X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=b5503cb501fbbcac919ae542231942203ec8f2eb;hb=d5e49a3ad44bde500102090e7fe2c19027a73b14;hp=e759b64242734a66ba22ad078065751f05e91609;hpb=dcb323bf0dda6277dad18513060cdf78cece47f2;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index e759b642..ad699cc0 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) 2008-2009 Marco Costalba + Copyright (C) 2008-2013 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 @@ -17,1032 +17,944 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include #include -#include +#include #include +#include +#include #include "bitcount.h" -#include "mersenne.h" #include "movegen.h" -#include "movepick.h" +#include "notation.h" #include "position.h" #include "psqtab.h" -#include "san.h" +#include "rkiss.h" +#include "thread.h" #include "tt.h" -#include "ucioption.h" using std::string; +using std::cout; +using std::endl; +static const string PieceToChar(" PNBRQK pnbrqk"); -//// -//// Variables -//// - -int Position::castleRightsMask[64]; - -Key Position::zobrist[2][8][64]; -Key Position::zobEp[64]; -Key Position::zobCastle[16]; -Key Position::zobMaterial[2][8][16]; -Key Position::zobSideToMove; - -Value Position::MgPieceSquareTable[16][64]; -Value Position::EgPieceSquareTable[16][64]; +CACHE_LINE_ALIGNMENT -static bool RequestPending = false; +Score pieceSquareTable[PIECE_NB][SQUARE_NB]; +Value PieceValue[PHASE_NB][PIECE_NB] = { +{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, +{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; -//// -//// Functions -//// +namespace Zobrist { -/// Constructors - -Position::Position(const Position& pos) { - copy(pos); -} - -Position::Position(const string& fen) { - from_fen(fen); -} +Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; +Key enpassant[FILE_NB]; +Key castle[CASTLE_RIGHT_NB]; +Key side; +Key exclusion; +/// init() 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 PSQT[] tables. Second, the black +/// halves of the tables are initialized by flipping and changing the sign of +/// the white scores. -/// Position::from_fen() initializes the position object with the given FEN -/// string. This function is not very robust - make sure that input FENs are -/// correct (this is assumed to be the responsibility of the GUI). +void init() { -void Position::from_fen(const string& fen) { + RKISS rk; - static const string pieceLetters = "KQRBNPkqrbnp"; - static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; + for (Color c = WHITE; c <= BLACK; c++) + for (PieceType pt = PAWN; pt <= KING; pt++) + for (Square s = SQ_A1; s <= SQ_H8; s++) + psq[c][pt][s] = rk.rand(); - clear(); + for (File f = FILE_A; f <= FILE_H; f++) + enpassant[f] = rk.rand(); - // Board - Rank rank = RANK_8; - File file = FILE_A; - size_t i = 0; - for ( ; fen[i] != ' '; i++) + for (int cr = CASTLES_NONE; cr <= ALL_CASTLES; cr++) { - 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 == string::npos) + Bitboard b = cr; + while (b) { - std::cout << "Error in FEN at character " << i << std::endl; - return; + Key k = castle[1ULL << pop_lsb(&b)]; + castle[cr] ^= k ? k : rk.rand(); } - 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); + side = rk.rand(); + exclusion = rk.rand(); - // Castling rights - i++; - if (fen[i] != ' ') + for (PieceType pt = PAWN; pt <= KING; pt++) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } + PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt]; + PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt]; - 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; + Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]); + + for (Square s = SQ_A1; s <= SQ_H8; s++) + { + pieceSquareTable[make_piece(WHITE, pt)][ s] = (v + PSQT[pt][s]); + pieceSquareTable[make_piece(BLACK, pt)][~s] = -(v + PSQT[pt][s]); } - } - else { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - i++; } +} - // Skip blanks - while (fen[i] == ' ') - i++; +} // namespace Zobrist - // En passant square - if ( i <= fen.length() - 2 - && (fen[i] >= 'a' && fen[i] <= 'h') - && (fen[i+1] == '3' || fen[i+1] == '6')) - st->epSquare = square_from_string(fen.substr(i, 2)); - // Various initialisation - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - castleRightsMask[sq] = ALL_CASTLES; +namespace { - 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; +/// next_attacker() is an helper function used by see() to locate the least +/// valuable attacker for the side to move, remove the attacker we just found +/// from the 'occupied' bitboard and scan for new X-ray attacks behind it. - find_checkers(); +template FORCE_INLINE +PieceType next_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers, + Bitboard& occupied, Bitboard& attackers) { - st->key = compute_key(); - st->pawnKey = compute_pawn_key(); - st->materialKey = compute_material_key(); - st->mgValue = compute_value(); - st->egValue = compute_value(); - st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); - st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); -} + if (stmAttackers & bb[Pt]) + { + Bitboard b = stmAttackers & bb[Pt]; + occupied ^= b & ~(b - 1); + if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); -/// Position::to_fen() converts the position object to a FEN string. This is -/// probably only useful for debugging. + if (Pt == ROOK || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); -const string Position::to_fen() const { + return (PieceType)Pt; + } + return next_attacker(bb, to, stmAttackers, occupied, attackers); +} - static const string pieceLetters = " PNBRQK pnbrqk"; - string fen; - int skip; +template<> FORCE_INLINE +PieceType next_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { + return KING; // No need to update bitboards, it is the last cycle +} - for (Rank rank = RANK_8; rank >= RANK_1; rank--) - { - skip = 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) - { - fen += (char)skip + '0'; - skip = 0; - } - fen += pieceLetters[piece_on(sq)]; - } - if (skip > 0) - fen += (char)skip + '0'; +} // namespace - fen += (rank > RANK_1 ? '/' : ' '); - } - fen += (sideToMove == WHITE ? "w " : "b "); - if (st->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 += '-'; - - fen += ' '; - if (ep_square() != SQ_NONE) - fen += square_to_string(ep_square()); - else - fen += '-'; - return fen; -} +/// CheckInfo c'tor +CheckInfo::CheckInfo(const Position& pos) { -/// Position::print() prints an ASCII representation of the position to -/// the standard output. If a move is given then also the san is print. + Color them = ~pos.side_to_move(); + ksq = pos.king_square(them); -void Position::print(Move m) const { + pinned = pos.pinned_pieces(); + dcCandidates = pos.discovered_check_candidates(); - static const string pieceLetters = " PNBRQK PNBRQK ."; + 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] = 0; +} - // Check for reentrancy, as example when called from inside - // MovePicker that is used also here in move_to_san() - if (RequestPending) - return; - RequestPending = true; +/// Position::operator=() creates a copy of 'pos'. We want the new born Position +/// object do not depend on any external data so we detach state pointer from +/// the source one. - std::cout << std::endl; - if (m != MOVE_NONE) - { - string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); - std::cout << "Move is: " << col << move_to_san(*this, m) << std::endl; - } - for (Rank rank = RANK_8; rank >= RANK_1; rank--) - { - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl; - for (File file = FILE_A; file <= FILE_H; file++) - { - Square sq = make_square(file, rank); - Piece piece = piece_on(sq); - if (piece == EMPTY && square_color(sq) == WHITE) - piece = NO_PIECE; +Position& Position::operator=(const Position& pos) { - char col = (color_of_piece_on(sq) == BLACK ? '=' : ' '); - std::cout << '|' << col << pieceLetters[piece] << col; - } - std::cout << '|' << std::endl; - } - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl - << "Fen is: " << to_fen() << std::endl - << "Key is: " << st->key << std::endl; + memcpy(this, &pos, sizeof(Position)); + startState = *st; + st = &startState; + nodes = 0; + + assert(pos_is_ok()); - RequestPending = false; + return *this; } -/// Position::copy() creates a copy of the input position. +/// Position::set() initializes the position object with the given FEN string. +/// This function is not very robust - make sure that input FENs are correct, +/// this is assumed to be the responsibility of the GUI. -void Position::copy(const Position& pos) { +void Position::set(const string& fenStr, bool isChess960, Thread* th) { +/* + A FEN string defines a particular position using only the ASCII character set. - memcpy(this, &pos, sizeof(Position)); - saveState(); // detach and copy state info -} + A FEN string contains six fields separated by 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 "/" + separates ranks. -/// Position:hidden_checkers<>() 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 pieces of the given color -/// candidate for a discovery check against the enemy king. -/// Note that checkersBB bitboard must be already updated. + 2) Active color. "w" means white moves next, "b" means black. -template -Bitboard Position::hidden_checkers(Color c) const { + 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). - Bitboard pinners, result = EmptyBoardBB; + 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. - // Pinned pieces protect our king, dicovery checks attack - // the enemy king. - Square ksq = king_square(FindPinned ? c : opposite_color(c)); + 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. - // Pinners are sliders, not checkers, that give check when - // candidate pinned is removed. - pinners = (pieces(ROOK, QUEEN, FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]) - | (pieces(BISHOP, QUEEN, FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]); + 6) Fullmove number. The number of the full move. It starts at 1, and is + incremented after Black's move. +*/ - if (FindPinned && pinners) - pinners &= ~st->checkersBB; + char col, row, token; + size_t p; + Square sq = SQ_A8; + std::istringstream ss(fenStr); - while (pinners) + clear(); + ss >> std::noskipws; + + // 1. Piece placement + while ((ss >> token) && !isspace(token)) { - Square s = pop_1st_bit(&pinners); - Bitboard b = squares_between(s, ksq) & occupied_squares(); + if (isdigit(token)) + sq += Square(token - '0'); // Advance the given number of files - assert(b); + else if (token == '/') + sq -= Square(16); - if ( !