/*
- 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/>.
*/
/// search captures, promotions and some checks) and about how important good
/// 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) {
+MovePicker::MovePicker(Position& p, bool pvnode, Move ttm, Move mk,
+ Move k1, Move k2, Depth d) {
+ pos = &p;
pvNode = pvnode;
ttMove = ttm;
mateKiller = (mk == ttm)? MOVE_NONE : mk;
// Next phase
phaseIndex++;
switch (PhaseTable[phaseIndex]) {
-
case PH_TT_MOVE:
if (ttMove != MOVE_NONE)
{
assert(move_is_ok(ttMove));
- if (generate_move_if_legal(pos, ttMove, pinned) != MOVE_NONE)
- return ttMove;
+ Move m = generate_move_if_legal(*pos, ttMove, pinned);
+ if (m != MOVE_NONE)
+ {
+ assert(m == ttMove);
+ return m;
+ }
}
break;
if (mateKiller != MOVE_NONE)
{
assert(move_is_ok(mateKiller));
- if (generate_move_if_legal(pos, mateKiller, pinned) != MOVE_NONE)
- return mateKiller;
- }
- break;
-
- case PH_GOOD_CAPTURES:
- numOfMoves = generate_captures(pos, moves);
+ Move m = generate_move_if_legal(*pos, mateKiller, pinned);
+ if (m != MOVE_NONE)
+ {
+ assert(m == mateKiller);
+ return m;
+ }
+ }
+ break;
+
+ case PH_GOOD_CAPTURES:
+ numOfMoves = generate_captures(*pos, moves);
score_captures();
movesPicked = 0;
break;
break;
case PH_NONCAPTURES:
- numOfMoves = generate_noncaptures(pos, moves);
+ numOfMoves = generate_noncaptures(*pos, moves);
score_noncaptures();
movesPicked = 0;
break;
case PH_EVASIONS:
- assert(pos.is_check());
- numOfMoves = generate_evasions(pos, moves);
+ assert(pos->is_check());
+ numOfMoves = generate_evasions(*pos, moves);
score_evasions();
movesPicked = 0;
break;
case PH_QCAPTURES:
- numOfMoves = generate_captures(pos, moves);
+ numOfMoves = generate_captures(*pos, moves);
score_qcaptures();
movesPicked = 0;
break;
case PH_QCHECKS:
- numOfMoves = generate_checks(pos, moves, dc);
+ numOfMoves = generate_checks(*pos, moves, dc);
movesPicked = 0;
break;
}
}
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;
+ Move m;
- lock_release(&lock);
- return m;
+ lock_grab(&lock);
+ if (finished)
+ {
+ lock_release(&lock);
+ return MOVE_NONE;
+ }
+ 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
// the subtree size.
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));
+ int seeValue = pos->see(moves[i].move);
+ if (seeValue >= 0)
+ {
+ if (move_promotion(moves[i].move))
+ moves[i].score = QueenValueMidgame;
+ else
+ moves[i].score = int(pos->midgame_value_of_piece_on(move_to(moves[i].move)))
+ -int(pos->type_of_piece_on(move_from(moves[i].move)));
+ } else
+ moves[i].score = seeValue;
}
}
else if (m == killer2)
moves[i].score = HistoryMax + 1;
else
- moves[i].score = 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;
-
- moves[i].score += pos.mg_pst_delta(moves[i].move);
+ moves[i].score = H.move_ordering_score(pos->piece_on(move_from(m)), m);
}
}
Move m = moves[i].move;
if (m == ttMove)
moves[i].score = 2*HistoryMax;
- else if (!pos.square_is_empty(move_to(m)))
+ 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
- moves[i].score = H.move_ordering_score(pos.piece_on(move_from(m)), m);
+ 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->midgame_value_of_piece_on(move_to(m))) / 64;
}
}
-/// find_best_index() loops across the moves and returns index of
-/// the highest scored one.
