X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=1fe723aec461e20a303582484349b9696ca9c552;hp=7725b934e1eb34824789ae7cbdeaf54078ab53fb;hb=dddaeff7d8d4a0c255310d054a53066296e71004;hpb=55f9afee2a079b2dd0b1aeda41082c58eb317ca3 diff --git a/src/position.cpp b/src/position.cpp index 7725b934..1fe723ae 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2009 Marco Costalba Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -27,21 +27,23 @@ #include #include +#include "bitcount.h" #include "mersenne.h" #include "movegen.h" #include "movepick.h" #include "position.h" #include "psqtab.h" #include "san.h" +#include "tt.h" #include "ucioption.h" +using std::string; + //// //// Variables //// -extern SearchStack EmptySearchStack; - int Position::castleRightsMask[64]; Key Position::zobrist[2][8][64]; @@ -65,7 +67,7 @@ Position::Position(const Position& pos) { copy(pos); } -Position::Position(const std::string& fen) { +Position::Position(const string& fen) { from_fen(fen); } @@ -74,9 +76,9 @@ Position::Position(const std::string& fen) { /// string. This function is not very robust - make sure that input FENs are /// correct (this is assumed to be the responsibility of the GUI). -void Position::from_fen(const std::string& fen) { +void Position::from_fen(const string& fen) { - static const std::string pieceLetters = "KQRBNPkqrbnp"; + static const string pieceLetters = "KQRBNPkqrbnp"; static const Piece pieces[] = { WK, WQ, WR, WB, WN, WP, BK, BQ, BR, BB, BN, BP }; clear(); @@ -100,7 +102,7 @@ void Position::from_fen(const std::string& fen) { continue; } size_t idx = pieceLetters.find(fen[i]); - if (idx == std::string::npos) + if (idx == string::npos) { std::cout << "Error in FEN at character " << i << std::endl; return; @@ -190,7 +192,7 @@ void Position::from_fen(const std::string& fen) { i++; // En passant square - if ( i < fen.length() - 2 + 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)); @@ -207,25 +209,24 @@ void Position::from_fen(const std::string& fen) { castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; find_checkers(); - find_pinned(); st->key = compute_key(); st->pawnKey = compute_pawn_key(); st->materialKey = compute_material_key(); st->mgValue = compute_value(); st->egValue = compute_value(); - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); } /// Position::to_fen() converts the position object to a FEN string. This is /// probably only useful for debugging. -const std::string Position::to_fen() const { +const string Position::to_fen() const { - static const std::string pieceLetters = " PNBRQK pnbrqk"; - std::string fen; + static const string pieceLetters = " PNBRQK pnbrqk"; + string fen; int skip; for (Rank rank = RANK_8; rank >= RANK_1; rank--) @@ -275,7 +276,7 @@ const std::string Position::to_fen() const { void Position::print(Move m) const { - static const std::string pieceLetters = " PNBRQK PNBRQK ."; + static const string pieceLetters = " PNBRQK PNBRQK ."; // Check for reentrancy, as example when called from inside // MovePicker that is used also here in move_to_san() @@ -287,7 +288,7 @@ void Position::print(Move m) const { std::cout << std::endl; if (m != MOVE_NONE) { - std::string col = (color_of_piece_on(move_from(m)) == BLACK ? ".." : ""); + 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--) @@ -315,90 +316,98 @@ void Position::print(Move m) const { /// Position::copy() creates a copy of the input position. -void Position::copy(const Position &pos) { +void Position::copy(const Position& pos) { memcpy(this, &pos, sizeof(Position)); + saveState(); // detach and copy state info } -/// Position:hidden_checks<>() returns a bitboard of all pinned (against the +/// 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 pinned pieces of opposite color -/// that are, indeed, the pieces candidate for a discovery check. +/// 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. -template -Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const { - Square s; - Bitboard sliders, result = EmptyBoardBB; +template +Bitboard Position::hidden_checkers(Color c) const { - if (Piece == ROOK) // Resolved at compile time - sliders = rooks_and_queens(FindPinned ? opposite_color(c) : c) & RookPseudoAttacks[ksq]; - else - sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]; + Bitboard pinners, result = EmptyBoardBB; + + // Pinned pieces protect our king, dicovery checks attack + // the enemy king. + Square ksq = king_square(FindPinned ? c : opposite_color(c)); + + // 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]); - if (sliders && (!FindPinned || (sliders & ~st->checkersBB))) + if (FindPinned && pinners) + pinners &= ~st->checkersBB; + + while (pinners) { - // King blockers are candidate pinned pieces - Bitboard candidate_pinned = piece_attacks(ksq) & pieces_of_color(c); - - // Pinners are sliders, not checkers, that give check when - // candidate pinned are removed. - pinners = (FindPinned ? sliders & ~st->checkersBB : sliders); - - if (Piece == ROOK) - pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - else - pinners &= bishop_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); - - // Finally for each pinner find the corresponding pinned piece (if same color of king) - // or discovery checker (if opposite color) among the candidates. - Bitboard p = pinners; - while (p) - { - s = pop_1st_bit(&p); - result |= (squares_between(s, ksq) & candidate_pinned); - } - } - else - pinners = EmptyBoardBB; + Square s = pop_1st_bit(&pinners); + Bitboard b = squares_between(s, ksq) & occupied_squares(); + assert(b); + + if ( !(b & (b - 1)) // Only one bit set? + && (b & pieces_of_color(c))) // Is an our piece? + result |= b; + } return result; } -/// Position::attacks_to() computes a bitboard containing all pieces which -/// attacks a given square. There are two versions of this function: One -/// which finds attackers of both colors, and one which only finds the -/// attackers for one side. +/// Position:pinned_pieces() returns a bitboard of all pinned (against the +/// king) pieces for the given color. -Bitboard Position::attacks_to(Square s) const { +Bitboard Position::pinned_pieces(Color c) const { - return (pawn_attacks(BLACK, s) & pawns(WHITE)) - | (pawn_attacks(WHITE, s) & pawns(BLACK)) - | (piece_attacks(s) & pieces_of_type(KNIGHT)) - | (piece_attacks(s) & rooks_and_queens()) - | (piece_attacks(s) & bishops_and_queens()) - | (piece_attacks(s) & pieces_of_type(KING)); + return hidden_checkers(c); } -/// Position::piece_attacks_square() tests whether the piece on square f -/// attacks square t. -bool Position::piece_attacks_square(Piece p, Square f, Square t) const { +/// Position:discovered_check_candidates() returns a bitboard containing all +/// pieces for the given side which are candidates for giving a discovered +/// check. + +Bitboard Position::discovered_check_candidates(Color c) const { + + return hidden_checkers(c); +} + +/// Position::attackers_to() computes a bitboard containing all pieces which +/// attacks a given square. - assert(square_is_ok(f)); - assert(square_is_ok(t)); +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::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 WP: return pawn_attacks_square(WHITE, f, t); - case BP: return pawn_attacks_square(BLACK, f, t); - case WN: case BN: return piece_attacks_square(f, t); - case WB: case BB: return piece_attacks_square(f, t); - case WR: case BR: return piece_attacks_square(f, t); - case WQ: case BQ: return piece_attacks_square(f, t); - case WK: case BK: return piece_attacks_square(f, t); + case WP: return attacks_from(s, WHITE); + case BP: return attacks_from(s, BLACK); + case WN: case BN: return attacks_from(s); + case WB: case BB: return attacks_from(s); + case WR: case BR: return attacks_from(s); + case WQ: case BQ: return attacks_from(s); + case WK: case BK: return attacks_from(s); default: break; } return false; @@ -417,7 +426,7 @@ bool Position::move_attacks_square(Move m, Square s) const { assert(square_is_occupied(f)); - if (piece_attacks_square(piece_on(f), t, s)) + if (bit_is_set(attacks_from(piece_on(f), t), s)) return true; // Move the piece and scan for X-ray attacks behind it @@ -425,79 +434,64 @@ bool Position::move_attacks_square(Move m, Square s) const { Color us = color_of_piece_on(f); clear_bit(&occ, f); set_bit(&occ, t); - Bitboard xray = ( (rook_attacks_bb(s, occ) & rooks_and_queens()) - |(bishop_attacks_bb(s, occ) & bishops_and_queens())) & pieces_of_color(us); + 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 & piece_attacks(s))); + return xray && (xray ^ (xray & attacks_from(s))); } /// Position::find_checkers() computes the checkersBB bitboard, which /// contains a nonzero bit for each checking piece (0, 1 or 2). It -/// currently works by calling Position::attacks_to, which is probably +/// 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. void Position::find_checkers() { Color us = side_to_move(); - st->checkersBB = attacks_to(king_square(us), opposite_color(us)); + st->checkersBB = attackers_to(king_square(us)) & pieces_of_color(opposite_color(us)); } -/// Position:find_pinned() computes the pinned, pinners and dcCandidates -/// bitboards for both colors. Bitboard checkersBB must be already updated. - -void Position::find_pinned() { +/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal - Bitboard p1, p2; - Square ksq; +bool Position::pl_move_is_legal(Move m) const { - for (Color c = WHITE; c <= BLACK; c++) - { - ksq = king_square(c); - st->pinned[c] = hidden_checks(c, ksq, p1) | hidden_checks(c, ksq, p2); - st->pinners[c] = p1 | p2; - ksq = king_square(opposite_color(c)); - st->dcCandidates[c] = hidden_checks(c, ksq, p1) | hidden_checks(c, ksq, p2); - } + // If we're in check, all pseudo-legal moves are legal, because our + // check evasion generator only generates true legal moves. + return is_check() || pl_move_is_legal(m, pinned_pieces(side_to_move())); } - -/// Position::pl_move_is_legal() tests whether a pseudo-legal move is legal - -bool Position::pl_move_is_legal(Move m) const { +bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { assert(is_ok()); assert(move_is_ok(m)); - - // If we're in check, all pseudo-legal moves are legal, because our - // check evasion generator only generates true legal moves. - if (is_check()) - return true; + assert(pinned == pinned_pieces(side_to_move())); + assert(!is_check()); // Castling moves are checked for legality during move generation. if (move_is_castle(m)) return true; Color us = side_to_move(); - Color them = opposite_color(us); Square from = move_from(m); - Square ksq = king_square(us); assert(color_of_piece_on(from) == us); - assert(piece_on(ksq) == piece_of_color_and_type(us, KING)); + assert(piece_on(king_square(us)) == piece_of_color_and_type(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)) { + Color them = opposite_color(us); Square to = move_to(m); Square capsq = make_square(square_file(to), square_rank(from)); Bitboard b = occupied_squares(); + Square ksq = king_square(us); assert(to == ep_square()); assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); @@ -508,19 +502,20 @@ bool Position::pl_move_is_legal(Move m) const { clear_bit(&b, capsq); set_bit(&b, to); - return !(rook_attacks_bb(ksq, b) & rooks_and_queens(them)) - && !(bishop_attacks_bb(ksq, b) & bishops_and_queens(them)); + return !(rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, them)) + && !(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, them)); } // If the moving piece is a king, check whether the destination // square is attacked by the opponent. - if (from == ksq) - return !(square_is_attacked(move_to(m), them)); + if (type_of_piece_on(from) == KING) + return !(attackers_to(move_to(m)) & pieces_of_color(opposite_color(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 ( !bit_is_set(pinned_pieces(us), from) - || (direction_between_squares(from, ksq) == direction_between_squares(move_to(m), ksq))); + return ( !pinned + || !bit_is_set(pinned, from) + || (direction_between_squares(from, king_square(us)) == direction_between_squares(move_to(m), king_square(us)))); } @@ -528,15 +523,21 @@ bool Position::pl_move_is_legal(Move m) const { bool Position::move_is_check(Move m) const { + Bitboard dc = discovered_check_candidates(side_to_move()); + return move_is_check(m, dc); +} + +bool Position::move_is_check(Move m, Bitboard dcCandidates) const { + assert(is_ok()); assert(move_is_ok(m)); + assert(dcCandidates == discovered_check_candidates(side_to_move())); 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); - Bitboard dcCandidates = discovered_check_candidates(us); assert(color_of_piece_on(from) == us); assert(piece_on(ksq) == piece_of_color_and_type(them, KING)); @@ -546,22 +547,23 @@ bool Position::move_is_check(Move m) const { { case PAWN: - if (bit_is_set(pawn_attacks(them, ksq), to)) // Normal check? + if (bit_is_set(attacks_from(ksq, them), to)) // Normal check? return true; - if ( bit_is_set(dcCandidates, from) // Discovered check? + if ( dcCandidates // Discovered check? + && bit_is_set(dcCandidates, from) && (direction_between_squares(from, ksq) != direction_between_squares(to, ksq))) return true; - if (move_promotion(m)) // Promotion with check? + if (move_is_promotion(m)) // Promotion with check? { Bitboard b = occupied_squares(); clear_bit(&b, from); - switch (move_promotion(m)) + switch (move_promotion_piece(m)) { case KNIGHT: - return bit_is_set(piece_attacks(to), ksq); + return bit_is_set(attacks_from(to), ksq); case BISHOP: return bit_is_set(bishop_attacks_bb(to, b), ksq); case ROOK: @@ -583,27 +585,29 @@ bool