(b & (b - 1)) // Only one bit set? - && (b & pieces_of_color(c))) // Is an our piece? - result |= b; + else if ((p = PieceToChar.find(token)) != string::npos) + { + put_piece(Piece(p), sq); + sq++; + } } - return result; -} + // 2. Active color + ss >> token; + sideToMove = (token == 'w' ? WHITE : BLACK); + ss >> token; + + // 3. Castling availability. Compatible with 3 standards: Normal FEN standard, + // Shredder-FEN that uses the letters of the columns on which the rooks began + // the game instead of KQkq and also X-FEN standard that, in case of Chess960, + // if an inner rook is associated with the castling right, the castling tag is + // replaced by the file letter of the involved rook, as for the Shredder-FEN. + while ((ss >> token) && !isspace(token)) + { + Square rsq; + Color c = islower(token) ? BLACK : WHITE; -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. + token = char(toupper(token)); -Bitboard Position::pinned_pieces(Color c) const { + if (token == 'K') + for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {} - return hidden_checkers(c); -} + else if (token == 'Q') + for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {} + else if (token >= 'A' && token <= 'H') + rsq = File(token - 'A') | relative_rank(c, RANK_1); -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the given side which are candidates for giving a discovered -/// check. + else + continue; -Bitboard Position::discovered_check_candidates(Color c) const { + set_castle_right(c, rsq); + } - return hidden_checkers(c); -} + // 4. En passant square. Ignore if no pawn capture is possible + if ( ((ss >> col) && (col >= 'a' && col <= 'h')) + && ((ss >> row) && (row == '3' || row == '6'))) + { + st->epSquare = File(col - 'a') | Rank(row - '1'); -/// Position::attackers_to() computes a bitboard containing all pieces which -/// attacks a given square. + if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) + st->epSquare = SQ_NONE; + } -Bitboard Position::attackers_to(Square s) const { + // 5-6. Halfmove clock and fullmove number + ss >> std::skipws >> st->rule50 >> gamePly; - 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)); + // Convert from fullmove starting from 1 to ply starting from 0, + // handle also common incorrect FEN with fullmove = 0. + gamePly = std::max(2 * (gamePly - 1), 0) + int(sideToMove == BLACK); + + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); + st->psqScore = compute_psq_score(); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); + chess960 = isChess960; + thisThread = th; + + assert(pos_is_ok()); } -/// Position::attacks_from() computes a bitboard of all attacks -/// of a given piece put in a given square. -Bitboard Position::attacks_from(Piece p, Square s) const { +/// Position::set_castle_right() is an helper function used to set castling +/// rights given the corresponding color and the rook starting square. - assert(square_is_ok(s)); +void Position::set_castle_right(Color c, Square rfrom) { - switch (p) - { - case WP: return attacks_from(s, WHITE); - case BP: return attacks_from(s, BLACK); - case WN: case BN: return attacks_from(s); - case WB: case BB: return attacks_from(s); - case WR: case BR: return attacks_from(s); - case WQ: case BQ: return attacks_from(s); - case WK: case BK: return attacks_from(s); - default: break; - } - return false; -} + Square kfrom = king_square(c); + CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; + CastleRight cr = make_castle_right(c, cs); + st->castleRights |= cr; + castleRightsMask[kfrom] |= cr; + castleRightsMask[rfrom] |= cr; + castleRookSquare[c][cs] = rfrom; -/// Position::move_attacks_square() tests whether a move from the current -/// position attacks a given square. + Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); + Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); -bool Position::move_attacks_square(Move m, Square s) const { + for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); s++) + if (s != kfrom && s != rfrom) + castlePath[c][cs] |= s; - assert(move_is_ok(m)); - assert(square_is_ok(s)); + for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); s++) + if (s != kfrom && s != rfrom) + castlePath[c][cs] |= s; +} - Square f = move_from(m), t = move_to(m); - assert(square_is_occupied(f)); +/// Position::fen() returns a FEN representation of the position. In case +/// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. - if (bit_is_set(attacks_from(piece_on(f), t), s)) - return true; +const string Position::fen() const { - // Move the piece and scan for X-ray attacks behind it - Bitboard occ = occupied_squares(); - Color us = color_of_piece_on(f); - clear_bit(&occ, f); - set_bit(&occ, t); - Bitboard xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN)) - |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))) & pieces_of_color(us); - - // 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))); -} + std::ostringstream ss; + for (Rank rank = RANK_8; rank >= RANK_1; rank--) + { + for (File file = FILE_A; file <= FILE_H; file++) + { + Square sq = file | rank; -/// 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::attackers_to, which is probably -/// inefficient. Consider rewriting this function to use the last move -/// played, like in non-bitboard versions of Glaurung. + if (is_empty(sq)) + { + int emptyCnt = 1; -void Position::find_checkers() { + for ( ; file < FILE_H && is_empty(sq++); file++) + emptyCnt++; - Color us = side_to_move(); - st->checkersBB = attackers_to(king_square(us)) & pieces_of_color(opposite_color(us)); -} + ss << emptyCnt; + } + else + ss << PieceToChar[piece_on(sq)]; + } + if (rank > RANK_1) + ss << '/'; + } -/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal + ss << (sideToMove == WHITE ? " w " : " b "); -bool Position::pl_move_is_legal(Move m) const { + if (can_castle(WHITE_OO)) + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, KING_SIDE)), false) : 'K'); - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); -} + if (can_castle(WHITE_OOO)) + ss << (chess960 ? file_to_char(file_of(castle_rook_square(WHITE, QUEEN_SIDE)), false) : 'Q'); -bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { + if (can_castle(BLACK_OO)) + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, KING_SIDE)), true) : 'k'); - assert(is_ok()); - assert(move_is_ok(m)); - assert(pinned == pinned_pieces(side_to_move())); - assert(!is_check()); + if (can_castle(BLACK_OOO)) + ss << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK, QUEEN_SIDE)), true) : 'q'); - // Castling moves are checked for legality during move generation. - if (move_is_castle(m)) - return true; + if (st->castleRights == CASTLES_NONE) + ss << '-'; - Color us = side_to_move(); - Square from = move_from(m); + ss << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") + << st->rule50 << " " << 1 + (gamePly - int(sideToMove == BLACK)) / 2; - assert(color_of_piece_on(from) == us); - assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING)); + return ss.str(); +} - // 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)) - { - Color them = opposite_color(us); - Square to = move_to(m); - Square capsq = make_square(square_file(to), square_rank(from)); - Bitboard b = occupied_squares(); - Square ksq = king_square(us); - assert(to == ep_square()); - assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); - assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN)); - assert(piece_on(to) == EMPTY); +/// Position::pretty() returns an ASCII representation of the position to be +/// printed to the standard output together with the move's san notation. - clear_bit(&b, from); - clear_bit(&b, capsq); - set_bit(&b, to); +const string Position::pretty(Move move) const { - return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) - && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); - } + const string dottedLine = "\n+---+---+---+---+---+---+---+---+"; + const string twoRows = dottedLine + "\n| | . | | . | | . | | . |" + + dottedLine + "\n| . | | . | | . | | . | |"; - // If the moving piece is a king, check whether the destination - // square is attacked by the opponent. - if (type_of_piece_on(from) == KING) - return !