In the (rare) cases when the two conditions
are true, then fully check again with a slow
but correct MoveList<LEGAL>(pos).size().
This is able to detect false positives like
this one:
8/8/8/Q7/5k1p/5P2/4KP2/8 b - - 0 17
When we have a possible simple pawn push that
is not stored in attacks[] array. Because the
third condition triggers very rarely, even if
it is slow, it does not alters in a measurable
way the average speed of the engine.
bench:
8678654
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <algorithm>
#include <cassert>
#include <iomanip>
#include <sstream>
-#include <algorithm>
#include "bitcount.h"
#include "evaluate.h"
// Stealmate detection
Color stm = pos.side_to_move();
if ( (ei.attackedBy[stm][ALL_PIECES] == ei.attackedBy[stm][KING])
- && (!(ei.attackedBy[stm][KING] & ~ei.attackedBy[~stm][ALL_PIECES])))
+ && (!(ei.attackedBy[stm][KING] & ~ei.attackedBy[~stm][ALL_PIECES]))
+ && !MoveList<LEGAL>(pos).size())
sf = SCALE_FACTOR_DRAW;
// Interpolate between a middlegame and a (scaled by 'sf') endgame score