_of_color_and_type(them, capture); - - // Update material: - if(capture != PAWN) - npMaterial[them] += piece_value_midgame(capture); - - // Update piece list: - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; - - // Update piece count: - pieceCount[them][capture]++; - } - else - board[to] = EMPTY; + // Update piece list, add a new captured piece in capsq square + index[capsq] = pieceCount[them][st->capturedType] - 1; + pieceList[them][st->capturedType][index[capsq]] = capsq; } + // Finally point our state pointer back to the previous state + st = st->previous; + assert(is_ok()); } /// Position::undo_castle_move() is a private method used to unmake a castling -/// move. It is called from the main Position::undo_move function. Note that +/// move. It is called from the main Position::undo_move function. Note that /// castling moves are encoded as "king captures friendly rook" moves, for /// instance white short castling in a non-Chess960 game is encoded as e1h1. void Position::undo_castle_move(Move m) { - Color us, them; - Square kfrom, kto, rfrom, rto; - assert(move_is_ok(m)); - assert(move_is_castle(m)); + assert(is_ok(m)); + assert(is_castle(m)); // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, + // Position::undo_move. In particular, the side to move has been switched, // so the code below is correct. - us = side_to_move(); - them = opposite_color(us); + Color us = side_to_move(); - // Find source squares for king and rook: - kfrom = move_from(m); - rfrom = move_to(m); // HACK: See comment at beginning of function. + // Find source squares for king and rook + Square kfrom = move_from(m); + Square rfrom = move_to(m); + Square kto, rto; - // Find destination squares for king and rook: - if(rfrom > kfrom) { // O-O - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); + // Find destination squares for king and rook + if (rfrom > kfrom) // O-O + { + kto = relative_square(us, SQ_G1); + rto = relative_square(us, SQ_F1); } - else { // O-O-O - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); + else // O-O-O + { + kto = relative_square(us, SQ_C1); + rto = relative_square(us, SQ_D1); } - assert(piece_on(kto) == king_of_color(us)); - assert(piece_on(rto) == rook_of_color(us)); - - // Remove pieces from destination squares: - clear_bit(&(byColorBB[us]), kto); - clear_bit(&(byTypeBB[KING]), kto); - clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rto); - clear_bit(&(byTypeBB[ROOK]), rto); - clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on source squares: - set_bit(&(byColorBB[us]), kfrom); - set_bit(&(byTypeBB[KING]), kfrom); - set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rfrom); - set_bit(&(byTypeBB[ROOK]), rfrom); - set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - - // Update board: - board[rto] = board[kto] = EMPTY; - board[rfrom] = rook_of_color(us); - board[kfrom] = king_of_color(us); - - // Update king square: - kingSquare[us] = kfrom; - - // Update piece lists: + assert(piece_on(kto) == make_piece(us, KING)); + assert(piece_on(rto) == make_piece(us, ROOK)); + + // Remove pieces from destination squares + clear_bit(&byColorBB[us], kto); + clear_bit(&byTypeBB[KING], kto); + clear_bit(&byTypeBB[0], kto); + clear_bit(&byColorBB[us], rto); + clear_bit(&byTypeBB[ROOK], rto); + clear_bit(&byTypeBB[0], rto); + + // Put pieces on source squares + set_bit(&byColorBB[us], kfrom); + set_bit(&byTypeBB[KING], kfrom); + set_bit(&byTypeBB[0], kfrom); + set_bit(&byColorBB[us], rfrom); + set_bit(&byTypeBB[ROOK], rfrom); + set_bit(&byTypeBB[0], rfrom); + + // Update board + Piece king = make_piece(us, KING); + Piece rook = make_piece(us, ROOK); + board[kto] = board[rto] = PIECE_NONE; + board[kfrom] = king; + board[rfrom] = rook; + + // Update piece lists pieceList[us][KING][index[kto]] = kfrom; pieceList[us][ROOK][index[rto]] = rfrom; - int tmp = index[rto]; // Necessary because we may have rto == kfrom in FRC. + int tmp = index[rto]; // In Chess960 could be rto == kfrom index[kfrom] = index[kto]; index[rfrom] = tmp; -} - - -/// Position::undo_promotion_move() is a private method used to unmake a -/// promotion move. It is called from the main Position::do_move -/// function. The UndoInfo object, which has been initialized in -/// Position::do_move, is used to put back the captured piece (if any). -void Position::undo_promotion_move(Move m, const UndoInfo &u) { - Color us, them; - Square from, to; - PieceType capture, promotion; - - assert(move_is_ok(m)); - assert(move_promotion(m)); + // Finally point our state pointer back to the previous state + st = st->previous; - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - us = side_to_move(); - them = opposite_color(us); + assert(is_ok()); +} - from = move_from(m); - to = move_to(m); - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == EMPTY); - - // Remove promoted piece: - promotion = move_promotion(m); - assert(piece_on(to)==piece_of_color_and_type(us, promotion)); - assert(promotion >= KNIGHT && promotion <= QUEEN); - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[promotion]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - - // Insert pawn at source square: - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = pawn_of_color(us); - - // Update material: - npMaterial[us] -= piece_value_midgame(promotion); - - // Update piece list: - pieceList[us][PAWN][pieceCount[us][PAWN]] = from; - index[from] = pieceCount[us][PAWN]; - pieceList[us][promotion][index[to]] = - pieceList[us][promotion][pieceCount[us][promotion] - 1]; - index[pieceList[us][promotion][index[to]]] = index[to]; - - // Update piece counts: - pieceCount[us][promotion]--; - pieceCount[us][PAWN]++; - - capture = u.capture; - if(capture) { - assert(capture != KING); +/// Position::do_null_move makes() a "null move": It switches the side to move +/// and updates the hash key without executing any move on the board. - // Insert captured piece: - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(them, capture); +void Position::do_null_move(StateInfo& backupSt) { - // Update material. Because the move is a promotion move, we know - // that the captured piece cannot be a pawn. - assert(capture != PAWN); - npMaterial[them] += piece_value_midgame(capture); + assert(!in_check()); - // Update piece list: - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; + // Back up the information necessary to undo the null move to the supplied + // StateInfo object. + // Note that differently from normal case here backupSt is actually used as + // a backup storage not as a new state to be used. + backupSt.key = st->key; + backupSt.epSquare = st->epSquare; + backupSt.value = st->value; + backupSt.previous = st->previous; + backupSt.pliesFromNull = st->pliesFromNull; + st->previous = &backupSt; + + // Update the necessary information + if (st->epSquare != SQ_NONE) + st->key ^= zobEp[st->epSquare]; + + st->key ^= zobSideToMove; + prefetch((char*)TT.first_entry(st->key)); + + sideToMove = flip(sideToMove); + st->epSquare = SQ_NONE; + st->rule50++; + st->pliesFromNull = 0; + st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue; - // Update piece count: - pieceCount[them][capture]++; - } - else - board[to] = EMPTY; + assert(is_ok()); } -/// Position::undo_ep_move() is a private method used to unmake an en passant -/// capture. It is called from the main Position::undo_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object from which to retrieve the captured piece. +/// Position::undo_null_move() unmakes a "null move". -void Position::undo_ep_move(Move m) { - Color us, them; - Square from, to, capsq; +void Position::undo_null_move() { - assert(move_is_ok(m)); - assert(move_is_ep(m)); + assert(!in_check()); - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - us = side_to_move(); - them = opposite_color(us); + // Restore information from the our backup StateInfo object + StateInfo* backupSt = st->previous; + st->key = backupSt->key; + st->epSquare = backupSt->epSquare; + st->value = backupSt->value; + st->previous = backupSt->previous; + st->pliesFromNull = backupSt->pliesFromNull; - // Find from, to and captures squares: - from = move_from(m); - to = move_to(m); - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == ep_square()); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == pawn_of_color(us)); - assert(piece_on(from) == EMPTY); - assert(piece_on(capsq) == EMPTY); - - // Replace captured piece: - set_bit(&(byColorBB[them]), capsq); - set_bit(&(byTypeBB[PAWN]), capsq); - set_bit(&(byTypeBB[0]), capsq); - board[capsq] = pawn_of_color(them); - - // Remove moving piece from destination square: - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[PAWN]), to); - clear_bit(&(byTypeBB[0]), to); - board[to] = EMPTY; - - // Replace moving piece at source square: - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); - board[from] = pawn_of_color(us); - - // Update piece list: - pieceList[us][PAWN][index[to]] = from; - index[from] = index[to]; - pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; - index[capsq] = pieceCount[them][PAWN]; + // Update the necessary information + sideToMove = flip(sideToMove); + st->rule50--; - // Update piece count: - pieceCount[them][PAWN]++; + assert(is_ok()); } -/// Position::do_null_move makes() a "null move": It switches the side to move -/// and updates the hash key without executing any move on the board. - -void Position::do_null_move(UndoInfo &u) { - assert(is_ok()); - assert(!is_check()); - - // Back up the information necessary to undo the null move to the supplied - // UndoInfo object. In the case of a null move, the only thing we need to - // remember is the last move made and the en passant square. - u.lastMove = lastMove; - u.epSquare = epSquare; - - // Save the current key to the history[] array, in order to be able to - // detect repetition draws: - history[gamePly] = key; - - // Update the necessary information. - sideToMove = opposite_color(sideToMove); - if(epSquare != SQ_NONE) - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; - rule50++; - gamePly++; - key ^= zobSideToMove; +/// Position::see() is a static exchange evaluator: It tries to estimate the +/// material gain or loss resulting from a move. There are three versions of +/// this function: One which takes a destination square as input, one takes a +/// move, and one which takes a 'from' and