/*
- Glaurung, a UCI chess playing engine.
- Copyright (C) 2004-2008 Tord Romstad
+ Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+ Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+ Copyright (C) 2008 Marco Costalba
- Glaurung is free software: you can redistribute it and/or modify
+ Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
-
- Glaurung is distributed in the hope that it will be useful,
+
+
+ Stockfish is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
-
+
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/// Variables
- MovePicker::MovegenPhase PhaseTable[32];
+ MovePicker::MovegenPhase PhaseTable[32];
int MainSearchPhaseIndex;
int EvasionsPhaseIndex;
int QsearchWithChecksPhaseIndex;
/// move ordering is at the current node.
MovePicker::MovePicker(const Position& p, bool pvnode, Move ttm, Move mk,
- Move k1, Move k2, Depth d) : pos(p) {
+ Move k1, Move k2, Depth d) : pos(p) {
pvNode = pvnode;
ttMove = ttm;
mateKiller = (mk == ttm)? MOVE_NONE : mk;
if (ttMove != MOVE_NONE)
{
assert(move_is_ok(ttMove));
- if (generate_move_if_legal(pos, ttMove, pinned) != MOVE_NONE)
+ if (move_is_legal(pos, ttMove, pinned))
return ttMove;
}
break;
if (mateKiller != MOVE_NONE)
{
assert(move_is_ok(mateKiller));
- if (generate_move_if_legal(pos, mateKiller, pinned) != MOVE_NONE)
+ if (move_is_legal(pos, mateKiller, pinned))
return mateKiller;
- }
- break;
+ }
+ break;
- case PH_GOOD_CAPTURES:
+ case PH_GOOD_CAPTURES:
numOfMoves = generate_captures(pos, moves);
score_captures();
movesPicked = 0;
break;
case PH_EVASIONS:
- assert(pos.is_check());
+ assert(pos.is_check());
numOfMoves = generate_evasions(pos, moves);
score_evasions();
movesPicked = 0;
break;
- case PH_QCAPTURES:
+ case PH_QCAPTURES:
numOfMoves = generate_captures(pos, moves);
score_qcaptures();
movesPicked = 0;
return MOVE_NONE;
}
}
- assert(false);
-
- return MOVE_NONE;
}
Move MovePicker::get_next_move(Lock &lock) {
- lock_grab(&lock);
- if (finished)
- {
- lock_release(&lock);
- return MOVE_NONE;
- }
- Move m = get_next_move();
- if (m == MOVE_NONE)
- finished = true;
-
- lock_release(&lock);
- return m;
+ lock_grab(&lock);
+ if (finished)
+ {
+ lock_release(&lock);
+ return MOVE_NONE;
+ }
+ Move m = get_next_move();
+ if (m == MOVE_NONE)
+ finished = true;
+
+ lock_release(&lock);
+ return m;
}
+
/// MovePicker::score_captures(), MovePicker::score_noncaptures(),
/// MovePicker::score_evasions() and MovePicker::score_qcaptures() assign a
/// numerical move ordering score to each move in a move list. The moves
/// with highest scores will be picked first by pick_move_from_list().
void MovePicker::score_captures() {
- // Winning and equal captures in the main search are ordered by MVV.
+ // 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
// 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
+ // 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.
+ // the subtree size. Instead of calculating SEE here to filter out
+ // loosing captures, we delay the filtering in pick_move_from_list()
+ Move m;
+
for (int i = 0; i < numOfMoves; i++)
{
- Move m = moves[i].move;
- moves[i].score = pos.see(m);
- if (moves[i].score >= 0)
- moves[i].score = move_promotion(m) ? QueenValueMidgame
- : pos.midgame_value_of_piece_on(move_to(m));
+ 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)));
}
}
void MovePicker::score_noncaptures() {
+ // 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;
+ int hs;
for (int i = 0; i < numOfMoves; i++)
{
- Move m = moves[i].move;
+ m = moves[i].move;
+
if (m == killer1)
- moves[i].score = HistoryMax + 2;
+ hs = HistoryMax + 2;
else if (m == killer2)
- moves[i].score = HistoryMax + 1;
+ hs = HistoryMax + 1;
else
- moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), m);
+ hs = H.move_ordering_score(pos.piece_on(move_from(m)), m);
// Ensure moves in history are always sorted as first
- if (moves[i].score > 0)
- moves[i].score += 1000;
+ if (hs > 0)
+ hs += 1000;
- moves[i].score += pos.mg_pst_delta(moves[i].move);
+ moves[i].score = hs + pos.mg_pst_delta(m);
}
}
moves[i].score = 2*HistoryMax;
else if (!pos.square_is_empty(move_to(m)))
{
- moves[i].score = pos.see(m);
- if (moves[i].score >= 0)
- moves[i].score += HistoryMax;