Position::move_is_check(Move m) const { clear_bit(&b, from); clear_bit(&b, capsq); set_bit(&b, to); - return (rook_attacks_bb(ksq, b) & rooks_and_queens(us)) - ||(bishop_attacks_bb(ksq, b) & bishops_and_queens(us)); + return (rook_attacks_bb(ksq, b) & pieces(ROOK, QUEEN, us)) + ||(bishop_attacks_bb(ksq, b) & pieces(BISHOP, QUEEN, us)); } return false; + // Test discovered check and normal check according to piece type case KNIGHT: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || bit_is_set(attacks_from(ksq), to); case BISHOP: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + return (dcCandidates && bit_is_set(dcCandidates, from)) + || (direction_is_diagonal(ksq, to) && bit_is_set(attacks_from(ksq), to)); case ROOK: - return bit_is_set(dcCandidates, from) // Discovered check? - || bit_is_set(piece_attacks(ksq), to); // Normal check? + 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 bit_is_set(piece_attacks(ksq), to); // Normal check? + 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? @@ -643,190 +647,240 @@ bool Position::move_is_check(Move m) const { } -/// Position::move_is_capture() tests whether a move from the current -/// position is a capture. Move must not be MOVE_NONE. - -bool Position::move_is_capture(Move m) const { - - assert(m != MOVE_NONE); - - return ( !square_is_empty(move_to(m)) - && (color_of_piece_on(move_to(m)) != color_of_piece_on(move_from(m))) - ) - || move_is_ep(m); -} - - -/// Position::update_checkers() is a private method to udpate chekers info +/// Position::update_checkers() udpates chekers info given the move. It is called +/// in do_move() and is faster then find_checkers(). template inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square from, Square to, Bitboard dcCandidates) { - if (Piece != KING && bit_is_set(piece_attacks(ksq), to)) + const bool Bishop = (Piece == QUEEN || Piece == BISHOP); + const bool Rook = (Piece == QUEEN || Piece == ROOK); + const bool Slider = Bishop || Rook; + + // 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); + + 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)) { if (Piece != ROOK) - (*pCheckersBB) |= (piece_attacks(ksq) & rooks_and_queens(side_to_move())); + (*pCheckersBB) |= (attacks_from(ksq) & pieces(ROOK, QUEEN, side_to_move())); if (Piece != BISHOP) - (*pCheckersBB) |= (piece_attacks(ksq) & bishops_and_queens(side_to_move())); + (*pCheckersBB) |= (attacks_from(ksq) & pieces(BISHOP, QUEEN, side_to_move())); } } -/// Position::init_new_state() copies from the current state the fields -/// that will be updated incrementally, skips the fields, like bitboards -/// that will be recalculated form scratch anyway. - -void Position::init_new_state(StateInfo& newSt) { - - newSt.key = st->key; - newSt.pawnKey = st->pawnKey; - newSt.materialKey = st->materialKey; - newSt.castleRights = st->castleRights; - newSt.rule50 = st->rule50; - newSt.epSquare = st->epSquare; - newSt.mgValue = st->mgValue; - newSt.egValue = st->egValue; - newSt.capture = NO_PIECE_TYPE; - newSt.previous = st; -} - - /// 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) { + do_move(m, newSt, discovered_check_candidates(side_to_move())); +} + +void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { + assert(is_ok()); assert(move_is_ok(m)); - // Get now the current (before to move) dc candidates that we will use - // in update_checkers(). - Bitboard oldDcCandidates = discovered_check_candidates(side_to_move()); + Bitboard key = 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. + struct ReducedStateInfo { + Key key, pawnKey, materialKey; + int castleRights, rule50, pliesFromNull; + Square epSquare; + Value mgValue, egValue; + Value npMaterial[2]; + }; - // Copy some fields of old state to our new StateInfo object (except the - // captured piece, which is taken care of later) and switch state pointer - // to point to the new, ready to be updated, state. - init_new_state(newSt); + 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] = st->key; + history[gamePly] = key; + gamePly++; + + // 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)) - do_castle_move(m); - else if (move_promotion(m)) - do_promotion_move(m); - else if (move_is_ep(m)) - do_ep_move(m); - else { - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); + st->key = key; + do_castle_move(m); + return; + } - assert(color_of_piece_on(from) == us); - assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY); + 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 piece = type_of_piece_on(from); + Piece piece = piece_on(from); + PieceType pt = type_of_piece(piece); - st->capture = type_of_piece_on(to); + 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); - if (st->capture) - do_capture_move(m, st->capture, them, to); + st->capture = ep ? PAWN : type_of_piece_on(to); - // Move the piece - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[piece]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[piece]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = board[from]; - board[from] = EMPTY; + if (st->capture) + do_capture_move(key, st->capture, them, to, ep); - // Update hash key - st->key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; + // Update hash key + key ^= zobrist[us][pt][from] ^ zobrist[us][pt][to]; - // Update incremental scores - st->mgValue -= pst(us, piece, from); - st->mgValue += pst(us, piece, to); - st->egValue -= pst(us, piece, from); - st->egValue += pst(us, piece, to); + // Reset en passant square + if (st->epSquare != SQ_NONE) + { + key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; + } - // If the moving piece was a king, update the king square - if (piece == KING) - kingSquare[us] = to; + // 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]; + } - // Reset en passant square - if (st->epSquare != SQ_NONE) - { - st->key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; - } + // Prefetch TT access as soon as we know key is updated + TT.prefetch(key); - // If the moving piece was a pawn do some special extra work - if (piece == PAWN) - { - // Reset rule 50 draw counter - st->rule50 = 0; - - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - - // Set en passant square, only if moved pawn can be captured - if (abs(int(to) - int(from)) == 16) - { - if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK))) - || (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE)))) - { - st->epSquare = Square((int(from) + int(to)) / 2); - st->key ^= zobEp[st->epSquare]; - } - } - } + // Move the piece + Bitboard move_bb = make_move_bb(from, to); + do_move_bb(&(byColorBB[us]), move_bb); + do_move_bb(&(byTypeBB[pt]), move_bb); + do_move_bb(&(byTypeBB[0]), move_bb); // HACK: byTypeBB[0] == occupied squares + + board[to] = board[from]; + board[from] = EMPTY; - // Update piece lists - pieceList[us][piece][index[from]] = to; - index[to] = index[from]; + // 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; - // Update castle rights - st->key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[from]; - st->castleRights &= castleRightsMask[to]; - st->key ^= zobCastle[st->castleRights]; + // If the moving piece was a pawn do some special extra work + if (pt == PAWN) + { + // Reset rule 50 draw counter + st->rule50 = 0; - // Update checkers bitboard, piece must be already moved - st->checkersBB = EmptyBoardBB; - Square ksq = king_square(them); - switch (piece) - { - case PAWN: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case KNIGHT: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case BISHOP: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case ROOK: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case QUEEN: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - case KING: update_checkers(&st->checkersBB, ksq, from, to, oldDcCandidates); break; - default: assert(false); break; - } + // Update pawn hash key + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + + // Set en passant square, only if moved pawn can be captured + if (abs(int(to) - int(from)) == 16) + { + if (attacks_from(from + (us == WHITE ? DELTA_N : DELTA_S), us) & pieces(PAWN, them)) + { + st->epSquare = Square((int(from) + int(to)) / 2); + key ^= zobEp[st->epSquare]; + } + } + } + + // Update incremental scores + st->mgValue += pst_delta(piece, from, to); + st->egValue += pst_delta(piece, from, to); + + if (pm) // promotion ? + { + 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->mgValue -= pst(us, PAWN, to); + st->mgValue += pst(us, promotion, to); + st->egValue -= pst(us, PAWN, to); + st->egValue += pst(us, promotion, to); + + // Update material + st->npMaterial[us] += piece_value_midgame(promotion); + } + + // Update the key with the final value + st->key = key; + + // 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; + } } // Finish - find_pinned(); - st->key ^= zobSideToMove; sideToMove = opposite_color(sideToMove); - gamePly++; st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; @@ -838,30 +892,42 @@ void Position::do_move(Move m, StateInfo& newSt) { /// 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(Move m, PieceType capture, Color them, Square to) { +void Position::do_capture_move(Bitboard& key, PieceType capture, Color them, Square to, bool ep) { assert(capture != KING); + Square capsq = to; + + 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)); + + board[capsq] = EMPTY; + } + // Remove captured piece - clear_bit(&(byColorBB[them]), to); - clear_bit(&(byTypeBB[capture]), to); + clear_bit(&(byColorBB[them]), capsq); + clear_bit(&(byTypeBB[capture]), capsq); + clear_bit(&(byTypeBB[0]), capsq); // Update hash key - st->key ^= zobrist[them][capture][to]; - - // If the captured piece was a pawn, update pawn hash key - if (capture == PAWN) - st->pawnKey ^= zobrist[them][PAWN][to]; + key ^= zobrist[them][capture][capsq]; // Update incremental scores - st->mgValue -= pst(them, capture, to); - st->egValue -= pst(them, capture, to); + st->mgValue -= pst(them, capture, capsq); + st->egValue -= pst(them, capture, capsq); - assert(!move_promotion(m) || capture != PAWN); - - // Update material - if (capture != PAWN) - npMaterial[them] -= piece_value_midgame(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); // Update material hash key st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; @@ -869,9 +935,17 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) // Update piece count pieceCount[them][capture]--; - // Update piece list - pieceList[them][capture][index[to]] = pieceList[them][capture][pieceCount[them][capture]]; - index[pieceList[them][capture][index[to]]] = index[to]; + // 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; @@ -885,13 +959,15 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) void Position::do_castle_move(Move m) { - assert(is_ok()); assert(move_is_ok(m)); assert(move_is_castle(m)); Color us = side_to_move(); Color them = opposite_color(us); + // 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 @@ -910,7 +986,7 @@ void Position::do_castle_move(Move m) { rto = relative_square(us, SQ_D1); } - // Remove pieces from source squares + // 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 @@ -918,38 +994,33 @@ void Position::do_castle_move(Move m) { clear_bit(&(byTypeBB[ROOK]), rfrom); clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares - // Put pieces on destination 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] = piece_of_color_and_type(us, KING); - board[rto] = piece_of_color_and_type(us, ROOK); - - // Update king square - kingSquare[us] = kto; + board[kto] = king; + board[rto] = rook; // Update piece lists pieceList[us][KING][index[kfrom]] = kto; pieceList[us][ROOK][index[rfrom]] = rto; - int tmp = index[rfrom]; + int tmp = index[rfrom]; // In Chess960 could be rto == kfrom index[kto] = index[kfrom]; index[rto] = tmp; // Update incremental scores - st->mgValue -= pst(us, KING, kfrom); - st->mgValue += pst(us, KING, kto); - st->egValue -= pst(us, KING, kfrom); - st->egValue += pst(us, KING, kto); - st->mgValue -= pst(us, ROOK, rfrom); - st->mgValue += pst(us, ROOK, rto); - st->egValue -= pst(us, ROOK, rfrom); - st->egValue += pst(us, ROOK, rto); + st->mgValue += pst_delta(king, kfrom, kto); + st->egValue += pst_delta(king, kfrom, kto); + st->mgValue += pst_delta(rook, rfrom, rto); + st->egValue += pst_delta(rook, rfrom, rto); // Update hash key st->key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; @@ -971,258 +1042,116 @@ void Position::do_castle_move(Move m) { st->rule50 = 0; // Update checkers BB - st->checkersBB = attacks_to(king_square(them), us); -} - - -/// Position::do_promotion_move() is a private method used to make a promotion -/// move. It is called from the main Position::do_move function. + st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); -void Position::do_promotion_move(Move m) { + // Finish + sideToMove = opposite_color(sideToMove); - Color us, them; - Square from, to; - PieceType promotion; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); - assert(move_is_ok(m)); - assert(move_promotion(m)); - - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); - assert(color_of_piece_on(to) == them || square_is_empty(to)); - - st->capture = type_of_piece_on(to); - - if (st->capture) - do_capture_move(m, st->capture, them, to); - - // Remove pawn - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = EMPTY; - - // Insert promoted piece - promotion = move_promotion(m); - assert(promotion >= KNIGHT && promotion <= QUEEN); - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[promotion]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(us, promotion); - - // Update