X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=05e093a8a6fc8b2bae8085d1d7f0eab1806ba324;hp=21b00f80536d45cd3fedd9784b7f3bbca1017089;hb=f9f30412e798b4ba06375a383a85a9e65bfe299f;hpb=9b257ba29de2b0d50b6bdbd175509fdb3aaf8e91 diff --git a/src/position.cpp b/src/position.cpp index 21b00f80..05e093a8 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -23,8 +23,9 @@ //// #include -#include +#include #include +#include #include "mersenne.h" #include "movegen.h" @@ -192,7 +193,7 @@ void Position::from_fen(const std::string& fen) { if ( i < fen.length() - 2 && (fen[i] >= 'a' && fen[i] <= 'h') && (fen[i+1] == '3' || fen[i+1] == '6')) - epSquare = square_from_string(fen.substr(i, 2)); + st->epSquare = square_from_string(fen.substr(i, 2)); // Various initialisation for (Square sq = SQ_A1; sq <= SQ_H8; sq++) @@ -206,12 +207,13 @@ void Position::from_fen(const std::string& fen) { castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; find_checkers(); + find_hidden_checks(); - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); - mgValue = compute_value(); - egValue = compute_value(); + 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); } @@ -249,7 +251,7 @@ const std::string Position::to_fen() const { fen += (rank > RANK_1 ? '/' : ' '); } fen += (sideToMove == WHITE ? "w " : "b "); - if (castleRights != NO_CASTLES) + if (st->castleRights != NO_CASTLES) { if (can_castle_kingside(WHITE)) fen += 'K'; if (can_castle_queenside(WHITE)) fen += 'Q'; @@ -305,7 +307,7 @@ void Position::print(Move m) const { } std::cout << "+---+---+---+---+---+---+---+---+" << std::endl << "Fen is: " << to_fen() << std::endl - << "Key is: " << key << std::endl; + << "Key is: " << st->key << std::endl; RequestPending = false; } @@ -319,44 +321,11 @@ void Position::copy(const Position &pos) { } -/// Position:pinned_pieces() returns a bitboard of all pinned (against the -/// king) pieces for the given color. -Bitboard Position::pinned_pieces(Color c) const { - - if (pinned[c] != ~EmptyBoardBB) - return pinned[c]; - - Bitboard p1, p2; - Square ksq = king_square(c); - pinned[c] = hidden_checks(c, ksq, p1) | hidden_checks(c, ksq, p2); - pinners[c] = p1 | p2; - return pinned[c]; -} - -Bitboard Position::pinned_pieces(Color c, Bitboard& p) const { - - if (pinned[c] == ~EmptyBoardBB) - pinned_pieces(c); - - p = pinners[c]; - return pinned[c]; -} - -Bitboard Position::discovered_check_candidates(Color c) const { - - if (dcCandidates[c] != ~EmptyBoardBB) - return dcCandidates[c]; - - Bitboard dummy; - Square ksq = king_square(opposite_color(c)); - dcCandidates[c] = hidden_checks(c, ksq, dummy) | hidden_checks(c, ksq, dummy); - return dcCandidates[c]; -} - /// Position:hidden_checks<>() returns a bitboard of all pinned (against the /// king) pieces for the given color and for the given pinner type. Or, when /// template parameter FindPinned is false, the pinned pieces of opposite color /// that are, indeed, the pieces candidate for a discovery check. +/// Note that checkersBB bitboard must be already updated. template Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const { @@ -368,14 +337,14 @@ Bitboard Position::hidden_checks(Color c, Square ksq, Bitboard& pinners) const { else sliders = bishops_and_queens(FindPinned ? opposite_color(c) : c) & BishopPseudoAttacks[ksq]; - if (sliders && (!FindPinned || (sliders & ~checkersBB))) + if (sliders && (!FindPinned || (sliders & ~st->checkersBB))) { // 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 & ~checkersBB : sliders); + pinners = (FindPinned ? sliders & ~st->checkersBB : sliders); if (Piece == ROOK) pinners &= rook_attacks_bb(ksq, occupied_squares() ^ candidate_pinned); @@ -466,7 +435,7 @@ bool Position::move_attacks_square(Move m, Square s) const { /// Position::find_checkers() computes the checkersBB bitboard, which -/// contains a nonzero bit for each checking piece (0, 1 or 2). It +/// contains a nonzero bit for each checking piece (0, 1 or 2). It /// currently works by calling Position::attacks_to, which is probably /// inefficient. Consider rewriting this function to use the last move /// played, like in non-bitboard versions of Glaurung. @@ -474,7 +443,28 @@ bool Position::move_attacks_square(Move m, Square s) const { void Position::find_checkers() { Color us = side_to_move(); - checkersBB = attacks_to(king_square(us), opposite_color(us)); + st->checkersBB = attacks_to(king_square(us), opposite_color(us)); +} + +/// Position:find_hidden_checks() computes the pinned, pinners and dcCandidates +/// bitboards. There are two versions of this function. One takes a color and +/// computes bitboards relative to that color only, the other computes both +/// colors. Bitboard checkersBB must be already updated. + +void Position::find_hidden_checks(Color us) { + + Bitboard p1, p2; + Color them = opposite_color(us); + Square ksq = king_square(them); + st->pinned[them] = hidden_checks(them, ksq, p1) | hidden_checks(them, ksq, p2); + st->pinners[them] = p1 | p2; + st->dcCandidates[us] = hidden_checks(us, ksq, p1) | hidden_checks(us, ksq, p2); +} + +void Position::find_hidden_checks() { + + for (Color c = WHITE; c <= BLACK; c++) + find_hidden_checks(c); } @@ -669,7 +659,8 @@ bool Position::move_is_capture(Move m) const { } -/// 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, @@ -689,36 +680,78 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square } -/// Position::do_move() makes a move, and backs up all information necessary -/// to undo the move to an UndoInfo object. The move is assumed to be legal. +/// Position::update_hidden_checks() udpates pinned, pinners and dcCandidates +/// bitboards incrementally, given the move. It is called in do_move and is +/// faster then find_hidden_checks(). + +void Position::update_hidden_checks(Square from, Square to) { + + Color us = sideToMove; + Color them = opposite_color(us); + Square ksq = king_square(opposite_color(us)); + + Bitboard moveSquares = EmptyBoardBB; + set_bit(&moveSquares, from); + set_bit(&moveSquares, to); + + // Our moving piece could have been a possible pinner or hidden checker behind a dcCandidates? + bool checkerMoved = (st->dcCandidates[us] | st->pinners[them]) && (moveSquares & sliders()); + + // If we are moving from/to an opponent king attack direction and we was a possible hidden checker + // or there exsist some possible hidden checker on that line then recalculate the position + // otherwise skip because our dcCandidates and opponent pinned pieces are not changed. + if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerMoved || (rooks_and_queens(us) & RookPseudoAttacks[ksq])) + || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerMoved || (bishops_and_queens(us) & BishopPseudoAttacks[ksq]))) + find_hidden_checks(us); + + ksq = king_square(us); + + if (ksq == to) + { + find_hidden_checks(them); + return; + } + + // It is possible that we have captured an opponent hidden checker? + Bitboard checkerCaptured = (st->dcCandidates[them] | st->pinners[us]) && st->capture; + + // If we are moving from/to an our king attack direction and there was/is some possible + // opponent hidden checker then calculate the position otherwise skip because opponent + // dcCandidates and our pinned pieces are not changed. + if ( (moveSquares & RookPseudoAttacks[ksq]) && (checkerCaptured || (rooks_and_queens(them) & RookPseudoAttacks[ksq])) + || (moveSquares & BishopPseudoAttacks[ksq]) && (checkerCaptured || (bishops_and_queens(them) & BishopPseudoAttacks[ksq]))) + find_hidden_checks(them); +} + + +/// 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, UndoInfo& u) { +void Position::do_move(Move m, StateInfo& newSt) { assert(is_ok()); assert(move_is_ok(m)); - // Get now the current (pre-move) dc candidates that we will use + // Get now the current (before to move) dc candidates that we will use // in update_checkers(). Bitboard oldDcCandidates = discovered_check_candidates(side_to_move()); - // Back up the necessary information to our UndoInfo object (except the - // captured piece, which is taken care of later. - u = undoInfoUnion; - u.capture = NO_PIECE_TYPE; - previous = &u; + // 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. + newSt = *st; + newSt.capture = NO_PIECE_TYPE; + newSt.previous = st; + st = &newSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. - history[gamePly] = key; + history[gamePly] = st->key; // Increment the 50 moves rule draw counter. Resetting it to zero in the // case of non-reversible moves is taken care of later. - rule50++; - - // Reset pinned bitboard and its friends - for (Color c = WHITE; c <= BLACK; c++) - pinners[c] = pinned[c] = dcCandidates[c] = ~EmptyBoardBB; + st->rule50++; if (move_is_castle(m)) do_castle_move(m); @@ -737,13 +770,11 @@ void Position::do_move(Move