Bitboard InFrontBB[2][8];
Bitboard StepAttacksBB[16][64];
Bitboard BetweenBB[64][64];
+Bitboard DistanceRingsBB[64][8];
Bitboard ForwardBB[2][64];
Bitboard PassedPawnMask[2][64];
Bitboard AttackSpanMask[2][64];
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;
+
for (int i = 0; i < 64; i++)
if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems
{