/*
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
{
searchTT = ttMoves[0].move = MOVE_NONE;
}
- phasePtr += !searchTT - 1;
+ phasePtr += int(!searchTT) - 1;
go_next_phase();
}
case PH_NONCAPTURES:
lastMove = generate_noncaptures(pos, moves);
score_noncaptures();
- sort_moves(moves, lastMove);
+ sort_moves(moves, lastMove, &lastGoodNonCapture);
return;
case PH_BAD_CAPTURES:
Move m;
Piece piece;
Square from, to;
+ int hs;
for (MoveStack* cur = moves; cur != lastMove; cur++)
{
from = move_from(m);
to = move_to(m);
piece = pos.piece_on(from);
- cur->score = H.move_ordering_score(piece, to);
+ hs = H.move_ordering_score(piece, to);
+
+ // Ensure history has always highest priority
+ if (hs > 0)
+ hs += 10000;
+
+ // Gain table based scoring
+ cur->score = hs + 16 * H.gain(piece, to);
}
}
{
m = cur->move;
if ((seeScore = pos.see_sign(m)) < 0)
- cur->score = seeScore;
+ cur->score = seeScore - HistoryMax; // Be sure are at the bottom
else if (pos.move_is_capture(m))
cur->score = pos.midgame_value_of_piece_on(move_to(m))
- pos.type_of_piece_on(move_from(m)) + HistoryMax;
{
// 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
break;
case PH_NONCAPTURES:
+
+ // Sort negative scored moves only when we get there
+ if (curMove == lastGoodNonCapture)
+ insertion_sort(lastGoodNonCapture, lastMove);
+
move = (curMove++)->move;
if ( move != ttMoves[0].move
&& move != ttMoves[1].move