-
-int MovePicker::find_best_index() {
-
- int bestScore = -10000000, bestIndex = -1;
-
- for (int i = movesPicked; i < numOfMoves; i++)
- if (moves[i].score > bestScore)
- {
- bestIndex = i;
- bestScore = moves[i].score;
- }
- return bestIndex;
-}
-
-
/// MovePicker::pick_move_from_list() picks the move with the biggest score
/// from a list of generated moves (moves[] or badCaptures[], depending on
/// the current move generation phase). It takes care not to return the
Move MovePicker::pick_move_from_list() {
+ int bestScore = -10000000;
int bestIndex;
Move move;
switch (PhaseTable[phaseIndex]) {
-
case PH_GOOD_CAPTURES:
- assert(!pos.is_check());
+ assert(!pos->is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
- int bestScore = -10000000;
+ bestScore = -10000000;
bestIndex = -1;
for (int i = movesPicked; i < numOfMoves; i++)
{
assert(numOfBadCaptures < 63);
badCaptures[numOfBadCaptures++] = moves[i];
moves[i--] = moves[--numOfMoves];
- }
- else if (moves[i].score > bestScore)
- {
- bestIndex = i;
- bestScore = moves[i].score;
- }
+ }
+ else if (moves[i].score > bestScore)
+ {
+ bestIndex = i;
+ bestScore = moves[i].score;
+ }
}
if (bestIndex != -1) // Found a good capture
{
- 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->move_is_legal(move, pinned))
return move;
}
}
break;
case PH_NONCAPTURES:
- assert(!pos.is_check());
+ assert(!pos->is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
+ bestScore = -10000000;
+
// 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);
+ if (pvNode || movesPicked < 12)
+ {
+ bestIndex = -1;
+ for (int i = movesPicked; i < numOfMoves; i++)
+ if (moves[i].score > bestScore)
+ {
+ bestIndex = i;
+ bestScore = moves[i].score;
+ }
+ } else
+ bestIndex = 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->move_is_legal(move, pinned))
return move;
- }
- }
- break;
+ }
+ }
+ break;
case PH_EVASIONS:
- assert(pos.is_check());
+ assert(pos->is_check());
assert(movesPicked >= 0);
+
while (movesPicked < numOfMoves)
{
- bestIndex = find_best_index();
+ bestScore = -10000000;
+ bestIndex = -1;
+ for (int i = movesPicked; i < numOfMoves; i++)
+ if(moves[i].score > bestScore)
+ {
+ bestIndex = i;
+ bestScore = moves[i].score;
+ }
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());
+ assert(!pos->is_check());
assert(badCapturesPicked >= 0);
// It's probably a good idea to use SEE move ordering here, instead
// of just picking the first move. FIXME
move = badCaptures[badCapturesPicked++].move;
if ( move != ttMove
&& move != mateKiller
- && pos.move_is_legal(move, pinned))
+ && pos->move_is_legal(move, pinned))
return move;
}
break;
case PH_QCAPTURES:
- assert(!pos.is_check());
+ assert(!pos->is_check());
assert(movesPicked >= 0);
while (movesPicked < numOfMoves)
{
- // FIXME makes sens to score qcaps?
- bestIndex = (movesPicked < 4 ? find_best_index() : movesPicked);
+ bestScore = -10000000;
+ if (movesPicked < 4)
+ {
+ bestIndex = -1;
+ for (int i = movesPicked; i < numOfMoves; i++)
+ if(moves[i].score > bestScore)
+ {
+ bestIndex = i;
+ bestScore = moves[i].score;
+ }
+ } else
+ bestIndex = 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->move_is_legal(move, pinned))
return move;
}
}
break;
case PH_QCHECKS:
- assert(!pos.is_check());
+ assert(!pos->is_check());
assert(movesPicked >= 0);
// Perhaps we should do something better than just picking the first
// 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->move_is_legal(move, pinned))
return move;
}
break;
return MOVE_NONE;
}
-
-/// MovePicker::current_move_type() returns the type of the just
-/// picked next move. It can be used in search to further differentiate
-/// according to the current move type: capture, non capture, escape, etc.
MovePicker::MovegenPhase MovePicker::current_move_type() const {
return PhaseTable[phaseIndex];
}
-
/// 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() {