X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fposition.cpp;h=1fe723aec461e20a303582484349b9696ca9c552;hp=46daf8f3b1ab407dca20075dac0d46400b8de520;hb=dddaeff7d8d4a0c255310d054a53066296e71004;hpb=c5f44ef45bd9929f5e2f1f4c25c5edd11202546e diff --git a/src/position.cpp b/src/position.cpp index 46daf8f3..1fe723ae 100644 --- a/src/position.cpp +++ b/src/position.cpp @@ -379,36 +379,35 @@ Bitboard Position::discovered_check_candidates(Color c) const { return hidden_checkers(c); } -/// Position::attacks_to() computes a bitboard containing all pieces which +/// Position::attackers_to() computes a bitboard containing all pieces which /// attacks a given square. -Bitboard Position::attacks_to(Square s) const { +Bitboard Position::attackers_to(Square s) const { - return (pawn_attacks(BLACK, s) & pieces(PAWN, WHITE)) - | (pawn_attacks(WHITE, s) & pieces(PAWN, BLACK)) - | (piece_attacks(s) & pieces(KNIGHT)) - | (piece_attacks(s) & pieces(ROOK, QUEEN)) - | (piece_attacks(s) & pieces(BISHOP, QUEEN)) - | (piece_attacks(s) & pieces(KING)); + 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::piece_attacks_square() tests whether the piece on square f -/// attacks square t. +/// Position::attacks_from() computes a bitboard of all attacks +/// of a given piece put in a given square. -bool Position::piece_attacks_square(Piece p, Square f, Square t) const { +Bitboard Position::attacks_from(Piece p, Square s) const { - assert(square_is_ok(f)); - assert(square_is_ok(t)); + 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; @@ -427,7 +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 @@ -440,20 +439,20 @@ bool Position::move_attacks_square(Move m, Square s) const { // 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)); } @@ -510,7 +509,7 @@ bool Position::pl_move_is_legal(Move m, Bitboard pinned) const { // If the moving piece is a king, check whether the destination // square is attacked by the opponent. if (type_of_piece_on(from) == KING) - return !(square_is_attacked(move_to(m), opposite_color(us))); + 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. @@ -548,7 +547,7 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) 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 ( dcCandidates // Discovered check? @@ -564,7 +563,7 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { 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: @@ -594,21 +593,21 @@ bool Position::move_is_check(Move m, Bitboard dcCandidates) const { // Test discovered check and normal check according to piece type case KNIGHT: return (dcCandidates && bit_is_set(dcCandidates, from)) - || bit_is_set(piece_attacks(ksq), to); + || bit_is_set(attacks_from(ksq), to); case BISHOP: return (dcCandidates && bit_is_set(dcCandidates, from)) - || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to)); + || (direction_is_diagonal(ksq, to) && bit_is_set(attacks_from(ksq), to)); case ROOK: return (dcCandidates && bit_is_set(dcCandidates, from)) - || (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)); + || (direction_is_straight(ksq, to) && bit_is_set(attacks_from(ksq), to)); case QUEEN: // Discovered checks are impossible! assert(!bit_is_set(dcCandidates, from)); - return ( (direction_is_straight(ksq, to) && bit_is_set(piece_attacks(ksq), to)) - || (direction_is_diagonal(ksq, to) && bit_is_set(piece_attacks(ksq), to))); + 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? @@ -662,22 +661,23 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square // Direct checks if ( ( (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to)) || (Rook && bit_is_set(RookPseudoAttacks[ksq], to))) - && bit_is_set(piece_attacks(ksq), to)) // slow, try to early skip + && 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 ? pawn_attacks(opposite_color(sideToMove), ksq) : piece_attacks(ksq), to)) + && 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) & pieces(ROOK, QUEEN, side_to_move())); + (*pCheckersBB) |= (attacks_from(ksq) & pieces(ROOK, QUEEN, side_to_move())); if (Piece != BISHOP) - (*pCheckersBB) |= (piece_attacks(ksq) & pieces(BISHOP, QUEEN, side_to_move())); + (*pCheckersBB) |= (attacks_from(ksq) & pieces(BISHOP, QUEEN, side_to_move())); } } @@ -703,8 +703,8 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { // pointer to point to the new, ready to be updated, state. struct ReducedStateInfo { Key key, pawnKey, materialKey; - int castleRights, rule50; - Square kingSquare[2], epSquare; + int castleRights, rule50, pliesFromNull; + Square epSquare; Value mgValue, egValue; Value npMaterial[2]; }; @@ -724,6 +724,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { // 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)) { @@ -784,10 +785,6 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { board[to] = board[from]; board[from] = EMPTY; - // If the moving piece was a king, update the king square - if (pt == KING) - st->kingSquare[us] = to; - // 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. @@ -806,7 +803,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { // Set en passant square, only if moved pawn can be captured if (abs(int(to) - int(from)) == 16) { - if (pawn_attacks(us, from + (us == WHITE ? DELTA_N : DELTA_S)) & pieces(PAWN, them)) + 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]; @@ -842,6 +839,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { 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; @@ -864,7 +862,7 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) { // Update checkers bitboard, piece must be already moved if (ep | pm) - st->checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); else { st->checkersBB = EmptyBoardBB; @@ -947,6 +945,7 @@ void Position::do_capture_move(Bitboard& key, PieceType capture, Color them, Squ 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; @@ -987,17 +986,22 @@ void Position::do_castle_move(Move m) { rto = relative_square(us, SQ_D1); } - // Move the pieces - Bitboard kmove_bb = make_move_bb(kfrom, kto); - do_move_bb(&(byColorBB[us]), kmove_bb); - do_move_bb(&(byTypeBB[KING]), kmove_bb); - do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares - - Bitboard rmove_bb = make_move_bb(rfrom, rto); - do_move_bb(&(byColorBB[us]), rmove_bb); - do_move_bb(&(byTypeBB[ROOK]), rmove_bb); - do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares - + // Remove pieces from source squares: + clear_bit(&(byColorBB[us]), kfrom); + clear_bit(&(byTypeBB[KING]), kfrom); + clear_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares + clear_bit(&(byColorBB[us]), rfrom); + clear_bit(&(byTypeBB[ROOK]), rfrom); + clear_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares + + // Put pieces on destination squares: + set_bit(&(byColorBB[us]), kto); + set_bit(&(byTypeBB[KING]), kto); + set_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares + set_bit(&(byColorBB[us]), rto); + set_bit(&(byTypeBB[ROOK]), rto); + set_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares + // Update board array Piece king = piece_of_color_and_type(us, KING); Piece rook = piece_of_color_and_type(us, ROOK); @@ -1005,9 +1009,6 @@ void Position::do_castle_move(Move m) { board[kto] = king; board[rto] = rook; - // Update king square - st->kingSquare[us] = kto; - // Update piece lists pieceList[us][KING][index[kfrom]] = kto; pieceList[us][ROOK][index[rfrom]] = rto; @@ -1041,7 +1042,7 @@ void Position::do_castle_move(Move m) { st->rule50 = 0; // Update checkers BB - st->checkersBB = attacks_to(king_square(them), us); + st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us); // Finish sideToMove = opposite_color(sideToMove); @@ -1106,10 +1107,12 @@ void Position::undo_move(Move m) { 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; } + // Put the piece back at the source square Bitboard move_bb = make_move_bb(to, from); do_move_bb(&(byColorBB[us]), move_bb); @@ -1187,17 +1190,22 @@ 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)); - - // Put the pieces back at the source square - Bitboard kmove_bb = make_move_bb(kto, kfrom); - do_move_bb(&(byColorBB[us]), kmove_bb); - do_move_bb(&(byTypeBB[KING]), kmove_bb); - do_move_bb(&(byTypeBB[0]), kmove_bb); // HACK: byTypeBB[0] == occupied squares - - Bitboard rmove_bb = make_move_bb(rto, rfrom); - do_move_bb(&(byColorBB[us]), rmove_bb); - do_move_bb(&(byTypeBB[ROOK]), rmove_bb); - do_move_bb(&(byTypeBB[0]), rmove_bb); // HACK: byTypeBB[0] == occupied squares + + // Remove pieces from destination squares: + clear_bit(&(byColorBB[us]), kto); + clear_bit(&(byTypeBB[KING]), kto); + clear_bit(&(byTypeBB[0]), kto); // HACK: byTypeBB[0] == occupied squares + clear_bit(&(byColorBB[us]), rto); + clear_bit(&(byTypeBB[ROOK]), rto); + clear_bit(&(byTypeBB[0]), rto); // HACK: byTypeBB[0] == occupied squares + + // Put pieces on source squares: + set_bit(&(byColorBB[us]), kfrom); + set_bit(&(byTypeBB[KING]), kfrom); + set_bit(&(byTypeBB[0]), kfrom); // HACK: byTypeBB[0] == occupied squares + set_bit(&(byColorBB[us]), rfrom); + set_bit(&(byTypeBB[ROOK]), rfrom); + set_bit(&(byTypeBB[0]), rfrom); // HACK: byTypeBB[0] == occupied squares // Update board board[rto] = board[kto] = EMPTY; @@ -1235,6 +1243,7 @@ void Position::do_null_move(StateInfo& backupSt) { 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 @@ -1251,6 +1260,7 @@ void Position::do_null_move(StateInfo& backupSt) { sideToMove = opposite_color(sideToMove); st->epSquare = SQ_NONE; st->rule50++; + st->pliesFromNull = 0; gamePly++; st->mgValue += (sideToMove == WHITE)? TempoValueMidgame : -TempoValueMidgame; @@ -1272,6 +1282,7 @@ void Position::undo_null_move() { st->mgValue = backupSt->mgValue; st->egValue = backupSt->egValue; st->previous = backupSt->previous; + st->pliesFromNull = backupSt->pliesFromNull; // Update the necessary information sideToMove = opposite_color(sideToMove); @@ -1289,13 +1300,13 @@ 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 { @@ -1311,10 +1322,10 @@ int Position::see_sign(Move m) const { && type_of_piece_on(from) != KING) return 1; - return see(from, to); + 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] = { @@ -1325,8 +1336,10 @@ int Position::see(Square from, Square to) const { 0, 0 }; - Bitboard attackers, stmAttackers, 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)); @@ -1337,10 +1350,27 @@ int Position::see(Square from, Square to) const { // Initialize pieces Piece piece = piece_on(from); Piece capture = piece_on(to); + Bitboard occ = occupied_squares(); - // Find all attackers to the destination square, with the moving piece - // removed, but possibly an X-ray attacker added behind it. - 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]; + + 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) @@ -1357,13 +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) & pieces(ROOK, QUEEN)) - | (bishop_attacks_bb(to, occ) & pieces(BISHOP, QUEEN)) - | (piece_attacks(to) & pieces(KNIGHT)) - | (piece_attacks(to) & pieces(KING)) - | (pawn_attacks(WHITE, to) & pieces(PAWN, BLACK)) - | (pawn_attacks(BLACK, to) & pieces(PAWN, WHITE)); + 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; @@ -1410,6 +1442,15 @@ int Position::see(Square from, Square to) const { 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 = stmAttackers & pieces(pt); @@ -1478,8 +1519,8 @@ void Position::clear() { for (int i = 0; i < 64; i++) board[i] = EMPTY; - for (int i = 0; i < 7; i++) - for (int j = 0; j < 8; j++) + for (int i = 0; i < 8; i++) + for (int j = 0; j < 16; j++) pieceList[0][i][j] = pieceList[1][i][j] = SQ_NONE; sideToMove = WHITE; @@ -1519,9 +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) - st->kingSquare[c] = s; } @@ -1680,7 +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; @@ -1923,7 +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; } @@ -2014,7 +2052,7 @@ bool Position::is_ok(int* failedStep) const { for(PieceType pt = PAWN; pt <= KING; pt++) for(int i = 0; i < pieceCount[c][pt]; i++) { - if (piece_on(piece_list(c, pt, i)) != (pieces(pt, c))) + if (piece_on(piece_list(c, pt, i)) != piece_of_color_and_type(c, pt)) return false; if (index[piece_list(c, pt, i)] != i)