m, UndoInfo& u) { assert(color_of_piece_on(to) == them || piece_on(to) == EMPTY); PieceType piece = type_of_piece_on(from); - PieceType capture = type_of_piece_on(to); - if (capture) - { - u.capture = capture; - do_capture_move(m, capture, them, to); - } + st->capture = type_of_piece_on(to); + + if (st->capture) + do_capture_move(m, st->capture, them, to); // Move the piece clear_bit(&(byColorBB[us]), from); @@ -756,33 +787,33 @@ void Position::do_move(Move m, UndoInfo& u) { board[from] = EMPTY; // Update hash key - key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; + st->key ^= zobrist[us][piece][from] ^ zobrist[us][piece][to]; // Update incremental scores - mgValue -= pst(us, piece, from); - mgValue += pst(us, piece, to); - egValue -= pst(us, piece, from); - egValue += pst(us, piece, to); + st->mgValue -= pst(us, piece, from); + st->mgValue += pst(us, piece, to); + st->egValue -= pst(us, piece, from); + st->egValue += pst(us, piece, to); // If the moving piece was a king, update the king square if (piece == KING) kingSquare[us] = to; // Reset en passant square - if (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // If the moving piece was a pawn do some special extra work if (piece == PAWN) { // Reset rule 50 draw counter - rule50 = 0; + st->rule50 = 0; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + 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) @@ -790,8 +821,8 @@ void Position::do_move(Move m, UndoInfo& u) { if ( (us == WHITE && (pawn_attacks(WHITE, from + DELTA_N) & pawns(BLACK))) || (us == BLACK && (pawn_attacks(BLACK, from + DELTA_S) & pawns(WHITE)))) { - epSquare = Square((int(from) + int(to)) / 2); - key ^= zobEp[epSquare]; + st->epSquare = Square((int(from) + int(to)) / 2); + st->key ^= zobEp[st->epSquare]; } } } @@ -801,33 +832,35 @@ void Position::do_move(Move m, UndoInfo& u) { index[to] = index[from]; // Update castle rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[from]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[from]; + st->castleRights &= castleRightsMask[to]; + st->key ^= zobCastle[st->castleRights]; // Update checkers bitboard, piece must be already moved - checkersBB = EmptyBoardBB; + st->checkersBB = EmptyBoardBB; Square ksq = king_square(them); switch (piece) { - case PAWN: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case KNIGHT: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case BISHOP: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case ROOK: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case QUEEN: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; - case KING: update_checkers(&checkersBB, ksq, from, to, oldDcCandidates); break; + 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_hidden_checks(from, to); } // Finish - key ^= zobSideToMove; + st->key ^= zobSideToMove; sideToMove = opposite_color(sideToMove); gamePly++; - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -845,15 +878,15 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) clear_bit(&(byTypeBB[capture]), to); // Update hash key - key ^= zobrist[them][capture][to]; + st->key ^= zobrist[them][capture][to]; // If the captured piece was a pawn, update pawn hash key if (capture == PAWN) - pawnKey ^= zobrist[them][PAWN][to]; + st->pawnKey ^= zobrist[them][PAWN][to]; // Update incremental scores - mgValue -= pst(them, capture, to); - egValue -= pst(them, capture, to); + st->mgValue -= pst(them, capture, to); + st->egValue -= pst(them, capture, to); assert(!move_promotion(m) || capture != PAWN); @@ -862,7 +895,7 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) npMaterial[them] -= piece_value_midgame(capture); // Update material hash key - materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; + st->materialKey ^= zobMaterial[them][capture][pieceCount[them][capture]]; // Update piece count pieceCount[them][capture]--; @@ -872,7 +905,7 @@ void Position::do_capture_move(Move m, PieceType capture, Color them, Square to) index[pieceList[them][capture][index[to]]] = index[to]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; } @@ -940,49 +973,50 @@ void Position::do_castle_move(Move m) { index[rto] = tmp; // Update incremental scores - mgValue -= pst(us, KING, kfrom); - mgValue += pst(us, KING, kto); - egValue -= pst(us, KING, kfrom); - egValue += pst(us, KING, kto); - mgValue -= pst(us, ROOK, rfrom); - mgValue += pst(us, ROOK, rto); - egValue -= pst(us, ROOK, rfrom); - egValue += pst(us, ROOK, rto); + 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); // Update hash key - key ^= zobrist[us][KING][kfrom] ^ zobrist[us][KING][kto]; - key ^= zobrist[us][ROOK][rfrom] ^ zobrist[us][ROOK][rto]; + 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 (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // Update castling rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[kfrom]; - key ^= zobCastle[castleRights]; + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[kfrom]; + st->key ^= zobCastle[st->castleRights]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); + + // Update hidden checks + find_hidden_checks(); } /// Position::do_promotion_move() is a private method used to make a promotion -/// move. It is called from the main Position::do_move function. The -/// UndoInfo object, which has been initialized in Position::do_move, is -/// used to store the captured piece (if any). +/// move. It is called from the main Position::do_move function. void Position::do_promotion_move(Move m) { Color us, them; Square from, to; - PieceType capture, promotion; + PieceType promotion; assert(is_ok()); assert(move_is_ok(m)); @@ -997,13 +1031,10 @@ void Position::do_promotion_move(Move m) { assert(piece_on(from) == piece_of_color_and_type(us, PAWN)); assert(color_of_piece_on(to) == them || square_is_empty(to)); - capture = type_of_piece_on(to); + st->capture = type_of_piece_on(to); - if (capture) - { - previous->capture = capture; - do_capture_move(m, capture, them, to); - } + if (st->capture) + do_capture_move(m, st->capture, them, to); // Remove pawn clear_bit(&(byColorBB[us]), from); @@ -1020,14 +1051,14 @@ void Position::do_promotion_move(Move m) { board[to] = piece_of_color_and_type(us, promotion); // Update hash key - key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; + st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][promotion][to]; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from]; + st->pawnKey ^= zobrist[us][PAWN][from]; // Update material key - materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; - materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; + st->materialKey ^= zobMaterial[us][PAWN][pieceCount[us][PAWN]]; + st->materialKey ^= zobMaterial[us][promotion][pieceCount[us][promotion]+1]; // Update piece counts pieceCount[us][PAWN]--; @@ -1040,38 +1071,39 @@ void Position::do_promotion_move(Move m) { index[to] = pieceCount[us][promotion] - 1; // Update incremental scores - mgValue -= pst(us, PAWN, from); - mgValue += pst(us, promotion, to); - egValue -= pst(us, PAWN, from); - egValue += pst(us, promotion, to); + 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 (epSquare != SQ_NONE) + if (st->epSquare != SQ_NONE) { - key ^= zobEp[epSquare]; - epSquare = SQ_NONE; + st->key ^= zobEp[st->epSquare]; + st->epSquare = SQ_NONE; } // Update castle rights - key ^= zobCastle[castleRights]; - castleRights &= castleRightsMask[to]; - key ^= zobCastle[castleRights]; + st->key ^= zobCastle[st->castleRights]; + st->castleRights &= castleRightsMask[to]; + st->key ^= zobCastle[st->castleRights]; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); + + // Update hidden checks + find_hidden_checks(); } /// Position::do_ep_move() is a private method used to make an en passant -/// capture. It is called from the main Position::do_move function. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object in which to store the captured piece. +/// capture. It is called from the main Position::do_move function. void Position::do_ep_move(Move m) { @@ -1088,7 +1120,7 @@ void Position::do_ep_move(Move m) { to = move_to(m); capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - assert(to == epSquare); + 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)); @@ -1113,7 +1145,7 @@ void Position::do_ep_move(Move m) { board[from] = EMPTY; // Update material hash key - materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; + st->materialKey ^= zobMaterial[them][PAWN][pieceCount[them][PAWN]]; // Update piece count pieceCount[them][PAWN]--; @@ -1125,37 +1157,38 @@ void Position::do_ep_move(Move m) { index[pieceList[them][PAWN][index[capsq]]] = index[capsq]; // Update hash key - key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - key ^= zobrist[them][PAWN][capsq]; - key ^= zobEp[epSquare]; + st->key ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + st->key ^= zobrist[them][PAWN][capsq]; + st->key ^= zobEp[st->epSquare]; // Update pawn hash key - pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; - pawnKey ^= zobrist[them][PAWN][capsq]; + st->pawnKey ^= zobrist[us][PAWN][from] ^ zobrist[us][PAWN][to]; + st->pawnKey ^= zobrist[them][PAWN][capsq]; // Update incremental scores - mgValue -= pst(them, PAWN, capsq); - mgValue -= pst(us, PAWN, from); - mgValue += pst(us, PAWN, to); - egValue -= pst(them, PAWN, capsq); - egValue -= pst(us, PAWN, from); - egValue += pst(us, PAWN, to); + 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); // Reset en passant square - epSquare = SQ_NONE; + st->epSquare = SQ_NONE; // Reset rule 50 counter - rule50 = 0; + st->rule50 = 0; // Update checkers BB - checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attacks_to(king_square(them), us); + + // Update hidden checks + find_hidden_checks(); } /// Position::undo_move() unmakes a move. When it returns, the position should -/// be restored to exactly the same state as before the move was made. It is -/// important that Position::undo_move is called with the same move and UndoInfo -/// object as the earlier call to Position::do_move. +/// be restored to exactly the same state as before the move was made. void Position::undo_move(Move m) { @@ -1165,10 +1198,6 @@ void Position::undo_move(Move m) { gamePly--; sideToMove = opposite_color(sideToMove); - // Restore information from our UndoInfo object (except the captured piece, - // which is taken care of later) - undoInfoUnion = *previous; - if (move_is_castle(m)) undo_castle_move(m); else if (move_promotion(m)) @@ -1209,30 +1238,33 @@ void Position::undo_move(Move m) { pieceList[us][piece][index[to]] = from; index[from] = index[to]; - if (capture) + if (st->capture) { - assert(capture != KING); + assert(st->capture != KING); // Replace the captured piece set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), to); + set_bit(&(byTypeBB[st->capture]), to); set_bit(&(byTypeBB[0]), to); - board[to] = piece_of_color_and_type(them, capture); + board[to] = piece_of_color_and_type(them, st->capture); // Update material - if (capture != PAWN) - npMaterial[them] += piece_value_midgame(capture); + if (st->capture != PAWN) + npMaterial[them] += piece_value_midgame(st->capture); // Update piece list - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; + pieceList[them][st->capture][pieceCount[them][st->capture]] = to; + index[to] = pieceCount[them][st->capture]; // Update piece count - pieceCount[them][capture]++; + pieceCount[them][st->capture]++; } else board[to] = EMPTY; } + // Finally point out state pointer back to the previous state + st = st->previous; + assert(is_ok()); } @@ -1305,8 +1337,7 @@ void Position::undo_castle_move(Move m) { /// Position::undo_promotion_move() is a private method used to unmake a /// promotion move. It is called from the main Position::do_move -/// function. The UndoInfo object, which has been initialized in -/// Position::do_move, is used to put back the captured piece (if any). +/// function. void Position::undo_promotion_move(Move m) { @@ -1356,36 +1387,34 @@ void Position::undo_promotion_move(Move m) { pieceCount[us][promotion]--; pieceCount[us][PAWN]++; - if (capture) + if (st->capture) { - assert(capture != KING); + assert(st->capture != KING); // Insert captured piece: set_bit(&(byColorBB[them]), to); - set_bit(&(byTypeBB[capture]), 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, capture); + 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(capture != PAWN); - npMaterial[them] += piece_value_midgame(capture); + assert(st->capture != PAWN); + npMaterial[them] += piece_value_midgame(st->capture); // Update piece list - pieceList[them][capture][pieceCount[them][capture]] = to; - index[to] = pieceCount[them][capture]; + pieceList[them][st->capture][pieceCount[them][st->capture]] = to; + index[to] = pieceCount[them][st->capture]; // Update piece count - pieceCount[them][capture]++; + 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. Because -/// the captured piece is always a pawn, we don't need to pass an UndoInfo -/// object from which to retrieve the captured piece. +/// capture. It is called from the main Position::undo_move function. void Position::undo_ep_move(Move m) { @@ -1401,7 +1430,7 @@ void Position::undo_ep_move(Move