hash key - st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; - - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from]; - - // 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 - pieceList[us][PAWN][index[from]] = pieceList[us][PAWN][pieceCount[us][PAWN]]; - index[pieceList[us][PAWN][index[from]]] = index[from]; - pieceList[us][promotion][pieceCount[us][promotion] - 1] = to; - index[to] = pieceCount[us][promotion] - 1; - - // Update incremental scores - st->mgValue -= pst(us, PAWN, from); - st->mgValue += pst(us, promotion, to); - st->egValue -= pst(us, PAWN, from); - st->egValue += pst(us, promotion, to); - - // Update material - npMaterial[us] += piece_value_midgame(promotion); - - // Clear the en passant square - if (st->epSquare != SQ_NONE) - { - st->key ^= zobEp[st->epSquare]; - st->epSquare = SQ_NONE; - } - - // Update castle rights - st->key ^= zobCastle[st->castleRights]; - st->castleRights &= castleRightsMask[to]; - st->key ^= zobCastle[st->castleRights]; - - // Reset rule 50 counter - st->rule50 = 0; - - // Update checkers BB - st->checkersBB = attacks_to(king_square(them), us); } -/// Position::do_ep_move() is a private method used to make an en passant -/// capture. It is called from the main Position::do_move function. - -void Position::do_ep_move(Move m) { +/// 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. - Color us, them; - Square from, to, capsq; +void Position::undo_move(Move m) { assert(is_ok()); assert(move_is_ok(m)); - assert(move_is_ep(m)); - - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == st->epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == EMPTY); - assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); - assert(piece_on(capsq) == piece_of_color_and_type(them, PAWN)); - - // Remove captured piece - clear_bit(&(byColorBB[them]), capsq); - clear_bit(&(byTypeBB[PAWN]), capsq); - clear_bit(&(byTypeBB[0]), capsq); // HACK: byTypeBB[0] == occupied squares - board[capsq] = EMPTY; - - // Remove moving piece from source square - clear_bit(&(byColorBB[us]), from); - clear_bit(&(byTypeBB[PAWN]), from); - clear_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - - // Put moving piece on destination square - set_bit(&(byColorBB[us]), to); - set_bit(&(byTypeBB[PAWN]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = board[from]; - board[from] = EMPTY; - // Update material hash key - st->materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; - - // Update piece count - pieceCount[them][PAWN]--; - - // Update piece list - pieceList[us][PAWN][index[from]] = to; - index[to] = index[from]; - pieceList[them][PAWN][index[capsq]] = pieceList[them][PAWN][pieceCount[them][PAWN]]; - index[pieceList[them][PAWN][index[capsq]]] = index[capsq]; + gamePly--; + sideToMove = opposite_color(sideToMove); - // Update hash key - st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - st->key ^= zobrist[them][PAWN][capsq]; - st->key ^= zobEp[st->epSquare]; + if (move_is_castle(m)) + { + undo_castle_move(m); + return; + } - // Update pawn hash key - st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - st->pawnKey ^= zobrist[them][PAWN][capsq]; + 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); - // Update incremental scores - st->mgValue -= pst(them, PAWN, capsq); - st->mgValue -= pst(us, PAWN, from); - st->mgValue += pst(us, PAWN, to); - st->egValue -= pst(them, PAWN, capsq); - st->egValue -= pst(us, PAWN, from); - st->egValue += pst(us, PAWN, to); + PieceType pt = type_of_piece_on(to); - // Reset en passant square - st->epSquare = SQ_NONE; + 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)); - // Reset rule 50 counter - st->rule50 = 0; + if (pm) // promotion ? + { + PieceType promotion = move_promotion_piece(m); + pt = PAWN; + + assert(promotion >= KNIGHT && promotion <= QUEEN); + assert(piece_on(to) == piece_of_color_and_type(us, promotion)); + + // Replace promoted piece with a pawn + clear_bit(&(byTypeBB[promotion]), to); + set_bit(&(byTypeBB[PAWN]), to); + + // Update piece counts + pieceCount[us][promotion]--; + pieceCount[us][PAWN]++; + + // Update piece list replacing promotion piece with a pawn + Square lastPromotionSquare = pieceList[us][promotion][pieceCount[us][promotion]]; + index[lastPromotionSquare] = index[to]; + pieceList[us][promotion][index[lastPromotionSquare]] = lastPromotionSquare; + pieceList[us][promotion][pieceCount[us][promotion]] = SQ_NONE; + index[to] = pieceCount[us][PAWN] - 1; + pieceList[us][PAWN][index[to]] = to; + } - // Update checkers BB - st->checkersBB = attacks_to(king_square(them), us); -} + // 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 -/// 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. + board[from] = piece_of_color_and_type(us, pt); + board[to] = EMPTY; -void Position::undo_move(Move m) { + // Update piece list + index[from] = index[to]; + pieceList[us][pt][index[from]] = from; - assert(is_ok()); - assert(move_is_ok(m)); + if (st->capture) + { + Square capsq = to; - gamePly--; - sideToMove = opposite_color(sideToMove); + if (ep) + capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - if (move_is_castle(m)) - undo_castle_move(m); - else if (move_promotion(m)) - undo_promotion_move(m); - else if (move_is_ep(m)) - undo_ep_move(m); - else - { - Color us, them; - Square from, to; - PieceType piece; - - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - - assert(piece_on(from) == EMPTY); - assert(color_of_piece_on(to) == us); - - // Put the piece back at the source square - piece = type_of_piece_on(to); - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[piece]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = piece_of_color_and_type(us, piece); - - // Clear the destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[piece]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - - // If the moving piece was a king, update the king square - if (piece == KING) - kingSquare[us] = from; - - // Update piece list - pieceList[us][piece][index[to]] = from; - index[from] = index[to]; - - if (st->capture) - { - assert(st->capture != KING); + assert(st->capture != KING); + assert(!ep || square_is_empty(capsq)); - // Replace the captured piece - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[st->capture]), to); - set_bit(&(byTypeBB[0]), to); - board[to] = piece_of_color_and_type(them, st->capture); + // Restore the captured piece + set_bit(&(byColorBB[them]), capsq); + set_bit(&(byTypeBB[st->capture]), capsq); + set_bit(&(byTypeBB[0]), capsq); - // Update material - if (st->capture != PAWN) - npMaterial[them] += piece_value_midgame(st->capture); + board[capsq] = piece_of_color_and_type(them, st->capture); - // Update piece list - pieceList[them][st->capture][pieceCount[them][st->capture]] = to; - index[to] = pieceCount[them][st->capture]; + // Update