a 'to' square. The function does +/// not yet understand promotions captures. - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; +int Position::see_sign(Move m) const { - assert(is_ok()); -} + assert(is_ok(m)); + Square from = move_from(m); + Square to = move_to(m); -/// Position::undo_null_move() unmakes a "null move". + // Early return if SEE cannot be negative because captured piece value + // is not less then capturing one. Note that king moves always return + // here because king midgame value is set to 0. + if (piece_value_midgame(piece_on(to)) >= piece_value_midgame(piece_on(from))) + return 1; -void Position::undo_null_move(const UndoInfo &u) { - assert(is_ok()); - assert(!is_check()); - - // Restore information from the supplied UndoInfo object: - lastMove = u.lastMove; - epSquare = u.epSquare; - if(epSquare != SQ_NONE) - key ^= zobEp[epSquare]; - - // Update the necessary information. - sideToMove = opposite_color(sideToMove); - rule50--; - gamePly--; - key ^= zobSideToMove; + return see(m); +} - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; +int Position::see(Move m) const { - assert(is_ok()); -} + Square from, to; + Bitboard occupied, attackers, stmAttackers, b; + int swapList[32], slIndex = 1; + PieceType capturedType, pt; + Color stm; + assert(is_ok(m)); -/// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. There are two versions of -/// this function: One which takes a move as input, and one which takes a -/// 'from' and a 'to' square. The function does not yet understand promotions -/// or en passant captures. + // As castle moves are implemented as capturing the rook, they have + // SEE == RookValueMidgame most of the times (unless the rook is under + // attack). + if (is_castle(m)) + return 0; -int Position::see(Square from, Square to) const { - // Approximate material values, with pawn = 1: - static const int seeValues[18] = { - 0, 1, 3, 3, 5, 10, 100, 0, 0, 1, 3, 3, 5, 10, 100, 0, 0, 0 - }; - Color us, them; - Piece piece, capture; - Bitboard attackers, occ, b; + from = move_from(m); + to = move_to(m); + capturedType = type_of(piece_on(to)); + occupied = occupied_squares(); - assert(square_is_ok(from)); - assert(square_is_ok(to)); + // Handle en passant moves + if (st->epSquare == to && type_of(piece_on(from)) == PAWN) + { + Square capQq = to - pawn_push(side_to_move()); - // Initialize colors: - us = color_of_piece_on(from); - them = opposite_color(us); + assert(capturedType == PIECE_TYPE_NONE); + assert(type_of(piece_on(capQq)) == PAWN); - // Initialize pieces: - piece = piece_on(from); - capture = piece_on(to); + // Remove the captured pawn + clear_bit(&occupied, capQq); + capturedType = PAWN; + } // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it: - occ = occupied_squares(); - clear_bit(&occ, from); - attackers = - (rook_attacks_bb(to, occ) & rooks_and_queens()) | - (bishop_attacks_bb(to, occ) & bishops_and_queens()) | - (piece_attacks(to) & knights()) | - (piece_attacks(to) & kings()) | - (pawn_attacks(WHITE, to) & pawns(BLACK)) | - (pawn_attacks(BLACK, to) & pawns(WHITE)); - attackers &= occ; - - // If the opponent has no attackers, we are finished: - if((attackers & pieces_of_color(them)) == EmptyBoardBB) - return seeValues[capture]; + // removed, but possibly an X-ray attacker added behind it. + clear_bit(&occupied, from); + attackers = attackers_to(to, occupied); + + // If the opponent has no attackers we are finished + stm = flip(color_of(piece_on(from))); + stmAttackers = attackers & pieces(stm); + if (!stmAttackers) + return PieceValueMidgame[capturedType]; // The destination square is defended, which makes things rather more - // difficult to compute. We proceed by building up a "swap list" containing + // difficult to compute. We proceed by building up a "swap list" containing // the material gain or loss at each stop in a sequence of captures to the - // destianation square, where the sides alternately capture, and always - // capture with the least valuable piece. After each capture, we look for + // destination square, where the sides alternately capture, and always + // capture with the least valuable piece. After each capture, we look for // new X-ray attacks from behind the capturing piece. - int lastCapturingPieceValue = seeValues[piece]; - int swapList[32], n = 1; - Color c = them; - PieceType pt; - - swapList[0] = seeValues[capture]; + swapList[0] = PieceValueMidgame[capturedType]; + capturedType = type_of(piece_on(from)); do { - // Locate the least valuable attacker for the side to move. The loop - // below looks like it is potentially infinite, but it isn't. We know - // that the side to move still has at least one attacker left. - for(pt = PAWN; !