- // Step 15. Full depth search
- if (doFullDepthSearch)
- {
- // Full depth non-pv search using alpha as upperbound
- value = -search<NonPV>(pos, ss+1, -(alpha+1), -alpha, newDepth, 1);
-
- // If we are above alpha then research at same depth but as PV
- // to get a correct score or eventually a fail high above beta.
- if (value > alpha)
- value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, 1);
- }
- }
-
- // Step 16. Undo move
- pos.undo_move(move);
-
- assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
-
- // Finished searching the move. If StopRequest is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV.
- if (StopRequest)
- break;
-
- // Remember searched nodes counts for this move
- rm->nodes += pos.nodes_searched() - nodes;
-
- // Step 17. Check for new best move
- if (!isPvMove && value <= alpha)
- rm->pv_score = -VALUE_INFINITE;
- else
- {
- // PV move or new best move!
-
- // Update PV
- ss->bestMove = move;
- rm->pv_score = value;
- rm->extract_pv_from_tt(pos);
-
- // We record how often the best move has been changed in each
- // iteration. This information is used for time managment: When
- // the best move changes frequently, we allocate some more time.
- if (!isPvMove && MultiPV == 1)
- BestMoveChangesByIteration[Iteration]++;
-
- // Inform GUI that PV has changed, in case of multi-pv UCI protocol
- // requires we send all the PV lines properly sorted.
- rml.sort_multipv(moveCount);
-
- for (int j = 0; j < Min(MultiPV, (int)rml.size()); j++)
- cout << rml[j].pv_info_to_uci(pos, alpha, beta, j) << endl;
-
- // Update alpha. In multi-pv we don't use aspiration window
- if (MultiPV == 1)
- {
- // Raise alpha to setup proper non-pv search upper bound
- if (value > alpha)
- alpha = bestValue = value;
- }
- else // Set alpha equal to minimum score among the PV lines
- alpha = bestValue = rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount?
-
- } // PV move or new best move
-
- ++rm;
-
- } // Root moves loop
-
- // Step 20. Update tables
- // If the search is not aborted, update the transposition table,
- // history counters, and killer moves.
- if (!StopRequest)
- {
- move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove;
- vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER
- : bestValue >= beta ? VALUE_TYPE_LOWER : VALUE_TYPE_EXACT;
-
- TT.store(posKey, value_to_tt(bestValue, 0), vt, depth, move, ss->eval, ss->evalMargin);
-
- // Update killers and history only for non capture moves that fails high
- if ( bestValue >= beta
- && !pos.move_is_capture_or_promotion(move))
- {
- update_history(pos, move, depth, movesSearched, moveCount);
- update_killers(move, ss->killers);
- }