- }
- else
+ 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);
}
// FIXME try psqt also here
void MovePicker::score_qcaptures() {
- // Use MVV ordering
+ // Use MVV/LVA ordering
for (int i = 0; i < numOfMoves; i++)
{
Move m = moves[i].move;
- moves[i].score = move_promotion(m) ? QueenValueMidgame
- : pos.midgame_value_of_piece_on(move_to(m));
+ 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)));
}
}
Move move;
switch (PhaseTable[phaseIndex]) {
-
case PH_GOOD_CAPTURES:
assert(!pos.is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
- int bestScore = -10000000;
- bestIndex = -1;
- for (int i = movesPicked; i < numOfMoves; i++)
+ bestIndex = find_best_index();
+
+ if (bestIndex != -1) // Found a possibly good capture
{
- if (moves[i].score < 0)
+ move = moves[bestIndex].move;
+ int seeValue = pos.see(move);
+ if (seeValue < 0)
{
// Losing capture, move it to the badCaptures[] array
assert(numOfBadCaptures < 63);
- badCaptures[numOfBadCaptures++] = moves[i];
- moves[i--] = moves[--numOfMoves];
- }
- else if (moves[i].score > bestScore)
- {
- bestIndex = i;
- bestScore = moves[i].score;
- }
- }
- if (bestIndex != -1) // Found a good capture
- {
- move = moves[bestIndex].move;\r
+ moves[bestIndex].score = seeValue;
+ badCaptures[numOfBadCaptures++] = moves[bestIndex];
+ moves[bestIndex] = moves[--numOfMoves];
+ continue;
+ }
moves[bestIndex] = moves[movesPicked++];
if ( move != ttMove
&& move != mateKiller
- && pos.move_is_legal(move, pinned))
+ && pos.pl_move_is_legal(move, pinned))
return move;
}
}
case PH_NONCAPTURES:
assert(!pos.is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
// If this is a PV node or we have only picked a few moves, scan
// the entire move list for the best move. If many moves have already
// been searched and it is not a PV node, we are probably failing low
// anyway, so we just pick the first move from the list.
- bestIndex = (movesPicked < 12 || pvNode ? find_best_index() : movesPicked);
+ bestIndex = (pvNode || movesPicked < 12) ? find_best_index() : movesPicked;
if (bestIndex != -1)
{
- move = moves[bestIndex].move;\r
+ move = moves[bestIndex].move;
moves[bestIndex] = moves[movesPicked++];
if ( move != ttMove
&& move != mateKiller
- && pos.move_is_legal(move, pinned))
+ && pos.pl_move_is_legal(move, pinned))
return move;
- }
- }
- break;
+ }
+ }
+ break;
case PH_EVASIONS:
assert(pos.is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
bestIndex = find_best_index();
if (bestIndex != -1)
{
- move = moves[bestIndex].move;\r
+ move = moves[bestIndex].move;
moves[bestIndex] = moves[movesPicked++];
return move;
}
- }
- break;
+ }
+ break;
case PH_BAD_CAPTURES:
assert(!pos.is_check());
move = badCaptures[badCapturesPicked++].move;
if ( move != ttMove
&& move != mateKiller
- && pos.move_is_legal(move, pinned))
+ && pos.pl_move_is_legal(move, pinned))
return move;
}
break;
assert(movesPicked >= 0);
while (movesPicked < numOfMoves)
{
- // FIXME makes sens to score qcaps?
bestIndex = (movesPicked < 4 ? find_best_index() : movesPicked);
if (bestIndex != -1)
{
- move = moves[bestIndex].move;\r
+ move = moves[bestIndex].move;
moves[bestIndex] = moves[movesPicked++];
- if (move != ttMove && pos.move_is_legal(move, pinned))
+ // Remember to change the line below if we decide to hash the qsearch!
+ // Maybe also postpone the legality check until after futility pruning?
+ if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
return move;
}
}
// move here? FIXME
while (movesPicked < numOfMoves)
{
- move = moves[movesPicked++].move;
- if (move != ttMove && pos.move_is_legal(move, pinned))
+ move = moves[movesPicked++].move;
+ // Remember to change the line below if we decide to hash the qsearch!
+ if (/* move != ttMove && */ pos.pl_move_is_legal(move, pinned))
return move;
}
break;
/// MovePicker::init_phase_table() initializes the PhaseTable[],
/// MainSearchPhaseIndex, EvasionPhaseIndex, QsearchWithChecksPhaseIndex
-/// and QsearchWithoutChecksPhaseIndex variables. It is only called once
+/// and QsearchWithoutChecksPhaseIndex variables. It is only called once
/// during program startup, and never again while the program is running.
void MovePicker::init_phase_table() {
projects / stockfish / blobdiff