X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=907357bd1f90ba09f6197f15763248970997965b;hp=bc9b5e0e2f6c1905d4739b2741b220aec1255d5f;hb=c549f71f64a29fd06f8537de697bc67fdc642753;hpb=3185c36a6554390d9061f1d74eb16a6c39caefb4 diff --git a/src/position.cpp b/src/position.cpp index bc9b5e0e..907357bd 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) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2012 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 @@ -22,6 +22,7 @@ #include #include #include +#include #include "bitcount.h" #include "movegen.h" @@ -69,7 +70,7 @@ namespace { const Score TempoValue = make_score(48, 22); // To convert a Piece to and from a FEN char - const string PieceToChar(".PNBRQK pnbrqk "); + const string PieceToChar(" PNBRQK pnbrqk ."); } @@ -77,8 +78,8 @@ namespace { CheckInfo::CheckInfo(const Position& pos) { - Color them = opposite_color(pos.side_to_move()); - Square ksq = pos.king_square(them); + Color them = flip(pos.side_to_move()); + ksq = pos.king_square(them); pinned = pos.pinned_pieces(); dcCandidates = pos.discovered_check_candidates(); @@ -88,7 +89,7 @@ CheckInfo::CheckInfo(const Position& pos) { checkSq[BISHOP] = pos.attacks_from(ksq); checkSq[ROOK] = pos.attacks_from(ksq); checkSq[QUEEN] = checkSq[BISHOP] | checkSq[ROOK]; - checkSq[KING] = EmptyBoardBB; + checkSq[KING] = 0; } @@ -96,13 +97,15 @@ CheckInfo::CheckInfo(const Position& pos) { /// or the FEN string, we want the new born Position object do not depend /// on any external data so we detach state pointer from the source one. -Position::Position(const Position& pos, int th) { +void Position::copy(const Position& pos, int th) { memcpy(this, &pos, sizeof(Position)); + startState = *st; + st = &startState; threadID = th; nodes = 0; - assert(is_ok()); + assert(pos_is_ok()); } Position::Position(const string& fen, bool isChess960, int th) { @@ -120,29 +123,35 @@ void Position::from_fen(const string& fenStr, bool isChess960) { /* A FEN string defines a particular position using only the ASCII character set. - A FEN string contains six fields. The separator between fields is a space. The fields are: + A FEN string contains six fields separated by a space. The fields are: - 1) Piece placement (from white's perspective). Each rank is described, starting with rank 8 and ending - with rank 1; within each rank, the contents of each square are described from file A through file H. - Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken - from the standard English names. White pieces are designated using upper-case letters ("PNBRQK") - while Black take lowercase ("pnbrqk"). Blank squares are noted using digits 1 through 8 (the number - of blank squares), and "/" separate ranks. + 1) Piece placement (from white's perspective). Each rank is described, starting + with rank 8 and ending with rank 1; within each rank, the contents of each + square are described from file A through file H. Following the Standard + Algebraic Notation (SAN), each piece is identified by a single letter taken + from the standard English names. White pieces are designated using upper-case + letters ("PNBRQK") while Black take lowercase ("pnbrqk"). Blank squares are + noted using digits 1 through 8 (the number of blank squares), and "/" + separates ranks. 2) Active color. "w" means white moves next, "b" means black. - 3) Castling availability. If neither side can castle, this is "-". Otherwise, this has one or more - letters: "K" (White can castle kingside), "Q" (White can castle queenside), "k" (Black can castle - kingside), and/or "q" (Black can castle queenside). + 3) Castling availability. If neither side can castle, this is "-". Otherwise, + this has one or more letters: "K" (White can castle kingside), "Q" (White + can castle queenside), "k" (Black can castle kingside), and/or "q" (Black + can castle queenside). - 4) En passant target square in algebraic notation. If there's no en passant target square, this is "-". - If a pawn has just made a 2-square move, this is the position "behind" the pawn. This is recorded - regardless of whether there is a pawn in position to make an en passant capture. + 4) En passant target square (in algebraic notation). If there's no en passant + target square, this is "-". If a pawn has just made a 2-square move, this + is the position "behind" the pawn. This is recorded regardless of whether + there is a pawn in position to make an en passant capture. - 5) Halfmove clock: This is the number of halfmoves since the last pawn advance or capture. This is used - to determine if a draw can be claimed under the fifty-move rule. + 5) Halfmove clock. This is the number of halfmoves since the last pawn advance + or capture. This is used to determine if a draw can be claimed under the + fifty-move rule. - 6) Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move. + 6) Fullmove number. The number of the full move. It starts at 1, and is + incremented after Black's move. */ char col, row, token; @@ -156,11 +165,11 @@ void Position::from_fen(const string& fenStr, bool isChess960) { // 1. Piece placement while ((fen >> token) && !isspace(token)) { - if (token == '/') - sq -= Square(16); // Jump back of 2 rows + if (isdigit(token)) + sq += Square(token - '0'); // Advance the given number of files - else if (isdigit(token)) - sq += Square(token - '0'); // Skip the given number of files + else if (token == '/') + sq = make_square(FILE_A, rank_of(sq) - Rank(2)); else if ((p = PieceToChar.find(token)) != string::npos) { @@ -174,31 +183,49 @@ void Position::from_fen(const string& fenStr, bool isChess960) { sideToMove = (token == 'w' ? WHITE : BLACK); fen >> token; - // 3. Castling availability + // 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 ((fen >> token) && !isspace(token)) - set_castling_rights(token); + { + Square rsq; + Color c = islower(token) ? BLACK : WHITE; + + token = char(toupper(token)); + + if (token == 'K') + for (rsq = relative_square(c, SQ_H1); type_of(piece_on(rsq)) != ROOK; rsq--) {} + + else if (token == 'Q') + for (rsq = relative_square(c, SQ_A1); type_of(piece_on(rsq)) != ROOK; rsq++) {} + + else if (token >= 'A' && token <= 'H') + rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); + + else + continue; + + set_castle_right(c, rsq); + } // 4. En passant square. Ignore if no pawn capture is possible if ( ((fen >> col) && (col >= 'a' && col <= 'h')) && ((fen >> row) && (row == '3' || row == '6'))) { st->epSquare = make_square(File(col - 'a'), Rank(row - '1')); - Color them = opposite_color(sideToMove); - if (!(attacks_from(st->epSquare, them) & pieces(PAWN, sideToMove))) + if (!