uint8_t PopCnt16[1 << 16];
uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
-Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
Bitboard LineBB[SQUARE_NB][SQUARE_NB];
Bitboard DistanceRingBB[SQUARE_NB][8];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
for (PieceType pt : { BISHOP, ROOK })
for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
if (PseudoAttacks[pt][s1] & s2)
- {
LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
- BetweenBB[s1][s2] = attacks_bb(pt, s1, square_bb(s2)) & attacks_bb(pt, s2, square_bb(s1));
- }
}
}
extern uint8_t PopCnt16[1 << 16];
extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
-extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
extern Bitboard DistanceRingBB[SQUARE_NB][8];
extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
}
-/// between_bb() returns a bitboard representing all the squares between the two
-/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
-/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank,
-/// file or diagonal, 0 is returned.
+/// between_bb() returns squares that are linearly between the given squares
+/// If the given squares are not on a same file/rank/diagonal, return 0.
inline Bitboard between_bb(Square s1, Square s2) {
- return BetweenBB[s1][s2];
+ return LineBB[s1][s2] & ( (AllSquares << (s1 + (s1 < s2)))
+ ^(AllSquares << (s2 + !(s1 < s2))));
}