X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fposition.cpp;h=ae63f26343f5026d14dbe989cf65f3e53415546a;hb=8a7876d48d4360d14d918c1ff444b5d6eb0382de;hp=77a6d604523f40a841a5f73ba6a2e67e41a760f3;hpb=f35ddb04af2a00bd9facf5b66ec97e4ab28d4480;p=stockfish diff --git a/src/position.cpp b/src/position.cpp index 77a6d604..918d50e5 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) 2008-2014 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 @@ -17,2010 +17,1269 @@ 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 "position.h" #include "psqtab.h" -#include "san.h" +#include "rkiss.h" +#include "thread.h" #include "tt.h" -#include "ucioption.h" +#include "uci.h" using std::string; +CACHE_LINE_ALIGNMENT -//// -//// 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 PieceValue[PHASE_NB][PIECE_NB] = { +{ VALUE_ZERO, PawnValueMg, KnightValueMg, BishopValueMg, RookValueMg, QueenValueMg }, +{ VALUE_ZERO, PawnValueEg, KnightValueEg, BishopValueEg, RookValueEg, QueenValueEg } }; -Score Position::PieceSquareTable[16][64]; +namespace Zobrist { -static bool RequestPending = false; - -//// -//// Functions -//// - -/// Constructors - -Position::Position(const Position& pos) { - copy(pos); + Key psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; + Key enpassant[FILE_NB]; + Key castling[CASTLING_RIGHT_NB]; + Key side; + Key exclusion; } -Position::Position(const string& fen) { - from_fen(fen); -} +Key Position::exclusion_key() const { return st->key ^ Zobrist::exclusion;} +namespace { -/// 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). +const string PieceToChar(" PNBRQK pnbrqk"); +Score psq[COLOR_NB][PIECE_TYPE_NB][SQUARE_NB]; -void Position::from_fen(const string& fen) { +// min_attacker() is a helper function used by see() to locate the least +// valuable attacker for the side to move, remove the attacker we just found +// from the bitboards and scan for new X-ray attacks behind it. - static const string pieceLetters = "KQRBNPkqrbnp"; - static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; +template FORCE_INLINE +PieceType min_attacker(const Bitboard* bb, const Square& to, const Bitboard& stmAttackers, + Bitboard& occupied, Bitboard& attackers) { - clear(); + Bitboard b = stmAttackers & bb[Pt]; + if (!b) + return min_attacker(bb, to, stmAttackers, occupied, attackers); - // Board - Rank rank = RANK_8; - File file = FILE_A; - size_t i = 0; - for ( ; fen[i] != ' '; i++) - { - 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) - { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - Square square = make_square(file, rank); - put_piece(pieces[idx], square); - file++; - } + occupied ^= b & ~(b - 1); - // 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); + if (Pt == PAWN || Pt == BISHOP || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[BISHOP] | bb[QUEEN]); - // Castling rights - i++; - if (fen[i] != ' ') - { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } + if (Pt == ROOK || Pt == QUEEN) + attackers |= attacks_bb(to, occupied) & (bb[ROOK] | bb[QUEEN]); - i++; - while(strchr("KQkqabcdefghABCDEFGH-", fen[i])) { - if (fen[i] == '-') - { - i++; - break; - } - else if(fen[i] == 'K') allow_oo(WHITE); - else if(fen[i] == 'Q') allow_ooo(WHITE); - else if(fen[i] == 'k') allow_oo(BLACK); - else if(fen[i] == 'q') allow_ooo(BLACK); - else if(fen[i] >= 'A' && fen[i] <= 'H') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B1; square <= SQ_G1; square++) - if(piece_on(square) == WK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'A') + FILE_A; - if(rookFile < initialKFile) { - allow_ooo(WHITE); - initialQRFile = rookFile; - } - else { - allow_oo(WHITE); - initialKRFile = rookFile; - } - } - else if(fen[i] >= 'a' && fen[i] <= 'h') { - File rookFile, kingFile = FILE_NONE; - for(Square square = SQ_B8; square <= SQ_G8; square++) - if(piece_on(square) == BK) - kingFile = square_file(square); - if(kingFile == FILE_NONE) { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - initialKFile = kingFile; - rookFile = File(fen[i] - 'a') + FILE_A; - if(rookFile < initialKFile) { - allow_ooo(BLACK); - initialQRFile = rookFile; - } - else { - allow_oo(BLACK); - initialKRFile = rookFile; - } - } - else { - std::cout << "Error in FEN at character " << i << std::endl; - return; - } - i++; - } + attackers &= occupied; // After X-ray that may add already processed pieces + return (PieceType)Pt; +} - // Skip blanks - while (fen[i] == ' ') - i++; - - // 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; - - castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO|WHITE_OOO); - castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO|BLACK_OOO); - castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO; - castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO; - castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO; - castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; - - find_checkers(); - - st->key = compute_key(); - st->pawnKey = compute_pawn_key(); - st->materialKey = compute_material_key(); - st->value = compute_value(); - st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); - st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); +template<> FORCE_INLINE +PieceType min_attacker(const Bitboard*, const Square&, const Bitboard&, Bitboard&, Bitboard&) { + return KING; // No need to update bitboards: it is the last cycle } +} // namespace -/// Position::to_fen() converts the position object to a FEN string. This is -/// probably only useful for debugging. -const string Position::to_fen() const { +/// CheckInfo c'tor - static const string pieceLetters = " PNBRQK pnbrqk"; - string fen; - int skip; +CheckInfo::CheckInfo(const Position& pos) { - 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'; + Color them = ~pos.side_to_move(); + ksq = pos.king_square(them); - 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 += '-'; + pinned = pos.pinned_pieces(pos.side_to_move()); + dcCandidates = pos.discovered_check_candidates(); - return fen; + 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; } -/// Position::print() prints an ASCII representation of the position to -/// the standard output. If a move is given then also the san is print. +/// Position::init() initializes at startup the various arrays used to compute +/// hash keys and the piece square tables. The latter is a two-step operation: +/// Firstly, the white halves of the tables are copied from PSQT[] tables. +/// Secondly, the black halves of the tables are initialized by flipping and +/// changing the sign of the white scores. -void Position::print(Move m) const { +void Position::init() { - static const string pieceLetters = " PNBRQK PNBRQK ."; + RKISS rk; - // Check for reentrancy, as example when called from inside - // MovePicker that is used also here in move_to_san() - if (RequestPending) - return; + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (Square s = SQ_A1; s <= SQ_H8; ++s) + Zobrist::psq[c][pt][s] = rk.rand(); - RequestPending = true; + for (File f = FILE_A; f <= FILE_H; ++f) + Zobrist::enpassant[f] = rk.rand(); - std::cout << std::endl; - if (m != MOVE_NONE) + for (int cf = NO_CASTLING; cf <= ANY_CASTLING; ++cf) { - 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++) + Bitboard b = cf; + while (b) { - Square sq = make_square(file, rank); - Piece piece = piece_on(sq); - if (piece == EMPTY && square_color(sq) == WHITE) - piece = NO_PIECE; - - char col = (color_of_piece_on(sq) == BLACK ? '=' : ' '); - std::cout << '|' << col << pieceLetters[piece] << col; + Key k = Zobrist::castling[1ULL << pop_lsb(&b)]; + Zobrist::castling[cf] ^= k ? k : rk.rand(); } - std::cout << '|' << std::endl; } - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl - << "Fen is: " << to_fen() << std::endl - << "Key is: " << st->key << std::endl; - - RequestPending = false; -} + Zobrist::side = rk.rand(); + Zobrist::exclusion = rk.rand(); -/// Position::copy() creates a copy of the input position. + for (PieceType pt = PAWN; pt <= KING; ++pt) + { + PieceValue[MG][make_piece(BLACK, pt)] = PieceValue[MG][pt]; + PieceValue[EG][make_piece(BLACK, pt)] = PieceValue[EG][pt]; -void Position::copy(const Position& pos) { + Score v = make_score(PieceValue[MG][pt], PieceValue[EG][pt]); - memcpy(this, &pos, sizeof(Position)); - saveState(); // detach and copy state info + for (Square s = SQ_A1; s <= SQ_H8; ++s) + { + psq[WHITE][pt][ s] = (v + PSQT[pt][s]); + psq[BLACK][pt][~s] = -(v + PSQT[pt][s]); + } + } } -/// 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. +/// Position::operator=() creates a copy of 'pos'. We want the new born Position +/// object to not depend on any external data so we detach state pointer from +/// the source one. -template -Bitboard Position::hidden_checkers(Color c) const { +Position& Position::operator=(const Position& pos) { - Bitboard pinners, result = EmptyBoardBB; + std::memcpy(this, &pos, sizeof(Position)); + startState = *st; + st = &startState; + nodes = 0; - // Pinned pieces protect our king, dicovery checks attack - // the enemy king. - Square ksq = king_square(FindPinned ? c : opposite_color(c)); + assert(pos_is_ok()); - // 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]); + return *this; +} - if (FindPinned && pinners) - pinners &= ~st->checkersBB; - while (pinners) - { - Square s = pop_1st_bit(&pinners); - Bitboard b = squares_between(s, ksq) & occupied_squares(); +/// Position::clear() erases the position object to a pristine state, with an +/// empty board, white to move, and no castling rights. - assert(b); +void Position::clear() { - if ( !