(attackers_to(st->epSquare) & pieces(PAWN, sideToMove))) st->epSquare = SQ_NONE; } // 5-6. Halfmove clock and fullmove number - fen >> std::skipws >> st->rule50 >> st->gamePly; + fen >> std::skipws >> st->rule50 >> startPosPly; // Convert from fullmove starting from 1 to ply starting from 0, // handle also common incorrect FEN with fullmove = 0. - st->gamePly = Max(2 * (st->gamePly - 1), 0) + int(sideToMove == BLACK); - - // Various initialisations - chess960 = isChess960; - st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(opposite_color(sideToMove)); + startPosPly = std::max(2 * (startPosPly - 1), 0) + int(sideToMove == BLACK); st->key = compute_key(); st->pawnKey = compute_pawn_key(); @@ -206,58 +233,27 @@ void Position::from_fen(const string& fenStr, bool isChess960) { st->value = compute_value(); st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove)); + chess960 = isChess960; - assert(is_ok()); + assert(pos_is_ok()); } -/// Position::set_castle() is an helper function used to set -/// correct castling related flags. +/// Position::set_castle_right() is an helper function used to set castling +/// rights given the corresponding color and the rook starting square. + +void Position::set_castle_right(Color c, Square rsq) { -void Position::set_castle(int f, Square ksq, Square rsq) { + int f = (rsq < king_square(c) ? WHITE_OOO : WHITE_OO) << c; st->castleRights |= f; - castleRightsMask[ksq] ^= f; + castleRightsMask[king_square(c)] ^= f; castleRightsMask[rsq] ^= f; castleRookSquare[f] = rsq; } -/// Position::set_castling_rights() sets castling parameters castling avaiability. -/// This function is compatible with 3 standards: Normal FEN standard, Shredder-FEN -/// that uses the letters of the columns on which the rooks began the game instead -/// of KQkq and also X-FEN standard that, in case of Chess960, if an inner Rook is -/// associated with the castling right, the traditional castling tag will be replaced -/// by the file letter of the involved rook as for the Shredder-FEN. - -void Position::set_castling_rights(char token) { - - Color c = islower(token) ? BLACK : WHITE; - - Square sqA = relative_square(c, SQ_A1); - Square sqH = relative_square(c, SQ_H1); - Square rsq, ksq = king_square(c); - - token = char(toupper(token)); - - if (token == 'K') - for (rsq = sqH; piece_on(rsq) != make_piece(c, ROOK); rsq--) {} - - else if (token == 'Q') - for (rsq = sqA; piece_on(rsq) != make_piece(c, ROOK); rsq++) {} - - else if (token >= 'A' && token <= 'H') - rsq = make_square(File(token - 'A'), relative_rank(c, RANK_1)); - - else return; - - if (square_file(rsq) < square_file(ksq)) - set_castle(WHITE_OOO << c, ksq, rsq); - else - set_castle(WHITE_OO << c, ksq, rsq); -} - - /// Position::to_fen() returns a FEN representation of the position. In case /// of Chess960 the Shredder-FEN notation is used. Mainly a debugging function. @@ -275,20 +271,20 @@ const string Position::to_fen() const { { sq = make_square(file, rank); - if (!square_is_empty(sq)) + if (square_is_empty(sq)) + emptyCnt++; + else { - if (emptyCnt) + if (emptyCnt > 0) { fen << emptyCnt; emptyCnt = 0; } fen << PieceToChar[piece_on(sq)]; } - else - emptyCnt++; } - if (emptyCnt) + if (emptyCnt > 0) fen << emptyCnt; if (rank > RANK_1) @@ -297,24 +293,23 @@ const string Position::to_fen() const { fen << (sideToMove == WHITE ? " w " : " b "); - if (st->castleRights != CASTLES_NONE) - { - if (can_castle(WHITE_OO)) - fen << (chess960 ? char(toupper(file_to_char(square_file(castle_rook_square(WHITE_OO))))) : 'K'); + if (can_castle(WHITE_OO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OO))))) : 'K'); - if (can_castle(WHITE_OOO)) - fen << (chess960 ? char(toupper(file_to_char(square_file(castle_rook_square(WHITE_OOO))))) : 'Q'); + if (can_castle(WHITE_OOO)) + fen << (chess960 ? char(toupper(file_to_char(file_of(castle_rook_square(WHITE_OOO))))) : 'Q'); - if (can_castle(BLACK_OO)) - fen << (chess960 ? file_to_char(square_file(castle_rook_square(BLACK_OO))) : 'k'); + if (can_castle(BLACK_OO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OO))) : 'k'); - if (can_castle(BLACK_OOO)) - fen << (chess960 ? file_to_char(square_file(castle_rook_square(BLACK_OOO))) : 'q'); - } else + if (can_castle(BLACK_OOO)) + fen << (chess960 ? file_to_char(file_of(castle_rook_square(BLACK_OOO))) : 'q'); + + if (st->castleRights == CASTLES_NONE) fen << '-'; - fen << (ep_square() == SQ_NONE ? " -" : " " + square_to_string(ep_square())) - << " " << st->rule50 << " " << 1 + (st->gamePly - int(sideToMove == BLACK)) / 2; + fen << (ep_square() == SQ_NONE ? " - " : " " + square_to_string(ep_square()) + " ") + << st->rule50 << " " << 1 + (startPosPly - int(sideToMove == BLACK)) / 2; return fen.str(); } @@ -330,8 +325,7 @@ void Position::print(Move move) const { if (move) { Position p(*this, thread()); - string dd = (sideToMove == BLACK ? ".." : ""); - cout << "\nMove is: " << dd << move_to_san(p, move); + cout << "\nMove is: " << (sideToMove == BLACK ? ".." : "") << move_to_san(p, move); } for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -341,11 +335,11 @@ void Position::print(Move move) const { { Square sq = make_square(file, rank); Piece piece = piece_on(sq); + char c = (color_of(piece) == BLACK ? '=' : ' '); - if (piece == PIECE_NONE && square_color(sq) == DARK) - piece = PIECE_NONE_DARK_SQ; + if (piece == NO_PIECE && !opposite_colors(sq, SQ_A1)) + piece++; // Index the dot - char c = (piece_color(piece_on(sq)) == BLACK ? '=' : ' '); cout << c << PieceToChar[piece] << c << '|'; } } @@ -357,18 +351,17 @@ void Position::print(Move move) const { /// king) pieces for the given color. Or, when template parameter FindPinned is /// false, the function return the pieces of the given color candidate for a /// discovery check against the enemy king. - template Bitboard Position::hidden_checkers() const { // Pinned pieces protect our king, dicovery checks attack the enemy king - Bitboard b, result = EmptyBoardBB; - Bitboard pinners = pieces(FindPinned ? opposite_color(sideToMove) : sideToMove); - Square ksq = king_square(FindPinned ? sideToMove : opposite_color(sideToMove)); + Bitboard b, result = 0; + Bitboard pinners = pieces(FindPinned ? flip(sideToMove) : sideToMove); + Square ksq = king_square(FindPinned ? sideToMove : flip(sideToMove)); // Pinners are sliders, that give check when candidate pinned is removed - pinners &= (pieces(ROOK, QUEEN) & RookPseudoAttacks[ksq]) - | (pieces(BISHOP, QUEEN) & BishopPseudoAttacks[ksq]); + pinners &= (pieces(ROOK, QUEEN) & PseudoAttacks[ROOK][ksq]) + | (pieces(BISHOP, QUEEN) & PseudoAttacks[BISHOP][ksq]); while (pinners) { @@ -381,37 +374,13 @@ Bitboard Position::hidden_checkers() const { return result; } +// Explicit template instantiations +template Bitboard Position::hidden_checkers() const; +template Bitboard Position::hidden_checkers() const; -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the side to move. - -Bitboard Position::pinned_pieces() const { - - return hidden_checkers(); -} - - -/// Position:discovered_check_candidates() returns a bitboard containing all -/// pieces for the side to move which are candidates for giving a discovered -/// check. - -Bitboard Position::discovered_check_candidates() const { - - return hidden_checkers(); -} - -/// Position::attackers_to() computes a bitboard containing all pieces which -/// attacks a given square. -Bitboard Position::attackers_to(Square s) const { - - 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)); -} +/// Position::attackers_to() computes a bitboard of all pieces which attack a +/// given square. Slider attacks use occ bitboard as occupancy. Bitboard Position::attackers_to(Square s, Bitboard occ) const { @@ -423,32 +392,20 @@ Bitboard Position::attackers_to(Square s, Bitboard occ) const { | (attacks_from(s) & pieces(KING)); } -/// Position::attacks_from() computes a bitboard of all attacks -/// of a given piece put in a given square. - -Bitboard Position::attacks_from(Piece p, Square s) const { - - assert(square_is_ok(s)); - switch (p) - { - case WB: case BB: return attacks_from(s); - case WR: case BR: return attacks_from(s); - case WQ: case BQ: return attacks_from(s); - default: return StepAttacksBB[p][s]; - } -} +/// Position::attacks_from() computes a bitboard of all attacks of a given piece +/// put in a given square. Slider attacks use occ bitboard as occupancy. Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { assert(square_is_ok(s)); - switch (p) + switch (type_of(p)) { - case WB: case BB: return bishop_attacks_bb(s, occ); - case WR: case BR: return rook_attacks_bb(s, occ); - case WQ: case BQ: return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ); - default: return StepAttacksBB[p][s]; + case BISHOP: return bishop_attacks_bb(s, occ); + case ROOK : return rook_attacks_bb(s, occ); + case QUEEN : return bishop_attacks_bb(s, occ) | rook_attacks_bb(s, occ); + default : return StepAttacksBB[p][s]; } } @@ -458,26 +415,29 @@ Bitboard Position::attacks_from(Piece p, Square s, Bitboard occ) { bool Position::move_attacks_square(Move m, Square s) const { - assert(move_is_ok(m)); + assert(is_ok(m)); assert(square_is_ok(s)); Bitboard occ, xray; - Square f = move_from(m), t = move_to(m); + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_on(from); + + assert(!square_is_empty(from)); - assert(!square_is_empty(f)); + // Update occupancy as if the piece is moving + occ = occupied_squares(); + do_move_bb(&occ, make_move_bb(from, to)); - if (bit_is_set(attacks_from(piece_on(f), t), s)) + // The piece moved in 'to' attacks the square 's' ? + if (bit_is_set(attacks_from(piece, to, occ), s)) return true; - // Move the piece and scan for X-ray attacks behind it - occ = occupied_squares(); - do_move_bb(&occ, make_move_bb(f, t)); - xray = ( (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN)) - |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN))) - & pieces(piece_color(piece_on(f))); + // Scan for possible X-ray attackers behind the moved piece + xray = (rook_attacks_bb(s, occ) & pieces(ROOK, QUEEN, color_of(piece))) + |(bishop_attacks_bb(s, occ) & pieces(BISHOP, QUEEN, color_of(piece))); - // If we have attacks we need to verify that are caused by our move - // and are not already existent ones. + // Verify attackers are triggered by our move and not already existing return xray && (xray ^ (xray & attacks_from(s))); } @@ -486,22 +446,22 @@ bool Position::move_attacks_square(Move m, Square s) const { bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { - assert(move_is_ok(m)); + assert(is_ok(m)); assert(pinned == pinned_pieces()); Color us = side_to_move(); - Square from = move_from(m); + Square from = from_sq(m); - assert(piece_color(piece_on(from)) == us); + assert(color_of(piece_on(from)) == us); assert(piece_on(king_square(us)) == make_piece(us, KING)); // En passant captures are a tricky special case. Because they are rather // uncommon, we do it simply by testing whether the king is attacked after // the move is made. - if (move_is_ep(m)) + if (is_enpassant(m)) { - Color them = opposite_color(us); - Square to = move_to(m); + Color them = flip(us); + Square to = to_sq(m); Square capsq = to + pawn_push(them); Square ksq = king_square(us); Bitboard b = occupied_squares(); @@ -509,7 +469,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { assert(to == ep_square()); assert(piece_on(from) == make_piece(us, PAWN)); assert(piece_on(capsq) == make_piece(them, PAWN)); - assert(piece_on(to) == PIECE_NONE); + assert(piece_on(to) == NO_PIECE); clear_bit(&b, from); clear_bit(&b, capsq); @@ -522,20 +482,20 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { // 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 (piece_type(piece_on(from)) == KING) - return move_is_castle(m) || !(attackers_to(move_to(m)) & pieces(opposite_color(us))); + if (type_of(piece_on(from)) == KING) + return is_castle(m) || !(attackers_to(to_sq(m)) & pieces(flip(us))); // A non-king move is legal if and only if it is not pinned or it // is moving along the ray towards or away from the king. return !pinned || !bit_is_set(pinned, from) - || squares_aligned(from, move_to(m), king_square(us)); + || squares_aligned(from, to_sq(m), king_square(us)); } -/// Position::move_is_legal() takes a move and tests whether the move -/// is legal. This version is not very fast and should be used only -/// in non time-critical paths. +/// Position::move_is_legal() takes a random move and tests whether the move +/// is legal. This version is not very fast and should be used only in non +/// time-critical paths. bool Position::move_is_legal(const Move m) const { @@ -547,36 +507,37 @@ bool Position::move_is_legal(const Move m) const { } -/// Fast version of Position::move_is_pl() that takes a move and a bitboard -/// of pinned pieces as input, and tests whether the move is pseudo legal. +/// Position::is_pseudo_legal() takes a random move and tests whether the move +/// is pseudo legal. It is used to validate moves from TT that can be corrupted +/// due to SMP concurrent access or hash position key aliasing. -bool Position::move_is_pl(const Move m) const { +bool Position::is_pseudo_legal(const Move m) const { Color us = sideToMove; - Color them = opposite_color(sideToMove); - Square from = move_from(m); - Square to = move_to(m); + Color them = flip(sideToMove); + Square from = from_sq(m); + Square to = to_sq(m); Piece pc = piece_on(from); // Use a slower but simpler function for uncommon cases - if (move_is_special(m)) + if (is_special(m)) return move_is_legal(m); // Is not a promotion, so promotion piece must be empty - if (promotion_piece_type(m) - 2 != PIECE_TYPE_NONE) + if (promotion_piece_type(m) - 2 != NO_PIECE_TYPE) return false; // If the from square is not occupied by a piece belonging to the side to // move, the move is obviously not legal. - if (pc == PIECE_NONE || piece_color(pc) != us) + if (pc == NO_PIECE || color_of(pc) != us) return false; // The destination square cannot be occupied by a friendly piece - if (piece_color(piece_on(to)) == us) + if (color_of(piece_on(to)) == us) return false; // Handle the special case of a pawn move - if (piece_type(pc) == PAWN) + if (type_of(pc) == PAWN) { // Move direction must be compatible with pawn color int direction = to - from; @@ -585,7 +546,7 @@ bool Position::move_is_pl(const Move m) const { // We have already handled promotion moves, so destination // cannot be on the 8/1th rank. - if (square_rank(to) == RANK_8 || square_rank(to) == RANK_1) + if (rank_of(to) == RANK_8 || rank_of(to) == RANK_1) return false; // Proceed according to the square delta between the origin and @@ -598,11 +559,11 @@ bool Position::move_is_pl(const Move m) const { case DELTA_SE: // Capture. The destination square must be occupied by an enemy // piece (en passant captures was handled earlier). - if (piece_color(piece_on(to)) != them) + if (color_of(piece_on(to)) != them) return false; // From and to files must be one file apart, avoids a7h5 - if (abs(square_file(from) - square_file(to)) != 1) + if (abs(file_of(from) - file_of(to)) != 1) return false; break; @@ -617,7 +578,7 @@ bool Position::move_is_pl(const Move m) const { // Double white pawn push. The destination square must be on the fourth // rank, and both the destination square and the square between the // source and destination squares must be empty. - if ( square_rank(to) != RANK_4 + if ( rank_of(to) != RANK_4 || !square_is_empty(to) || !square_is_empty(from + DELTA_N)) return false; @@ -627,7 +588,7 @@ bool Position::move_is_pl(const Move m) const { // Double black pawn push. The destination square must be on the fifth // rank, and both the destination square and the square between the // source and destination squares must be empty. - if ( square_rank(to) != RANK_5 + if ( rank_of(to) != RANK_5 || !square_is_empty(to) || !square_is_empty(from + DELTA_S)) return false; @@ -640,15 +601,18 @@ bool Position::move_is_pl(const Move m) const { else if (!bit_is_set(attacks_from(pc, from), to)) return false; + // Evasions generator already takes care to avoid some kind of illegal moves + // and pl_move_is_legal() relies on this. So we have to