// Map the square as if strongSide is white and strongSide's only pawn
// is on the left half of the board.
public Square normalize(Position pos, Color strongSide, Square sq)
{
Debug.Assert(pos.count(strongSide, PieceTypeS.PAWN) == 1);
if (Types.file_of(pos.list(strongSide, PieceTypeS.PAWN)[0]) >= FileS.FILE_E)
{
sq = (Square)(sq ^ 7); // Mirror SQ_H1 -> SQ_A1
}
if (strongSide == ColorS.BLACK)
{
sq = Types.notSquare(sq);
}
return(sq);
}
/// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the
/// defending king towards a corner square of the right color.
public Value KBNK(Position pos)
{
Debug.Assert(verify_material(pos, strongSide, ValueS.KnightValueMg + ValueS.BishopValueMg, 0));
Debug.Assert(verify_material(pos, weakSide, ValueS.VALUE_ZERO, 0));
Square winnerKSq = pos.king_square(strongSide);
Square loserKSq = pos.king_square(weakSide);
Square bishopSq = pos.list(strongSide, PieceTypeS.BISHOP)[0];
// kbnk_mate_table() tries to drive toward corners A1 or H8. If we have a
// bishop that cannot reach the above squares, we flip the kings in order
// to drive the enemy toward corners A8 or H1.
if (Types.opposite_colors(bishopSq, SquareS.SQ_A1))
{
winnerKSq = Types.notSquare(winnerKSq);
loserKSq = Types.notSquare(loserKSq);
}
Value result = ValueS.VALUE_KNOWN_WIN
+ PushClose[BitBoard.square_distance(winnerKSq, loserKSq)]
+ PushToCorners[loserKSq];
return(strongSide == pos.side_to_move() ? result : -result);
}