template<> inline int distance<Rank>(Square x, Square y) { return distance(rank_of(x), rank_of(y)); }
+/// Magic holds all magic relevant data for a single square
+struct Magic {
+
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+};
+
/// attacks_bb() returns a bitboard representing all the squares attacked by a
/// piece of type Pt (bishop or rook) placed on 's'. The helper magic_index()
/// looks up the index using the 'magic bitboards' approach.
template<PieceType Pt>
inline unsigned magic_index(Square s, Bitboard occupied) {
- extern Bitboard RookMasks[SQUARE_NB];
- extern Bitboard RookMagics[SQUARE_NB];
- extern unsigned RookShifts[SQUARE_NB];
- extern Bitboard BishopMasks[SQUARE_NB];
- extern Bitboard BishopMagics[SQUARE_NB];
- extern unsigned BishopShifts[SQUARE_NB];
+ extern Magic RookMagics[SQUARE_NB];
+ extern Magic BishopMagics[SQUARE_NB];
- Bitboard* const Masks = Pt == ROOK ? RookMasks : BishopMasks;
- Bitboard* const Magics = Pt == ROOK ? RookMagics : BishopMagics;
- unsigned* const Shifts = Pt == ROOK ? RookShifts : BishopShifts;
+ const Magic* Magics = Pt == ROOK ? RookMagics : BishopMagics;
+ Bitboard mask = Magics[s].mask;
+ Bitboard magic = Magics[s].magic;
+ unsigned shift = Magics[s].shift;
if (HasPext)
- return unsigned(pext(occupied, Masks[s]));
+ return unsigned(pext(occupied, mask));
if (Is64Bit)
- return unsigned(((occupied & Masks[s]) * Magics[s]) >> Shifts[s]);
+ return unsigned(((occupied & mask) * magic) >> shift);
- unsigned lo = unsigned(occupied) & unsigned(Masks[s]);
- unsigned hi = unsigned(occupied >> 32) & unsigned(Masks[s] >> 32);
- return (lo * unsigned(Magics[s]) ^ hi * unsigned(Magics[s] >> 32)) >> Shifts[s];
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
}
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
- extern Bitboard* RookAttacks[SQUARE_NB];
- extern Bitboard* BishopAttacks[SQUARE_NB];
+ extern Magic RookMagics[SQUARE_NB];
+ extern Magic BishopMagics[SQUARE_NB];
- return (Pt == ROOK ? RookAttacks : BishopAttacks)[s][magic_index<Pt>(s, occupied)];
+ return (Pt == ROOK ? RookMagics : BishopMagics)[s].attacks[magic_index<Pt>(s, occupied)];
}
inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {