bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
ttCapture, singularQuietLMR, noLMRExtension;
Piece movedPiece;
- int moveCount, captureCount, quietCount, bestMoveCount;
+ int moveCount, captureCount, quietCount, bestMoveCount, improvement;
// Step 1. Initialize node
ss->inCheck = pos.checkers();
// Skip early pruning when in check
ss->staticEval = eval = VALUE_NONE;
improving = false;
+ improvement = 0;
goto moves_loop;
}
else if (ss->ttHit)
thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus;
}
- // Set up improving flag that is used in various pruning heuristics
- // We define position as improving if static evaluation of position is better
- // Than the previous static evaluation at our turn
- // In case of us being in check at our previous move we look at move prior to it
- improving = (ss-2)->staticEval == VALUE_NONE
- ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE
- : ss->staticEval > (ss-2)->staticEval;
+ // Set up the improvement variable, which is the difference between the current
+ // static evaluation and the previous static evaluation at our turn (if we were
+ // in check at our previous move we look at the move prior to it). The improvement
+ // margin and the improving flag are used in various pruning heuristics.
+ improvement = (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
+ : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
+ : 200;
+
+ improving = improvement > 0;
// Step 7. Futility pruning: child node (~50 Elo).
// The depth condition is important for mate finding.
&& (ss-1)->statScore < 23767
&& eval >= beta
&& eval >= ss->staticEval
- && ss->staticEval >= beta - 20 * depth - 22 * improving + 168 * ss->ttPv + 177
+ && ss->staticEval >= beta - 20 * depth - improvement / 15 + 168 * ss->ttPv + 177
&& !excludedMove
&& pos.non_pawn_material(us)
&& (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))