(b & (b - 1)) // Only one bit set? - && (b & pieces_of_color(c))) // Is an our piece? - result |= b; - } - return result; + std::memset(this, 0, sizeof(Position)); + startState.epSquare = SQ_NONE; + st = &startState; + + for (int i = 0; i < PIECE_TYPE_NB; ++i) + for (int j = 0; j < 16; ++j) + pieceList[WHITE][i][j] = pieceList[BLACK][i][j] = SQ_NONE; } -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. +/// 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. -Bitboard Position::pinned_pieces(Color c) const { +void Position::set(const string& fenStr, bool isChess960, Thread* th) { +/* + A FEN string defines a particular position using only the ASCII character set. - return hidden_checkers(c); -} + 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") whilst Black uses lowercase ("pnbrqk"). Blank squares are + noted using digits 1 through 8 (the number of blank squares), and "/" + separates ranks. -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the given side which are candidates for giving a discovered -/// check. + 2) Active color. "w" means white moves next, "b" means black. -Bitboard Position::discovered_check_candidates(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). - return hidden_checkers(c); -} + 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. -/// Position::attackers_to() computes a bitboard containing all pieces which -/// attacks a given square. + 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. -Bitboard Position::attackers_to(Square s) const { + 6) Fullmove number. The number of the full move. It starts at 1, and is + incremented after Black's move. +*/ - 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)); -} + unsigned char col, row, token; + size_t idx; + Square sq = SQ_A8; + std::istringstream ss(fenStr); -/// Position::attacks_from() computes a bitboard of all attacks -/// of a given piece put in a given square. + clear(); + ss >> std::noskipws; -Bitboard Position::attacks_from(Piece p, Square s) const { + // 1. Piece placement + while ((ss >> token) && !isspace(token)) + { + if (isdigit(token)) + sq += Square(token - '0'); // Advance the given number of files - assert(square_is_ok(s)); + else if (token == '/') + sq -= Square(16); - 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; + else if ((idx = PieceToChar.find(token)) != string::npos) + { + put_piece(sq, color_of(Piece(idx)), type_of(Piece(idx))); + ++sq; + } } - return false; -} + // 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::move_attacks_square() tests whether a move from the current -/// position attacks a given square. + token = char(toupper(token)); -bool Position::move_attacks_square(Move m, Square s) const { + if (token == 'K') + for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; --rsq) {} - assert(move_is_ok(m)); - assert(square_is_ok(s)); + else if (token == 'Q') + for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; ++rsq) {} - Square f = move_from(m), t = move_to(m); + else if (token >= 'A' && token <= 'H') + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); - assert(square_is_occupied(f)); + else + continue; - if (bit_is_set(attacks_from(piece_on(f), t), s)) - return true; + set_castling_right(c, rsq); + } - // 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))); -} + // 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 = make_square(File(col - 'a'), Rank(row - '1')); + if (!(attackers_to(st->epSquare) & pieces(sideToMove, PAWN))) + st->epSquare = SQ_NONE; + } -/// 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. + // 5-6. Halfmove clock and fullmove number + ss >> std::skipws >> st->rule50 >> gamePly; -void Position::find_checkers() { + // 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) + (sideToMove == BLACK); - Color us = side_to_move(); - st->checkersBB = attackers_to(king_square(us)) & pieces_of_color(opposite_color(us)); -} + chess960 = isChess960; + thisThread = th; + set_state(st); + assert(pos_is_ok()); +} -/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal -bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { +/// Position::set_castling_right() is a helper function used to set castling +/// rights given the corresponding color and the rook starting square. - assert(is_ok()); - assert(move_is_ok(m)); - assert(pinned == pinned_pieces(side_to_move())); +void Position::set_castling_right(Color c, Square rfrom) { - // Castling moves are checked for legality during move generation. - if (move_is_castle(m)) - return true; + Square kfrom = king_square(c); + CastlingSide cs = kfrom < rfrom ? KING_SIDE : QUEEN_SIDE; + CastlingRight cr = (c | cs); - Color us = side_to_move(); - Square from = move_from(m); + st->castlingRights |= cr; + castlingRightsMask[kfrom] |= cr; + castlingRightsMask[rfrom] |= cr; + castlingRookSquare[cr] = rfrom; - assert(color_of_piece_on(from) == us); - assert(piece_on(king_square(us)) == piece_of_color_and_type(us, KING)); + Square kto = relative_square(c, cs == KING_SIDE ? SQ_G1 : SQ_C1); + Square rto = relative_square(c, cs == KING_SIDE ? SQ_F1 : SQ_D1); - // 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); + for (Square s = std::min(rfrom, rto); s <= std::max(rfrom, rto); ++s) + if (s != kfrom && s != rfrom) + castlingPath[cr] |= s; - 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); + for (Square s = std::min(kfrom, kto); s <= std::max(kfrom, kto); ++s) + if (s != kfrom && s != rfrom) + castlingPath[cr] |= s; +} - clear_bit(&b, from); - clear_bit(&b, capsq); - set_bit(&b, to); - return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) - && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); - } +/// Position::set_state() computes the hash keys of the position, and other +/// data that once computed is updated incrementally as moves are made. +/// The function is only used when a new position is set up, and to verify +/// the correctness of the StateInfo data when running in debug mode. - // 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))); +void Position::set_state(StateInfo* si) const { - // 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)))); -} + si->key = si->pawnKey = si->materialKey = 0; + si->npMaterial[WHITE] = si->npMaterial[BLACK] = VALUE_ZERO; + si->psq = SCORE_ZERO; + si->checkersBB = attackers_to(king_square(sideToMove)) & pieces(~sideToMove); -/// Position::pl_move_is_evasion() tests whether a pseudo-legal move is a legal evasion + for (Bitboard b = pieces(); b; ) + { + Square s = pop_lsb(&b); + Piece pc = piece_on(s); + si->key ^= Zobrist::psq[color_of(pc)][type_of(pc)][s]; + si->psq += psq[color_of(pc)][type_of(pc)][s]; + } -bool Position::pl_move_is_evasion(Move m, Bitboard pinned) const -{ - assert(is_check()); + if (ep_square() != SQ_NONE) + si->key ^= Zobrist::enpassant[file_of(ep_square())]; - Color us = side_to_move(); - Square from = move_from(m); - Square to = move_to(m); + if (sideToMove == BLACK) + si->key ^= Zobrist::side; - // King moves and en-passant captures are verified in pl_move_is_legal() - if (type_of_piece_on(from) == KING || move_is_ep(m)) - return pl_move_is_legal(m, pinned); + si->key ^= Zobrist::castling[st->castlingRights]; - Bitboard target = checkers(); - Square checksq = pop_1st_bit(&target); + for (Bitboard b = pieces(PAWN); b; ) + { + Square s = pop_lsb(&b); + si->pawnKey ^= Zobrist::psq[color_of(piece_on(s))][PAWN][s]; + } - if (target) // double check ? - return false; + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (int cnt = 0; cnt < pieceCount[c][pt]; ++cnt) + si->materialKey ^= Zobrist::psq[c][pt][cnt]; - // Our move must be a blocking evasion or a capture of the checking piece - target = squares_between(checksq, king_square(us)) | checkers(); - return bit_is_set(target, to) && pl_move_is_legal(m, pinned); + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = KNIGHT; pt <= QUEEN; ++pt) + si->npMaterial[c] += pieceCount[c][pt] * PieceValue[MG][pt]; } -/// Position::move_is_check() tests whether a pseudo-legal move is a check +/// Position::fen() returns a FEN representation of the position. In case of +/// Chess960 the Shredder-FEN notation is used. This is mainly a debugging function. -bool Position::move_is_check(Move m) const { +const string Position::fen() const { - Bitboard dc = discovered_check_candidates(side_to_move()); - return move_is_check(m, dc); -} + int emptyCnt; + std::ostringstream ss; -bool Position::move_is_check(Move m, Bitboard dcCandidates) const { + for (Rank r = RANK_8; r >= RANK_1; --r) + { + for (File f = FILE_A; f <= FILE_H; ++f) + { + for (emptyCnt = 0; f <= FILE_H && empty(make_square(f, r)); ++f) + ++emptyCnt; - assert(is_ok()); - assert(move_is_ok(m)); - assert(dcCandidates == discovered_check_candidates(side_to_move())); + if (emptyCnt) + ss << emptyCnt; - 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); + if (f <= FILE_H) + ss << PieceToChar[piece_on(make_square(f, r))]; + } - assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); + if (r > RANK_1) + ss << '/'; + } - // Proceed according to the type of the moving piece - switch (type_of_piece_on(from)) - { - case PAWN: + ss << (sideToMove == WHITE ? " w " : " b "); - if (bit_is_set(attacks_from(ksq, them), to)) // Normal check? - return true; + if (can_castle(WHITE_OO)) + ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | KING_SIDE)) : 'K'); - if ( dcCandidates // Discovered check? - && bit_is_set(dcCandidates, from) - && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) - return true; + if (can_castle(WHITE_OOO)) + ss << (chess960 ? 'A' + file_of(castling_rook_square(WHITE | QUEEN_SIDE)) : 'Q'); - if (move_is_promotion(m)) // Promotion with check? - { - Bitboard b = occupied_squares(); - clear_bit(&b, from); + if (can_castle(BLACK_OO)) + ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | KING_SIDE)) : 'k'); - 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; + if (can_castle(BLACK_OOO)) + ss << (chess960 ? 'a' + file_of(castling_rook_square(BLACK | QUEEN_SIDE)) : 'q'); - // 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; - - // Castling with check? - if (move_is_castle(m)) - { - Square kfrom, kto, rfrom, rto; - Bitboard b = occupied_squares(); - kfrom = from; - rfrom = to; + if (!can_castle(WHITE) && !can_castle(BLACK)) + ss << '-'; - 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; + ss << (ep_square() == SQ_NONE ? " - " : " " + UCI::format_square(ep_square()) + " ") + << st->rule50 << " " << 1 + (gamePly - (sideToMove == BLACK)) / 2; - default: // NO_PIECE_TYPE - break; - } - assert(false); - return false; + return ss.str(); } -/// Position::update_checkers() udpates chekers info given the move. It is called -/// in do_move() and is faster then find_checkers(). +/// Position::pretty() returns an ASCII representation of the position -template -inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, - Square to, Bitboard dcCandidates) { +const string Position::pretty() const { - const bool Bishop = (Piece == QUEEN || Piece == BISHOP); - const bool Rook = (Piece == QUEEN || Piece == ROOK); - const bool Slider = Bishop || Rook; + std::ostringstream ss; - // 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); + ss << "\n +---+---+---+---+---+---+---+---+\n"; - else if ( Piece != KING - && !Slider - && bit_is_set(Piece == PAWN ? attacks_from(ksq, opposite_color(sideToMove)) - : attacks_from(ksq), to)) - set_bit(pCheckersBB, to); - - // Discovery checks - if (Piece != QUEEN && bit_is_set(dcCandidates, from)) + for (Rank r = RANK_8; r >= RANK_1; --r) { - if (Piece != ROOK) - (*pCheckersBB) |= (attacks_from(ksq) & pieces(ROOK, QUEEN, side_to_move())); + for (File f = FILE_A; f <= FILE_H; ++f) + ss << " | " << PieceToChar[piece_on(make_square(f, r))]; - if (Piece != BISHOP) - (*pCheckersBB) |= (attacks_from(ksq) & pieces(BISHOP, QUEEN, side_to_move())); + ss << " |\n +---+---+---+---+---+---+---+---+\n"; } -} + ss << "\nFen: " << fen() << "\nKey: " << std::hex << std::uppercase + << std::setfill('0') << std::setw(16) << st->key << "\nCheckers: "; -/// 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) { + for (Bitboard b = checkers(); b; ) + ss << UCI::format_square(pop_lsb(&b)) << " "; - do_move(m, newSt, discovered_check_candidates(side_to_move())); + return ss.str(); } -void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { - assert(is_ok()); - assert(move_is_ok(m)); +/// Position::game_phase() calculates the game phase interpolating total non-pawn +/// material between endgame and midgame limits. - Bitboard key = st->key; +Phase Position::game_phase() 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 pawnKey, materialKey; - int castleRights, rule50, pliesFromNull; - Square epSquare; - Value value; - Value npMaterial[2]; - }; + Value npm = st->npMaterial[WHITE] + st->npMaterial[BLACK]; - memcpy(&newSt, st, sizeof(ReducedStateInfo)); - newSt.previous = st; - st = &newSt; - - // Save the current key to the history[] array, in order to be able to - // detect repetition draws. - history[gamePly] = key; - gamePly++; + npm = std::max(EndgameLimit, std::min(npm, MidgameLimit)); - // Update side to move - key ^= zobSideToMove; - - // Increment the 50 moves rule draw counter. Resetting it to zero in the - // case of non-reversible moves is taken care of later. - st->rule50++; - st->pliesFromNull++; - - if (move_is_castle(m)) - { - st->key = key; - do_castle_move(m); - return; - } + return Phase(((npm - EndgameLimit) * 128) / (MidgameLimit - EndgameLimit)); +} - 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); - Piece piece = piece_on(from); - PieceType pt = type_of_piece(piece); - PieceType capture = ep ? PAWN : type_of_piece_on(to); +/// Position::check_blockers() returns a bitboard of all the pieces with color +/// 'c' that are blocking check on the king with color 'kingColor'. A piece +/// blocks a check if removing that piece from the board would result in a +/// position where the king is in check. A check blocking piece can be either a +/// pinned or a discovered check piece, according if its color 'c' is the same +/// or the opposite of 'kingColor'. - 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); +Bitboard Position::check_blockers(Color c, Color kingColor) const { - if (capture) - do_capture_move(key, capture, them, to, ep); + Bitboard b, pinners, result = 0; + Square ksq = king_square(kingColor); - // Update hash key - key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; + // Pinners are sliders that give check when a pinned piece is removed + pinners = ( (pieces( ROOK, QUEEN) & PseudoAttacks[ROOK ][ksq]) + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq])) & pieces(~kingColor); - // Reset en passant square - if (st->epSquare != SQ_NONE) + while (pinners) { - key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; - } + b = between_bb(ksq, pop_lsb(&pinners)) & pieces(); - // Update castle rights, try to shortcut a common case - int cm = castleRightsMask[from] & castleRightsMask[to]; - if (cm != ALL_CASTLES && ((cm & st->castleRights) != st->castleRights)) - { - key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[from]; - st->castleRights &= castleRightsMask[to]; - key ^= zobCastle[st->castleRights]; + if (!more_than_one(b)) + result |= b & pieces(c); } + return result; +} - // Prefetch TT access as soon as we know key is updated - TT.prefetch(key); - // 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 +/// Position::attackers_to() computes a bitboard of all pieces which attack a +/// given square. Slider attacks use the occ bitboard to indicate occupancy. - board[to] = board[from]; - board[from] = EMPTY; +Bitboard Position::attackers_to(Square s, Bitboard occ) const { - // 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; + 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 the moving piece was a pawn do some special extra work - if (pt == PAWN) - { - // Reset rule 50 draw counter - st->rule50 = 0; - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; +/// Position::legal() tests whether a pseudo-legal move is legal - // Set en passant square, only if moved pawn can be captured - if ((to ^ 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]; - } - } - } +bool Position::legal(Move m, Bitboard pinned) const { - // Update incremental scores - st->value += pst_delta(piece, from, to); + assert(is_ok(m)); + assert(pinned == pinned_pieces(sideToMove)); - // Set capture piece - st->capture = capture; + Color us = sideToMove; + Square from = from_sq(m); + + assert(color_of(moved_piece(m)) == us); + assert(piece_on(king_square(us)) == make_piece(us, KING)); - if (pm) // promotion ? + // 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) { - PieceType promotion = move_promotion_piece(m); - - assert(promotion >= KNIGHT && promotion <= QUEEN); - - // 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; - pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; - index[to] = pieceCount[us][promotion] - 1; - pieceList[us][promotion][index[to]] = to; - - // Partially revert hash keys update - key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; - st->pawnKey ^= zobrist[us][PAWN][to]; - - // Partially revert and update incremental scores - st->value -= pst(us, PAWN, to); - st->value += pst(us, promotion, to); - - // Update material - st->npMaterial[us] += piece_value_midgame(promotion); - } + Square ksq = king_square(us); + Square to = to_sq(m); + Square capsq = to - pawn_push(us); + Bitboard occ = (pieces() ^ from ^ capsq) | to; - // Update the key with the final value - st->key = key; + assert(to == ep_square()); + assert(moved_piece(m) == make_piece(us, PAWN)); + assert(piece_on(capsq) == make_piece(~us, PAWN)); + assert(piece_on(to) == NO_PIECE); - // Update checkers bitboard, piece must be already moved - if (ep | pm) - st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); - else - { - 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; - } + return !(attacks_bb< ROOK>(ksq, occ) & pieces(~us, QUEEN, ROOK)) + && !(attacks_bb(ksq, occ) & pieces(~us, QUEEN, BISHOP)); } - // Finish - sideToMove = opposite_color(sideToMove); - st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); + // 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) == CASTLING || !(attackers_to(to_sq(m)) & pieces(~us)); - assert(is_ok()); + // 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) + || aligned(from, to_sq(m), king_square(us)); } -/// Position::do_capture_move() is a private method used to update captured -/// piece info. It is called from the main Position::do_move function. +/// Position::pseudo_legal() takes a random move and tests whether the move is +/// pseudo legal. It is used to validate moves from TT that can be corrupted +/// due to SMP concurrent access or hash position key aliasing. -void Position::do_capture_move(Bitboard& key, PieceType capture, Color them, Square to, bool ep) { +bool Position::pseudo_legal(const Move m) const { - assert(capture != KING); + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = moved_piece(m); - Square capsq = to; + // Use a slower but simpler function for uncommon cases + if (type_of(m) != NORMAL) + return MoveList(*this).contains(m); - if (ep) // en passant ? - { - capsq = (them == BLACK)? (to - DELTA_N) : (to - DELTA_S); - - 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)); + // Is not a promotion, so promotion piece must be empty + if (promotion_type(m) - 2 != NO_PIECE_TYPE) + return false; - board[capsq] = EMPTY; - } + // 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; - // Remove captured piece - clear_bit(&(byColorBB[them]), capsq); - clear_bit(&(byTypeBB[capture]), capsq); - clear_bit(&(byTypeBB[0]), capsq); + // The destination square cannot be occupied by a friendly piece + if (pieces(us) & to) + return false; - // Update hash key - key ^= zobrist[them][capture][capsq]; + // Handle the special case of a pawn move + if (type_of(pc) == PAWN) + { + // We have already handled promotion moves, so destination + // cannot be on the 8th/1st rank. + if (rank_of(to) == relative_rank(us, RANK_8)) + return false; - // Update incremental scores - st->value -= pst(them, capture, capsq); + if ( !(attacks_from(from, us) & pieces(~us) & to) // Not a capture - // 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); + && !((from + pawn_push(us) == to) && empty(to)) // Not a single push - // Update material hash key - st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + && !( (from + 2 * pawn_push(us) == to) // Not a double push + && (rank_of(from) == relative_rank(us, RANK_2)) + && empty(to) + && empty(to - pawn_push(us)))) + return false; + } + else if (!(attacks_from(pc, from) & to)) + return false; - // Update piece count - pieceCount[them][capture]--; + // Evasions generator already takes care to avoid some kind of illegal moves + // and legal() relies on this. We therefore have to take care that the same + // kind of moves are filtered out here. + if (checkers()) + { + if (type_of(pc) != KING) + { + // Double check? In this case a king move is required + if (more_than_one(checkers())) + return false; - // Update piece list, move the last piece at index[capsq] position - // - // WARNING: This is a not perfectly revresible operation. When we - // will reinsert the captured piece in undo_move() we will put it - // at the end of the list and not in its original place, it means - // index[] and pieceList[] are not guaranteed to be invariant to a - // do_move() + undo_move() sequence. - Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]]; - index[lastPieceSquare] = index[capsq]; - pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare; - pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; + // 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 as to catch + // invalid moves like b1a1 when opposite queen is on c1. + else if (attackers_to(to, pieces() ^ from) & pieces(~us)) + return false; + } - // Reset rule 50 counter - st->rule50 = 0; + return true; } -/// 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. +/// Position::gives_check() tests whether a pseudo-legal move gives a check -void Position::do_castle_move(Move m) { +bool Position::gives_check(Move m, const CheckInfo& ci) const { - assert(move_is_ok(m)); - assert(move_is_castle(m)); + assert(is_ok(m)); + assert(ci.dcCandidates == discovered_check_candidates()); + assert(color_of(moved_piece(m)) == sideToMove); - Color us = side_to_move(); - Color them = opposite_color(us); + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); - // Reset capture field - st->capture = NO_PIECE_TYPE; - - // 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; + // Is there a direct check? + if (ci.checkSq[pt] & to) + return true; - assert(piece_on(kfrom) == piece_of_color_and_type(us, KING)); - assert(piece_on(rfrom) == piece_of_color_and_type(us, ROOK)); + // Is there a discovered check? + if ( unlikely(ci.dcCandidates) + && (ci.dcCandidates & from) + && !aligned(from, to, ci.ksq)) + return true; - // Find destination squares for king and rook - if (rfrom > kfrom) // O-O + switch (type_of(m)) { - 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); - } - - // Remove pieces from source squares: - clear_bit(&(byColorBB[us]), kfrom); - clear_bit(&(byTypeBB[KING]), kfrom); - clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rfrom); - clear_bit(&(byTypeBB[ROOK]), rfrom); - clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on destination squares: - set_bit(&(byColorBB[us]), kto); - set_bit(&(byTypeBB[KING]), kto); - set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rto); - set_bit(&(byTypeBB[ROOK]), rto); - set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares - - // Update board array - 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->value += pst_delta(king, kfrom, kto); - st->value += pst_delta(rook, rfrom, rto); + case NORMAL: + return false; - // Update hash key - st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; + case PROMOTION: + return attacks_bb(Piece(promotion_type(m)), to, pieces() ^ from) & ci.ksq; - // Clear en passant square - if (st->epSquare != SQ_NONE) + // En passant capture with check? We have already handled the case + // of direct checks and ordinary discovered check, so the only case we + // need to handle is the unusual case of a discovered check through + // the