(attackers&pieces_of_color_and_type(c, pt)); pt++) - assert(pt < KING); - - // Remove the attacker we just found from the 'attackers' bitboard, - // and scan for new X-ray attacks behind the attacker: - b = attackers & pieces_of_color_and_type(c, pt); - occ ^= (b & -b); - attackers |= - (rook_attacks_bb(to, occ) & rooks_and_queens()) | - (bishop_attacks_bb(to, occ) & bishops_and_queens()); - attackers &= occ; - - // Add the new entry to the swap list: - assert(n < 32); - swapList[n] = -swapList[n - 1] + lastCapturingPieceValue; - n++; - - // Remember the value of the capturing piece, and change the side to move - // before beginning the next iteration: - lastCapturingPieceValue = seeValues[pt]; - c = opposite_color(c); - - // Stop after a king capture: - if(pt == KING && (attackers & pieces_of_color(c))) { - assert(n < 32); - swapList[n++] = 100; - break; - } - } while(attackers & pieces_of_color(c)); + // Locate the least valuable attacker for the side to move. The loop + // below looks like it is potentially infinite, but it isn't. We know + // that the side to move still has at least one attacker left. + for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++) + assert(pt < KING); + + // Remove the attacker we just found from the 'occupied' bitboard, + // and scan for new X-ray attacks behind the attacker. + b = stmAttackers & pieces(pt); + occupied ^= (b & (~b + 1)); + attackers |= (rook_attacks_bb(to, occupied) & pieces(ROOK, QUEEN)) + | (bishop_attacks_bb(to, occupied) & pieces(BISHOP, QUEEN)); + + attackers &= occupied; // Cut out pieces we've already done + + // Add the new entry to the swap list + assert(slIndex < 32); + swapList[slIndex] = -swapList[slIndex - 1] + PieceValueMidgame[capturedType]; + slIndex++; + + // Remember the value of the capturing piece, and change the side to + // move before beginning the next iteration. + capturedType = pt; + stm = flip(stm); + stmAttackers = attackers & pieces(stm); + + // Stop before processing a king capture + if (capturedType == KING && stmAttackers) + { + assert(slIndex < 32); + swapList[slIndex++] = QueenValueMidgame*10; + break; + } + } while (stmAttackers); // Having built the swap list, we negamax through it to find the best - // achievable score from the point of view of the side to move: - while(--n) swapList[n-1] = Min(-swapList[n], swapList[n-1]); + // achievable score from the point of view of the side to move. + while (--slIndex) + swapList[slIndex-1] = Min(-swapList[slIndex], swapList[slIndex-1]); return swapList[0]; } -int Position::see(Move m) const { - assert(move_is_ok(m)); - return see(move_from(m), move_to(m)); -} - - /// Position::clear() erases the position object to a pristine state, with an /// empty board, white to move, and no castling rights. void Position::clear() { - int i, j; - - for(i = 0; i < 64; i++) { - board[i] = EMPTY; - index[i] = 0; - } - for(i = 0; i < 2; i++) - byColorBB[i] = EmptyBoardBB; + st = &startState; + memset(st, 0, sizeof(StateInfo)); + st->epSquare = SQ_NONE; - for(i = 0; i < 7; i++) { - byTypeBB[i] = EmptyBoardBB; - pieceCount[0][i] = pieceCount[1][i] = 0; - for(j = 0; j < 8; j++) - pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - } - - checkersBB = EmptyBoardBB; + memset(byColorBB, 0, sizeof(Bitboard) * 2); + memset(byTypeBB, 0, sizeof(Bitboard) * 8); + memset(pieceCount, 0, sizeof(int) * 2 * 8); + memset(index, 0, sizeof(int) * 64); - lastMove = MOVE_NONE; + for (int i = 0; i < 8; i++) + for (int j = 0; j < 16; j++) + pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; + for (Square sq = SQ_A1; sq <= SQ_H8; sq++) + { + board[sq] = PIECE_NONE; + castleRightsMask[sq] = ALL_CASTLES; + } sideToMove = WHITE; - castleRights = NO_CASTLES; - initialKFile = FILE_E; - initialKRFile = FILE_H; - initialQRFile = FILE_A; - epSquare = SQ_NONE; - rule50 = 0; - gamePly = 0; -} - - -/// Position::reset_game_ply() simply sets gamePly to 0. It is used from the -/// UCI interface code, whenever a non-reversible move is made in a -/// 'position fen moves m1 m2 ...' command. This makes it possible -/// for the program to handle games of arbitrary length, as long as the GUI -/// handles draws by the 50 move rule correctly. - -void Position::reset_game_ply() { - gamePly = 0; + nodes = 0; } /// Position::put_piece() puts a piece on the given square of the board, -/// updating the board array, bitboards, and piece counts. +/// updating the board array, pieces list, bitboards, and piece counts. void Position::put_piece(Piece p, Square s) { - Color c = color_of_piece(p); - PieceType pt = type_of_piece(p); + + Color c = color_of(p); + PieceType pt = type_of(p); board[s] = p; - index[s] = pieceCount[c][pt]; + index[s] = pieceCount[c][pt]++; pieceList[c][pt][index[s]] = s; - set_bit(&(byTypeBB[pt]), s); - set_bit(&(byColorBB[c]), s); + set_bit(&byTypeBB[pt], s); + set_bit(&byColorBB[c], s); set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares. - - pieceCount[c][pt]++; - - if(pt == KING) - kingSquare[c] = s; -} - - -/// Position::allow_oo() gives the given side the right to castle kingside. -/// Used when setting castling rights during parsing of FEN strings. - -void Position::allow_oo(Color c) { - castleRights |= (1 + int(c)); -} - - -/// Position::allow_ooo() gives the given side the right to castle queenside. -/// Used when setting castling rights during parsing of FEN strings. - -void Position::allow_ooo(Color c) { - castleRights |= (4 + 4*int(c)); } -/// Position::compute_key() computes the hash key of the position. The hash +/// Position::compute_key() computes the hash key of the position. The hash /// key is usually updated incrementally as moves