-extern Bitboard SquaresByColorBB[2];
-extern Bitboard FileBB[8];
-extern Bitboard NeighboringFilesBB[8];
-extern Bitboard ThisAndNeighboringFilesBB[8];
-extern Bitboard RankBB[8];
-extern Bitboard InFrontBB[2][8];
-
-extern Bitboard SetMaskBB[65];
-extern Bitboard ClearMaskBB[65];
-
-extern Bitboard StepAttacksBB[16][64];
-extern Bitboard BetweenBB[64][64];
-
-extern Bitboard SquaresInFrontMask[2][64];
-extern Bitboard PassedPawnMask[2][64];
-extern Bitboard AttackSpanMask[2][64];
-
-extern uint64_t RMult[64];
-extern int RShift[64];
-extern Bitboard RMask[64];
-extern Bitboard* RAttacks[64];
+CACHE_LINE_ALIGNMENT
+
+extern Bitboard RMasks[SQUARE_NB];
+extern Bitboard RMagics[SQUARE_NB];
+extern Bitboard* RAttacks[SQUARE_NB];
+extern unsigned RShifts[SQUARE_NB];
+
+extern Bitboard BMasks[SQUARE_NB];
+extern Bitboard BMagics[SQUARE_NB];
+extern Bitboard* BAttacks[SQUARE_NB];
+extern unsigned BShifts[SQUARE_NB];
+
+extern Bitboard SquareBB[SQUARE_NB];
+extern Bitboard FileBB[FILE_NB];
+extern Bitboard RankBB[RANK_NB];
+extern Bitboard AdjacentFilesBB[FILE_NB];
+extern Bitboard InFrontBB[COLOR_NB][RANK_NB];
+extern Bitboard StepAttacksBB[PIECE_NB][SQUARE_NB];
+extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
+extern Bitboard DistanceRingsBB[SQUARE_NB][8];
+extern Bitboard ForwardBB[COLOR_NB][SQUARE_NB];
+extern Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB];
+extern Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB];
+extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
+
+extern int SquareDistance[SQUARE_NB][SQUARE_NB];
+
+const Bitboard DarkSquares = 0xAA55AA55AA55AA55ULL;
+
+/// Overloads of bitwise operators between a Bitboard and a Square for testing
+/// whether a given bit is set in a bitboard, and for setting and clearing bits.
+
+inline Bitboard operator&(Bitboard b, Square s) {
+ return b & SquareBB[s];
+}