extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
+/// Magic holds all magic bitboards relevant data for a single square
+struct Magic {
+ Bitboard mask;
+ Bitboard magic;
+ Bitboard* attacks;
+ unsigned shift;
+};
+
+extern Magic RookMagics[SQUARE_NB];
+extern Magic BishopMagics[SQUARE_NB];
+
+
/// 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.
/// pawn_attack_span() returns a bitboard representing all the squares that can be
/// attacked by a pawn of the given color when it moves along its file, starting
/// from the given square:
-/// PawnAttackSpan[c][s] = in_front_bb(c, rank_of(s)) & adjacent_files_bb(s);
+/// PawnAttackSpan[c][s] = in_front_bb(c, rank_of(s)) & adjacent_files_bb(file_of(s));
inline Bitboard pawn_attack_span(Color c, Square s) {
return PawnAttackSpan[c][s];
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 Magic RookMagics[SQUARE_NB];
- extern Magic BishopMagics[SQUARE_NB];
-
- const Magic* Magics = Pt == ROOK ? RookMagics : BishopMagics;
- Bitboard mask = Magics[s].mask;
- Bitboard magic = Magics[s].magic;
- unsigned shift = Magics[s].shift;
+inline unsigned magic_index(const Magic& m, Bitboard occupied) {
if (HasPext)
- return unsigned(pext(occupied, mask));
+ return unsigned(pext(occupied, m.mask));
if (Is64Bit)
- return unsigned(((occupied & mask) * magic) >> shift);
+ return unsigned(((occupied & m.mask) * m.magic) >> m.shift);
- unsigned lo = unsigned(occupied) & unsigned(mask);
- unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
- return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ unsigned lo = unsigned(occupied) & unsigned(m.mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(m.mask >> 32);
+ return (lo * unsigned(m.magic) ^ hi * unsigned(m.magic >> 32)) >> m.shift;
}
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
- extern Magic RookMagics[SQUARE_NB];
- extern Magic BishopMagics[SQUARE_NB];
-
- return (Pt == ROOK ? RookMagics : BishopMagics)[s].attacks[magic_index<Pt>(s, occupied)];
+ const Magic& M = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
+ return M.attacks[magic_index(M, occupied)];
}
inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
switch (pt)
{
case BISHOP: return attacks_bb<BISHOP>(s, occupied);
- case ROOK : return attacks_bb<ROOK>(s, occupied);
+ case ROOK : return attacks_bb< ROOK>(s, occupied);
case QUEEN : return attacks_bb<BISHOP>(s, occupied) | attacks_bb<ROOK>(s, occupied);
default : return PseudoAttacks[pt][s];
}