/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 Marco Costalba
+ Copyright (C) 2008-2009 Marco Costalba
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
/// search captures, promotions and some checks) and about how important good
/// move ordering is at the current node.
-MovePicker::MovePicker(const Position& p, bool pv, Move ttm,
- const SearchStack& ss, Depth d) : pos(p) {
- pvNode = pv;
+MovePicker::MovePicker(const Position& p, Move ttm, Depth d,
+ const History& h, SearchStack* ss) : pos(p), H(h) {
ttMove = ttm;
- mateKiller = (ss.mateKiller == ttm)? MOVE_NONE : ss.mateKiller;
- killer1 = ss.killers[0];
- killer2 = ss.killers[1];
- depth = d;
- movesPicked = 0;
- numOfMoves = 0;
- numOfBadCaptures = 0;
+ if (ss)
+ {
+ mateKiller = (ss->mateKiller == ttm)? MOVE_NONE : ss->mateKiller;
+ killer1 = ss->killers[0];
+ killer2 = ss->killers[1];
+ } else
+ mateKiller = killer1 = killer2 = MOVE_NONE;
+
+ movesPicked = numOfMoves = numOfBadCaptures = 0;
+ checkKillers = checkLegal = finished = false;
if (p.is_check())
phaseIndex = EvasionsPhaseIndex;
- else if (depth > Depth(0))
+ else if (d > Depth(0))
phaseIndex = MainSearchPhaseIndex;
- else if (depth == Depth(0))
+ else if (d == Depth(0))
phaseIndex = QsearchWithChecksPhaseIndex;
else
phaseIndex = QsearchWithoutChecksPhaseIndex;
movesPicked = 0;
break;
- case PH_BAD_CAPTURES:
- // It's probably a good idea to use SEE move ordering here. FIXME
- movesPicked = 0;
+ case PH_KILLERS:
+ movesPicked = numOfMoves = 0;
+ if (killer1 != MOVE_NONE && move_is_legal(pos, killer1, pinned) && !pos.move_is_capture(killer1))
+ moves[numOfMoves++].move = killer1;
+ if (killer2 != MOVE_NONE && move_is_legal(pos, killer2, pinned) && !pos.move_is_capture(killer2))
+ moves[numOfMoves++].move = killer2;
break;
case PH_NONCAPTURES:
+ checkKillers = (numOfMoves != 0); // previous phase is PH_KILLERS
+ checkLegal = true;
numOfMoves = generate_noncaptures(pos, moves);
score_noncaptures();
std::sort(moves, moves + numOfMoves);
movesPicked = 0;
break;
+ case PH_BAD_CAPTURES:
+ // Bad captures SEE value is already calculated so just sort them
+ // to get SEE move ordering.
+ std::sort(badCaptures, badCaptures + numOfBadCaptures);
+ movesPicked = 0;
+ break;
+
case PH_EVASIONS:
assert(pos.is_check());
numOfMoves = generate_evasions(pos, moves, pinned);
case PH_QCAPTURES:
numOfMoves = generate_captures(pos, moves);
- score_qcaptures();
+ score_captures();
std::sort(moves, moves + numOfMoves);
movesPicked = 0;
break;
void MovePicker::score_captures() {
// Winning and equal captures in the main search are ordered by MVV/LVA.
// Suprisingly, this appears to perform slightly better than SEE based
- // move ordering. The reason is probably that in a position with a winning
+ // move ordering. The reason is probably that in a position with a winning
// capture, capturing a more valuable (but sufficiently defended) piece
- // first usually doesn't hurt. The opponent will have to recapture, and
+ // first usually doesn't hurt. The opponent will have to recapture, and
// the hanging piece will still be hanging (except in the unusual cases
// where it is possible to recapture with the hanging piece). Exchanging
// big pieces before capturing a hanging piece probably helps to reduce
// the subtree size.
- // While scoring captures it moves all captures with negative SEE values
- // to the badCaptures[] array.
+ // In main search we want to push captures with negative SEE values to
+ // badCaptures[] array, but instead of doing it now we delay till when
+ // the move has been picked up in pick_move_from_list(), this way we save
+ // some SEE calls in case we get a cutoff (idea from Pablo Vazquez).
