/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
Time.init(Limits, us, rootPos.game_ply());
TT.new_search();
+ Eval::verify_NNUE();
+
if (rootMoves.empty())
{
rootMoves.emplace_back(MOVE_NONE);
if (value >= probcutBeta)
{
- tte->save(posKey, value_to_tt(value, ss->ply), ttPv,
- BOUND_LOWER,
- depth - 3, move, ss->staticEval);
+ if ( !(ttHit
+ && tte->depth() >= depth - 3
+ && ttValue != VALUE_NONE))
+ tte->save(posKey, value_to_tt(value, ss->ply), ttPv,
+ BOUND_LOWER,
+ depth - 3, move, ss->staticEval);
return value;
}
}
thisThread->rootMoves.begin() + thisThread->pvLast, move))
continue;
+ // Check for legality
+ if (!rootNode && !pos.legal(move))
+ continue;
+
ss->moveCount = ++moveCount;
if (rootNode && thisThread == Threads.main() && Time.elapsed() > 3000)
// search of (alpha-s, beta-s), and just one fails high on (alpha, beta),
// then that move is singular and should be extended. To verify this we do
// a reduced search on all the other moves but the ttMove and if the
- // result is lower than ttValue minus a margin then we will extend the ttMove.
+ // result is lower than ttValue minus a margin, then we will extend the ttMove.
if ( depth >= 6
&& move == ttMove
&& !rootNode
if (type_of(move) == CASTLING)
extension = 1;
- // Late irreversible move extension
- if ( move == ttMove
- && pos.rule50_count() > 80
- && (captureOrPromotion || type_of(movedPiece) == PAWN))
- extension = 2;
-
// Add extension to new depth
newDepth += extension;
// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
- // Check for legality just before making the move
- if (!rootNode && !pos.legal(move))
- {
- ss->moveCount = --moveCount;
- continue;
- }
-
// Update the current move (this must be done after singular extension search)
ss->currentMove = move;
ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
{
Depth r = reduction(improving, depth, moveCount);
+ // Decrease reduction at non-check cut nodes for second move at low depths
+ if ( cutNode
+ && depth <= 10
+ && moveCount <= 2
+ && !ss->inCheck)
+ r--;
+
// Decrease reduction if the ttHit running average is large
if (thisThread->ttHitAverage > 473 * TtHitAverageResolution * TtHitAverageWindow / 1024)
r--;