piece count + pieceCount[them][st->capture]++; - // Update piece count - pieceCount[them][st->capture]++; - } else - board[to] = EMPTY; + // 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; } - // Finally point out state pointer back to the previous state + // Finally point our state pointer back to the previous state st = st->previous; assert(is_ok()); @@ -1261,16 +1190,16 @@ void Position::undo_castle_move(Move m) { 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 + + // 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 + + // 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 @@ -1283,182 +1212,59 @@ void Position::undo_castle_move(Move m) { board[rfrom] = piece_of_color_and_type(us, ROOK); board[kfrom] = piece_of_color_and_type(us, KING); - // Update king square - kingSquare[us] = kfrom; - // Update piece lists pieceList[us][KING][index[kto]] = kfrom; pieceList[us][ROOK][index[rto]] = rfrom; - int tmp = index[rto]; // Necessary because we may have rto == kfrom in FRC. + int tmp = index[rto]; // In Chess960 could be rto == kfrom index[kfrom] = index[kto]; index[rfrom] = tmp; -} - - -/// Position::undo_promotion_move() is a private method used to unmake a -/// promotion move. It is called from the main Position::do_move -/// function. - -void Position::undo_promotion_move(Move m) { - - Color us, them; - Square from, to; - PieceType promotion; - - assert(move_is_ok(m)); - assert(move_promotion(m)); - - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - us = side_to_move(); - them = opposite_color(us); - from = move_from(m); - to = move_to(m); - - assert(relative_rank(us, to) == RANK_8); - assert(piece_on(from) == EMPTY); - - // Remove promoted piece - promotion = move_promotion(m); - assert(piece_on(to)==piece_of_color_and_type(us, promotion)); - assert(promotion >= KNIGHT && promotion <= QUEEN); - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[promotion]), to); - clear_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - - // Insert pawn at source square - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); // HACK: byTypeBB[0] == occupied squares - board[from] = piece_of_color_and_type(us, PAWN); - - // Update material - npMaterial[us] -= piece_value_midgame(promotion); - - // Update piece list - pieceList[us][PAWN][pieceCount[us][PAWN]] = from; - index[from] = pieceCount[us][PAWN]; - pieceList[us][promotion][index[to]] = - pieceList[us][promotion][pieceCount[us][promotion] - 1]; - index[pieceList[us][promotion][index[to]]] = index[to]; - - // Update piece counts - pieceCount[us][promotion]--; - pieceCount[us][PAWN]++; - - if (st->capture) - { - assert(st->capture != KING); - - // Insert captured piece: - set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[st->capture]), to); - set_bit(&(byTypeBB[0]), to); // HACK: byTypeBB[0] == occupied squares - board[to] = piece_of_color_and_type(them, st->capture); - - // Update material. Because the move is a promotion move, we know - // that the captured piece cannot be a pawn. - assert(st->capture != PAWN); - npMaterial[them] += piece_value_midgame(st->capture); - - // Update piece list - pieceList[them][st->capture][pieceCount[them][st->capture]] = to; - index[to] = pieceCount[them][st->capture]; - - // Update piece count - pieceCount[them][st->capture]++; - } else - board[to] = EMPTY; -} - - -/// Position::undo_ep_move() is a private method used to unmake an en passant -/// capture. It is called from the main Position::undo_move function. - -void Position::undo_ep_move(Move m) { - - assert(move_is_ok(m)); - assert(move_is_ep(m)); - - // When we have arrived here, some work has already been done by - // Position::undo_move. In particular, the side to move has been switched, - // so the code below is correct. - Color us = side_to_move(); - Color them = opposite_color(us); - Square from = move_from(m); - Square to = move_to(m); - Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - - assert(to == st->previous->epSquare); - assert(relative_rank(us, to) == RANK_6); - assert(piece_on(to) == piece_of_color_and_type(us, PAWN)); - assert(piece_on(from) == EMPTY); - assert(piece_on(capsq) == EMPTY); - - // Replace captured piece - set_bit(&(byColorBB[them]), capsq); - set_bit(&(byTypeBB[PAWN]), capsq); - set_bit(&(byTypeBB[0]), capsq); - board[capsq] = piece_of_color_and_type(them, PAWN); - - // Remove moving piece from destination square - clear_bit(&(byColorBB[us]), to); - clear_bit(&(byTypeBB[PAWN]), to); - clear_bit(&(byTypeBB[0]), to); - board[to] = EMPTY; - // Replace moving piece at source square - set_bit(&(byColorBB[us]), from); - set_bit(&(byTypeBB[PAWN]), from); - set_bit(&(byTypeBB[0]), from); - board[from] = piece_of_color_and_type(us, PAWN); - - // Update piece list: - pieceList[us][PAWN][index[to]] = from; - index[from] = index[to]; - pieceList[them][PAWN][pieceCount[them][PAWN]] = capsq; - index[capsq] = pieceCount[them][PAWN]; + // Finally point our state pointer back to the previous state + st = st->previous; - // Update piece count: - pieceCount[them][PAWN]++; + assert(is_ok()); } /// Position::do_null_move makes() a "null move": It switches the side to move /// and updates the hash key without executing any move on the board. -void Position::do_null_move(StateInfo& newSt) { +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. In the case of a null move, the only thing we need to - // remember is the last move made and the en passant square. - newSt.lastMove = st->lastMove; - newSt.epSquare = st->epSquare; - newSt.previous = st->previous; - st->previous = &newSt; + // StateInfo object. + // Note that differently from normal case here backupSt is actually used as + // a backup storage not as a new state to be used. + backupSt.key = st->key; + backupSt.epSquare = st->epSquare; + backupSt.mgValue = st->mgValue; + backupSt.egValue = st->egValue; + backupSt.previous = st->previous; + backupSt.pliesFromNull = st->pliesFromNull; + st->previous = &backupSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. history[gamePly] = st->key; // Update the necessary information - sideToMove = opposite_color(sideToMove); if (st->epSquare != SQ_NONE) st->key ^= zobEp[st->epSquare]; + st->key ^= zobSideToMove; + TT.prefetch(st->key); + + sideToMove = opposite_color(sideToMove); st->epSquare = SQ_NONE; st->rule50++; + st->pliesFromNull = 0; gamePly++; - st->key ^= zobSideToMove; st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; - - assert(is_ok()); } @@ -1469,24 +1275,19 @@ void Position::undo_null_move() { assert(is_ok()); assert(!is_check()); - // Restore information from the our StateInfo object - st->lastMove = st->previous->lastMove; - st->epSquare = st->previous->epSquare; - st->previous = st->previous->previous; - - if (st->epSquare != SQ_NONE) - st->key ^= zobEp[st->epSquare]; + // Restore information from the our backup StateInfo object + StateInfo* backupSt = st->previous; + st->key = backupSt->key; + st->epSquare = backupSt->epSquare; + st->mgValue = backupSt->mgValue; + st->egValue = backupSt->egValue; + st->previous = backupSt->previous; + st->pliesFromNull = backupSt->pliesFromNull; // Update the necessary information sideToMove = opposite_color(sideToMove); st->rule50--; gamePly--; - st->key ^= zobSideToMove; - - st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; - - assert(is_ok()); } @@ -1499,16 +1300,32 @@ void Position::undo_null_move() { int Position::see(Square to) const { assert(square_is_ok(to)); - return see(SQ_NONE, to); + return see(SQ_NONE, to, false); } int Position::see(Move m) const { assert(move_is_ok(m)); - return see(move_from(m), move_to(m)); + return see(move_from(m), move_to(m), false); +} + +int Position::see_sign(Move m) const { + + assert(move_is_ok(m)); + + Square from = move_from(m); + Square to = move_to(m); + + // Early return if SEE cannot be negative because capturing piece value + // is not bigger then captured one. + if ( midgame_value_of_piece_on(from) <= midgame_value_of_piece_on(to) + && type_of_piece_on(from) != KING) + return 1; + + return see(from, to, true); } -int Position::see(Square from, Square to) const { +int Position::see(Square from, Square to, bool shortcut) const { // Material values static const int seeValues[18] = { @@ -1519,8 +1336,10 @@ int Position::see(Square from, Square to) const { 0, 0 }; - Bitboard attackers, occ, b; + Bitboard attackers, stmAttackers, b; + int pieceDiff = 0; + assert(!shortcut || from != SQ_NONE); assert(square_is_ok(from) || from == SQ_NONE); assert(square_is_ok(to)); @@ -1528,18 +1347,30 @@ int Position::see(Square from, Square to) const { Color us = (from != SQ_NONE ? color_of_piece_on(from) : opposite_color(color_of_piece_on(to))); Color them = opposite_color(us); - // Initialize pinned and pinners bitboards - Bitboard pinned[2], pinners[2]; - pinned[us] = pinned_pieces(us, pinners[us]); - pinned[them] = pinned_pieces(them, pinners[them]); - // Initialize pieces Piece piece = piece_on(from); Piece capture = piece_on(to); + Bitboard occ = occupied_squares(); + + // King cannot be recaptured + if (type_of_piece(piece) == KING) + return seeValues[capture]; + + // If captured piece is defended by enemy pawns or knights then SEE is negative + // when captured piece value does not compensate the lost of capturing one. + if (shortcut) + { + pieceDiff = seeValues[piece] - seeValues[capture]; - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - occ = occupied_squares(); + if ( pieceDiff > seeValues[PAWN] + &&(attacks_from(to, us) & pieces(PAWN, them))) + return -(pieceDiff - seeValues[PAWN] / 2); + + if ( pieceDiff > seeValues[KNIGHT] + && pieces(KNIGHT, them) + &&(pieces(KNIGHT, them) & attacks_from(to))) + return -(pieceDiff - seeValues[KNIGHT] / 2); + } // Handle en passant moves if (st->epSquare == to && type_of_piece_on(from) == PAWN) @@ -1548,7 +1379,6 @@ int Position::see(Square from, Square to) const { 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 @@ -1557,24 +1387,15 @@ int Position::see(Square from, Square to) const { while (true) { + // 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) & rooks_and_queens()) - | (bishop_attacks_bb(to, occ) & bishops_and_queens()) - | (piece_attacks(to) & knights()) - | (piece_attacks(to) & kings()) - | (pawn_attacks(WHITE, to) & pawns(BLACK)) - | (pawn_attacks(BLACK, to) & pawns(WHITE)); - - // Remove our pinned pieces from attacks if the captured piece is not - // a pinner, otherwise we could remove a valid "capture the pinner" attack. - if (pinned[us] != EmptyBoardBB && !bit_is_set(pinners[us], to)) - attackers &= ~pinned[us]; - - // Remove opponent pinned pieces from attacks if the moving piece is not - // a pinner, otherwise we could remove a piece that is no more pinned - // due to our pinner piece is moving away. - if (pinned[them] != EmptyBoardBB && !bit_is_set(pinners[them], from)) - attackers &= ~pinned[them]; + 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; @@ -1585,16 +1406,18 @@ int Position::see(Square from, Square to) const { // 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; !(attackers & pieces_of_color_and_type(us, pt)); pt++) + for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++) assert(pt < KING); - from = first_1(attackers & pieces_of_color_and_type(us, pt)); + from = first_1(stmAttackers & pieces(pt)); piece = piece_on(from); } // If the opponent has no attackers we are finished - if ((attackers & pieces_of_color(them)) == EmptyBoardBB) + stmAttackers = attackers & pieces_of_color(them); + if (!stmAttackers) return seeValues[capture]; attackers &= occ; // Remove the moving piece @@ -1616,15 +1439,24 @@ int Position::see(Square from, Square to) const { // Locate the least valuable attacker for the side to move. The loop // below looks like it is potentially infinite, but it isn't. We know // that the side to move still has at least one attacker left. - for (pt = PAWN; !(attackers & pieces_of_color_and_type(c, pt)); pt++) + for (pt = PAWN; !(stmAttackers & pieces(pt)); pt++) assert(pt < KING); + // If captured piece is defended by an enemy piece then SEE is negative + // if captured piece value does not compensate the lost of capturing one. + if (pieceDiff > seeValues[pt]) + { + assert(shortcut); + return -(pieceDiff - seeValues[pt] / 2); + } else + pieceDiff = 0; // Only first cycle + // Remove the attacker we just found from the 'attackers' bitboard, // and scan for new X-ray attacks behind the attacker. - b = attackers & pieces_of_color_and_type(c, pt); - occ ^= (b & -b); - attackers |= (rook_attacks_bb(to, occ) & rooks_and_queens()) - | (bishop_attacks_bb(to, occ) & bishops_and_queens()); + 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; @@ -1637,21 +1469,16 @@ int Position::see(Square from, Square to) const { // before beginning the next iteration lastCapturingPieceValue = seeValues[pt]; c = opposite_color(c); - - // Remove pinned pieces from attackers - if ( pinned[c] != EmptyBoardBB - && !bit_is_set(pinners[c], to) - && !