captured pawn. + case ENPASSANT: { - st->key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; - } - - // Update castling rights - st->key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[kfrom]; - st->key ^= zobCastle[st->castleRights]; - - // Reset rule 50 counter - st->rule50 = 0; + Square capsq = make_square(file_of(to), rank_of(from)); + Bitboard b = (pieces() ^ from ^ capsq) | to; - // Update checkers BB - st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); - - // Finish - sideToMove = opposite_color(sideToMove); - st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); + return (attacks_bb< ROOK>(ci.ksq, b) & pieces(sideToMove, QUEEN, ROOK)) + | (attacks_bb(ci.ksq, b) & pieces(sideToMove, QUEEN, BISHOP)); + } + case CASTLING: + { + Square kfrom = from; + Square rfrom = to; // Castling is encoded as 'King captures the rook' + Square kto = relative_square(sideToMove, rfrom > kfrom ? SQ_G1 : SQ_C1); + Square rto = relative_square(sideToMove, rfrom > kfrom ? SQ_F1 : SQ_D1); - assert(is_ok()); + return (PseudoAttacks[ROOK][rto] & ci.ksq) + && (attacks_bb(rto, (pieces() ^ kfrom ^ rfrom) | rto | kto) & ci.ksq); + } + default: + assert(false); + return false; + } } -/// Position::undo_move() unmakes a move. When it returns, the position should -/// be restored to exactly the same state as before the move was made. +/// 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::undo_move(Move m) { +void Position::do_move(Move m, StateInfo& newSt) { - assert(is_ok()); - assert(move_is_ok(m)); + CheckInfo ci(*this); + do_move(m, newSt, ci, gives_check(m, ci)); +} - gamePly--; - sideToMove = opposite_color(sideToMove); +void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) { - if (move_is_castle(m)) - { - undo_castle_move(m); - return; - } + assert(is_ok(m)); + assert(&newSt != st); - 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); + ++nodes; + Key k = st->key; - PieceType pt = type_of_piece_on(to); + // Copy some fields of the old state to our new StateInfo object except the + // ones which are going to be recalculated from scratch anyway and then switch + // our state pointer to point to the new (ready to be updated) state. + std::memcpy(&newSt, st, StateCopySize64 * sizeof(uint64_t)); - 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)); + newSt.previous = st; + st = &newSt; - if (pm) // promotion ? + // Update side to move + k ^= Zobrist::side; + + // Increment ply counters. In particular, rule50 will be reset to zero later on + // in case of a capture or a pawn move. + ++gamePly; + ++st->rule50; + ++st->pliesFromNull; + + Color us = sideToMove; + Color them = ~us; + Square from = from_sq(m); + Square to = to_sq(m); + Piece pc = piece_on(from); + PieceType pt = type_of(pc); + PieceType captured = type_of(m) == ENPASSANT ? PAWN : type_of(piece_on(to)); + + assert(color_of(pc) == us); + assert(piece_on(to) == NO_PIECE || color_of(piece_on(to)) == them || type_of(m) == CASTLING); + assert(captured != KING); + + if (type_of(m) == CASTLING) { - PieceType promotion = move_promotion_piece(m); - pt = PAWN; - - assert(promotion >= KNIGHT && promotion <= QUEEN); - assert(piece_on(to) == piece_of_color_and_type(us, promotion)); + assert(pc == make_piece(us, KING)); - // Replace promoted piece with a pawn - clear_bit(&(byTypeBB[promotion]), to); - set_bit(&(byTypeBB[PAWN]), to); + Square rfrom, rto; + do_castling(from, to, rfrom, rto); - // Update piece counts - pieceCount[us][promotion]--; - pieceCount[us][PAWN]++; - - // Update piece list replacing promotion piece with a pawn - Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]]; - index[lastPromotionSquare] = index[to]; - pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare; - pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; - index[to] = pieceCount[us][PAWN] - 1; - pieceList[us][PAWN][index[to]] = to; + captured = NO_PIECE_TYPE; + st->psq += psq[us][ROOK][rto] - psq[us][ROOK][rfrom]; + k ^= Zobrist::psq[us][ROOK][rfrom] ^ Zobrist::psq[us][ROOK][rto]; } - - // 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; - - // Update piece list - index[from] = index[to]; - pieceList[us][pt][index[from]] = from; - - if (st->capture) + if (captured) { Square capsq = to; - if (ep) - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(st->capture != KING); - assert(!ep || square_is_empty(capsq)); - - // 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); - - // Update piece count - pieceCount[them][st->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; - } + // If the captured piece is a pawn, update pawn hash key, otherwise + // update non-pawn material. + if (captured == PAWN) + { + if (type_of(m) == ENPASSANT) + { + capsq += pawn_push(them); - // Finally point our state pointer back to the previous state - st = st->previous; + 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)); - assert(is_ok()); -} + board[capsq] = NO_PIECE; + } + st->pawnKey ^= Zobrist::psq[them][PAWN][capsq]; + } + else + st->npMaterial[them] -= PieceValue[MG][captured]; -/// 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. + // Update board and piece lists + remove_piece(capsq, them, captured); -void Position::undo_castle_move(Move m) { + // Update material hash key and prefetch access to materialTable + k ^= Zobrist::psq[them][captured][capsq]; + st->materialKey ^= Zobrist::psq[them][captured][pieceCount[them][captured]]; + prefetch((char*)thisThread->materialTable[st->materialKey]); - assert(move_is_ok(m)); - assert(move_is_castle(m)); + // Update incremental scores + st->psq -= psq[them][captured][capsq]; - // 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(); + // Reset rule 50 counter + st->rule50 = 0; + } - // 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; + // Update hash key + k ^= Zobrist::psq[us][pt][from] ^ Zobrist::psq[us][pt][to]; - // Find destination squares for king and rook - if (rfrom > kfrom) // O-O + // Reset en passant square + if (st->epSquare != SQ_NONE) { - 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); + k ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; } - assert(piece_on(kto) == piece_of_color_and_type(us, KING)); - assert(piece_on(rto) == piece_of_color_and_type(us, ROOK)); - - // Remove pieces from destination squares: - clear_bit(&(byColorBB[us]), kto); - clear_bit(&(byTypeBB[KING]), kto); - clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares - clear_bit(&(byColorBB[us]), rto); - clear_bit(&(byTypeBB[ROOK]), rto); - clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares - - // Put pieces on source squares: - set_bit(&(byColorBB[us]), kfrom); - set_bit(&(byTypeBB[KING]), kfrom); - set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), rfrom); - set_bit(&(byTypeBB[ROOK]), rfrom); - set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - - // Update board - board[rto] = board[kto] = EMPTY; - board[rfrom] = piece_of_color_and_type(us, ROOK); - board[kfrom] = piece_of_color_and_type(us, KING); - - // 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; - - // Finally point our state pointer back to the previous state - st = st->previous; - - assert(is_ok()); -} - - -/// Position::do_null_move makes() a "null move": It switches the side to move -/// and updates the hash key without executing any move on the board. - -void Position::do_null_move(StateInfo& backupSt) { - - assert(is_ok()); - assert(!is_check()); - - // Back up the information necessary to undo the null move to the supplied - // StateInfo object. - // Note that differently from normal case here backupSt is actually used as - // a backup storage not as a new state to be used. - backupSt.key = st->key; - backupSt.epSquare = st->epSquare; - backupSt.value = st->value; - backupSt.previous = st->previous; - backupSt.pliesFromNull = st->pliesFromNull; - st->previous = &backupSt; + // Update castling rights if needed + if (st->castlingRights && (castlingRightsMask[from] | castlingRightsMask[to])) + { + int cr = castlingRightsMask[from] | castlingRightsMask[to]; + k ^= Zobrist::castling[st->castlingRights & cr]; + st->castlingRights &= ~cr; + } - // Save the current key to the history[] array, in order to be able to - // detect repetition draws. - history[gamePly] = st->key; + // Move the piece. The tricky Chess960 castling is handled earlier + if (type_of(m) != CASTLING) + move_piece(from, to, us, pt); - // Update the necessary information - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; + // If the