(attackers_to(move_to(m)) & pieces_of_color(opposite_color(us))); + string brd = twoRows + twoRows + twoRows + twoRows + dottedLine; - // A non-king move is legal if and only if it is not pinned or it - // is moving along the ray towards or away from the king. - return ( !pinned - || !bit_is_set(pinned, from) - || (direction_between_squares(from, king_square(us)) == direction_between_squares(move_to(m), king_square(us)))); -} + std::ostringstream ss; + if (move) + ss << "\nMove: " << (sideToMove == BLACK ? ".." : "") + << move_to_san(*const_cast(this), move); -/// Position::move_is_check() tests whether a pseudo-legal move is a check + for (Square sq = SQ_A1; sq <= SQ_H8; sq++) + if (piece_on(sq) != NO_PIECE) + brd[513 - 68*rank_of(sq) + 4*file_of(sq)] = PieceToChar[piece_on(sq)]; + + ss << brd << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: "; -bool Position::move_is_check(Move m) const { + for (Bitboard b = checkers(); b; ) + ss << square_to_string(pop_lsb(&b)) << " "; - Bitboard dc = discovered_check_candidates(side_to_move()); - return move_is_check(m, dc); + ss << "\nLegal moves: "; + for (MoveList ml(*this); !ml.end(); ++ml) + ss << move_to_san(*const_cast(this), ml.move()) << " "; + + return ss.str(); } -bool Position::move_is_check(Move m, Bitboard dcCandidates) const { - assert(is_ok()); - assert(move_is_ok(m)); - assert(dcCandidates == discovered_check_candidates(side_to_move())); +/// 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. +template +Bitboard Position::hidden_checkers() const { - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); - Square ksq = king_square(them); + // Pinned pieces protect our king, dicovery checks attack the enemy king + Bitboard b, result = 0; + Bitboard pinners = pieces(FindPinned ? ~sideToMove : sideToMove); + Square ksq = king_square(FindPinned ? sideToMove : ~sideToMove); - assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); + // Pinners are sliders, that give check when candidate pinned is removed + pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq]) + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]); - // Proceed according to the type of the moving piece - switch (type_of_piece_on(from)) + while (pinners) { - case PAWN: + b = between_bb(ksq, pop_lsb(&pinners)) & pieces(); - if (bit_is_set(attacks_from(ksq, them), to)) // Normal check? - return true; + if (b && !more_than_one(b) && (b & pieces(sideToMove))) + result |= b; + } + return result; +} - if ( dcCandidates // Discovered check? - && bit_is_set(dcCandidates, from) - && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) - return true; +// Explicit template instantiations +template Bitboard Position::hidden_checkers() const; +template Bitboard Position::hidden_checkers() const; - if (move_is_promotion(m)) // Promotion with check? - { - Bitboard b = occupied_squares(); - clear_bit(&b, from); - switch (move_promotion_piece(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); - } - } - // 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)) - { - 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) & pieces(ROOK, QUEEN, us)) - ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us)); - } - return false; +/// Position::attackers_to() computes a bitboard of all pieces which attack a +/// given square. Slider attacks use occ bitboard as occupancy. - // Test discovered check and normal check according to piece type - case KNIGHT: - return (dcCandidates && bit_is_set(dcCandidates, from)) - || bit_is_set(attacks_from(ksq), to); - - case BISHOP: - return (dcCandidates && bit_is_set(dcCandidates, from)) - || (direction_is_diagonal(ksq, to) && bit_is_set(attacks_from(ksq), to)); - - case ROOK: - return (dcCandidates && bit_is_set(dcCandidates, from)) - || (direction_is_straight(ksq, to) && bit_is_set(attacks_from(ksq), to)); - - case QUEEN: - // Discovered checks are impossible! - assert(!bit_is_set(dcCandidates, from)); - return ( (direction_is_straight(ksq, to) && bit_is_set(attacks_from(ksq), to)) - || (direction_is_diagonal(ksq, to) && bit_is_set(attacks_from(ksq), to))); - - case KING: - // Discovered check? - if ( bit_is_set(dcCandidates, from) - && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) - return true; +Bitboard Position::attackers_to(Square s, Bitboard occ) const { - // Castling with check? - if (move_is_castle(m)) - { - Square kfrom, kto, rfrom, rto; - Bitboard b = occupied_squares(); - kfrom = from; - rfrom = to; + return (attacks_from(s, BLACK) & pieces(WHITE, PAWN)) + | (attacks_from(s, WHITE) & pieces(BLACK, PAWN)) + | (attacks_from(s) & pieces(KNIGHT)) + | (attacks_bb(s, occ) & pieces(ROOK, QUEEN)) + | (attacks_bb(s, occ) & pieces(BISHOP, QUEEN)) + | (attacks_from(s) & pieces(KING)); +} - 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); - } - return false; - default: // NO_PIECE_TYPE - break; +/// Position::attacks_from() computes a bitboard of all attacks of a given piece +/// put in a given square. Slider attacks use occ bitboard as occupancy. + +Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { + + assert(is_ok(s)); + + switch (type_of(p)) + { + case BISHOP: return attacks_bb(s, occ); + case ROOK : return attacks_bb(s, occ); + case QUEEN : return attacks_bb(s, occ) | attacks_bb(s, occ); + default : return StepAttacksBB[p][s]; } - assert(false); - return false; } -/// Position::update_checkers() udpates chekers info given the move. It is called -/// in do_move() and is faster then find_checkers(). +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal -template -inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, - Square to, Bitboard dcCandidates) { +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { - const bool Bishop = (Piece == QUEEN || Piece == BISHOP); - const bool Rook = (Piece == QUEEN || Piece == ROOK); - const bool Slider = Bishop || Rook; + assert(is_ok(m)); + assert(pinned == pinned_pieces()); - // Direct checks - if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to)) - || (Rook && bit_is_set(RookPseudoAttacks[ksq], to))) - && bit_is_set(attacks_from(ksq), to)) // slow, try to early skip - set_bit(pCheckersBB, to); + Color us = sideToMove; + Square from = from_sq(m); - else if ( Piece != KING - && !Slider - && bit_is_set(Piece == PAWN ? attacks_from(ksq, opposite_color(sideToMove)) - : attacks_from(ksq), to)) - set_bit(pCheckersBB, to); + assert(color_of(piece_moved(m)) == us); + assert(piece_on(king_square(us)) == make_piece(us, KING)); - // Discovery checks - if (Piece != QUEEN && bit_is_set(dcCandidates, from)) + // En passant captures are a tricky special case. Because they are rather + // uncommon, we do it simply by testing whether the king is attacked after + // the move is made. + if (type_of(m) == ENPASSANT) { - if (Piece != ROOK) - (*pCheckersBB) |= (attacks_from(ksq) & pieces(ROOK, QUEEN, side_to_move())); - - if (Piece != BISHOP) - (*pCheckersBB) |= (attacks_from(ksq) & pieces(BISHOP, QUEEN, side_to_move())); - } -} + Color them = ~us; + Square to = to_sq(m); + Square capsq = to + pawn_push(them); + Square ksq = king_square(us); + Bitboard b = (pieces() ^ from ^ capsq) | to; + assert(to == ep_square()); + assert(piece_moved(m) == make_piece(us, PAWN)); + assert(piece_on(capsq) == make_piece(them, PAWN)); + assert(piece_on(to) == NO_PIECE); -/// 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. + return !(attacks_bb< ROOK>(ksq, b) & pieces(them, QUEEN, ROOK)) + && !(attacks_bb(ksq, b) & pieces(them, QUEEN, BISHOP)); + } -void Position::do_move(Move m, StateInfo& newSt) { + // If the moving piece is a king, check whether the destination + // square is attacked by the opponent. Castling moves are checked + // for legality during move generation. + if (type_of(piece_on(from)) == KING) + return type_of(m) == CASTLE || !(attackers_to(to_sq(m)) & pieces(~us)); - do_move(m, newSt, discovered_check_candidates(side_to_move())); + // A non-king move is legal if and only if it is not pinned or it + // is moving along the ray towards or away from the king. + return !pinned + || !