(pinners[c] & attackers)) - attackers &= ~pinned[c]; + stmAttackers = attackers & pieces_of_color(c); // Stop after a king capture - if (pt == KING && (attackers & pieces_of_color(c))) + if (pt == KING && stmAttackers) { assert(n < 32); - swapList[n++] = 100; + swapList[n++] = QueenValueMidgame*10; break; } - } while (attackers & pieces_of_color(c)); + } 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 @@ -1662,15 +1489,16 @@ int Position::see(Square from, Square to) const { } -/// Position::setStartState() copies the content of the argument +/// Position::saveState() copies the content of the current state /// inside startState and makes st point to it. This is needed /// when the st pointee could become stale, as example because /// the caller is about to going out of scope. -void Position::setStartState(const StateInfo& s) { +void Position::saveState() { - startState = s; + startState = *st; st = &startState; + st->previous = NULL; // as a safe guard } @@ -1683,19 +1511,17 @@ void Position::clear() { memset(st, 0, sizeof(StateInfo)); st->epSquare = SQ_NONE; - memset(index, 0, sizeof(int) * 64); - memset(byColorBB, 0, sizeof(Bitboard) * 2); + memset(byColorBB, 0, sizeof(Bitboard) * 2); + memset(byTypeBB, 0, sizeof(Bitboard) * 8); + memset(pieceCount, 0, sizeof(int) * 2 * 8); + memset(index, 0, sizeof(int) * 64); for (int i = 0; i < 64; i++) board[i] = EMPTY; - for (int i = 0; i < 7; i++) - { - byTypeBB[i] = EmptyBoardBB; - pieceCount[0][i] = pieceCount[1][i] = 0; - for (int j = 0; j < 8; j++) + for (int i = 0; i < 8; i++) + for (int j = 0; j < 16; j++) pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; - } sideToMove = WHITE; gamePly = 0; @@ -1734,9 +1560,6 @@ void Position::put_piece(Piece p, Square s) { set_bit(&byTypeBB[0], s); // HACK: byTypeBB[0] contains all occupied squares. pieceCount[c][pt]++; - - if (pt == KING) - kingSquare[c] = s; } @@ -1796,7 +1619,7 @@ Key Position::compute_pawn_key() const { for (Color c = WHITE; c <= BLACK; c++) { - b = pawns(c); + b = pieces(PAWN, c); while(b) { s = pop_1st_bit(&b); @@ -1841,7 +1664,7 @@ Value Position::compute_value() const { for (Color c = WHITE; c <= BLACK; c++) for (PieceType pt = PAWN; pt <= KING; pt++) { - b = pieces_of_color_and_type(c, pt); + b = pieces(pt, c); while(b) { s = pop_1st_bit(&b); @@ -1864,15 +1687,14 @@ Value Position::compute_value() const { Value Position::compute_non_pawn_material(Color c) const { Value result = Value(0); - Square s; for (PieceType pt = KNIGHT; pt <= QUEEN; pt++) { - Bitboard b = pieces_of_color_and_type(c, pt); - while(b) + Bitboard b = pieces(pt, c); + while (b) { - s = pop_1st_bit(&b); - assert(piece_on(s) == piece_of_color_and_type(c, pt)); + assert(piece_on(first_1(b)) == piece_of_color_and_type(c, pt)); + pop_1st_bit(&b); result += piece_value_midgame(pt); } } @@ -1880,21 +1702,6 @@ Value Position::compute_non_pawn_material(Color c) const { } -/// Position::is_mate() returns true or false depending on whether the -/// side to move is checkmated. Note that this function is currently very -/// slow, and shouldn't be used frequently inside the search. - -bool Position::is_mate() const { - - if (is_check()) - { - MovePicker mp = MovePicker(*this, false, MOVE_NONE, EmptySearchStack, Depth(0)); - return mp.get_next_move() == MOVE_NONE; - } - return false; -} - - /// 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. @@ -1902,7 +1709,7 @@ bool Position::is_mate() const { bool Position::is_draw() const { // Draw by material? - if ( !pawns() + if ( !pieces(PAWN) && (non_pawn_material(WHITE) + non_pawn_material(BLACK) <= BishopValueMidgame)) return true; @@ -1911,7 +1718,7 @@ bool Position::is_draw() const { return true; // Draw by repetition? - for (int i = 2; i < Min(gamePly, st->rule50); i += 2) + for (int i = 2; i < Min(Min(gamePly, st->rule50), st->pliesFromNull); i += 2) if (history[gamePly - i] == st->key) return true; @@ -1919,21 +1726,25 @@ 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 { + + MoveStack moves[256]; + + return is_check() && (generate_evasions(*this, moves, pinned_pieces(sideToMove)) == moves); +} + + /// Position::has_mate_threat() tests whether a given color has a mate in one -/// from the current position. This function is quite slow, but it doesn't -/// matter, because it is currently only called from PV nodes, which are rare. +/// from the current position. bool Position::has_mate_threat(Color c) { StateInfo st1, st2; Color stm = side_to_move(); - // The following lines are useless and silly, but prevents gcc from - // emitting a stupid warning stating that u1.lastMove and u1.epSquare might - // be used uninitialized. - st1.lastMove = st->lastMove; - st1.epSquare = st->epSquare; - if (is_check()) return false; @@ -1942,20 +1753,26 @@ bool Position::has_mate_threat(Color c) { do_null_move(st1); MoveStack mlist[120]; - int count; bool result = false; + Bitboard dc = discovered_check_candidates(sideToMove); + Bitboard pinned = pinned_pieces(sideToMove); - // Generate legal moves - count = generate_legal_moves(*this, mlist); + // Generate pseudo-legal non-capture and capture check moves + MoveStack* last = generate_non_capture_checks(*this, mlist, dc); + last = generate_captures(*this, last); // Loop through the moves, and see if one of them is mate - for (int i = 0; i < count; i++) + for (MoveStack* cur = mlist; cur != last; cur++) { - do_move(mlist[i].move, st2); + Move move = cur->move; + if (!pl_move_is_legal(move, pinned)) + continue; + + do_move(move, st2); if (is_mate()) result = true; - undo_move(mlist[i].move); + undo_move(move); } // Undo null move, if necessary @@ -2025,7 +1842,7 @@ void Position::init_piece_square_tables() { /// 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) { +void Position::flipped_copy(const Position& pos) { assert(pos.is_ok()); @@ -2076,8 +1893,8 @@ void Position::flipped_copy(const Position &pos) { st->egValue = compute_value(); // Material - npMaterial[WHITE] = compute_non_pawn_material(WHITE); - npMaterial[BLACK] = compute_non_pawn_material(BLACK); + st->npMaterial[WHITE] = compute_non_pawn_material(WHITE); + st->npMaterial[BLACK] = compute_non_pawn_material(BLACK); assert(is_ok()); } @@ -2144,7 +1961,7 @@ bool Position::is_ok(int* failedStep) const { Color us = side_to_move(); Color them = opposite_color(us); Square ksq = king_square(them); - if (square_is_attacked(ksq, us)) + if (attackers_to(ksq) & pieces_of_color(us)) return false; } @@ -2169,7 +1986,7 @@ bool Position::is_ok(int* failedStep) const { // Separate piece type bitboards must have empty intersections for (PieceType p1 = PAWN; p1 <= KING; p1++) for (PieceType p2 = PAWN; p2 <= KING; p2++) - if (p1 != p2 && (pieces_of_type(p1) & pieces_of_type(p2))) + if (p1 != p2 && (pieces(p1) & pieces(p2))) return false; } @@ -2213,10 +2030,10 @@ bool Position::is_ok(int* failedStep) const { if (failedStep) (*failedStep)++; if (debugNonPawnMaterial) { - if (npMaterial[WHITE] != compute_non_pawn_material(WHITE)) + if (st->npMaterial[WHITE] != compute_non_pawn_material(WHITE)) return false; - if (npMaterial[BLACK] != compute_non_pawn_material(BLACK)) + if (st->npMaterial[BLACK] != compute_non_pawn_material(BLACK)) return false; } @@ -2225,7 +2042,7 @@ 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_of_color_and_type(c, pt))) + if (pieceCount[c][pt] != count_1s(pieces(pt, c))) return false; if (failedStep) (*failedStep)++;