take care that the + // same kind of moves are filtered out here. if (in_check()) { // In case of king moves under check we have to remove king so to catch // as invalid moves like b1a1 when opposite queen is on c1. - if (piece_type(piece_on(from)) == KING) + if (type_of(piece_on(from)) == KING) { Bitboard b = occupied_squares(); clear_bit(&b, from); - if (attackers_to(move_to(m), b) & pieces(opposite_color(us))) + if (attackers_to(to_sq(m), b) & pieces(flip(us))) return false; } else @@ -661,7 +625,7 @@ bool Position::move_is_pl(const Move m) const { // Our move must be a blocking evasion or a capture of the checking piece target = squares_between(checksq, king_square(us)) | checkers(); - if (!bit_is_set(target, move_to(m))) + if (!bit_is_set(target, to_sq(m))) return false; } } @@ -670,17 +634,17 @@ bool Position::move_is_pl(const Move m) const { } -/// Position::move_gives_check() tests whether a pseudo-legal move is a check +/// Position::move_gives_check() tests whether a pseudo-legal move gives a check bool Position::move_gives_check(Move m, const CheckInfo& ci) const { - assert(move_is_ok(m)); + assert(is_ok(m)); assert(ci.dcCandidates == discovered_check_candidates()); - assert(piece_color(piece_on(move_from(m))) == side_to_move()); + assert(color_of(piece_moved(m)) == side_to_move()); - Square from = move_from(m); - Square to = move_to(m); - PieceType pt = piece_type(piece_on(from)); + Square from = from_sq(m); + Square to = to_sq(m); + PieceType pt = type_of(piece_on(from)); // Direct check ? if (bit_is_set(ci.checkSq[pt], to)) @@ -691,45 +655,32 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { { // For pawn and king moves we need to verify also direction if ( (pt != PAWN && pt != KING) - || !squares_aligned(from, to, king_square(opposite_color(side_to_move())))) + || !squares_aligned(from, to, king_square(flip(side_to_move())))) return true; } // Can we skip the ugly special cases ? - if (!move_is_special(m)) + if (!is_special(m)) return false; Color us = side_to_move(); Bitboard b = occupied_squares(); - Square ksq = king_square(opposite_color(us)); + Square ksq = king_square(flip(us)); // Promotion with check ? - if (move_is_promotion(m)) + if (is_promotion(m)) { clear_bit(&b, from); - - switch (promotion_piece_type(m)) - { - case KNIGHT: - return bit_is_set(attacks_from(to), ksq); - case BISHOP: - return bit_is_set(bishop_attacks_bb(to, b), ksq); - case ROOK: - return bit_is_set(rook_attacks_bb(to, b), ksq); - case QUEEN: - return bit_is_set(queen_attacks_bb(to, b), ksq); - default: - assert(false); - } + return bit_is_set(attacks_from(Piece(promotion_piece_type(m)), to, b), ksq); } // En passant capture with check ? We have already handled the case // of direct checks and ordinary discovered check, the only case we // need to handle is the unusual case of a discovered check through // the captured pawn. - if (move_is_ep(m)) + if (is_enpassant(m)) { - Square capsq = make_square(square_file(to), square_rank(from)); + Square capsq = make_square(file_of(to), rank_of(from)); clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to); @@ -738,7 +689,7 @@ bool Position::move_gives_check(Move m, const CheckInfo& ci) const { } // Castling with check ? - if (move_is_castle(m)) + if (is_castle(m)) { Square kfrom, kto, rfrom, rto; kfrom = from; @@ -775,21 +726,21 @@ void Position::do_move(Move m, StateInfo& newSt) { void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveIsCheck) { - assert(move_is_ok(m)); + assert(is_ok(m)); assert(&newSt != st); nodes++; - Key key = st->key; + Key k = st->key; - // 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. + // 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, gamePly, pliesFromNull; - Square epSquare; - Score value; Value npMaterial[2]; + int castleRights, rule50, pliesFromNull; + Score value; + Square epSquare; }; memcpy(&newSt, st, sizeof(ReducedStateInfo)); @@ -798,47 +749,93 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st = &newSt; // Update side to move - key ^= zobSideToMove; + k ^= 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->gamePly++; st->pliesFromNull++; - if (move_is_castle(m)) + if (is_castle(m)) { - st->key = key; - do_castle_move(m); + st->key = k; + do_castle_move(m); return; } 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); - + Color them = flip(us); + Square from = from_sq(m); + Square to = to_sq(m); Piece piece = piece_on(from); - PieceType pt = piece_type(piece); - PieceType capture = ep ? PAWN : piece_type(piece_on(to)); + PieceType pt = type_of(piece); + PieceType capture = is_enpassant(m) ? PAWN : type_of(piece_on(to)); - assert(piece_color(piece_on(from)) == us); - assert(piece_color(piece_on(to)) == them || square_is_empty(to)); - assert(!(ep || pm) || piece == make_piece(us, PAWN)); - assert(!pm || relative_rank(us, to) == RANK_8); + assert(color_of(piece) == us); + assert(color_of(piece_on(to)) != us); + assert(capture != KING); if (capture) - do_capture_move(key, capture, them, to, ep); + { + Square capsq = to; + + // If the captured piece is a pawn, update pawn hash key, otherwise + // update non-pawn material. + if (capture == PAWN) + { + if (is_enpassant(m)) + { + capsq += pawn_push(them); + + 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)); + + board[capsq] = NO_PIECE; + } + + st->pawnKey ^= zobrist[them][PAWN][capsq]; + } + else + st->npMaterial[them] -= PieceValueMidgame[capture]; + + // Remove the captured piece + clear_bit(&byColorBB[them], capsq); + clear_bit(&byTypeBB[capture], capsq); + clear_bit(&occupied, capsq); + + // Update piece list, move the last piece at index[capsq] position and + // shrink the list. + // + // WARNING: This is a not 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 lastSquare = pieceList[them][capture][--pieceCount[them][capture]]; + index[lastSquare] = index[capsq]; + pieceList[them][capture][index[lastSquare]] = lastSquare; + pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; + + // Update hash keys + k ^= zobrist[them][capture][capsq]; + st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]]; + + // Update incremental scores + st->value -= pst(make_piece(them, capture), capsq); + + // Reset rule 50 counter + st->rule50 = 0; + } // Update hash key - key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; + k ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; // Reset en passant square if (st->epSquare != SQ_NONE) { - key ^= zobEp[st->epSquare]; + k ^= zobEp[st->epSquare]; st->epSquare = SQ_NONE; } @@ -846,87 +843,79 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if ( st->castleRights != CASTLES_NONE && (castleRightsMask[from] & castleRightsMask[to]) != ALL_CASTLES) { - key ^= zobCastle[st->castleRights]; + k ^= zobCastle[st->castleRights]; st->castleRights &= castleRightsMask[from] & castleRightsMask[to]; - key ^= zobCastle[st->castleRights]; + k ^= zobCastle[st->castleRights]; } // Prefetch TT access as soon as we know key is updated - prefetch((char*)TT.first_entry(key)); + prefetch((char*)TT.first_entry(k)); // 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 + do_move_bb(&occupied, move_bb); board[to] = board[from]; - board[from] = PIECE_NONE; + board[from] = NO_PIECE; - // 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. + // Update piece lists, index[from] is not updated and becomes stale. This + // works as long as index[] is accessed just by known occupied squares. index[to] = index[from]; pieceList[us][pt][index[to]] = to; - // If the moving piece was a pawn do some special extra work + // If the moving piece is a pawn do some special extra