(pinned & from) + || squares_aligned(from, to_sq(m), king_square(us)); } -void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { - assert(is_ok()); - assert(move_is_ok(m)); +/// 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. - Bitboard key = st->key; +bool Position::is_pseudo_legal(const Move m) const { - // 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 key, pawnKey, materialKey; - int castleRights, rule50; - Square epSquare; - Value mgValue, egValue; - Value npMaterial[2]; - }; - - memcpy(&newSt, st, sizeof(ReducedStateInfo)); - newSt.previous = st; - st = &newSt; + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_moved(m); - // Save the current key to the history[] array, in order to be able to - // detect repetition draws. - history[gamePly] = key; - gamePly++; + // Use a slower but simpler function for uncommon cases + if (type_of(m) != NORMAL) + return MoveList(*this).contains(m); - // Update side to move - key ^= zobSideToMove; + // Is not a promotion, so promotion piece must be empty + if (promotion_type(m) - 2 != NO_PIECE_TYPE) + return false; - // 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++; + // If the from square is not occupied by a piece belonging to the side to + // move, the move is obviously not legal. + if (pc == NO_PIECE || color_of(pc) != us) + return false; + + // The destination square cannot be occupied by a friendly piece + if (piece_on(to) != NO_PIECE && color_of(piece_on(to)) == us) + return false; - if (move_is_castle(m)) + // Handle the special case of a pawn move + if (type_of(pc) == PAWN) { - st->key = key; - do_castle_move(m); - return; - } + // Move direction must be compatible with pawn color + int direction = to - from; + if ((us == WHITE) != (direction > 0)) + return false; - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); - bool ep = move_is_ep(m); - bool pm = move_is_promotion(m); + // 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; - Piece piece = piece_on(from); - PieceType pt = type_of_piece(piece); + // Proceed according to the square delta between the origin and + // destination squares. + switch (direction) + { + 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 (piece_on(to) == NO_PIECE || color_of(piece_on(to)) != ~us) + return false; - assert(color_of_piece_on(from) == us); - assert(color_of_piece_on(to) == them || square_is_empty(to)); - assert(!(ep || pm) || piece == piece_of_color_and_type(us, PAWN)); - assert(!pm || relative_rank(us, to) == RANK_8); + // From and to files must be one file apart, avoids a7h5 + if (abs(file_of(from) - file_of(to)) != 1) + return false; + break; - st->capture = ep ? PAWN : type_of_piece_on(to); + case DELTA_N: + case DELTA_S: + // Pawn push. The destination square must be empty. + if (!is_empty(to)) + return false; + break; - if (st->capture) - do_capture_move(key, st->capture, them, to, ep); + 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 + || !is_empty(to) + || !is_empty(from + DELTA_N)) + return false; + break; - // Update hash key - key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; + 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 + || !is_empty(to) + || !is_empty(from + DELTA_S)) + return false; + break; - // Reset en passant square - if (st->epSquare != SQ_NONE) - { - key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; + default: + return false; + } } + else if (!(attacks_from(pc, from) & to)) + return false; - // Update castle rights, try to shortcut a common case - int cm = castleRightsMask[from] & castleRightsMask[to]; - if (cm != ALL_CASTLES && ((cm & st->castleRights) != st->castleRights)) + // Evasions generator already takes care to avoid some kind of illegal moves + // and pl_move_is_legal() relies on this. So we have to take care that the + // same kind of moves are filtered out here. + if (checkers()) { - key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[from]; - st->castleRights &= castleRightsMask[to]; - key ^= zobCastle[st->castleRights]; + if (type_of(pc) != KING) + { + // Double check? In this case a king move is required + if (more_than_one(checkers())) + return false; + + // Our move must be a blocking evasion or a capture of the checking piece + if (!((between_bb(lsb(checkers()), king_square(us)) | checkers()) & to)) + return false; + } + // 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. + else if (attackers_to(to, pieces() ^ from) & pieces(~us)) + return false; } - // Prefetch TT access as soon as we know key is updated - TT.prefetch(key); + return true; +} - // 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 - board[to] = board[from]; - board[from] = EMPTY; +/// Position::move_gives_check() tests whether a pseudo-legal move gives a check - // 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; +bool Position::move_gives_check(Move m, const CheckInfo& ci) const { - // If the moving piece was a pawn do some special extra work - if (pt == PAWN) - { - // Reset rule 50 draw counter - st->rule50 = 0; + assert(is_ok(m)); + assert(ci.dcCandidates == discovered_check_candidates()); + assert(color_of(piece_moved(m)) == sideToMove); - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - - // Set en passant square, only if moved pawn can be captured - if (abs(int(to) - int(from)) == 16) - { - if (attacks_from(from + (us == WHITE ? DELTA_N : DELTA_S), us) & pieces(PAWN, them)) - { - st->epSquare = Square((int(from) + int(to)) / 2); - key ^= zobEp[st->epSquare]; - } - } - } + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); - // Update incremental scores - st->mgValue += pst_delta(piece, from, to); - st->egValue += pst_delta(piece, from, to); + // Direct check ? + if (ci.checkSq[pt] & to) + return true; - if (pm) // promotion ? + // Discovery check ? + if (ci.dcCandidates && (ci.dcCandidates & from)) { - PieceType promotion = move_promotion_piece(m); + // For pawn and king moves we need to verify also direction + if ( (pt != PAWN && pt != KING) + || !squares_aligned(from, to, king_square(~sideToMove))) + return true; + } - assert(promotion >= KNIGHT && promotion <= QUEEN); + // Can we skip the ugly special cases ? + if (type_of(m) == NORMAL) + return false; - // Insert promoted piece instead of pawn - clear_bit(&(byTypeBB[PAWN]), to); - set_bit(&(byTypeBB[promotion]), to); - board[to] = piece_of_color_and_type(us, promotion); - - // Update material key - st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; - st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; - - // Update piece counts - pieceCount[us][PAWN]--; - pieceCount[us][promotion]++; - - // 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; - 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->mgValue -= pst(us, PAWN, to); - st->mgValue += pst(us, promotion, to); - st->egValue -= pst(us, PAWN, to); - st->egValue += pst(us, promotion, to); - - // Update material - st->npMaterial[us] += piece_value_midgame(promotion); - } + Color us = sideToMove; + Square ksq = king_square(~us); - // Update the key with the final value - st->key = key; + switch (type_of(m)) + { + case PROMOTION: + return attacks_from(Piece(promotion_type(m)), to, pieces() ^ from) & ksq; + + // 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. + case ENPASSANT: + { + Square capsq = file_of(to) | rank_of(from); + Bitboard b = (pieces() ^ from ^ capsq) | to; - // Update checkers bitboard, piece must be already moved - if (ep | pm) - st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); - else + return (attacks_bb< ROOK>(ksq, b) & pieces(us, QUEEN, ROOK)) + | (attacks_bb(ksq, b) & pieces(us, QUEEN, BISHOP)); + } + case CASTLE: { - st->checkersBB = EmptyBoardBB; - Square ksq = king_square(them); - switch (pt) - { - case PAWN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - case KNIGHT: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - case BISHOP: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - case ROOK: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - case QUEEN: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - case KING: update_checkers(&(st->checkersBB), ksq, from, to, dcCandidates); break; - default: assert(false); break; - } + Square kfrom = from; + Square rfrom = to; // 'King captures the rook' notation + Square kto = relative_square(us, rfrom > kfrom ? SQ_G1 : SQ_C1); + Square rto = relative_square(us, rfrom > kfrom ? SQ_F1 : SQ_D1); + Bitboard b = (pieces() ^ kfrom ^ rfrom) | rto | kto; + + return attacks_bb(rto, b) & ksq; } + default: + assert(false); + return false; + } +} - // Finish - sideToMove = opposite_color(sideToMove); - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; +/// 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. + +void Position::do_move(Move m, StateInfo& newSt) { - assert(is_ok()); + 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::do_capture_move() is a private method used to update captured -/// piece info. It is called from the main Position::do_move function. + assert(is_ok(m)); + assert(&newSt != st); -void Position::do_capture_move(Bitboard& key, PieceType capture, Color them, Square to, bool ep) { + nodes++; + Key k = st->key; - assert(capture != KING); + // Copy some fields of old state to our new StateInfo object except the ones + // which are going to be recalculated from scratch anyway, then switch our state + // pointer to point to the new, ready to be updated, state. + memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t)); - Square capsq = to; + newSt.previous = st; + st = &newSt; - if (ep) // en passant ? - { - capsq = (them == BLACK)? (to - DELTA_N) : (to - DELTA_S); + // Update side to move + k ^= Zobrist::side; + + // Increment ply counters.In particular rule50 will be later reset it to zero + // in case of a capture or a pawn move. + gamePly++; + st->rule50++; + st->pliesFromNull++; - assert(to == st->epSquare); - assert(relative_rank(opposite_color(them), to) == RANK_6); - assert(piece_on(to) == EMPTY); - assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN)); + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_on(from); + PieceType pt = type_of(piece); + PieceType capture = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); + + assert(color_of(piece) == us); + assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLE); + assert(capture != KING); - board[capsq] = EMPTY; - } + if (type_of(m) == CASTLE) + { + assert(piece == make_piece(us, KING)); - // Remove captured piece - clear_bit(&(byColorBB[them]), capsq); - clear_bit(&(byTypeBB[capture]), capsq); - clear_bit(&(byTypeBB[0]), capsq); + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; - // Update hash key - key ^= zobrist[them][capture][capsq]; + do_castle(from, to, rfrom, rto); - // Update incremental scores - st->mgValue -= pst(them, capture, capsq); - st->egValue -= pst(them, capture, capsq); + st->psqScore += psq_delta(make_piece(us, ROOK), rfrom, rto); + k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; + } - // If the captured piece was a pawn, update pawn hash key, - // otherwise update non-pawn material. - if (capture == PAWN) - st->pawnKey ^= zobrist[them][PAWN][capsq]; - else - st->npMaterial[them] -= piece_value_midgame(capture); + if (capture) + { + Square capsq = to; - // Update material hash key - st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + // If the captured piece is a pawn, update pawn hash key, otherwise + // update non-pawn material. + if (capture == PAWN) + { + if (type_of(m) == ENPASSANT) + { + capsq += pawn_push(them); - // Update piece count - pieceCount[them][capture]--; + assert(pt == PAWN); + assert(to == st->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(to) == NO_PIECE); + assert(piece_on(capsq) == make_piece(them, PAWN)); - // 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; + board[capsq] = NO_PIECE; + } - // Reset rule 50 counter - st->rule50 = 0; -} + st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; + } + else + st->npMaterial[them] -= PieceValue[MG][capture]; + + // Remove the captured piece + byTypeBB[ALL_PIECES] ^= capsq; + byTypeBB[capture] ^= capsq; + byColorBB[them] ^= capsq; + + // Update piece list, move the last piece at index[capsq] position and + // shrink the list. + // + // WARNING: This is a not reversible 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 lastSquare = pieceList[them][capture][--pieceCount[them][capture]]; + index[lastSquare] = index[capsq]; + pieceList[them][capture][index[lastSquare]] = lastSquare; + pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; + + // Update material hash key and prefetch access to materialTable + k ^= Zobrist::psq[them][capture][capsq]; + st->materialKey ^= Zobrist::psq[them][capture][pieceCount[them][capture]]; + prefetch((char*)thisThread->materialTable[st->materialKey]); + + // Update incremental scores + st->psqScore -= pieceSquareTable[make_piece(them, capture)][capsq]; + + // Reset rule 50 counter + st->rule50 = 0; + } + // Update hash key + k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to]; -/// 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 -/// castling moves are encoded as "king captures friendly rook" moves, for -/// instance white short castling in a non-Chess960 game is encoded as e1h1. + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + k ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } -void Position::do_castle_move(Move m) { + // Update castle rights if needed + if (st->castleRights && (castleRightsMask[from] | castleRightsMask[to])) + { + int cr = castleRightsMask[from] | castleRightsMask[to]; + k ^= Zobrist::castle[st->castleRights & cr]; + st->castleRights &= ~cr; + } - assert(move_is_ok(m)); - assert(move_is_castle(m)); + // Prefetch TT access as soon as we know the new hash key + prefetch((char*)TT.first_entry(k)); - Color us = side_to_move(); - Color them = opposite_color(us); + // Move the piece. The tricky Chess960 castle is handled earlier + if (type_of(m) != CASTLE) + { + Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; + byTypeBB[ALL_PIECES] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + byColorBB[us] ^= from_to_bb; + + board[from] = NO_PIECE; + board[to] = piece; + + // Update piece lists, 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; + } - // Reset capture field - st->capture = NO_PIECE_TYPE; + // If the moving piece is a pawn do some special extra work + if (pt == PAWN) + { + // Set en-passant square, only if moved pawn can be captured + if ( (int(to) ^ int(from)) == 16 + && (attacks_from(from + pawn_push(us), us) & pieces(them, PAWN))) + { + st->epSquare = Square((from + to) / 2); + k ^= Zobrist::enpassant[file_of(st->epSquare)]; + } - // Find source squares for king and rook - Square kfrom = move_from(m); - Square rfrom = move_to(m); // HACK: See comment at beginning of function - Square kto, rto; + if (type_of(m) == PROMOTION) + { + PieceType promotion = promotion_type(m); + + assert(relative_rank(us, to) == RANK_8); + assert(promotion >= KNIGHT && promotion <= QUEEN); + + // Replace the pawn with the promoted piece + byTypeBB[PAWN] ^= to; + byTypeBB[promotion] |= to; + board[to] = make_piece(us, promotion); + + // Update piece lists, move the last pawn at index[to] position + // and shrink the list. Add a new promotion piece to the list. + Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]]; + index[lastSquare] = index[to]; + pieceList[us][PAWN][index[lastSquare]] = lastSquare; + pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; + index[to] = pieceCount[us][promotion]; + pieceList[us][promotion][index[to]] = to; + + // Update hash keys + k ^= Zobrist::psq[us][PAWN][to] ^ Zobrist::psq[us][promotion][to]; + st->pawnKey ^= Zobrist::psq[us][PAWN][to]; + st->materialKey ^= Zobrist::psq[us][promotion][pieceCount[us][promotion]++] + ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]]; + + // Update incremental score + st->psqScore += pieceSquareTable[make_piece(us, promotion)][to] + - pieceSquareTable[make_piece(us, PAWN)][to]; + + // Update material + st->npMaterial[us] += PieceValue[MG][promotion]; + } - assert(piece_on(kfrom) == piece_of_color_and_type(us, KING)); - assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK)); + // Update pawn hash key and prefetch access to pawnsTable + st->pawnKey ^= Zobrist::psq[us][PAWN][from] ^ Zobrist::psq[us][PAWN][to]; + prefetch((char*)thisThread->pawnsTable[st->pawnKey]); - // 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); + // Reset rule 50 draw counter + st->rule50 = 0; } - // Move the pieces - Bitboard kmove_bb = make_move_bb(kfrom, kto); - do_move_bb(&(byColorBB[us]), kmove_bb); - do_move_bb(&(byTypeBB[KING]), kmove_bb); - do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares - - Bitboard rmove_bb = make_move_bb(rfrom, rto); - do_move_bb(&(byColorBB[us]), rmove_bb); - do_move_bb(&(byTypeBB[ROOK]), rmove_bb); - do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares - - // Update board array - Piece king = piece_of_color_and_type(us, KING); - Piece rook = piece_of_color_and_type(us, ROOK); - board[kfrom] = board[rfrom] = EMPTY; - 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]; // In Chess960 could be rto == kfrom - index[kto] = index[kfrom]; - index[rto] = tmp; - // Update incremental scores - st->mgValue += pst_delta(king, kfrom, kto); - st->egValue += pst_delta(king, kfrom, kto); - st->mgValue += pst_delta(rook, rfrom, rto); - st->egValue += pst_delta(rook, rfrom, rto); + st->psqScore += psq_delta(piece, from, to); - // Update hash key - st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; + // Set capture piece + st->capturedType = capture; - // Clear en passant square - if (st->epSquare != SQ_NONE) - { - st->key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; - } + // Update the key with the final value + st->key = k; - // Update castling rights - st->key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[kfrom]; - st->key ^= zobCastle[st->castleRights]; + // Update checkers bitboard, piece must be already moved + st->checkersBB = 0; - // Reset rule 50 counter - st->rule50 = 0; + if (moveIsCheck) + { + if (type_of(m) != NORMAL) + st->checkersBB = attackers_to(king_square(them)) & pieces(us); + else + { + // Direct checks + if (ci.checkSq[pt] & to) + st->checkersBB |= to; - // Update checkers BB - st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); + // Discovery checks + if (ci.dcCandidates && (ci.dcCandidates & from)) + { + if (pt != ROOK) + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, ROOK); - // Finish - sideToMove = opposite_color(sideToMove); + if (pt != BISHOP) + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, BISHOP); + } + } + } - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + sideToMove = ~sideToMove; - assert(is_ok()); + assert(pos_is_ok()); } @@ -1051,225 +963,168 @@ void Position::do_castle_move(Move m) { void Position::undo_move(Move m) { - assert(is_ok()); - assert(move_is_ok(m)); - - gamePly--; - sideToMove = opposite_color(sideToMove); - - if (move_is_castle(m)) - { - undo_castle_move(m); - return; - } + assert(is_ok(m)); - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); - bool ep = move_is_ep(m); - bool pm = move_is_promotion(m); + sideToMove = ~sideToMove; - PieceType pt = type_of_piece_on(to); + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(to)); + PieceType capture = st->capturedType; - 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) == piece_of_color_and_type(us, PAWN)); + assert(is_empty(from) || type_of(m) == CASTLE); + assert(capture != KING); - if (pm) // promotion ? + if (type_of(m) == PROMOTION) { - PieceType promotion = move_promotion_piece(m); - pt = PAWN; + PieceType promotion = promotion_type(m); + assert(promotion == pt); + assert(relative_rank(us, to) == RANK_8); assert(promotion >= KNIGHT && promotion <= QUEEN); - assert(piece_on(to) == piece_of_color_and_type(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; - index[to] = pieceCount[us][PAWN] - 1; + // Replace the promoted piece with the pawn + byTypeBB[promotion] ^= to; + byTypeBB[PAWN] |= to; + board[to] = make_piece(us, PAWN); + + // Update piece lists, move the last promoted piece at index[to] position + // and shrink the list. Add a new pawn to the list. + Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]]; + index[lastSquare] = index[to]; + pieceList[us][promotion][index[lastSquare]] = lastSquare; + pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; + index[to] = pieceCount[us][PAWN]++; pieceList[us][PAWN][index[to]] = to; - } - - // 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 - board[from] = piece_of_color_and_type(us, pt); - board[to] = EMPTY; + pt = PAWN; + } - // Update piece list - index[from] = index[to]; - pieceList[us][pt][index[from]] = from; + if (type_of(m) == CASTLE) + { + bool kingSide = to > from; + Square rfrom = to; // Castle is encoded as "king captures friendly rook" + Square rto = relative_square(us, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(us, kingSide ? SQ_G1 : SQ_C1); + capture = NO_PIECE_TYPE; + pt = KING; + do_castle(to, from, rto, rfrom); + } + else + { + // Put the piece back at the source square + Bitboard from_to_bb = SquareBB[from] ^ SquareBB[to]; + byTypeBB[ALL_PIECES] ^= from_to_bb; + byTypeBB[pt] ^= from_to_bb; + byColorBB[us] ^= from_to_bb; + + board[to] = NO_PIECE; + board[from] = make_piece(us, pt); + + // Update piece lists, index[to] is not updated and becomes stale. This + // works as long as index[] is accessed just by known occupied squares. + index[from] = index[to]; + pieceList[us][pt][index[from]] = from; + } - if (st->capture) + if (capture) { Square capsq = to; - if (ep) - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); + if (type_of(m) == ENPASSANT) + { + capsq -= pawn_push(us); - assert(st->capture != KING); - assert(!ep || square_is_empty(capsq)); + assert(pt == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + } // Restore the captured piece - set_bit(&(byColorBB[them]), capsq); - set_bit(&(byTypeBB[st->capture]), capsq); - set_bit(&(byTypeBB[0]), capsq); - - board[capsq] = piece_of_color_and_type(them, st->capture); + byTypeBB[ALL_PIECES] |= capsq; + byTypeBB[capture] |= capsq; + byColorBB[them] |= capsq; - // Update piece count - pieceCount[them][st->capture]++; + board[capsq] = make_piece(them, capture); // Update piece list, add a new captured piece in capsq square - index[capsq] = pieceCount[them][st->capture] - 1; - pieceList[them][st->capture][index[capsq]] = capsq; + index[capsq] = pieceCount[them][capture]++; + pieceList[them][capture][index[capsq]] = capsq; } // Finally point our state pointer back to the previous state st = st->previous; + gamePly--; - assert(is_ok()); + assert(pos_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 -/// 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) { - - assert(move_is_ok(m)); - assert(move_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, - // so the code below is correct. - Color us = side_to_move(); - - // Find source squares for king and rook - Square kfrom = move_from(m); - Square rfrom = move_to(m); // HACK: See comment at beginning of function - 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); - } else { // O-O-O - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); - } - - assert(piece_on(kto) == piece_of_color_and_type(us, KING)); - assert(piece_on(rto) == piece_of_color_and_type(us, ROOK)); - - // Put the pieces back at the source square - Bitboard kmove_bb = make_move_bb(kto, kfrom); - do_move_bb(&(byColorBB[us]), kmove_bb); - do_move_bb(&(byTypeBB[KING]), kmove_bb); - do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares +/// Position::do_castle() is a helper used to do/undo a castling move. This +/// is a bit tricky, especially in Chess960. - Bitboard rmove_bb = make_move_bb(rto, rfrom); - do_move_bb(&(byColorBB[us]), rmove_bb); - do_move_bb(&(byTypeBB[ROOK]), rmove_bb); - do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares +void Position::do_castle(Square kfrom, Square kto, Square rfrom, Square rto) { - // Update board - board[rto] = board[kto] = EMPTY; - board[rfrom] = piece_of_color_and_type(us, ROOK); - board[kfrom] = piece_of_color_and_type(us, KING); + Color us = sideToMove; + Bitboard k_from_to_bb = SquareBB[kfrom] ^ SquareBB[kto]; + Bitboard r_from_to_bb = SquareBB[rfrom] ^ SquareBB[rto]; + byTypeBB[KING] ^= k_from_to_bb; + byTypeBB[ROOK] ^= r_from_to_bb; + byTypeBB[ALL_PIECES] ^= k_from_to_bb ^ r_from_to_bb; + byColorBB[us] ^= k_from_to_bb ^ r_from_to_bb; - // Update piece lists - pieceList[us][KING][index[kto]] = kfrom; - pieceList[us][ROOK][index[rto]] = rfrom; - int tmp = index[rto]; // In Chess960 could be rto == kfrom - index[kfrom] = index[kto]; - index[rfrom] = tmp; + // Could be from == to, so first set NO_PIECE then KING and ROOK + board[kfrom] = board[rfrom] = NO_PIECE; + board[kto] = make_piece(us, KING); + board[rto] = make_piece(us, ROOK); - // Finally point our state pointer back to the previous state - st = st->previous; - - assert(is_ok()); + // Could be kfrom == rto, so use a 'tmp' variable + int tmp = index[kfrom]; + index[rto] = index[rfrom]; + index[kto] = tmp; + pieceList[us][KING][index[kto]] = kto; + pieceList[us][ROOK][index[rto]] = rto; } -/// 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. +/// Position::do(undo)_null_move() is used to do(undo) a "null move": It flips +/// the side to move without executing any move on the board. -void Position::do_null_move(StateInfo& backupSt) { +void Position::do_null_move(StateInfo& newSt) { - assert(is_ok()); - assert(!is_check()); + assert(!checkers()); - // 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.mgValue = st->mgValue; - backupSt.egValue = st->egValue; - backupSt.previous = st->previous; - st->previous = &backupSt; + memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here - // Save the current key to the history[] array, in order to be able to - // detect repetition draws. - history[gamePly] = st->key; + newSt.previous = st; + st = &newSt; - // Update the necessary information if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; + { + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } - st->key ^= zobSideToMove; - TT.prefetch(st->key); + st->key ^= Zobrist::side; + prefetch((char*)TT.first_entry(st->key)); - sideToMove = opposite_color(sideToMove); - st->epSquare = SQ_NONE; st->rule50++; - gamePly++; - - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; -} + st->pliesFromNull = 0; + sideToMove = ~sideToMove; -/// Position::undo_null_move() unmakes a "null move". + assert(pos_is_ok()); +} void Position::undo_null_move() { - assert(is_ok()); - assert(!is_check()); + assert(!checkers()); - // Restore information from the our backup StateInfo object - StateInfo* backupSt = st->previous; - st->key = backupSt->key; - st->epSquare = backupSt->epSquare; - st->mgValue = backupSt->mgValue; - st->egValue = backupSt->egValue; - st->previous = backupSt->previous; - - // Update the necessary information - sideToMove = opposite_color(sideToMove); - st->rule50--; - gamePly--; + st = st->previous; + sideToMove = ~sideToMove; } @@ -1279,109 +1134,61 @@ void Position::undo_null_move() { /// move, and one which takes a 'from' and a 'to' square. The function does /// not yet understand promotions captures. -int Position::see(Square to) const { - - assert(square_is_ok(to)); - return see(SQ_NONE, to); -} - -int Position::see(Move m) const { - - assert(move_is_ok(m)); - return see(move_from(m), move_to(m)); -} - int Position::see_sign(Move m) const { - assert(move_is_ok(m)); + assert(is_ok(m)); - Square from = move_from(m); - Square to = move_to(m); + // 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 (PieceValue[MG][piece_on(to_sq(m))] >= PieceValue[MG][piece_moved(m)]) + return 1; - // Early return if SEE cannot be negative because capturing piece value - // is not bigger then captured one. - if ( midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to) - && type_of_piece_on(from) != KING) - return 1; - - return see(from, to); + return see(m); } -int Position::see(Square from, Square to) const { - - // Material values - static const int seeValues[18] = { - 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, - RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0, - 0, PawnValueMidgame, KnightValueMidgame, BishopValueMidgame, - RookValueMidgame, QueenValueMidgame, QueenValueMidgame*10, 0, - 0, 0 - }; - - Bitboard attackers, stmAttackers, occ, b; - - assert(square_is_ok(from) || from == SQ_NONE); - assert(square_is_ok(to)); +int Position::see(Move m) const { - // Initialize colors - Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to))); - Color them = opposite_color(us); + Square from, to; + Bitboard occupied, attackers, stmAttackers; + int swapList[32], slIndex = 1; + PieceType captured; + Color stm; - // Initialize pieces - Piece piece = piece_on(from); - Piece capture = piece_on(to); + assert(is_ok(m)); - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - occ = occupied_squares(); + from = from_sq(m); + to = to_sq(m); + captured = type_of(piece_on(to)); + occupied = pieces() ^ from; // Handle en passant moves - if (st->epSquare == to && type_of_piece_on(from) == PAWN) + if (type_of(m) == ENPASSANT) { - assert(capture == EMPTY); + Square capQq = to - pawn_push(sideToMove); - Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S); - capture = piece_on(capQq); - assert(type_of_piece_on(capQq) == PAWN); + assert(!captured); + assert(type_of(piece_on(capQq)) == PAWN); // Remove the captured pawn - clear_bit(&occ, capQq); + occupied ^= capQq; + captured = PAWN; } + else if (type_of(m) == CASTLE) + // Castle moves are implemented as king capturing the rook so cannot be + // handled correctly. Simply return 0 that is always the correct value + // unless the rook is ends up under attack. + return 0; - while (true) - { - clear_bit(&occ, from); - attackers = (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN)) - | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN)) - | (attacks_from(to) & pieces(KNIGHT)) - | (attacks_from(to) & pieces(KING)) - | (attacks_from(to, WHITE) & pieces(PAWN, BLACK)) - | (attacks_from(to, BLACK) & pieces(PAWN, WHITE)); - - if (from != SQ_NONE) - break; - - // If we don't have any attacker we are finished - if ((attackers & pieces_of_color(us)) == EmptyBoardBB) - return 0; - - // Locate the least valuable attacker to the destination square - // and use it to initialize from square. - stmAttackers = attackers & pieces_of_color(us); - PieceType pt; - for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++) - assert(pt < KING); - - from = first_1(stmAttackers & pieces(pt)); - piece = piece_on(from); - } + // Find all attackers to the destination square, with the moving piece + // removed, but possibly an X-ray attacker added behind it. + attackers = attackers_to(to, occupied); // If the opponent has no attackers we are finished - stmAttackers = attackers & pieces_of_color(them); + stm = ~color_of(piece_on(from)); + stmAttackers = attackers & pieces(stm); if (!stmAttackers) - return seeValues[capture]; - - attackers &= occ; // Remove the moving piece + return PieceValue[MG][captured]; // The destination square is defended, which makes things rather more // difficult to compute. We proceed by building up a "swap list" containing @@ -1389,147 +1196,73 @@ int Position::see(Square from, Square to) const { // 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] = PieceValue[MG][captured]; + captured = 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; !(stmAttackers & pieces(pt)); pt++) - assert(pt < KING); + assert(slIndex < 32); - // Remove the attacker we just found from the 'attackers' bitboard, - // and scan for new X-ray attacks behind the attacker. - b = stmAttackers & pieces(pt); - occ ^= (b & (~b + 1)); - attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN)) - | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN)); + // Add the new entry to the swap list + swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; + slIndex++; - attackers &= occ; + // Locate and remove from 'occupied' the next least valuable attacker + captured = next_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - // 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); - stmAttackers = attackers & pieces_of_color(c); - - // Stop after a king capture - if (pt == KING && stmAttackers) + attackers &= occupied; // Remove the just found attacker + stm = ~stm; + stmAttackers = attackers & pieces(stm); + + if (captured == KING) { - assert(n < 32); - swapList[n++] = QueenValueMidgame*10; + // Stop before processing a king capture + if (stmAttackers) + swapList[slIndex++] = QueenValueMg * 16; + 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] = std::min(-swapList[slIndex], swapList[slIndex-1]); return swapList[0]; } -/// Position::saveState() copies the content of the current state -/// inside startState and makes st point to it. This is needed -/// when the st pointee could become stale, as example because -/// the caller is about to going out of scope. - -void Position::saveState() { - - startState = *st; - st = &startState; - st->previous = NULL; // as a safe guard -} - - /// Position::clear() erases the position object to a pristine state, with an /// empty board, white to move, and no castling rights. void Position::clear() { + memset(this, 0, sizeof(Position)); + startState.epSquare = SQ_NONE; st = &startState; - memset(st, 0, sizeof(StateInfo)); - st->epSquare = SQ_NONE; - 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); - - for (int i = 0; i < 64; i++) - board[i] = EMPTY; - - for (int i = 0; i < 7; i++) - for (int j = 0; j < 8; j++) + for (int i = 0; i < 8; i++) + for (int j = 0; j < 16; j++) pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - - sideToMove = WHITE; - gamePly = 0; - initialKFile = FILE_E; - initialKRFile = FILE_H; - initialQRFile = FILE_A; -} - - -/// 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; } /// 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[0], s); // HACK: byTypeBB[0] contains all occupied squares. - - pieceCount[c][pt]++; -} - - -/// 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) { - - st->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) { - - st->castleRights |= (4 + 4*int(c)); + byTypeBB[ALL_PIECES] |= s; + byTypeBB[pt] |= s; + byColorBB[c] |= s; } @@ -1540,20 +1273,21 @@ void Position::allow_ooo(Color c) { Key Position::compute_key() const { - Key result = Key(0ULL); + Key k = Zobrist::castle[st->castleRights]; - 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]; + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + k ^= Zobrist::psq[color_of(piece_on(s))][type_of(piece_on(s))][s]; + } if (ep_square() != SQ_NONE) - result ^= zobEp[ep_square()]; + k ^= Zobrist::enpassant[file_of(ep_square())]; - result ^= zobCastle[st->castleRights]; - if (side_to_move() == BLACK) - result ^= zobSideToMove; + if (sideToMove == BLACK) + k ^= Zobrist::side; - return result; + return k; } @@ -1565,20 +1299,15 @@ Key Position::compute_key() const { Key Position::compute_pawn_key() const { - Key result = Key(0ULL); - Bitboard b; - Square s; + Key k = 0; - for (Color c = WHITE; c <= BLACK; c++) + for (Bitboard b = pieces(PAWN); b; ) { - b = pieces(PAWN, c); - while(b) - { - s = pop_1st_bit(&b); - result ^= zobrist[c][PAWN][s]; - } + Square s = pop_lsb(&b); + k ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; } - return result; + + return k; } @@ -1590,349 +1319,201 @@ Key Position::compute_pawn_key() const { Key Position::compute_material_key() const { - Key result = Key(0ULL); + Key k = 0; + 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; + for (int cnt = 0; cnt < piece_count(c, pt); cnt++) + k ^= Zobrist::psq[c][pt][cnt]; + + return k; } -/// Position::compute_value() compute the incremental scores for the middle +/// Position::compute_psq_score() computes 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. -template -Value Position::compute_value() const { +Score Position::compute_psq_score() const { - Value result = Value(0); - Bitboard b; - Square s; + Score score = SCORE_ZERO; - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - { - b = pieces(pt, c); - while(b) - { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); - result += pst(c, pt, s); - } - } + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + score += pieceSquareTable[piece_on(s)][s]; + } - const Value TempoValue = (Phase == MidGame ? TempoValueMidgame : TempoValueEndgame); - result += (side_to_move() == WHITE)? TempoValue / 2 : -TempoValue / 2; - return result; + return score; } /// 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); + Value value = VALUE_ZERO; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) - { - Bitboard b = pieces(pt, c); - while (b) - { - assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt)); - pop_1st_bit(&b); - result += piece_value_midgame(pt); - } - } - return result; + value += piece_count(c, pt) * PieceValue[MG][pt]; + + return value; } /// Position::is_draw() tests whether the position is drawn by material, /// 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 ( !pieces(PAWN) - && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame)) + && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMg)) return true; // Draw by the 50 moves rule? - if (st->rule50 > 100 || (st->rule50 == 100 && !is_check())) + if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; // Draw by repetition? - for (int i = 2; i < Min(gamePly, st->rule50); i += 2) - if (history[gamePly - i] == st->key) - return true; - - return false; -} - - -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. - -bool Position::is_mate() const { - - MoveStack moves[256]; - - return is_check() && (generate_evasions(*this, moves, pinned_pieces(sideToMove)) == moves); -} - - -/// Position::has_mate_threat() tests whether a given color has a mate in one -/// from the current position. - -bool Position::has_mate_threat(Color c) { - - StateInfo st1, st2; - Color stm = side_to_move(); - - if (is_check()) - return false; - - // If the input color is not equal to the side to move, do a null move - if (c != stm) - do_null_move(st1); - - MoveStack mlist[120]; - bool result = false; - Bitboard dc = discovered_check_candidates(sideToMove); - Bitboard pinned = pinned_pieces(sideToMove); - - // Generate