m) { Square to = move_to(m); Square capsq = (us == WHITE)? (to - DELTA_N) : (to - DELTA_S); - assert(to == ep_square()); + 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); @@ -1439,33 +1468,35 @@ void Position::undo_ep_move(Move m) { /// Position::do_null_move makes() a "null move": It switches the side to move /// and updates the hash key without executing any move on the board. -void Position::do_null_move(UndoInfo& u) { +void Position::do_null_move(StateInfo& newSt) { assert(is_ok()); assert(!is_check()); // Back up the information necessary to undo the null move to the supplied - // UndoInfo object. In the case of a null move, the only thing we need to + // 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. - u.lastMove = lastMove; - u.epSquare = epSquare; + newSt.lastMove = st->lastMove; + newSt.epSquare = st->epSquare; + newSt.previous = st->previous; + st->previous = &newSt; // Save the current key to the history[] array, in order to be able to // detect repetition draws. - history[gamePly] = key; + history[gamePly] = st->key; // Update the necessary information sideToMove = opposite_color(sideToMove); - if (epSquare != SQ_NONE) - key ^= zobEp[epSquare]; + if (st->epSquare != SQ_NONE) + st->key ^= zobEp[st->epSquare]; - epSquare = SQ_NONE; - rule50++; + st->epSquare = SQ_NONE; + st->rule50++; gamePly++; - key ^= zobSideToMove; + st->key ^= zobSideToMove; - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } @@ -1473,32 +1504,34 @@ void Position::do_null_move(UndoInfo& u) { /// Position::undo_null_move() unmakes a "null move". -void Position::undo_null_move(const UndoInfo &u) { +void Position::undo_null_move() { assert(is_ok()); assert(!is_check()); - // Restore information from the supplied UndoInfo object: - lastMove = u.lastMove; - epSquare = u.epSquare; - if (epSquare != SQ_NONE) - key ^= zobEp[epSquare]; + // 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]; - // Update the necessary information. + // Update the necessary information sideToMove = opposite_color(sideToMove); - rule50--; + st->rule50--; gamePly--; - key ^= zobSideToMove; + st->key ^= zobSideToMove; - mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; - egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; + st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; + st->egValue += (sideToMove == WHITE)? TempoValueEndgame : -TempoValueEndgame; assert(is_ok()); } /// 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 +/// material gain or loss resulting from a move. There are three versions of /// this function: One which takes a destination square as input, one takes a /// move, and one which takes a 'from' and a 'to' square. The function does /// not yet understand promotions captures. @@ -1535,6 +1568,11 @@ 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); @@ -1544,7 +1582,7 @@ int Position::see(Square from, Square to) const { occ = occupied_squares(); // Handle en passant moves - if (epSquare == to && type_of_piece_on(from) == PAWN) + if (st->epSquare == to && type_of_piece_on(from) == PAWN) { assert(capture == EMPTY); @@ -1567,6 +1605,17 @@ int Position::see(Square from, Square to) const { | (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]; + if (from != SQ_NONE) break; @@ -1604,7 +1653,7 @@ int Position::see(Square from, Square to) const { swapList[0] = seeValues[capture]; do { - // Locate the least valuable attacker for the side to move. The loop + // 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++) @@ -1629,6 +1678,12 @@ int Position::see(Square from, Square to) const { 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]; + // Stop after a king capture if (pt == KING && (attackers & pieces_of_color(c))) { @@ -1647,19 +1702,32 @@ int Position::see(Square from, Square to) const { } +/// Position::setStartState() copies the content of the argument +/// 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) { + + startState = s; + st = &startState; +} + + /// Position::clear() erases the position object to a pristine state, with an /// empty board, white to move, and no castling rights. void Position::clear() { + st = &startState; + memset(st, 0, sizeof(StateInfo)); + st->epSquare = SQ_NONE; + + memset(index, 0, sizeof(int) * 64); + memset(byColorBB, 0, sizeof(Bitboard) * 2); + for (int i = 0; i < 64; i++) - { board[i] = EMPTY; - index[i] = 0; - } - - for (int i = 0; i < 