// Different node types, used as template parameter
enum NodeType { Root, PV, NonPV, SplitPointRoot, SplitPointPV, SplitPointNonPV };
- // Lookup table to check if a Piece is a slider and its access function
- const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
- inline bool piece_is_slider(Piece p) { return Slidings[p]; }
-
// Dynamic razoring margin based on depth
inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); }
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
void id_loop(Position& pos);
- bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta);
- bool connected_moves(const Position& pos, Move m1, Move m2);
Value value_to_tt(Value v, int ply);
Value value_from_tt(Value v, int ply);
- bool connected_threat(const Position& pos, Move m, Move threat);
+ bool check_is_dangerous(Position& pos, Move move, Value futilityBase, Value beta);
+ bool yields_to_threat(const Position& pos, Move move, Move threat);
+ bool prevents_threat(const Position& pos, Move move, Move threat);
string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
struct Skill {
}
// Sort the PV lines searched so far and update the GUI
- sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx);
+ sort<RootMove>(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
}
if ( depth < 5 * ONE_PLY
&& (ss-1)->reduction
&& threatMove != MOVE_NONE
- && connected_moves(pos, (ss-1)->currentMove, threatMove))
+ && yields_to_threat(pos, (ss-1)->currentMove, threatMove))
return beta - 1;
}
}
// Move count based pruning
if ( depth < 16 * ONE_PLY
&& moveCount >= FutilityMoveCounts[depth]
- && (!threatMove || !connected_threat(pos, move, threatMove)))
+ && (!threatMove || !prevents_threat(pos, move, threatMove)))
{
if (SpNode)
sp->mutex.lock();
&& depth >= Threads.min_split_depth()
&& bestValue < beta
&& Threads.available_slave_exists(thisThread))
- {
bestValue = Threads.split<FakeSplit>(pos, ss, alpha, beta, bestValue, &bestMove,
depth, threatMove, moveCount, mp, NT);
- break;
- }
}
if (SpNode)
}
- // connected_moves() tests whether two moves are 'connected' in the sense
- // that the first move somehow made the second move possible (for instance
- // if the moving piece is the same in both moves). The first move is assumed
- // to be the move that was made to reach the current position, while the
- // second move is assumed to be a move from the current position.
-
- bool connected_moves(const Position& pos, Move m1, Move m2) {
+ // yields_to_threat() tests whether the move at previous ply yields to the so
+ // called threat move (the best move returned from a null search that fails
+ // low). Here 'yields to' means that the move somehow made the threat possible
+ // for instance if the moving piece is the same in both moves.
- Square f1, t1, f2, t2;
- Piece p1, p2;
- Square ksq;
+ bool yields_to_threat(const Position& pos, Move move, Move threat) {
- assert(is_ok(m1));
- assert(is_ok(m2));
+ assert(is_ok(move));
+ assert(is_ok(threat));
+ assert(color_of(pos.piece_on(from_sq(threat))) == ~pos.side_to_move());
- // Case 1: The moving piece is the same in both moves
- f2 = from_sq(m2);
- t1 = to_sq(m1);
- if (f2 == t1)
- return true;
+ Square mfrom = from_sq(move);
+ Square mto = to_sq(move);
+ Square tfrom = from_sq(threat);
+ Square tto = to_sq(threat);
- // Case 2: The destination square for m2 was vacated by m1
- t2 = to_sq(m2);
- f1 = from_sq(m1);
- if (t2 == f1)
+ // The piece is the same or threat's destination was vacated by the move
+ if (mto == tfrom || tto == mfrom)
return true;
- // Case 3: Moving through the vacated square
- p2 = pos.piece_on(f2);
- if (piece_is_slider(p2) && (between_bb(f2, t2) & f1))
+ // Threat moves through the vacated square
+ if (between_bb(tfrom, tto) & mfrom)
return true;
- // Case 4: The destination square for m2 is defended by the moving piece in m1
- p1 = pos.piece_on(t1);
- if (pos.attacks_from(p1, t1) & t2)
+ // Threat's destination is defended by the move's piece
+ Bitboard matt = pos.attacks_from(pos.piece_on(mto), mto, pos.pieces() ^ tfrom);
+ if (matt & tto)
return true;
- // Case 5: Discovered check, checking piece is the piece moved in m1
- ksq = pos.king_square(pos.side_to_move());
- if ( piece_is_slider(p1)
- && (between_bb(t1, ksq) & f2)
- && (pos.attacks_from(p1, t1, pos.pieces() ^ f2) & ksq))
+ // Threat gives a discovered check through the move's checking piece
+ if (matt & pos.king_square(pos.side_to_move()))
+ {
+ assert(between_bb(mto, pos.king_square(pos.side_to_move())) & tfrom);
return true;
+ }
return false;
}
- // connected_threat() tests whether it is safe to forward prune a move or if
- // is somehow connected to the threat move returned by null search.
+ // prevents_threat() tests whether a move is able to defend against the so
+ // called threat move (the best move returned from a null search that fails
+ // low). In this case will not be pruned.
- bool connected_threat(const Position& pos, Move m, Move threat) {
+ bool prevents_threat(const Position& pos, Move move, Move threat) {
- assert(is_ok(m));
+ assert(is_ok(move));
assert(is_ok(threat));
- assert(!pos.is_capture_or_promotion(m));
- assert(!pos.is_passed_pawn_push(m));
+ assert(!pos.is_capture_or_promotion(move));
+ assert(!pos.is_passed_pawn_push(move));
- Square mfrom = from_sq(m);
- Square mto = to_sq(m);
+ Square mfrom = from_sq(move);
+ Square mto = to_sq(move);
Square tfrom = from_sq(threat);
Square tto = to_sq(threat);
- // Case 1: Don't prune moves which move the threatened piece
+ // Don't prune moves of the threatened piece
if (mfrom == tto)
return true;
- // Case 2: If the threatened piece has value less than or equal to the
- // value of the threatening piece, don't prune moves which defend it.
+ // If the threatened piece has value less than or equal to the value of the
+ // threat piece, don't prune moves which defend it.
if ( pos.is_capture(threat)
&& ( PieceValue[MG][pos.piece_on(tfrom)] >= PieceValue[MG][pos.piece_on(tto)]
|| type_of(pos.piece_on(tfrom)) == KING))
return true;
}
- // Case 3: If the moving piece in the threatened move is a slider, don't
- // prune safe moves which block its ray.
- if ( piece_is_slider(pos.piece_on(tfrom))
- && (between_bb(tfrom, tto) & mto)
- && pos.see_sign(m) >= 0)
+ // Don't prune safe moves which block the threat path
+ if ((between_bb(tfrom, tto) & mto) && pos.see_sign(move) >= 0)
return true;
return false;
projects / stockfish / blobdiff