pseudo-legal non-capture and capture check moves - MoveStack* last = generate_non_capture_checks(*this, mlist, dc); - last = generate_captures(*this, last); - - // Loop through the moves, and see if one of them is mate - for (MoveStack* cur = mlist; cur != last; cur++) + if (!SkipRepetition) { - Move move = cur->move; - if (!pl_move_is_legal(move, pinned)) - continue; - - do_move(move, st2); - if (is_mate()) - result = true; - - undo_move(move); - } - - // Undo null move, if necessary - if (c != stm) - undo_null_move(); - - return result; -} - - -/// Position::init_zobrist() is a static member function which initializes the -/// various arrays used to compute hash keys. - -void Position::init_zobrist() { - - 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()); - - for (int i = 0; i < 64; i++) - zobEp[i] = Key(genrand_int64()); - - for (int i = 0; i < 16; i++) - zobCastle[i] = genrand_int64(); + int i = 4, e = std::min(st->rule50, st->pliesFromNull); - zobSideToMove = genrand_int64(); - - 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); - - for (int i = 0; i < 16; i++) - zobMaterial[0][KING][i] = zobMaterial[1][KING][i] = Key(0ULL); -} + if (i <= e) + { + StateInfo* stp = st->previous->previous; + do { + stp = stp->previous->previous; -/// 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. + if (stp->key == st->key) + return true; -void Position::init_piece_square_tables() { + i += 2; - 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); + } while (i <= e); } + } - 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)]; - } + return false; } +// Explicit template instantiations +template bool Position::is_draw() const; +template bool Position::is_draw() const; -/// 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::flipped_copy(const Position& pos) { - assert(pos.is_ok()); - - clear(); - - // 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)); +/// Position::flip() flips position with the white and black sides reversed. This +/// is only useful for debugging especially for finding evaluation symmetry bugs. - // Side to move - sideToMove = opposite_color(pos.side_to_move()); +void Position::flip() { - // 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); + const Position pos(*this); - initialKFile = pos.initialKFile; - initialKRFile = pos.initialKRFile; - initialQRFile = pos.initialQRFile; + clear(); - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - castleRightsMask[sq] = ALL_CASTLES; + sideToMove = ~pos.side_to_move(); + thisThread = pos.this_thread(); + nodes = pos.nodes_searched(); + chess960 = pos.is_chess960(); + gamePly = pos.game_ply(); - 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; + for (Square s = SQ_A1; s <= SQ_H8; s++) + if (!pos.is_empty(s)) + put_piece(Piece(pos.piece_on(s) ^ 8), ~s); + + if (pos.can_castle(WHITE_OO)) + set_castle_right(BLACK, ~pos.castle_rook_square(WHITE, KING_SIDE)); + if (pos.can_castle(WHITE_OOO)) + set_castle_right(BLACK, ~pos.castle_rook_square(WHITE, QUEEN_SIDE)); + if (pos.can_castle(BLACK_OO)) + set_castle_right(WHITE, ~pos.castle_rook_square(BLACK, KING_SIDE)); + if (pos.can_castle(BLACK_OOO)) + set_castle_right(WHITE, ~pos.castle_rook_square(BLACK, QUEEN_SIDE)); - // En passant square if (pos.st->epSquare != SQ_NONE) - st->epSquare = flip_square(pos.st->epSquare); + st->epSquare = ~pos.st->epSquare; - // Checkers - find_checkers(); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); - // Hash keys st->key = compute_key(); st->pawnKey = compute_pawn_key(); st->materialKey = compute_material_key(); - - // Incremental scores - st->mgValue = compute_value(); - st->egValue = compute_value(); - - // Material + st->psqScore = compute_psq_score(); st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); - assert(is_ok()); + assert(pos_is_ok()); } -/// Position::is_ok() performs some consitency checks for the position object. +/// Position::pos_is_ok() performs some consitency checks for the position object. /// This is meant to be helpful when debugging. -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; - - if (failedStep) *failedStep = 1; - - // Side to move OK? - if (!color_is_ok(side_to_move())) - return false; +bool Position::pos_is_ok(int* failedStep) const { - // Are the king squares in the position correct? - if (failedStep) (*failedStep)++; - if (piece_on(king_square(WHITE)) != WK) - return false; + int dummy, *step = failedStep ? failedStep : &dummy; - if (failedStep) (*failedStep)++; - if (piece_on(king_square(BLACK)) != BK) + // What features of the position should be verified? + const bool all = false; + + const bool debugBitboards = all || false; + const bool debugKingCount = all || false; + const bool debugKingCapture = all || false; + const bool debugCheckerCount = all || false; + const bool debugKey = all || false; + const bool debugMaterialKey = all || false; + const bool debugPawnKey = all || false; + const bool debugIncrementalEval = all || false; + const bool debugNonPawnMaterial = all || false; + const bool debugPieceCounts = all || false; + const bool debugPieceList = all || false; + const bool debugCastleSquares = all || false; + + *step = 1; + + if (sideToMove != WHITE && sideToMove != BLACK) return false; - // Castle files OK? - if (failedStep) (*failedStep)++; - if (!file_is_ok(initialKRFile)) + if ((*step)++, piece_on(king_square(WHITE)) != W_KING) return false; - if (!file_is_ok(initialQRFile)) + if ((*step)++, piece_on(king_square(BLACK)) != B_KING) return false; - // Do both sides have exactly one king? - if (failedStep) (*failedStep)++; - if (debugKingCount) + if ((*step)++, debugKingCount) { - int kingCount[2] = {0, 0}; + int kingCount[COLOR_NB] = {}; + for (Square s = SQ_A1; s <= SQ_H8; s++) - if (type_of_piece_on(s) == KING) - kingCount[color_of_piece_on(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 (attackers_to(ksq) & pieces_of_color(us)) + if ((*step)++, debugKingCapture) + if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) return false; - } - // Is there more than 2 checkers? - if (failedStep) (*failedStep)++; - if (debugCheckerCount && count_1s(st->checkersBB) > 2) + if ((*step)++, debugCheckerCount && popcount(st->checkersBB) > 2) return false; - // Bitboards OK? - if (failedStep) (*failedStep)++; - if (debugBitboards) + if ((*step)++, debugBitboards) { // The intersection of the white and black pieces must be empty - if ((pieces_of_color(WHITE) & pieces_of_color(BLACK)) != EmptyBoardBB) + if (pieces(WHITE) & pieces(BLACK)) 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()) + if ((pieces(WHITE) | pieces(BLACK)) != pieces()) return false; // Separate piece type bitboards must have empty intersections @@ -1942,75 +1523,63 @@ bool Position::is_ok(int* failedStep) const { 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; - } - - // Hash key OK? - if (failedStep) (*failedStep)++; - if (debugKey && st->key != compute_key()) + if ((*step)++, ep_square() != SQ_NONE && relative_rank(sideToMove, ep_square()) != RANK_6) return false; - // Pawn hash key OK? - if (failedStep) (*failedStep)++; - if (debugPawnKey && st->pawnKey != compute_pawn_key()) + if ((*step)++, debugKey && st->key != compute_key()) return false; - // Material hash key OK? - if (failedStep) (*failedStep)++; - if (debugMaterialKey && st->materialKey != compute_material_key()) + if ((*step)++, debugPawnKey && st->pawnKey != compute_pawn_key()) return false; - // Incremental eval OK? - if (failedStep) (*failedStep)++; - if (debugIncrementalEval) - { - if (st->mgValue != compute_value()) - return false; + if ((*step)++, debugMaterialKey && st->materialKey != compute_material_key()) + return false; - if (st->egValue != compute_value()) - return false; - } + if ((*step)++, debugIncrementalEval && st->psqScore != compute_psq_score()) + return false; - // Non-pawn material OK? - if (failedStep) (*failedStep)++; - if (debugNonPawnMaterial) + if ((*step)++, debugNonPawnMaterial) { - if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) - return false; - - if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if ( st->npMaterial[WHITE] != compute_non_pawn_material(WHITE) + || st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; } - // Piece counts OK? - if (failedStep) (*failedStep)++; - if (debugPieceCounts) + if ((*step)++, debugPieceCounts) for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= KING; pt++) - if (pieceCount[c][pt] != count_1s(pieces(pt, c))) + if (pieceCount[c][pt] != popcount(pieces(c, pt))) 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 ((*step)++, 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)) + if (piece_on(piece_list(c, pt)[i]) != make_piece(c, pt)) return false; - if (index[piece_list(c, pt, i)] != i) + if (index[piece_list(c, pt)[i]] != i) return false; } - } - if (failedStep) *failedStep = 0; + + if ((*step)++, debugCastleSquares) + for (Color c = WHITE; c <= BLACK; c++) + for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) + { + CastleRight cr = make_castle_right(c, s); + + if (!can_castle(cr)) + continue; + + if ((castleRightsMask[king_square(c)] & cr) != cr) + return false; + + if ( piece_on(castleRookSquare[c][s]) != make_piece(c, ROOK) + || castleRightsMask[castleRookSquare[c][s]] != cr) + return false; + } + + *step = 0; return true; }