- moveIsCheck = pos.move_is_check(move, ci);
-
- // Futility pruning
- if ( !PvNode
- && !isCheck
- && !moveIsCheck
- && move != ttMove
- && enoughMaterial
- && !move_is_promotion(move)
- && !pos.move_is_passed_pawn_push(move))
- {
- futilityValue = futilityBase
- + pos.endgame_value_of_piece_on(move_to(move))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0));
-
- if (futilityValue < alpha)
- {
- if (futilityValue > bestValue)
- bestValue = futilityValue;
- continue;
- }
- }
-
- // Detect blocking evasions that are candidate to be pruned
- evasionPrunable = isCheck
- && bestValue > value_mated_in(PLY_MAX)
- && !pos.move_is_capture(move)
- && pos.type_of_piece_on(move_from(move)) != KING
- && !pos.can_castle(pos.side_to_move());
-
- // Don't search moves with negative SEE values
- if ( !PvNode
- && (!isCheck || evasionPrunable)
- && move != ttMove
- && !move_is_promotion(move)
- && pos.see_sign(move) < 0)
- continue;
-
- // Update current move
- ss->currentMove = move;
-
- // Make and search the move
- pos.do_move(move, st, ci, moveIsCheck);
- value = -qsearch<PvNode>(pos, ss+1, -beta, -alpha, depth-OnePly);
- pos.undo_move(move);
-
- assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
-
- // New best move?
- if (value > bestValue)
- {
- bestValue = value;
- if (value > alpha)
- {
- alpha = value;
- update_pv(ss, ply);
- }
- }
- }
-
- // All legal moves have been searched. A special case: If we're in check
- // and no legal moves were found, it is checkmate.
- if (isCheck && bestValue == -VALUE_INFINITE)
- return value_mated_in(ply);
-
- // Update transposition table
- Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
- if (bestValue <= oldAlpha)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, d, MOVE_NONE, ss->eval, ei.kingDanger[pos.side_to_move()]);
- else if (bestValue >= beta)
- {
- move = ss->pv[ply];
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move, ss->eval, ei.kingDanger[pos.side_to_move()]);
-
- // Update killers only for good checking moves
- if (!pos.move_is_capture_or_promotion(move))
- update_killers(move, ss);
- }
- else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss->pv[ply], ss->eval, ei.kingDanger[pos.side_to_move()]);
-
- assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
-
- return bestValue;
- }
-
-
- // sp_search() is used to search from a split point. This function is called
- // by each thread working at the split point. It is similar to the normal
- // search() function, but simpler. Because we have already probed the hash
- // table, done a null move search, and searched the first move before
- // splitting, we don't have to repeat all this work in sp_search(). We
- // also don't need to store anything to the hash table here: This is taken
- // care of after we return from the split point.
-
- template <NodeType PvNode>
- void sp_search(SplitPoint* sp, int threadID) {
-
- assert(threadID >= 0 && threadID < TM.active_threads());
- assert(TM.active_threads() > 1);
-
- StateInfo st;
- Move move;
- Depth ext, newDepth;
- Value value;
- Value futilityValueScaled; // NonPV specific
- bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
- int moveCount;
- value = -VALUE_INFINITE;
-
- Position pos(*sp->pos, threadID);
- CheckInfo ci(pos);
- int ply = pos.ply();
- SearchStack* ss = sp->sstack[threadID] + 1;
- isCheck = pos.is_check();
-
- // Step 10. Loop through moves
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
- lock_grab(&(sp->lock));
-
- while ( sp->bestValue < sp->beta
- && (move = sp->mp->get_next_move()) != MOVE_NONE
- && !TM.thread_should_stop(threadID))
- {
- moveCount = ++sp->moveCount;
- lock_release(&(sp->lock));
-
- assert(move_is_ok(move));
-
- moveIsCheck = pos.move_is_check(move, ci);
- captureOrPromotion = pos.move_is_capture_or_promotion(move);
-
- // Step 11. Decide the new search depth
- ext = extension<PvNode>(pos, move, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
- newDepth = sp->depth - OnePly + ext;
-
- // Update current move
- ss->currentMove = move;
-
- // Step 12. Futility pruning (is omitted in PV nodes)
- if ( !PvNode
- && !captureOrPromotion
- && !isCheck
- && !dangerous
- && !move_is_castle(move))
- {
- // Move count based pruning
- if ( moveCount >= futility_move_count(sp->depth)
- && !(ss->threatMove && connected_threat(pos, move, ss->threatMove))
- && sp->bestValue > value_mated_in(PLY_MAX))
- {
- lock_grab(&(sp->lock));
- continue;
- }