S( 9, 10), S( 2, 10), S( 1, -8), S(-20,-12),
S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10)
};
+
+ // Protector[PieceType][distance] contains a protecting bonus for our king,
+ // indexed by piece type and distance between the piece and the king.
+ const Score Protector[PIECE_TYPE_NB][8] = {
+ {}, {},
+ { S(0, 0), S( 7, 9), S( 7, 1), S( 1, 5), S(-10,-4), S( -1,-4), S( -7,-3), S(-16,-10) }, // Knight
+ { S(0, 0), S(11, 8), S(-7,-1), S(-1,-2), S( -1,-7), S(-11,-3), S( -9,-1), S(-16, -1) }, // Bishop
+ { S(0, 0), S(10, 0), S(-2, 2), S(-5, 4), S( -6, 2), S(-14,-3), S( -2,-9), S(-12, -7) }, // Rook
+ { S(0, 0), S( 3,-5), S( 2,-5), S(-4, 0), S( -9,-6), S(-4, 7), S(-13,-7), S(-10, -7) } // Queen
+ };
// Assorted bonuses and penalties used by evaluation
const Score MinorBehindPawn = S(16, 0);
int mob = popcount(b & ei.mobilityArea[Us]);
mobility[Us] += MobilityBonus[Pt][mob];
+
+ // Bonus for this piece as a king protector
+ score += Protector[Pt][distance(s, pos.square<KING>(Us))];
if (Pt == BISHOP || Pt == KNIGHT)
{