mobility += MobilityBonus[Piece][mob];
+ // Add a bonus if a slider is pinning an enemy piece
+ if ( (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
+ && (PseudoAttacks[Piece][pos.king_square(Them)] & s))
+ {
+ b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
+
+ assert(b);
+
+ if (!more_than_one(b) && (b & pos.pieces(Them)))
+ score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
+ }
+
// Decrease score if we are attacked by an enemy pawn. Remaining part
// of threat evaluation must be done later when we have full attack info.
if (ei.attackedBy[Them][PAWN] & s)
& ~ei.attackedBy[Them][0];
if (undefendedMinors)
- score += UndefendedMinorPenalty;
+ score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
+ : UndefendedMinorPenalty;
// Enemy pieces not defended by a pawn and under our attack
weakEnemies = pos.pieces(Them)