- 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;
- }
-
- // Value based pruning
- Depth predictedDepth = newDepth - reduction<NonPV>(sp->depth, moveCount);
- futilityValueScaled = ss->eval + futility_margin(predictedDepth, moveCount)
- + H.gain(pos.piece_on(move_from(move)), move_to(move));
-
- if (futilityValueScaled < sp->beta)
- {
- lock_grab(&(sp->lock));
-
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = futilityValueScaled;
- continue;
- }
- }
-
- // Step 13. Make the move
- pos.do_move(move, st, ci, moveIsCheck);
-
- // Step 14. Reduced search
- // If the move fails high will be re-searched at full depth.
- bool doFullDepthSearch = true;
-
- if ( !captureOrPromotion
- && !dangerous
- && !move_is_castle(move)
- && !move_is_killer(move, ss))
- {
- ss->reduction = reduction<PvNode>(sp->depth, moveCount);
- if (ss->reduction)
- {
- Value localAlpha = sp->alpha;
- Depth d = newDepth - ss->reduction;
- value = d < OnePly ? -qsearch<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, Depth(0), sp->ply+1)
- : - search<NonPV>(pos, ss+1, -(localAlpha+1), -localAlpha, d, sp->ply+1);
-
- doFullDepthSearch = (value > localAlpha);
- }