are made and unmade, the /// compute_key() function is only used when a new position is set up, and /// to verify the correctness of the hash key when running in debug mode. Key Position::compute_key() const { - Key result = Key(0ULL); - for(Square s = SQ_A1; s <= SQ_H8; s++) - if(square_is_occupied(s)) - result ^= - zobrist[color_of_piece_on(s)][type_of_piece_on(s)][s]; + Key result = zobCastle[st->castleRights]; + + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (!square_is_empty(s)) + result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s]; + + if (ep_square() != SQ_NONE) + result ^= zobEp[ep_square()]; - if(ep_square() != SQ_NONE) - result ^= zobEp[ep_square()]; - result ^= zobCastle[castleRights]; - if(side_to_move() == BLACK) result ^= zobSideToMove; + if (side_to_move() == BLACK) + result ^= zobSideToMove; return result; } -/// Position::compute_pawn_key() computes the hash key of the position. The +/// Position::compute_pawn_key() computes the hash key of the position. The /// hash key is usually updated incrementally as moves are made and unmade, /// the compute_pawn_key() function is only used when a new position is set /// up, and to verify the correctness of the pawn hash key when running in /// debug mode. Key Position::compute_pawn_key() const { - Key result = Key(0ULL); + Bitboard b; - Square s; + Key result = 0; - for(Color c = WHITE; c <= BLACK; c++) { - b = pawns(c); - while(b) { - s = pop_1st_bit(&b); - result ^= zobrist[c][PAWN][s]; - } + for (Color c = WHITE; c <= BLACK; c++) + { + b = pieces(PAWN, c); + while (b) + result ^= zobrist[c][PAWN][pop_1st_bit(&b)]; } return result; } @@ -1826,270 +1586,190 @@ Key Position::compute_pawn_key() const { /// debug mode. Key Position::compute_material_key() const { - Key result = Key(0ULL); - for(Color c = WHITE; c <= BLACK; c++) - for(PieceType pt = PAWN; pt <= QUEEN; pt++) { - int count = piece_count(c, pt); - for(int i = 0; i <= count; i++) - result ^= zobMaterial[c][pt][i]; - } - return result; -} + Key result = 0; -/// Position::compute_mg_value() and Position::compute_eg_value() compute the -/// incremental scores for the middle game and the endgame. These functions -/// are used to initialize the incremental scores when a new position is set -/// up, and to verify that the scores are correctly updated by do_move -/// and undo_move when the program is running in debug mode. + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= QUEEN; pt++) + for (int i = 0, cnt = piece_count(c, pt); i < cnt; i++) + result ^= zobrist[c][pt][i]; -Value Position::compute_mg_value() const { - Value result = Value(0); - Bitboard b; - Square s; - - for(Color c = WHITE; c <= BLACK; c++) - for(PieceType pt = PAWN; pt <= KING; pt++) { - b = pieces_of_color_and_type(c, pt); - while(b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += mg_pst(c, pt, s); - } - } - result += (side_to_move() == WHITE)? - (TempoValueMidgame / 2) : -(TempoValueMidgame / 2); return result; } -Value Position::compute_eg_value() const { - Value result = Value(0); + +/// Position::compute_value() compute the incremental scores for the middle +/// game and the endgame. These functions are used to initialize the incremental +/// scores when a new position is set up, and to verify that the scores are correctly +/// updated by do_move and undo_move when the program is running in debug mode. +Score Position::compute_value() const { + Bitboard b; - Square s; - - for(Color c = WHITE; c <= BLACK; c++) - for(PieceType pt = PAWN; pt <= KING; pt++) { - b = pieces_of_color_and_type(c, pt); - while(b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += eg_pst(c, pt, s); + Score result = SCORE_ZERO; + + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + { + b = pieces(pt, c); + while (b) + result += pst(make_piece(c, pt), pop_1st_bit(&b)); } - } - result += (side_to_move() == WHITE)? - (TempoValueEndgame / 2) : -(TempoValueEndgame / 2); + + result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2); return result; } /// Position::compute_non_pawn_material() computes the total non-pawn middle -/// game material score for the given side. Material scores are updated +/// game material value for the given side. Material values are updated /// incrementally during the search, this function is only used while /// initializing a new Position object. Value Position::compute_non_pawn_material(Color c) const { - Value result = Value(0); - Square s; - - for(PieceType pt = KNIGHT; pt <= QUEEN; pt++) { - Bitboard b = pieces_of_color_and_type(c, pt); - while(b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += piece_value_midgame(pt); - } - } - return result; -} + Value result = VALUE_ZERO; -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. Note that this function is currently very -/// slow, and shouldn't be used frequently inside the search. - -bool Position::is_mate() { - if(is_check()) { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, MOVE_NONE, MOVE_NONE, - MOVE_NONE, Depth(0)); - return mp.get_next_move() == MOVE_NONE; - } - else - return false; + for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) + result += piece_count(c, pt) * PieceValueMidgame[pt]; + + return