- for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
- for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
- SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2));
-
- for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++)
- for (int d = 1; d < 8; d++)
- for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
- if (SquareDistance[s1][s2] == d)
- DistanceRingsBB[s1][d - 1] |= s2;
-
- int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 },
- {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } };
+ // Helper returning the target bitboard of a step from a square
+ auto landing_square_bb = [&](Square s, int step)
+ {
+ Square to = Square(s + step);
+ return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0);
+ };