2; i++) - byColorBB[i] = EmptyBoardBB; for (int i = 0; i < 7; i++) { @@ -1669,21 +1737,11 @@ void Position::clear() { pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; } - checkersBB = EmptyBoardBB; - for (Color c = WHITE; c <= BLACK; c++) - pinners[c] = pinned[c] = dcCandidates[c] = ~EmptyBoardBB; - - lastMove = MOVE_NONE; - sideToMove = WHITE; - castleRights = NO_CASTLES; + gamePly = 0; initialKFile = FILE_E; initialKRFile = FILE_H; initialQRFile = FILE_A; - epSquare = SQ_NONE; - rule50 = 0; - gamePly = 0; - previous = NULL; } @@ -1727,7 +1785,7 @@ void Position::put_piece(Piece p, Square s) { void Position::allow_oo(Color c) { - castleRights |= (1 + int(c)); + st->castleRights |= (1 + int(c)); } @@ -1736,7 +1794,7 @@ void Position::allow_oo(Color c) { void Position::allow_ooo(Color c) { - castleRights |= (4 + 4*int(c)); + st->castleRights |= (4 + 4*int(c)); } @@ -1756,7 +1814,7 @@ Key Position::compute_key() const { if (ep_square() != SQ_NONE) result ^= zobEp[ep_square()]; - result ^= zobCastle[castleRights]; + result ^= zobCastle[st->castleRights]; if (side_to_move() == BLACK) result ^= zobSideToMove; @@ -1889,12 +1947,12 @@ bool Position::is_draw() const { return true; // Draw by the 50 moves rule? - if (rule50 > 100 || (rule50 == 100 && !is_check())) + if (st->rule50 > 100 || (st->rule50 == 100 && !is_check())) return true; // Draw by repetition? - for (int i = 2; i < Min(gamePly, rule50); i += 2) - if (history[gamePly - i] == key) + for (int i = 2; i < Min(gamePly, st->rule50); i += 2) + if (history[gamePly - i] == st->key) return true; return false; @@ -1907,21 +1965,21 @@ bool Position::is_draw() const { bool Position::has_mate_threat(Color c) { - UndoInfo u1, u2; + 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. - u1.lastMove = lastMove; - u1.epSquare = epSquare; + st1.lastMove = st->lastMove; + st1.epSquare = st->epSquare; if (is_check()) return false; // If the input color is not equal to the side to move, do a null move if (c != stm) - do_null_move(u1); + do_null_move(st1); MoveStack mlist[120]; int count; @@ -1933,7 +1991,7 @@ bool Position::has_mate_threat(Color c) { // Loop through the moves, and see if one of them is mate for (int i = 0; i < count; i++) { - do_move(mlist[i].move, u2); + do_move(mlist[i].move, st2); if (is_mate()) result = true; @@ -1942,7 +2000,7 @@ bool Position::has_mate_threat(Color c) { // Undo null move, if necessary if (c != stm) - undo_null_move(u1); + undo_null_move(); return result; } @@ -2042,20 +2100,20 @@ void Position::flipped_copy(const Position &pos) { castleRightsMask[make_square(initialQRFile, RANK_8)] ^= BLACK_OOO; // En passant square - if (pos.epSquare != SQ_NONE) - epSquare = flip_square(pos.epSquare); + if (pos.st->epSquare != SQ_NONE) + st->epSquare = flip_square(pos.st->epSquare); // Checkers find_checkers(); // Hash keys - key = compute_key(); - pawnKey = compute_pawn_key(); - materialKey = compute_material_key(); + st->key = compute_key(); + st->pawnKey = compute_pawn_key(); + st->materialKey = compute_material_key(); // Incremental scores - mgValue = compute_value(); - egValue = compute_value(); + st->mgValue = compute_value(); + st->egValue = compute_value(); // Material npMaterial[WHITE] = compute_non_pawn_material(WHITE); @@ -2132,7 +2190,7 @@ bool Position::is_ok(int* failedStep) const { // Is there more than 2 checkers? if (failedStep) (*failedStep)++; - if (debugCheckerCount && count_1s(checkersBB) > 2) + if (debugCheckerCount && count_1s(st->checkersBB) > 2) return false; // Bitboards OK? @@ -2167,27 +2225,27 @@ bool Position::is_ok(int* failedStep) const { // Hash key OK? if (failedStep) (*failedStep)++; - if (debugKey && key != compute_key()) + if (debugKey && st->key != compute_key()) return false; // Pawn hash key OK? if (failedStep) (*failedStep)++; - if (debugPawnKey && pawnKey != compute_pawn_key()) + if (debugPawnKey && st->pawnKey != compute_pawn_key()) return false; // Material hash key OK? if (failedStep) (*failedStep)++; - if (debugMaterialKey && materialKey != compute_material_key()) + if (debugMaterialKey && st->materialKey != compute_material_key()) return false; // Incremental eval OK? if (failedStep) (*failedStep)++; if (debugIncrementalEval) { - if (mgValue != compute_value()) + if (st->mgValue != compute_value()) return false; - if (egValue != compute_value()) + if (st->egValue != compute_value()) return false; }