Move m;
- int seeValue;
+ // Use MVV/LVA ordering
for (int i = 0; i < numOfMoves; i++)
{
m = moves[i].move;
- seeValue = pos.see(m);
- if (seeValue >= 0)
- {
- if (move_promotion(m))
- moves[i].score = QueenValueMidgame;
- else
- moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(m)));
- }
+ if (move_is_promotion(m))
+ moves[i].score = QueenValueMidgame;
else
- {
- // Losing capture, move it to the badCaptures[] array
- assert(numOfBadCaptures < 63);
- moves[i].score = seeValue;
- badCaptures[numOfBadCaptures++] = moves[i];
- moves[i--] = moves[--numOfMoves];
- }
+ moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
+ -int(pos.type_of_piece_on(move_from(m)));
}
}
// First score by history, when no history is available then use
// piece/square tables values. This seems to be better then a
// random choice when we don't have an history for any move.
- Move m;
+ Piece piece;
+ Square from, to;
int hs;
for (int i = 0; i < numOfMoves; i++)
{
- m = moves[i].move;
-
- if (m == killer1)
- hs = HistoryMax + 2;
- else if (m == killer2)
- hs = HistoryMax + 1;
- else
- hs = H.move_ordering_score(pos.piece_on(move_from(m)), m);
+ from = move_from(moves[i].move);
+ to = move_to(moves[i].move);
+ piece = pos.piece_on(from);
+ hs = H.move_ordering_score(piece, to);
// Ensure history is always preferred to pst
if (hs > 0)
hs += 1000;
// pst based scoring
- moves[i].score = hs + pos.mg_pst_delta(m);
+ moves[i].score = hs + pos.pst_delta<Position::MidGame>(piece, from, to);
}
}
int seeScore = pos.see(m);
moves[i].score = (seeScore >= 0)? seeScore + HistoryMax : seeScore;
} else
- moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), m);
- }
-}
-
-void MovePicker::score_qcaptures() {
-
- // Use MVV/LVA ordering
- for (int i = 0; i < numOfMoves; i++)
- {
- Move m = moves[i].move;
- if (move_promotion(m))
- moves[i].score = QueenValueMidgame;
- else
- moves[i].score = int(pos.midgame_value_of_piece_on(move_to(m)))
- -int(pos.type_of_piece_on(move_from(m)));
+ moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), move_to(m));
}
}
switch (PhaseTable[phaseIndex]) {
case PH_GOOD_CAPTURES:
- case PH_NONCAPTURES:
while (movesPicked < numOfMoves)
{
Move move = moves[movesPicked++].move;
if ( move != ttMove
&& move != mateKiller
&& pos.pl_move_is_legal(move, pinned))
+ {
+ // Check for a non negative SEE now
+ int seeValue = pos.see_sign(move);
+ if (seeValue >= 0)
+ return move;
+
+ // Losing capture, move it to the badCaptures[] array, note
+ // that move has now been already checked for legality.
+ assert(numOfBadCaptures < 63);
+ badCaptures[numOfBadCaptures].move = move;
+ badCaptures[numOfBadCaptures++].score = seeValue;
+ }
+ }
+ break;
+ case PH_KILLERS:
+ case PH_NONCAPTURES:
+ while (movesPicked < numOfMoves)
+ {
+ Move move = moves[movesPicked++].move;
+ if ( move != ttMove
+ && move != mateKiller
+ && (!checkKillers || (move != killer1 && move != killer2))
+ && (!checkLegal || pos.pl_move_is_legal(move, pinned)))
return move;
}
break;
case PH_EVASIONS:
if (movesPicked < numOfMoves)
return moves[movesPicked++].move;
-
break;
case PH_BAD_CAPTURES:
- while (movesPicked < numOfBadCaptures)
- {
- Move move = badCaptures[movesPicked++].move;
- if ( move != ttMove
- && move != mateKiller
- && pos.pl_move_is_legal(move, pinned))
- return move;
- }
+ if (movesPicked < numOfBadCaptures)
+ return badCaptures[movesPicked++].move;
break;
case PH_QCAPTURES:
PhaseTable[i++] = PH_TT_MOVE;
PhaseTable[i++] = PH_MATE_KILLER;
PhaseTable[i++] = PH_GOOD_CAPTURES;
- // PH_KILLER_1 and PH_KILLER_2 are not yet used.
- // PhaseTable[i++] = PH_KILLER_1;
- // PhaseTable[i++] = PH_KILLER_2;
+ PhaseTable[i++] = PH_KILLERS;
PhaseTable[i++] = PH_NONCAPTURES;
PhaseTable[i++] = PH_BAD_CAPTURES;
PhaseTable[i++] = PH_STOP;
projects / stockfish / blobdiff