work if (pt == PAWN) { - // Reset rule 50 draw counter - st->rule50 = 0; - - // Update pawn hash key and prefetch in L1/L2 cache - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - - // Set en passant square, only if moved pawn can be captured - if ((to ^ from) == 16) + // Set en-passant square, only if moved pawn can be captured + if ( (to ^ from) == 16 + && (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them))) { - if (attacks_from(from + pawn_push(us), us) & pieces(PAWN, them)) - { - st->epSquare = Square((int(from) + int(to)) / 2); - key ^= zobEp[st->epSquare]; - } + st->epSquare = Square((from + to) / 2); + k ^= zobEp[st->epSquare]; } - if (pm) // promotion ? + if (is_promotion(m)) { PieceType promotion = promotion_piece_type(m); + assert(relative_rank(us, to) == RANK_8); assert(promotion >= KNIGHT && promotion <= QUEEN); - // Insert promoted piece instead of pawn + // Replace the pawn with the promoted piece clear_bit(&byTypeBB[PAWN], to); set_bit(&byTypeBB[promotion], to); board[to] = make_piece(us, promotion); - // Update piece counts - pieceCount[us][promotion]++; - pieceCount[us][PAWN]--; - - // Update material key - st->materialKey ^= zobrist[us][PAWN][pieceCount[us][PAWN]]; - st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]-1]; - // Update piece lists, move the last pawn at index[to] position // and shrink the list. Add a new promotion piece to the list. - Square lastPawnSquare = pieceList[us][PAWN][pieceCount[us][PAWN]]; - index[lastPawnSquare] = index[to]; - pieceList[us][PAWN][index[lastPawnSquare]] = lastPawnSquare; + Square lastSquare = pieceList[us][PAWN][--pieceCount[us][PAWN]]; + index[lastSquare] = index[to]; + pieceList[us][PAWN][index[lastSquare]] = lastSquare; pieceList[us][PAWN][pieceCount[us][PAWN]] = SQ_NONE; - index[to] = pieceCount[us][promotion] - 1; + index[to] = pieceCount[us][promotion]; pieceList[us][promotion][index[to]] = to; - // Partially revert hash keys update - key ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; + // Update hash keys + k ^= zobrist[us][PAWN][to] ^ zobrist[us][promotion][to]; st->pawnKey ^= zobrist[us][PAWN][to]; + st->materialKey ^= zobrist[us][promotion][pieceCount[us][promotion]++] + ^ zobrist[us][PAWN][pieceCount[us][PAWN]]; - // Partially revert and update incremental scores - st->value -= pst(make_piece(us, PAWN), to); - st->value += pst(make_piece(us, promotion), to); + // Update incremental score + st->value += pst(make_piece(us, promotion), to) + - pst(make_piece(us, PAWN), to); // Update material st->npMaterial[us] += PieceValueMidgame[promotion]; } + + // Update pawn hash key + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + + // Reset rule 50 draw counter + st->rule50 = 0; } // Prefetch pawn and material hash tables @@ -940,14 +929,14 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI st->capturedType = capture; // Update the key with the final value - st->key = key; + st->key = k; // Update checkers bitboard, piece must be already moved - st->checkersBB = EmptyBoardBB; + st->checkersBB = 0; if (moveIsCheck) { - if (ep | pm) + if (is_special(m)) st->checkersBB = attackers_to(king_square(them)) & pieces(us); else { @@ -959,182 +948,19 @@ void Position::do_move(Move m, StateInfo& newSt, const CheckInfo& ci, bool moveI if (ci.dcCandidates && bit_is_set(ci.dcCandidates, from)) { if (pt != ROOK) - st->checkersBB |= (attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us)); + st->checkersBB |= attacks_from(king_square(them)) & pieces(ROOK, QUEEN, us); if (pt != BISHOP) - st->checkersBB |= (attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us)); + st->checkersBB |= attacks_from(king_square(them)) & pieces(BISHOP, QUEEN, us); } } } // Finish - sideToMove = opposite_color(sideToMove); - st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); - - assert(is_ok()); -} - - -/// Position::do_capture_move() is a private method used to update captured -/// piece info. It is called from the main Position::do_move function. - -void Position::do_capture_move(Key& key, PieceType capture, Color them, Square to, bool ep) { - - assert(capture != KING); - - Square capsq = to; - - // If the captured piece was a pawn, update pawn hash key, - // otherwise update non-pawn material. - if (capture == PAWN) - { - if (ep) // en passant ? - { - capsq = to + pawn_push(them); - - assert(to == st->epSquare); - assert(relative_rank(opposite_color(them), to) == RANK_6); - assert(piece_on(to) == PIECE_NONE); - assert(piece_on(capsq) == make_piece(them, PAWN)); - - board[capsq] = PIECE_NONE; - } - st->pawnKey ^= zobrist[them][PAWN][capsq]; - } - else - st->npMaterial[them] -= PieceValueMidgame[capture]; - - // Remove captured piece - clear_bit(&byColorBB[them], capsq); - clear_bit(&byTypeBB[capture], capsq); - clear_bit(&byTypeBB[0], capsq); - - // Update hash key - key ^= zobrist[them][capture][capsq]; - - // Update incremental scores - st->value -= pst(make_piece(them, capture), capsq); - - // Update piece count - pieceCount[them][capture]--; - - // Update material hash key - st->materialKey ^= zobrist[them][capture][pieceCount[them][capture]]; - - // Update piece list, move the last piece at index[capsq] position - // - // WARNING: This is a not perfectly revresible operation. When we - // will reinsert the captured piece in undo_move() we will put it - // at the end of the list and not in its original place, it means - // index[] and pieceList[] are not guaranteed to be invariant to a - // do_move() + undo_move() sequence. - Square lastPieceSquare = pieceList[them][capture][pieceCount[them][capture]]; - index[lastPieceSquare] = index[capsq]; - pieceList[them][capture][index[lastPieceSquare]] = lastPieceSquare; - pieceList[them][capture][pieceCount[them][capture]] = SQ_NONE; - - // Reset rule 50 counter - st->rule50 = 0; -} - - -/// Position::do_castle_move() is a private method used to make a castling -/// move. It is called from the main Position::do_move function. Note that -/// castling moves are encoded as "king captures friendly rook" moves, for -/// instance white short castling in a non-Chess960 game is encoded as e1h1. - -void Position::do_castle_move(Move m) { - - assert(move_is_ok(m)); - assert(move_is_castle(m)); - - Color us = side_to_move(); - Color them = opposite_color(us); - - // Find source squares for king and rook - Square kfrom = move_from(m); - Square rfrom = move_to(m); - Square kto, rto; - - assert(piece_on(kfrom) == make_piece(us, KING)); - assert(piece_on(rfrom) == make_piece(us, ROOK)); - - // Find destination squares for king and rook - if (rfrom > kfrom) // O-O - { - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); - } - 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); - clear_bit(&byColorBB[us], rfrom); - clear_bit(&byTypeBB[ROOK], rfrom); - clear_bit(&byTypeBB[0], rfrom); - - // Put pieces on destination squares - set_bit(&byColorBB[us], kto); - set_bit(&byTypeBB[KING], kto); - set_bit(&byTypeBB[0], kto); - set_bit(&byColorBB[us], rto); - set_bit(&byTypeBB[ROOK], rto); - set_bit(&byTypeBB[0], rto); - - // Update board - Piece king = make_piece(us, KING); - Piece rook = make_piece(us, ROOK); - board[kfrom] = board[rfrom] = PIECE_NONE; - board[kto] = king; - board[rto] = rook; - - // Update piece lists - pieceList[us][KING][index[kfrom]] = kto; - pieceList[us][ROOK][index[rfrom]] = rto; - int tmp = index[rfrom]; // In Chess960 could be kto == rfrom - index[kto] = index[kfrom]; - index[rto] = tmp; - - // Reset capture field - st->capturedType = PIECE_TYPE_NONE; - - // Update incremental scores - st->value += pst_delta(king, kfrom, kto); - st->value += pst_delta(rook, rfrom, rto); - - // Update hash key - st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; - - // Clear en passant square - if (st->epSquare != SQ_NONE) - { - 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; - - // Update checkers BB - st->checkersBB = attackers_to(king_square(them)) & pieces(us); - - // Finish - sideToMove = opposite_color(sideToMove); + sideToMove = flip(sideToMove); st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); - assert(is_ok()); + assert(pos_is_ok()); } @@ -1143,232 +969,253 @@ void Position::do_castle_move(Move m) { void Position::undo_move(Move m) { - assert(move_is_ok(m)); + assert(is_ok(m)); - sideToMove = opposite_color(sideToMove); + sideToMove = flip(sideToMove); - if (move_is_castle(m)) + if (is_castle(m)) { - undo_castle_move(m); + do_castle_move(m); return; } 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); - - PieceType pt = piece_type(piece_on(to)); + Color them = flip(us); + Square from = from_sq(m); + Square to = to_sq(m); + Piece piece = piece_on(to); + PieceType pt = type_of(piece); + PieceType capture = st->capturedType; assert(square_is_empty(from)); - assert(piece_color(piece_on(to)) == us); - assert(!pm || relative_rank(us, to) == RANK_8); - assert(!ep || to == st->previous->epSquare); - assert(!ep || relative_rank(us, to) == RANK_6); - assert(!ep || piece_on(to) == make_piece(us, PAWN)); + assert(color_of(piece) == us); + assert(capture != KING); - if (pm) // promotion ? + if (is_promotion(m)) { PieceType promotion = promotion_piece_type(m); - pt = PAWN; + assert(promotion == pt); + assert(relative_rank(us, to) == RANK_8); assert(promotion >= KNIGHT && promotion <= QUEEN); - assert(piece_on(to) == make_piece(us, promotion)); - // Replace promoted piece with a pawn + // Replace the promoted piece with the pawn clear_bit(&byTypeBB[promotion], to); set_bit(&byTypeBB[PAWN], to); + board[to] = make_piece(us, PAWN); - // 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; + // Update piece lists, move the last promoted piece at index[to] position + // and shrink the list. Add a new pawn to the list. + Square lastSquare = pieceList[us][promotion][--pieceCount[us][promotion]]; + index[lastSquare] = index[to]; + pieceList[us][promotion][index[lastSquare]] = lastSquare; pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; - index[to] = pieceCount[us][PAWN] - 1; + index[to] = pieceCount[us][PAWN]++; pieceList[us][PAWN][index[to]] = to; + + pt = PAWN; } // 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 + do_move_bb(&occupied, move_bb); - board[from] = make_piece(us, pt); - board[to] = PIECE_NONE; + board[from] = board[to]; + board[to] = NO_PIECE; - // Update piece list + // Update piece lists, index[to] is not updated and becomes stale. This + // works as long as index[] is accessed just by known occupied squares. index[from] = index[to]; pieceList[us][pt][index[from]] = from; - if (st->capturedType) + if (capture) { Square capsq = to; - if (ep) - capsq = to - pawn_push(us); + if (is_enpassant(m)) + { + capsq -= pawn_push(us); - assert(st->capturedType != KING); - assert(!ep || square_is_empty(capsq)); + assert(pt == PAWN); + assert(to == st->previous->epSquare); + assert(relative_rank(us, to) == RANK_6); + assert(piece_on(capsq) == NO_PIECE); + } // Restore the captured piece set_bit(&byColorBB[them], capsq); - set_bit(&byTypeBB[st->capturedType], capsq); - set_bit(&byTypeBB[0], capsq); - - board[capsq] = make_piece(them, st->capturedType); + set_bit(&byTypeBB[capture], capsq); + set_bit(&occupied, capsq); - // Update piece count - pieceCount[them][st->capturedType]++; + board[capsq] = make_piece(them, capture); // Update piece list, add a new captured piece in capsq square - index[capsq] = pieceCount[them][st->capturedType] - 1; - pieceList[them][st->capturedType][index[capsq]] = capsq; + index[capsq] = pieceCount[them][capture]++; + pieceList[them][capture][index[capsq]] = capsq; } // Finally point our state pointer back to the previous state st = st->previous; - assert(is_ok()); + assert(pos_is_ok()); } -/// Position::undo_castle_move() is a private method used to unmake a castling -/// move. It is called from the main Position::undo_move function. Note that -/// castling moves are encoded as "king captures friendly rook" moves, for -/// instance white short castling in a non-Chess960 game is encoded as e1h1. +/// Position::do_castle_move() is a private method used to do/undo a castling +/// move. 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. +template +void Position::do_castle_move(Move m) { -void Position::undo_castle_move(Move m) { + assert(is_ok(m)); + assert(is_castle(m)); - assert(move_is_ok(m)); - assert(move_is_castle(m)); + Square kto, kfrom, rfrom, rto, kAfter, rAfter; - // 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(); + Square kBefore = from_sq(m); + Square rBefore = to_sq(m); - // Find source squares for king and rook - Square kfrom = move_from(m); - Square rfrom = move_to(m); - Square kto, rto; - - // Find destination squares for king and rook - if (rfrom > kfrom) // O-O + // Find after-castle squares for king and rook + if (rBefore > kBefore) // O-O { - kto = relative_square(us, SQ_G1); - rto = relative_square(us, SQ_F1); + kAfter = relative_square(us, SQ_G1); + rAfter = relative_square(us, SQ_F1); } else // O-O-O { - kto = relative_square(us, SQ_C1); - rto = relative_square(us, SQ_D1); + kAfter = relative_square(us, SQ_C1); + rAfter = relative_square(us, SQ_D1); } - assert(piece_on(kto) == make_piece(us, KING)); - assert(piece_on(rto) == make_piece(us, ROOK)); - - // Remove pieces from destination squares - clear_bit(&byColorBB[us], kto); - clear_bit(&byTypeBB[KING], kto); - clear_bit(&byTypeBB[0], kto); - clear_bit(&byColorBB[us], rto); - clear_bit(&byTypeBB[ROOK], rto); - clear_bit(&byTypeBB[0], rto); - - // Put pieces on source squares - set_bit(&byColorBB[us], kfrom); - set_bit(&byTypeBB[KING], kfrom); - set_bit(&byTypeBB[0], kfrom); - set_bit(&byColorBB[us], rfrom); - set_bit(&byTypeBB[ROOK], rfrom); - set_bit(&byTypeBB[0], rfrom); + kfrom = Do ? kBefore : kAfter; + rfrom = Do ? rBefore : rAfter; + + kto = Do ? kAfter : kBefore; + rto = Do ? rAfter : rBefore; + + assert(piece_on(kfrom) == make_piece(us, KING)); + assert(piece_on(rfrom) == make_piece(us, ROOK)); + + // Remove pieces from source squares + clear_bit(&byColorBB[us], kfrom); + clear_bit(&byTypeBB[KING], kfrom); + clear_bit(&occupied, kfrom); + clear_bit(&byColorBB[us], rfrom); + clear_bit(&byTypeBB[ROOK], rfrom); + clear_bit(&occupied, rfrom); + + // Put pieces on destination squares + set_bit(&byColorBB[us], kto); + set_bit(&byTypeBB[KING], kto); + set_bit(&occupied, kto); + set_bit(&byColorBB[us], rto); + set_bit(&byTypeBB[ROOK], rto); + set_bit(&occupied, rto); // Update board Piece king = make_piece(us, KING); Piece rook = make_piece(us, ROOK); - board[kto] = board[rto] = PIECE_NONE; - board[kfrom] = king; - board[rfrom] = rook; + board[kfrom] = board[rfrom] = NO_PIECE; + board[kto] = king; + board[rto] = rook; // 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; + pieceList[us][KING][index[kfrom]] = kto; + pieceList[us][ROOK][index[rfrom]] = rto; + int tmp = index[rfrom]; // In Chess960 could be kto == rfrom + index[kto] = index[kfrom]; + index[rto] = tmp; - assert(is_ok()); -} + if (Do) + { + // Reset capture field + st->capturedType = NO_PIECE_TYPE; + // Update incremental scores + st->value += pst_delta(king, kfrom, kto); + st->value += pst_delta(rook, rfrom, rto); -/// Position::do_null_move makes() a "null