result; } /// Position::is_draw() tests whether the position is drawn by material, -/// repetition, or the 50 moves rule. It does not detect stalemates, this +/// repetition, or the 50 moves rule. It does not detect stalemates, this /// must be done by the search. - +template bool Position::is_draw() const { + // Draw by material? - if(!pawns() && - non_pawn_material(WHITE) + non_pawn_material(BLACK) - <= BishopValueMidgame) - return true; + if ( !pieces(PAWN) + && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame)) + return true; // Draw by the 50 moves rule? - if(rule50 > 100 || (rule50 == 100 && !is_check())) - return true; - - // Draw by repetition? - for(int i = 2; i < Min(gamePly, rule50); i += 2) - if(history[gamePly - i] == key) + if (st->rule50 > 99 && !is_mate()) return true; - return false; -} + // Draw by repetition? + if (!SkipRepetition) + { + int i = 4, e = Min(st->rule50, st->pliesFromNull); + if (i <= e) + { + StateInfo* stp = st->previous->previous; -/// Position::has_mate_threat() tests whether a given color has a mate in one -/// from the current position. This function is quite slow, but it doesn't -/// matter, because it is currently only called from PV nodes, which are rare. + do { + stp = stp->previous->previous; -bool Position::has_mate_threat(Color c) { - UndoInfo u1, u2; - Color stm = side_to_move(); + if (stp->key == st->key) + return true; - // The following lines are useless and silly, but prevents gcc from - // emitting a stupid warning stating that u1.lastMove and u1.epSquare might - // be used uninitialized. - u1.lastMove = lastMove; - u1.epSquare = epSquare; + i +=2; - if(is_check()) - return false; + } while (i <= e); + } + } - // If the input color is not equal to the side to move, do a null move - if(c != stm) do_null_move(u1); + return false; +} - MoveStack mlist[120]; - int count; - bool result = false; +// Explicit template instantiations +template bool Position::is_draw() const; +template bool Position::is_draw() const; - // Generate legal moves - count = generate_legal_moves(*this, mlist); - // Loop through the moves, and see if one of them is mate. - for(int i = 0; i < count; i++) { - do_move(mlist[i].move, u2); - if(is_mate()) result = true; - undo_move(mlist[i].move, u2); - } +/// Position::is_mate() returns true or false depending on whether the +/// side to move is checkmated. - // Undo null move, if necessary - if(c != stm) undo_null_move(u1); +bool Position::is_mate() const { - return result; + return in_check() && !MoveList(*this).size(); } -/// Position::init_zobrist() is a static member function which initializes the -/// various arrays used to compute hash keys. +/// Position::init() is a static member function which initializes at +/// startup the various arrays used to compute hash keys and the piece +/// square tables. The latter is a two-step operation: First, the white +/// halves of the tables are copied from the MgPST[][] and EgPST[][] arrays. +/// Second, the black halves of the tables are initialized by flipping +/// and changing the sign of the corresponding white scores. -void Position::init_zobrist() { +void Position::init() { - for(int i = 0; i < 2; i++) - for(int j = 0; j < 8; j++) - for(int k = 0; k < 64; k++) - zobrist[i][j][k] = Key(genrand_int64()); + RKISS rk; - for(int i = 0; i < 64; i++) - zobEp[i] = Key(genrand_int64()); + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + for (Square s = SQ_A1; s <= SQ_H8; s++) + zobrist[c][pt][s] = rk.rand(); - for(int i = 0; i < 16; i++) - zobCastle[i] = genrand_int64(); + for (Square s = SQ_A1; s <= SQ_H8; s++) + zobEp[s] = rk.rand(); - zobSideToMove = genrand_int64(); + for (int i = 0; i < 16; i++) + zobCastle[i] = rk.rand(); - for(int i = 0; i < 2; i++) - for(int j = 0; j < 8; j++) - for(int k = 0; k < 16; k++) - zobMaterial[i][j][k] = (k > 0)? Key(genrand_int64()) : Key(0LL); + zobSideToMove = rk.rand(); + zobExclusion = rk.rand(); - for(int i = 0; i < 16; i++) - zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL); + for (Piece p = WP; p <= WK; p++) + for (Square s = SQ_A1; s <= SQ_H8; s++) + { + pieceSquareTable[p][s] = make_score(MgPST[p][s], EgPST[p][s]); + pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s]; + } } -/// Position::init_piece_square_tables() initializes the piece square tables. -/// This is a two-step operation: First, the white halves of the tables are -/// copied from the MgPST[][] and EgPST[][] arrays, with a small random number -/// added to each entry if the "Randomness" UCI parameter is non-zero. -/// Second, the black halves of the tables are initialized by mirroring -/// and changing the sign of the corresponding white scores. - -void Position::init_piece_square_tables() { - int r = get_option_value_int("Randomness"), i; - for(Square s = SQ_A1; s <= SQ_H8; s++) { - for(Piece p = WP; p <= WK; p++) { - i = (r == 0)? 