moving piece is a pawn do some special extra work + if (pt == PAWN) + { + // Set en-passant square if the 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)]; + } - st->key ^= zobSideToMove; - TT.prefetch(st->key); + else if (type_of(m) == PROMOTION) + { + PieceType promotion = promotion_type(m); - sideToMove = opposite_color(sideToMove); - st->epSquare = SQ_NONE; - st->rule50++; - st->pliesFromNull = 0; - st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue; - gamePly++; -} + assert(relative_rank(us, to) == RANK_8); + assert(promotion >= KNIGHT && promotion <= QUEEN); + remove_piece(to, us, PAWN); + put_piece(to, us, promotion); -/// Position::undo_null_move() unmakes a "null move". + // 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]-1] + ^ Zobrist::psq[us][PAWN][pieceCount[us][PAWN]]; -void Position::undo_null_move() { + // Update incremental score + st->psq += psq[us][promotion][to] - psq[us][PAWN][to]; - assert(is_ok()); - assert(!is_check()); - - // Restore information from the our backup StateInfo object - StateInfo* backupSt = st->previous; - st->key = backupSt->key; - st->epSquare = backupSt->epSquare; - st->value = backupSt->value; - st->previous = backupSt->previous; - st->pliesFromNull = backupSt->pliesFromNull; - - // Update the necessary information - sideToMove = opposite_color(sideToMove); - st->rule50--; - gamePly--; -} + // Update material + st->npMaterial[us] += PieceValue[MG][promotion]; + } + // 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]); -/// Position::see() is a static exchange evaluator: It tries to estimate the -/// material gain or loss resulting from a move. There are three versions of -/// this function: One which takes a destination square as input, one takes a -/// move, and one which takes a 'from' and a 'to' square. The function does -/// not yet understand promotions captures. + // Reset rule 50 draw counter + st->rule50 = 0; + } -int Position::see(Square to) const { + // Update incremental scores + st->psq += psq[us][pt][to] - psq[us][pt][from]; - assert(square_is_ok(to)); - return see(SQ_NONE, to); -} + // Set capture piece + st->capturedType = captured; -int Position::see(Move m) const { + // Update the key with the final value + st->key = k; - assert(move_is_ok(m)); - return see(move_from(m), move_to(m)); -} + // Update checkers bitboard: piece must be already moved due to attacks_from() + st->checkersBB = 0; -int Position::see_sign(Move m) const { + 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; - assert(move_is_ok(m)); + // Discovered checks + if (unlikely(ci.dcCandidates) && (ci.dcCandidates & from)) + { + if (pt != ROOK) + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, ROOK); - Square from = move_from(m); - Square to = move_to(m); + if (pt != BISHOP) + st->checkersBB |= attacks_from(king_square(them)) & pieces(us, QUEEN, BISHOP); + } + } + } - // 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; + sideToMove = ~sideToMove; - return see(from, to); + assert(pos_is_ok()); } -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 - }; +/// Position::undo_move() unmakes a move. When it returns, the position should +/// be restored to exactly the same state as before the move was made. - Bitboard attackers, stmAttackers, b; +void Position::undo_move(Move m) { - assert(square_is_ok(from) || from == SQ_NONE); - assert(square_is_ok(to)); + assert(is_ok(m)); - // Initialize colors - Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to))); - Color them = opposite_color(us); + sideToMove = ~sideToMove; - // Initialize pieces - Piece piece = piece_on(from); - Piece capture = piece_on(to); - Bitboard occ = occupied_squares(); + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(to)); - // King cannot be recaptured - if (type_of_piece(piece) == KING) - return seeValues[capture]; + assert(empty(from) || type_of(m) == CASTLING); + assert(st->capturedType != KING); - // Handle en passant moves - if (st->epSquare == to && type_of_piece_on(from) == PAWN) + if (type_of(m) == PROMOTION) { - assert(capture == EMPTY); + assert(pt == promotion_type(m)); + assert(relative_rank(us, to) == RANK_8); + assert(promotion_type(m) >= KNIGHT && promotion_type(m) <= QUEEN); - Square capQq = (side_to_move() == WHITE)? (to - DELTA_N) : (to - DELTA_S); - capture = piece_on(capQq); - assert(type_of_piece_on(capQq) == PAWN); - - // Remove the captured pawn - clear_bit(&occ, capQq); + remove_piece(to, us, promotion_type(m)); + put_piece(to, us, PAWN); + pt = PAWN; } - while (true) + if (type_of(m) == CASTLING) { - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - 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); + Square rfrom, rto; + do_castling(from, to, rfrom, rto); } + else + { + move_piece(to, from, us, pt); // Put the piece back at the source square - // If the opponent has no attackers we are finished - stmAttackers = attackers & pieces_of_color(them); - if (!stmAttackers) - return seeValues[capture]; - - attackers &= occ; // Remove the moving piece - - // The destination square is defended, which makes things rather more - // difficult to compute. We proceed by building up a "swap list" containing - // the material gain or loss at each stop in a sequence of captures to the - // 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]; - - 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); - - // 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)); - - attackers &= occ; - - // Add the new entry to the swap list - assert(n < 32); - swapList[n] = -swapList[n - 1] + lastCapturingPieceValue; - n++; - - // Remember the value of the capturing piece, and change the side to move - // before beginning the next iteration - lastCapturingPieceValue = seeValues[pt]; - c = opposite_color(c); - stmAttackers = attackers & pieces_of_color(c); - - // Stop after a king capture - if (pt == KING && stmAttackers) + if (st->capturedType) { - assert(n < 32); - swapList[n++] = QueenValueMidgame*10; - break; - } - } while (stmAttackers); - - // Having built the swap list, we negamax through it to find the best - // achievable score from the point of view of the side to move - while (--n) - swapList[n-1] = Min(-swapList[n], swapList[n-1]); + Square capsq = to; - return swapList[0]; -} + if (type_of(m) == ENPASSANT) + { + capsq -= pawn_push(us); + assert(pt == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + } -/// 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. + put_piece(capsq, ~us, st->capturedType); // Restore the captured piece + } + } -void Position::saveState() { + // Finally point our state pointer back to the previous state + st = st->previous; + --gamePly; - startState = *st; - st = &startState; - st->previous = NULL; // as a safe guard + assert(pos_is_ok()); } -/// Position::clear() erases the position object to a pristine state, with an -/// empty board, white to move, and no castling rights. +/// Position::do_castling() is a helper used to do/undo a castling move. This +/// is a bit tricky, especially in Chess960. +template +void Position::do_castling(Square from, Square& to, Square& rfrom, Square& rto) { -void Position::clear() { + bool kingSide = to > from; + rfrom = to; // Castling is encoded as "king captures friendly rook" + rto = relative_square(sideToMove, kingSide ? SQ_F1 : SQ_D1); + to = relative_square(sideToMove, kingSide ? SQ_G1 : SQ_C1); - 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 < 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; + // Remove both pieces first since squares could overlap in Chess960 + remove_piece(Do ? from : to, sideToMove, KING); + remove_piece(Do ? rfrom : rto, sideToMove, ROOK); + board[Do ? from : to] = board[Do ? rfrom : rto] = NO_PIECE; // Since remove_piece doesn't do it for us + put_piece(Do ? to : from, sideToMove, KING); + put_piece(Do ? rto : rfrom, sideToMove, ROOK); } -/// 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. +/// 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::reset_game_ply() { +void Position::do_null_move(StateInfo& newSt) { - gamePly = 0; -} + assert(!checkers()); + std::memcpy(&newSt, st, sizeof(StateInfo)); // Fully copy here -/// Position::put_piece() puts a piece on the given square of the board, -/// updating the board array, bitboards, and piece counts. + newSt.previous = st; + st = &newSt; -void Position::put_piece(Piece p, Square s) { + if (st->epSquare != SQ_NONE) + { + st->key ^= Zobrist::enpassant[file_of(st->epSquare)]; + st->epSquare = SQ_NONE; + } - Color c = color_of_piece(p); - PieceType pt = type_of_piece(p); + st->key ^= Zobrist::side; + prefetch((char*)TT.first_entry(st->key)); - board[s] = p; - index[s] = pieceCount[c][pt]; - pieceList[c][pt][index[s]] = s; + ++st->rule50; + st->pliesFromNull = 0; - set_bit(&(byTypeBB[pt]), s); - set_bit(&(byColorBB[c]), s); - set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares. + sideToMove = ~sideToMove; - pieceCount[c][pt]++; + assert(pos_is_ok()); } +void Position::undo_null_move() { -/// 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) { + assert(!checkers()); - st->castleRights |= (1 + int(c)); + st = st->previous; + sideToMove = ~sideToMove; } -/// Position::allow_ooo() gives the given side the right to castle queenside. -/// Used when setting castling rights during parsing of FEN strings. +/// Position::key_after() computes the new hash key after the given moven. Needed +/// for speculative prefetch. It doesn't recognize special moves like castling, +/// en-passant and promotions. -void Position::allow_ooo(Color c) { +Key Position::key_after(Move m) const { - st->castleRights |= (4 + 4*int(c)); -} + Color us = sideToMove; + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); + PieceType captured = type_of(piece_on(to)); + Key k = st->key ^ Zobrist::side; + if (captured) + k ^= Zobrist::psq[~us][captured][to]; -/// Position::compute_key() computes the hash key of the position. The hash -/// key is usually updated incrementally as moves are made and unmade, the -/// compute_key() function is only used when a new position is set up, and -/// to verify the correctness of the hash key when running in debug mode. + return k ^ Zobrist::psq[us][pt][to] ^ Zobrist::psq[us][pt][from]; +} -Key Position::compute_key() const { - Key result = Key(0ULL); +/// Position::see() is a static exchange evaluator: It tries to estimate the +/// material gain or loss resulting from a move. - 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]; +Value Position::see_sign(Move m) const { - if (ep_square() != SQ_NONE) - result ^= zobEp[ep_square()]; + assert(is_ok(m)); - result ^= zobCastle[st->castleRights]; - if (side_to_move() == BLACK) - result ^= zobSideToMove; + // 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][moved_piece(m)] <= PieceValue[MG][piece_on(to_sq(m))]) + return VALUE_KNOWN_WIN; - return result; + return see(m); } +Value Position::see(Move m) const { -/// Position::compute_pawn_key() computes the hash key of the position. The -/// hash key is usually updated incrementally as moves are made and unmade, -/// the compute_pawn_key() function is only used when a new position is set -/// up, and to verify the correctness of the pawn hash key when running in -/// debug mode. + Square from, to; + Bitboard occupied, attackers, stmAttackers; + Value swapList[32]; + int slIndex = 1; + PieceType captured; + Color stm; -Key Position::compute_pawn_key() const { + assert(is_ok(m)); - Key result = Key(0ULL); - Bitboard b; - Square s; + from = from_sq(m); + to = to_sq(m); + swapList[0] = PieceValue[MG][piece_on(to)]; + stm = color_of(piece_on(from)); + occupied = pieces() ^ from; - for (Color c = WHITE; c <= BLACK; c++) + // Castling moves are implemented as king capturing the rook so cannot be + // handled correctly. Simply return 0 that is always the correct value + // unless in the rare case the rook ends up under attack. + if (type_of(m) == CASTLING) + return VALUE_ZERO; + + if (type_of(m) == ENPASSANT) { - b = pieces(PAWN, c); - while(b) - { - s = pop_1st_bit(&b); - result ^= zobrist[c][PAWN][s]; - } + occupied ^= to - pawn_push(stm); // Remove the captured pawn + swapList[0] = PieceValue[MG][PAWN]; } - return result; -} + // 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) & occupied; -/// Position::compute_material_key() computes the hash key of the position. -/// The hash key is usually updated incrementally as moves are made and unmade, -/// the compute_material_key() function is only used when a new position is set -/// up, and to verify the correctness of the material hash key when running in -/// debug mode. - -Key Position::compute_material_key() const { + // If the opponent has no attackers we are finished + stm = ~stm; + stmAttackers = attackers & pieces(stm); + if (!stmAttackers) + return swapList[0]; - Key result = Key(0ULL); - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= QUEEN; pt++) - { - int count = piece_count(c, pt); - for (int i = 0; i <= count; i++) - result ^= zobMaterial[c][pt][i]; - } - return result; -} + // The destination square is defended, which makes things rather more + // difficult to compute. We proceed by building up a "swap list" containing + // the material gain or loss at each stop in a sequence of captures to the + // 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. + captured = type_of(piece_on(from)); + do { + assert(slIndex < 32); -/// Position::compute_value() compute the incremental scores for the middle -/// game and the endgame. These functions are used to initialize the incremental -/// scores when a new position is set up, and to verify that the scores are correctly -/// updated by do_move and undo_move when the program is running in debug mode. -Score Position::compute_value() const { + // Add the new entry to the swap list + swapList[slIndex] = -swapList[slIndex - 1] + PieceValue[MG][captured]; - Score result = make_score(0, 0); - Bitboard b; - Square s; + // Locate and remove the next least valuable attacker + captured = min_attacker(byTypeBB, to, stmAttackers, occupied, attackers); - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) + // Stop before processing a king capture + if (captured == KING) { - 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); - } - } - - result += (side_to_move() == WHITE ? TempoValue / 2 : -TempoValue / 2); - return result; -} + if (stmAttackers == attackers) + ++slIndex; + break; + } -/// Position::compute_non_pawn_material() computes the total non-pawn middle -/// game material score for the given side. Material scores are updated -/// incrementally during the search, this function is only used while -/// initializing a new Position object. + stm = ~stm; + stmAttackers = attackers & pieces(stm); + ++slIndex; -Value Position::compute_non_pawn_material(Color c) const { + } while (stmAttackers); - Value result = Value(0); + // 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 (--slIndex) + swapList[slIndex - 1] = std::min(-swapList[slIndex], swapList[slIndex - 1]); - 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; + return swapList[0]; } -/// 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. +/// Position::is_draw() tests whether the position is drawn by material, 50 moves +/// rule or repetition. It does not detect stalemates. bool Position::is_draw() const { - // Draw by material? - if ( !pieces(PAWN) - && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame)) + if (st->rule50 > 99 && (!checkers() || MoveList(*this).size())) return true; - // Draw by the 50 moves rule? - if (st->rule50 > 100 || (st->rule50 == 100 && !is_check())) - return true; + StateInfo* stp = st; + for (int i = 2, e = std::min(st->rule50, st->pliesFromNull); i <= e; i += 2) + { + stp = stp->previous->previous; - // Draw by repetition? - for (int i = 2; i < Min(Min(gamePly, st->rule50), st->pliesFromNull); i += 2) - if (history[gamePly - i] == st->key) - return true; + if (stp->key == st->key) + return true; // Draw at first repetition + } return false; } -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. +/// Position::flip() flips position with the white and black sides reversed. This +/// is only useful for debugging e.g. for finding evaluation symmetry bugs. -bool Position::is_mate() const { - - MoveStack moves[256]; - return is_check() && (generate_moves(*this, moves, false) == moves); +static char toggle_case(char c) { + return char(islower(c) ? toupper(c) : tolower(c)); } +void Position::flip() { -/// 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 pinned = pinned_pieces(sideToMove); + string f, token; + std::stringstream ss(fen()); - // Generate pseudo-legal non-capture and capture check moves - MoveStack* last = generate_non_capture_checks(*this, mlist); - last = generate_captures(*this, last); - - // Loop through the moves, and see if one of them is mate - for (MoveStack* cur = mlist; cur != last; cur++) + for (Rank r = RANK_8; r >= RANK_1; --r) // Piece placement { - Move move = cur->move; - if (!pl_move_is_legal(move, pinned)) - continue; - - do_move(move, st2); - if (is_mate()) - result = true; - - undo_move(move); + std::getline(ss, token, r > RANK_1 ? '/' : ' '); + f.insert(0, token + (f.empty() ? " " : "/")); } - // 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. + ss >> token; // Active color + f += (token == "w" ? "B " : "W "); // Will be lowercased later -void Position::init_zobrist() { + ss >> token; // Castling availability + f += token + " "; - 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()); + std::transform(f.begin(), f.end(), f.begin(), toggle_case); - for (int i = 0; i < 64; i++) - zobEp[i] = Key(genrand_int64()); + ss >> token; // En passant square + f += (token == "-" ? token : token.replace(1, 1, token[1] == '3' ? "6" : "3")); - for (int i = 0; i < 16; i++) - zobCastle[i] = genrand_int64(); + std::getline(ss, token); // Half and full moves + f += token; - zobSideToMove = genrand_int64(); + set(f, is_chess960(), this_thread()); - 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); + assert(pos_is_ok()); } -/// Position::init_piece_square_tables() initializes the piece square tables. -/// This is a two-step operation: First, the white halves of the tables are -/// copied from the MgPST[][] and EgPST[][] arrays, with a small random number -/// added to each entry if the "Randomness" UCI parameter is non-zero. -/// Second, the black halves of the tables are initialized by mirroring -/// and changing the sign of the corresponding white scores. - -void Position::init_piece_square_tables() { - - int r = get_option_value_int("Randomness"), i; - for (Square s = SQ_A1; s <= SQ_H8; s++) - for (Piece p = WP; p <= WK; p++) - { - i = (r == 0)? 0 : (genrand_int32() % (r*2) - r); - PieceSquareTable[p][s] = make_score(MgPST[p][s] + i, EgPST[p][s] + i); - } - - for (Square s = SQ_A1; s <= SQ_H8; s++) - for (Piece p = BP; p <= BK; p++) - PieceSquareTable[p][s] = -PieceSquareTable[p-8][flip_square(s)]; -} - - -/// 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)); - - // Side to move - sideToMove = opposite_color(pos.side_to_move()); - - // Castling rights - if (pos.can_castle_kingside(WHITE)) allow_oo(BLACK); - if (pos.can_castle_queenside(WHITE)) allow_ooo(BLACK); - if (pos.can_castle_kingside(BLACK)) allow_oo(WHITE); - if (pos.can_castle_queenside(BLACK)) allow_ooo(WHITE); - - initialKFile = pos.initialKFile; - initialKRFile = pos.initialKRFile; - initialQRFile = pos.initialQRFile; - - for (Square sq = SQ_A1; sq <= SQ_H8; sq++) - castleRightsMask[sq] = ALL_CASTLES; - - castleRightsMask[make_square(initialKFile, RANK_1)] ^= (WHITE_OO | WHITE_OOO); - castleRightsMask[make_square(initialKFile, RANK_8)] ^= (BLACK_OO | BLACK_OOO); - castleRightsMask[make_square(initialKRFile, RANK_1)] ^= WHITE_OO; - castleRightsMask[make_square(initialKRFile, RANK_8)] ^= BLACK_OO; - castleRightsMask[make_square(initialQRFile, RANK_1)] ^= WHITE_OOO; - castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; - - // En passant square - if (pos.st->epSquare != SQ_NONE) - st->epSquare = flip_square(pos.st->epSquare); - - // Checkers - find_checkers(); - - // Hash keys - st->key = compute_key(); - st->pawnKey = compute_pawn_key(); - st->materialKey = compute_material_key(); - - // Incremental scores - st->value = compute_value(); - - // Material - st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); - st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); - - assert(is_ok()); -} - - -/// Position::is_ok() performs some consitency checks for the position object. +/// Position::pos_is_ok() performs some consistency 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* step) const { - // Are the king squares in the position correct? - if (failedStep) (*failedStep)++; - if (piece_on(king_square(WHITE)) != WK) - return false; + // Which parts of the position should be verified? + const bool all = false; - if (failedStep) (*failedStep)++; - if (piece_on(king_square(BLACK)) != BK) - return false; + const bool testBitboards = all || false; + const bool testState = all || false; + const bool testKingCount = all || false; + const bool testKingCapture = all || false; + const bool testPieceCounts = all || false; + const bool testPieceList = all || false; + const bool testCastlingSquares = all || false; - // Castle files OK? - if (failedStep) (*failedStep)++; - if (!file_is_ok(initialKRFile)) - return false; + if (step) + *step = 1; - if (!file_is_ok(initialQRFile)) + if ( (sideToMove != WHITE && sideToMove != BLACK) + || piece_on(king_square(WHITE)) != W_KING + || piece_on(king_square(BLACK)) != B_KING + || ( ep_square() != SQ_NONE + && relative_rank(sideToMove, ep_square()) != RANK_6)) return false; - // Do both sides have exactly one king? - if (failedStep) (*failedStep)++; - if (debugKingCount) - { - int kingCount[2] = {0, 0}; - for (Square s = SQ_A1; s <= SQ_H8; s++) - if (type_of_piece_on(s) == KING) - kingCount[color_of_piece_on(s)]++; - - if (kingCount[0] != 1 || kingCount[1] != 1) - return false; - } - - // 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)) - return false; - } - - // Is there more than 2 checkers? - if (failedStep) (*failedStep)++; - if (debugCheckerCount && count_1s(st->checkersBB) > 2) - return false; - - // Bitboards OK? - if (failedStep) (*failedStep)++; - if (debugBitboards) + if (step && ++*step, testBitboards) { // 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 - for (PieceType p1 = PAWN; p1 <= KING; p1++) - for (PieceType p2 = PAWN; p2 <= KING; p2++) + for (PieceType p1 = PAWN; p1 <= KING; ++p1) + for (PieceType p2 = PAWN; p2 <= KING; ++p2) if (p1 != p2 && (pieces(p1) & pieces(p2))) return false; } - // En passant square OK? - if (failedStep) (*failedStep)++; - if (ep_square() != SQ_NONE) + if (step && ++*step, testState) { - // 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) + StateInfo si; + set_state(&si); + if ( st->key != si.key + || st->pawnKey != si.pawnKey + || st->materialKey != si.materialKey + || st->npMaterial[WHITE] != si.npMaterial[WHITE] + || st->npMaterial[BLACK] != si.npMaterial[BLACK] + || st->psq != si.psq + || st->checkersBB != si.checkersBB) return false; } - // Hash key OK? - if (failedStep) (*failedStep)++; - if (debugKey && st->key != compute_key()) - return false; - - // Pawn hash key OK? - if (failedStep) (*failedStep)++; - if (debugPawnKey && st->pawnKey != compute_pawn_key()) - return false; - - // Material hash key OK? - if (failedStep) (*failedStep)++; - if (debugMaterialKey && st->materialKey != compute_material_key()) - return false; - - // Incremental eval OK? - if (failedStep) (*failedStep)++; - if (debugIncrementalEval && st->value != compute_value()) - return false; - - // Non-pawn material OK? - if (failedStep) (*failedStep)++; - if (debugNonPawnMaterial) - { - if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + if (step && ++*step, testKingCount) + if ( std::count(board, board + SQUARE_NB, W_KING) != 1 + || std::count(board, board + SQUARE_NB, B_KING) != 1) return false; - if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (step && ++*step, testKingCapture) + if (attackers_to(king_square(~sideToMove)) & pieces(sideToMove)) return false; - } - // Piece counts OK? - if (failedStep) (*failedStep)++; - if (debugPieceCounts) - for (Color c = WHITE; c <= BLACK; c++) - for (PieceType pt = PAWN; pt <= KING; pt++) - if (pieceCount[c][pt] != count_1s(pieces(pt, c))) + if (step && ++*step, testPieceCounts) + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + 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 (piece_on(piece_list(c, pt, i)) != piece_of_color_and_type(c, pt)) + if (step && ++*step, testPieceList) + for (Color c = WHITE; c <= BLACK; ++c) + for (PieceType pt = PAWN; pt <= KING; ++pt) + for (int i = 0; i < pieceCount[c][pt]; ++i) + if ( board[pieceList[c][pt][i]] != make_piece(c, pt) + || index[pieceList[c][pt][i]] != i) return false; - if (index[piece_list(c, pt, i)] != i) - return false; - } - } - if (failedStep) *failedStep = 0; + if (step && ++*step, testCastlingSquares) + for (Color c = WHITE; c <= BLACK; ++c) + for (CastlingSide s = KING_SIDE; s <= QUEEN_SIDE; s = CastlingSide(s + 1)) + { + if (!can_castle(c | s)) + continue; + + if ( (castlingRightsMask[king_square(c)] & (c | s)) != (c | s) + || piece_on(castlingRookSquare[c | s]) != make_piece(c, ROOK) + || castlingRightsMask[castlingRookSquare[c | s]] != (c | s)) + return false; + } + return true; }