move": It switches the side to move -/// and updates the hash key without executing any move on the board. + // Update hash key + st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; + st->key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; -void Position::do_null_move(StateInfo& backupSt) { + // Clear en passant square + if (st->epSquare != SQ_NONE) + { + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; + } - assert(!in_check()); + // Update castling rights + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[kfrom]; + st->key ^= zobCastle[st->castleRights]; - // Back up the information necessary to undo the null move to the supplied - // StateInfo object. - // Note that differently from normal case here backupSt is actually used as - // a backup storage not as a new state to be used. - backupSt.key = st->key; - backupSt.epSquare = st->epSquare; - backupSt.value = st->value; - backupSt.previous = st->previous; - backupSt.pliesFromNull = st->pliesFromNull; - st->previous = &backupSt; - - // Update the necessary information - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; + // Reset rule 50 counter + st->rule50 = 0; - st->key ^= zobSideToMove; - prefetch((char*)TT.first_entry(st->key)); + // Update checkers BB + st->checkersBB = attackers_to(king_square(flip(us))) & pieces(us); - sideToMove = opposite_color(sideToMove); - st->epSquare = SQ_NONE; - st->rule50++; - st->gamePly++; - st->pliesFromNull = 0; - st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue; + // Finish + sideToMove = flip(sideToMove); + st->value += (sideToMove == WHITE ? TempoValue : -TempoValue); + } + else + // Undo: point our state pointer back to the previous state + st = st->previous; - assert(is_ok()); + assert(pos_is_ok()); } -/// Position::undo_null_move() unmakes a "null move". - -void Position::undo_null_move() { +/// Position::do_null_move() is used to do/undo a "null move": It flips the side +/// to move and updates the hash key without executing any move on the board. +template +void Position::do_null_move(StateInfo& backupSt) { assert(!in_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; + // 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 the new state. This reduces + // the number of fields to be copied. + StateInfo* src = Do ? st : &backupSt; + StateInfo* dst = Do ? &backupSt : st; - // Update the necessary information - sideToMove = opposite_color(sideToMove); - st->rule50--; - st->gamePly--; + dst->key = src->key; + dst->epSquare = src->epSquare; + dst->value = src->value; + dst->rule50 = src->rule50; + dst->pliesFromNull = src->pliesFromNull; + + sideToMove = flip(sideToMove); + + if (Do) + { + if (st->epSquare != SQ_NONE) + st->key ^= zobEp[st->epSquare]; + + st->key ^= zobSideToMove; + prefetch((char*)TT.first_entry(st->key)); + + st->epSquare = SQ_NONE; + st->rule50++; + st->pliesFromNull = 0; + st->value += (sideToMove == WHITE) ? TempoValue : -TempoValue; + } - assert(is_ok()); + assert(pos_is_ok()); } +// Explicit template instantiations +template void Position::do_null_move(StateInfo& backupSt); +template void Position::do_null_move(StateInfo& backupSt); + /// 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 @@ -1378,15 +1225,15 @@ void Position::undo_null_move() { int Position::see_sign(Move m) const { - assert(move_is_ok(m)); + assert(is_ok(m)); - Square from = move_from(m); - Square to = move_to(m); + Square from = from_sq(m); + Square to = to_sq(m); // Early return if SEE cannot be negative because captured piece value // is not less then capturing one. Note that king moves always return // here because king midgame value is set to 0. - if (piece_value_midgame(piece_on(to)) >= piece_value_midgame(piece_on(from))) + if (PieceValueMidgame[piece_on(to)] >= PieceValueMidgame[piece_on(from)]) return 1; return see(m); @@ -1395,44 +1242,44 @@ int Position::see_sign(Move m) const { int Position::see(Move m) const { Square from, to; - Bitboard occupied, attackers, stmAttackers, b; + Bitboard occ, attackers, stmAttackers, b; int swapList[32], slIndex = 1; PieceType capturedType, pt; Color stm; - assert(move_is_ok(m)); + assert(is_ok(m)); // As castle moves are implemented as capturing the rook, they have // SEE == RookValueMidgame most of the times (unless the rook is under // attack). - if (move_is_castle(m)) + if (is_castle(m)) return 0; - from = move_from(m); - to = move_to(m); - capturedType = piece_type(piece_on(to)); - occupied = occupied_squares(); + from = from_sq(m); + to = to_sq(m); + capturedType = type_of(piece_on(to)); + occ = occupied_squares(); // Handle en passant moves - if (st->epSquare == to && piece_type(piece_on(from)) == PAWN) + if (is_enpassant(m)) { Square capQq = to - pawn_push(side_to_move()); - assert(capturedType == PIECE_TYPE_NONE); - assert(piece_type(piece_on(capQq)) == PAWN); + assert(capturedType == NO_PIECE_TYPE); + assert(type_of(piece_on(capQq)) == PAWN); // Remove the captured pawn - clear_bit(&occupied, capQq); + clear_bit(&occ, capQq); capturedType = PAWN; } // Find all attackers to the destination square, with the moving piece // removed, but possibly an X-ray attacker added behind it. - clear_bit(&occupied, from); - attackers = attackers_to(to, occupied); + clear_bit(&occ, from); + attackers = attackers_to(to, occ); // If the opponent has no attackers we are finished - stm = opposite_color(piece_color(piece_on(from))); + stm = flip(color_of(piece_on(from))); stmAttackers = attackers & pieces(stm); if (!stmAttackers) return PieceValueMidgame[capturedType]; @@ -1444,7 +1291,7 @@ int Position::see(Move m) const { // capture with the least valuable piece. After each capture, we look for // new X-ray attacks from behind the capturing piece. swapList[0] = PieceValueMidgame[capturedType]; - capturedType = piece_type(piece_on(from)); + capturedType = type_of(piece_on(from)); do { // Locate the least valuable attacker for the side to move. The loop @@ -1456,11 +1303,11 @@ int Position::see(Move m) const { // Remove the attacker we just found from the 'occupied' bitboard, // and scan for new X-ray attacks behind the attacker. b = stmAttackers & pieces(pt); - occupied ^= (b & (~b + 1)); - attackers |= (rook_attacks_bb(to, occupied) & pieces(ROOK, QUEEN)) - | (bishop_attacks_bb(to, occupied) & pieces(BISHOP, QUEEN)); + occ ^= (b & (~b + 1)); + attackers |= (rook_attacks_bb(to, occ) & pieces(ROOK, QUEEN)) + | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN)); - attackers &= occupied; // Cut out pieces we've already done + attackers &= occ; // Cut out pieces we've already done // Add the new entry to the swap list assert(slIndex < 32); @@ -1470,7 +1317,7 @@ int Position::see(Move m) const { // Remember the value of the capturing piece, and change the side to // move before beginning the next iteration. capturedType = pt; - stm = opposite_color(stm); + stm = flip(stm); stmAttackers = attackers & pieces(stm); // Stop before processing a king capture @@ -1485,7 +1332,7 @@ int Position::see(Move m) const { // 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] = Min(-swapList[slIndex], swapList[slIndex-1]); + swapList[slIndex-1] = std::min(-swapList[slIndex], swapList[slIndex-1]); return swapList[0]; } @@ -1511,11 +1358,12 @@ void Position::clear() { for (Square sq = SQ_A1; sq <= SQ_H8; sq++) { - board[sq] = PIECE_NONE; + board[sq] = NO_PIECE; castleRightsMask[sq] = ALL_CASTLES; } sideToMove = WHITE; nodes = 0; + occupied = 0; } @@ -1524,8 +1372,8 @@ void Position::clear() { void Position::put_piece(Piece p, Square s) { - Color c = piece_color(p); - PieceType pt = piece_type(p); + Color