0 : (genrand_int32() % (r*2) - r); - MgPieceSquareTable[p][s] = Value(MgPST[p][s] + i); - EgPieceSquareTable[p][s] = Value(EgPST[p][s] + i); - } - } - for(Square s = SQ_A1; s <= SQ_H8; s++) - for(Piece p = BP; p <= BK; p++) { - MgPieceSquareTable[p][s] = -MgPieceSquareTable[p-8][flip_square(s)]; - EgPieceSquareTable[p][s] = -EgPieceSquareTable[p-8][flip_square(s)]; - } -} - +/// Position::flip_me() flips position with the white and black sides reversed. This +/// is only useful for debugging especially for finding evaluation symmetry bugs. -/// Position::flipped_copy() makes a copy of the input position, but with -/// the white and black sides reversed. This is only useful for debugging, -/// especially for finding evaluation symmetry bugs. +void Position::flip_me() { -void Position::flipped_copy(const Position &pos) { - assert(pos.is_ok()); + // Make a copy of current position before to start changing + const Position pos(*this, threadID); clear(); + threadID = pos.thread(); // Board - for(Square s = SQ_A1; s <= SQ_H8; s++) - if(!pos.square_is_empty(s)) - put_piece(Piece(int(pos.piece_on(s)) ^ 8), flip_square(s)); + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (!pos.square_is_empty(s)) + put_piece(Piece(pos.piece_on(s) ^ 8), flip(s)); // Side to move - sideToMove = opposite_color(pos.side_to_move()); + sideToMove = flip(pos.side_to_move()); // Castling rights - if(pos.can_castle_kingside(WHITE)) allow_oo(BLACK); - if(pos.can_castle_queenside(WHITE)) allow_ooo(BLACK); - if(pos.can_castle_kingside(BLACK)) allow_oo(WHITE); - if(pos.can_castle_queenside(BLACK)) allow_ooo(WHITE); - - initialKFile = pos.initialKFile; - initialKRFile = pos.initialKRFile; - initialQRFile = pos.initialQRFile; - - for(Square sq = SQ_A1; sq <= SQ_H8; sq++) - castleRightsMask[sq] = ALL_CASTLES; - castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO); - castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO); - castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO; - castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO; - castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO; - castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; + if (pos.can_castle(WHITE_OO)) + set_castle(BLACK_OO, king_square(BLACK), flip(pos.castle_rook_square(WHITE_OO))); + if (pos.can_castle(WHITE_OOO)) + set_castle(BLACK_OOO, king_square(BLACK), flip(pos.castle_rook_square(WHITE_OOO))); + if (pos.can_castle(BLACK_OO)) + set_castle(WHITE_OO, king_square(WHITE), flip(pos.castle_rook_square(BLACK_OO))); + if (pos.can_castle(BLACK_OOO)) + set_castle(WHITE_OOO, king_square(WHITE), flip(pos.castle_rook_square(BLACK_OOO))); // En passant square - if(pos.epSquare != SQ_NONE) - epSquare = flip_square(pos.epSquare); + if (pos.st->epSquare != SQ_NONE) + st->epSquare = flip(pos.st->epSquare); // Checkers - find_checkers(); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove)); // Hash keys - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); // Incremental scores - mgValue = compute_mg_value(); - egValue = compute_eg_value(); + st->value = compute_value(); // Material - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); assert(is_ok()); } @@ -2101,149 +1781,161 @@ void Position::flipped_copy(const Position &pos) { bool Position::is_ok(int* failedStep) const { // What features of the position should be verified? - static const bool debugBitboards = false; - static const bool debugKingCount = false; - static const bool debugKingCapture = false; - static const bool debugCheckerCount = false; - static const bool debugKey = false; - static const bool debugMaterialKey = false; - static const bool debugPawnKey = false; - static const bool debugIncrementalEval = false; - static const bool debugNonPawnMaterial = false; - static const bool debugPieceCounts = false; - static const bool debugPieceList = false; + const bool debugAll = false; + + const bool debugBitboards = debugAll || false; + const bool debugKingCount = debugAll || false; + const bool debugKingCapture = debugAll || false; + const bool debugCheckerCount = debugAll || false; + const bool debugKey = debugAll || false; + const bool debugMaterialKey = debugAll || false; + const bool debugPawnKey = debugAll || false; + const bool debugIncrementalEval = debugAll || false; + const bool debugNonPawnMaterial = debugAll || false; + const bool debugPieceCounts = debugAll || false; + const bool debugPieceList = debugAll || false; + const bool debugCastleSquares = debugAll || false; if (failedStep) *failedStep = 1; // Side to move OK? - if(!color_is_ok(side_to_move())) - return false; + if (side_to_move() != WHITE && side_to_move() != BLACK) + return false; // Are the king squares in the position correct? if (failedStep) (*failedStep)++; - if(piece_on(king_square(WHITE)) != WK) - return false; - - if (failedStep) (*failedStep)++; - if(piece_on(king_square(BLACK)) != BK) - return false; + if (piece_on(king_square(WHITE)) != WK) + return false; - // Castle files OK? if (failedStep) (*failedStep)++; - if(!file_is_ok(initialKRFile)) - return false; - if(!file_is_ok(initialQRFile)) - return false; + if (piece_on(king_square(BLACK)) != BK) + return false; // Do both sides have exactly one king? if (failedStep) (*failedStep)++; - if(debugKingCount) { - int kingCount[2] = {0, 0}; - for(Square s = SQ_A1; s <= SQ_H8; s++) - if(type_of_piece_on(s) == KING) - kingCount[color_of_piece_on(s)]++; - if(kingCount[0] != 1 || kingCount[1] != 1) - return false; + if (debugKingCount) + { + int kingCount[2] = {0, 0}; + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (type_of(piece_on(s)) == KING) + kingCount[color_of(piece_on(s))]++; + + if (kingCount[0] != 1 || kingCount[1] != 1) + return false; } // Can the side to move capture the opponent's king? if (failedStep) (*failedStep)++; - if(debugKingCapture) { - Color us = side_to_move(); - Color them = opposite_color(us); - Square ksq = king_square(them); - if(square_is_attacked(ksq, us)) - return false; + if (debugKingCapture) + { + Color us = side_to_move(); + Color them = flip(us); + Square ksq = king_square(them); + if (attackers_to(ksq) & pieces(us)) + return false; } // Is there more than 2 checkers? if (failedStep) (*failedStep)++; - if(debugCheckerCount && count_1s(checkersBB) > 2) - return false; + if (debugCheckerCount && count_1s(st->checkersBB) > 2) + return false; // Bitboards OK? if (failedStep) (*failedStep)++; - if(debugBitboards) { - // The intersection of the white and black pieces must be empty: - if((pieces_of_color(WHITE) & pieces_of_color(BLACK)) - != EmptyBoardBB) - return false; - - // The union of the white and black pieces must be equal to all - // occupied squares: - if((pieces_of_color(WHITE) | pieces_of_color(BLACK)) - != occupied_squares()) - return false; + if (debugBitboards) + { + // The intersection of the white and black pieces must be empty + if ((pieces(WHITE) & pieces(BLACK)) != EmptyBoardBB) + return false; - // Separate piece type bitboards must have empty intersections: - for(PieceType p1 = PAWN; p1 <= KING; p1++) - for(PieceType p2 = PAWN; p2 <= KING; p2++) - if(p1 != p2 && (pieces_of_type(p1) & pieces_of_type(p2))) + // The union of the white and black pieces must be equal to all + // occupied squares + if ((pieces(WHITE) | pieces(BLACK)) != occupied_squares()) return false; + + // Separate piece type bitboards must have empty intersections + for (PieceType p1 = PAWN; p1 <= KING; p1++) + for (PieceType p2 = PAWN; p2 <= KING; p2++) + if (p1 != p2 && (pieces(p1) & pieces(p2))) + return false; } // En passant square OK? if (failedStep) (*failedStep)++; - if(ep_square() != SQ_NONE) { - // The en passant square must be on rank 6, from the point of view of the - // side to move. - if(relative_rank(side_to_move(), ep_square()) != RANK_6) - return false; + if (ep_square() != SQ_NONE) + { + // The en passant square must be on rank 6, from the point of view of the + // side to move. + if (relative_rank(side_to_move(), ep_square()) != RANK_6) + return false; } // Hash key OK? if (failedStep) (*failedStep)++; - if(debugKey && key != compute_key()) - return false; + if (debugKey && st->key != compute_key()) + return false; // Pawn hash key OK? if (failedStep) (*failedStep)++; - if(debugPawnKey && pawnKey != compute_pawn_key()) - return false; + if (debugPawnKey && st->pawnKey != compute_pawn_key()) + return false; // Material hash key OK? if (failedStep) (*failedStep)++; - if(debugMaterialKey && materialKey != compute_material_key()) - return false; + if (debugMaterialKey && st->materialKey != compute_material_key()) + return false; // Incremental eval OK? if (failedStep) (*failedStep)++; - if(debugIncrementalEval) { - if(mgValue != compute_mg_value()) + if (debugIncrementalEval && st->value != compute_value()) return false; - if(egValue != compute_eg_value()) - return false; - } // Non-pawn material OK? if (failedStep) (*failedStep)++; - if(debugNonPawnMaterial) { - if(npMaterial[WHITE] != compute_non_pawn_material(WHITE)) - return false; - if(npMaterial[BLACK] != compute_non_pawn_material(BLACK)) - return false; + if (debugNonPawnMaterial) + { + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + return false; + + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + return false; } // Piece counts OK? if (failedStep) (*failedStep)++; - if(debugPieceCounts) - for(Color c = WHITE; c <= BLACK; c++) - for(PieceType pt = PAWN; pt <= KING; pt++) - if(pieceCount[c][pt] != count_1s(pieces_of_color_and_type(c, pt))) - return false; + if (debugPieceCounts) + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + if (pieceCount[c][pt] != count_1s(pieces(pt, c))) + return false; if (failedStep) (*failedStep)++; - if(debugPieceList) { - for(Color c = WHITE; c <= BLACK; c++) - for(PieceType pt = PAWN; pt <= KING; pt++) - for(int i = 0; i < pieceCount[c][pt]; i++) { - if(piece_on(piece_list(c, pt, i)) != - piece_of_color_and_type(c, pt)) - return false; - if(index[piece_list(c, pt, i)] != i) - return false; - } - } + if (debugPieceList) + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + for (int i = 0; i < pieceCount[c][pt]; i++) + { + if (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt)) + return false; + + if (index[piece_list(c, pt)[i]] != i) + return false; + } + + if (failedStep) (*failedStep)++; + if (debugCastleSquares) + for (CastleRight f = WHITE_OO; f <= BLACK_OOO; f = CastleRight(f << 1)) + { + if (!can_castle(f)) + continue; + + Piece rook = (f & (WHITE_OO | WHITE_OOO) ? WR : BR); + + if ( castleRightsMask[castleRookSquare[f]] != (ALL_CASTLES ^ f) + || piece_on(castleRookSquare[f]) != rook) + return false; + } + if (failedStep) *failedStep = 0; return true; }