/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
/// move ordering is at the current node.
MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
- const History& h, SearchStack* ss) : pos(p), H(h) {
+ const History& h, SearchStack* ss, Value beta) : pos(p), H(h) {
int searchTT = ttm;
ttMoves[0].move = ttm;
lastBadCapture = badCaptures;
+ badCaptureThreshold = 0;
pinned = p.pinned_pieces(pos.side_to_move());
if (p.is_check())
phasePtr = EvasionsPhaseTable;
else if (d > Depth(0))
+ {
+ // Consider sligtly negative captures as good if at low
+ // depth and far from beta.
+ if (ss && ss->eval < beta - PawnValueMidgame && d < 3 * OnePly)
+ badCaptureThreshold = -PawnValueMidgame;
+
phasePtr = MainSearchPhaseTable;
- else if (d == Depth(0))
+ } else if (d == Depth(0))
phasePtr = QsearchWithChecksPhaseTable;
else
{
{
// Check for a non negative SEE now
int seeValue = pos.see_sign(move);
- if (seeValue >= 0)
+ if (seeValue >= badCaptureThreshold)
return move;
// Losing capture, move it to the badCaptures[] array, note