// Step 1. Initialize node
Thread* thisThread = pos.this_thread();
inCheck = pos.checkers();
+ Color us = pos.side_to_move();
moveCount = captureCount = quietCount = ss->moveCount = 0;
bestValue = -VALUE_INFINITE;
maxValue = VALUE_INFINITE;
else if (!pos.capture_or_promotion(ttMove))
{
int penalty = -stat_bonus(depth);
- thisThread->mainHistory[pos.side_to_move()][from_to(ttMove)] << penalty;
+ thisThread->mainHistory[us][from_to(ttMove)] << penalty;
update_continuation_histories(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
}
}
&& eval >= beta
&& ss->staticEval >= beta - 36 * depth / ONE_PLY + 225
&& !excludedMove
- && pos.non_pawn_material(pos.side_to_move())
- && (ss->ply >= thisThread->nmp_ply || ss->ply % 2 != thisThread->nmp_odd))
+ && pos.non_pawn_material(us)
+ && (ss->ply > thisThread->nmp_min_ply || us != thisThread->nmp_color))
{
assert(eval - beta >= 0);
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
nullValue = beta;
- if (abs(beta) < VALUE_KNOWN_WIN && (depth < 12 * ONE_PLY || thisThread->nmp_ply))
+ if (thisThread->nmp_min_ply || (abs(beta) < VALUE_KNOWN_WIN && depth < 12 * ONE_PLY))
return nullValue;
- // Do verification search at high depths. Disable null move pruning
- // for side to move for the first part of the remaining search tree.
- thisThread->nmp_ply = ss->ply + 3 * (depth-R) / 4;
- thisThread->nmp_odd = ss->ply % 2;
+ assert(!thisThread->nmp_min_ply); // Recursive verification is not allowed
+
+ // Do verification search at high depths, with null move pruning disabled
+ // for us, until ply exceeds nmp_min_ply.
+ thisThread->nmp_min_ply = ss->ply + 3 * (depth-R) / 4 - 1;
+ thisThread->nmp_color = us;
Value v = search<NonPV>(pos, ss, beta-1, beta, depth-R, false);
- thisThread->nmp_odd = thisThread->nmp_ply = 0;
+ thisThread->nmp_min_ply = 0;
if (v >= beta)
return nullValue;
// Step 14. Pruning at shallow depth (~170 Elo)
if ( !rootNode
- && pos.non_pawn_material(pos.side_to_move())
+ && pos.non_pawn_material(us)
&& bestValue > VALUE_MATED_IN_MAX_PLY)
{
if ( !captureOrPromotion
Depth r = reduction<PvNode>(improving, depth, moveCount);
if (captureOrPromotion) // (~5 Elo)
+ {
+ //Increase reduction by comparing opponent's stat score
+ if ( (ss-1)->statScore >= 0
+ && thisThread->captureHistory[movedPiece][to_sq(move)][type_of(pos.captured_piece())] < 0)
+ r += ONE_PLY;
+
r -= r ? ONE_PLY : DEPTH_ZERO;
+ }
else
{
// Decrease reduction if opponent's move count is high (~5 Elo)
&& !pos.see_ge(make_move(to_sq(move), from_sq(move))))
r -= 2 * ONE_PLY;
- ss->statScore = thisThread->mainHistory[~pos.side_to_move()][from_to(move)]
+ ss->statScore = thisThread->mainHistory[us][from_to(move)]
+ (*contHist[0])[movedPiece][to_sq(move)]
+ (*contHist[1])[movedPiece][to_sq(move)]
+ (*contHist[3])[movedPiece][to_sq(move)]