c = color_of(p); + PieceType pt = type_of(p); board[s] = p; index[s] = pieceCount[c][pt]++; @@ -1533,7 +1381,7 @@ void Position::put_piece(Piece p, Square s) { set_bit(&byTypeBB[pt], s); set_bit(&byColorBB[c], s); - set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares. + set_bit(&occupied, s); } @@ -1548,7 +1396,7 @@ Key Position::compute_key() const { for (Square s = SQ_A1; s <= SQ_H8; s++) if (!square_is_empty(s)) - result ^= zobrist[piece_color(piece_on(s))][piece_type(piece_on(s))][s]; + result ^= zobrist[color_of(piece_on(s))][type_of(piece_on(s))][s]; if (ep_square() != SQ_NONE) result ^= zobEp[ep_square()]; @@ -1593,7 +1441,7 @@ Key Position::compute_material_key() const { for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= QUEEN; pt++) - for (int i = 0, cnt = piece_count(c, pt); i < cnt; i++) + for (int i = 0; i < piece_count(c, pt); i++) result ^= zobrist[c][pt][i]; return result; @@ -1650,13 +1498,13 @@ bool Position::is_draw() const { return true; // Draw by the 50 moves rule? - if (st->rule50 > 99 && !is_mate()) + if (st->rule50 > 99 && (!in_check() || MoveList(*this).size())) return true; // Draw by repetition? if (!SkipRepetition) { - int i = 4, e = Min(st->rule50, st->pliesFromNull); + int i = 4, e = std::min(st->rule50, st->pliesFromNull); if (i <= e) { @@ -1682,21 +1530,11 @@ template bool Position::is_draw() const; template bool Position::is_draw() const; -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. - -bool Position::is_mate() const { - - return in_check() && !MoveList(*this).size(); -} - - -/// Position::init() is a static member function which initializes at -/// startup the various arrays used to compute hash keys and the piece -/// square tables. The latter is a two-step operation: First, the white -/// halves of the tables are copied from the MgPST[][] and EgPST[][] arrays. -/// Second, the black halves of the tables are initialized by mirroring -/// and changing the sign of the corresponding white scores. +/// Position::init() is a static member function which initializes at startup +/// the various arrays used to compute hash keys and the piece square tables. +/// The latter is a two-step operation: First, the white halves of the tables +/// are copied from PSQT[] tables. Second, the black halves of the tables are +/// initialized by flipping and changing the sign of the white scores. void Position::init() { @@ -1716,20 +1554,23 @@ void Position::init() { zobSideToMove = rk.rand(); zobExclusion = rk.rand(); - for (Square s = SQ_A1; s <= SQ_H8; s++) - for (Piece p = WP; p <= WK; p++) - pieceSquareTable[p][s] = make_score(MgPST[p][s], EgPST[p][s]); + for (Piece p = W_PAWN; p <= W_KING; p++) + { + Score ps = make_score(PieceValueMidgame[p], PieceValueEndgame[p]); - 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)]; + for (Square s = SQ_A1; s <= SQ_H8; s++) + { + pieceSquareTable[p][s] = ps + PSQT[p][s]; + pieceSquareTable[p+8][flip(s)] = -pieceSquareTable[p][s]; + } + } } -/// Position::flip() flips position with the white and black sides reversed. This +/// Position::flip_me() flips position with the white and black sides reversed. This /// is only useful for debugging especially for finding evaluation symmetry bugs. -void Position::flip() { +void Position::flip_me() { // Make a copy of current position before to start changing const Position pos(*this, threadID); @@ -1740,27 +1581,27 @@ void Position::flip() { // Board for (Square s = SQ_A1; s <= SQ_H8; s++) if (!pos.square_is_empty(s)) - put_piece(Piece(pos.piece_on(s) ^ 8), flip_square(s)); + put_piece(Piece(pos.piece_on(s) ^ 8), flip(s)); // Side to move - sideToMove = opposite_color(pos.side_to_move()); + sideToMove = flip(pos.side_to_move()); // Castling rights if (pos.can_castle(WHITE_OO)) - set_castle(BLACK_OO, king_square(BLACK), flip_square(pos.castle_rook_square(WHITE_OO))); + set_castle_right(BLACK, flip(pos.castle_rook_square(WHITE_OO))); if (pos.can_castle(WHITE_OOO)) - set_castle(BLACK_OOO, king_square(BLACK), flip_square(pos.castle_rook_square(WHITE_OOO))); + set_castle_right(BLACK, flip(pos.castle_rook_square(WHITE_OOO))); if (pos.can_castle(BLACK_OO)) - set_castle(WHITE_OO, king_square(WHITE), flip_square(pos.castle_rook_square(BLACK_OO))); + set_castle_right(WHITE, flip(pos.castle_rook_square(BLACK_OO))); if (pos.can_castle(BLACK_OOO)) - set_castle(WHITE_OOO, king_square(WHITE), flip_square(pos.castle_rook_square(BLACK_OOO))); + set_castle_right(WHITE, flip(pos.castle_rook_square(BLACK_OOO))); // En passant square if (pos.st->epSquare != SQ_NONE) - st->epSquare = flip_square(pos.st->epSquare); + st->epSquare = flip(pos.st->epSquare); // Checkers - st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(opposite_color(sideToMove)); + st->checkersBB = attackers_to(king_square(sideToMove)) & pieces(flip(sideToMove)); // Hash keys st->key = compute_key(); @@ -1774,14 +1615,14 @@ void Position::flip() { st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); - assert(is_ok()); + assert(pos_is_ok()); } -/// Position::is_ok() performs some consitency checks for the position object. +/// Position::pos_is_ok() performs some consitency checks for the position object. /// This is meant to be helpful when debugging. -bool Position::is_ok(int* failedStep) const { +bool Position::pos_is_ok(int* failedStep) const { // What features of the position should be verified? const bool debugAll = false; @@ -1807,11 +1648,11 @@ bool Position::is_ok(int* failedStep) const { // Are the king squares in the position correct? if (failedStep) (*failedStep)++; - if (piece_on(king_square(WHITE)) != WK) + if (piece_on(king_square(WHITE)) != W_KING) return false; if (failedStep) (*failedStep)++; - if (piece_on(king_square(BLACK)) != BK) + if (piece_on(king_square(BLACK)) != B_KING) return false; // Do both sides have exactly one king? @@ -1820,8 +1661,8 @@ bool Position::is_ok(int* failedStep) const { { int kingCount[2] = {0, 0}; for (Square s = SQ_A1; s <= SQ_H8; s++) - if (piece_type(piece_on(s)) == KING) - kingCount[piece_color(piece_on(s))]++; + if (type_of(piece_on(s)) == KING) + kingCount[color_of(piece_on(s))]++; if (kingCount[0] != 1 || kingCount[1] != 1) return false; @@ -1832,7 +1673,7 @@ bool Position::is_ok(int* failedStep) const { if (debugKingCapture) { Color us = side_to_move(); - Color them = opposite_color(us); + Color them = flip(us); Square ksq = king_square(them); if (attackers_to(ksq) & pieces(us)) return false; @@ -1840,7 +1681,7 @@ bool Position::is_ok(int* failedStep) const { // Is there more than 2 checkers? if (failedStep) (*failedStep)++; - if (debugCheckerCount && count_1s(st->checkersBB) > 2) + if (debugCheckerCount && popcount(st->checkersBB) > 2) return false; // Bitboards OK? @@ -1848,7 +1689,7 @@ bool Position::is_ok(int* failedStep) const { if (debugBitboards) { // The intersection of the white and black pieces must be empty - if ((pieces(WHITE) & pieces(BLACK)) != EmptyBoardBB) + if (!(pieces(WHITE) & pieces(BLACK))) return false; // The union of the white and black pieces must be equal to all @@ -1909,7 +1750,7 @@ bool Position::is_ok(int* failedStep) const { 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 (pieceCount[c][pt] != popcount(pieces(pt, c))) return false; if (failedStep) (*failedStep)++; @@ -1932,7 +1773,7 @@ bool Position::is_ok(int* failedStep) const { if (!can_castle(f)) continue; - Piece rook = (f & (WHITE_OO | WHITE_OOO) ? WR : BR); + Piece rook = (f & (WHITE_OO | WHITE_OOO) ? W_ROOK : B_ROOK); if ( castleRightsMask[castleRookSquare[f]] != (ALL_CASTLES ^ f) || piece_on(castleRookSquare[f]) != rook)