Bitboard RookTable[0x19000]; // To store rook attacks
Bitboard BishopTable[0x1480]; // To store bishop attacks
- typedef unsigned (Fn)(const Magic&, Bitboard);
-
- void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index);
+ void init_magics(Bitboard table[], Magic magics[], Square deltas[]);
// bsf_index() returns the index into BSFTable[] to look up the bitscan. Uses
// Matt Taylor's folding for 32 bit case, extended to 64 bit by Kim Walisch.
Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST };
Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST };
- init_magics(RookTable, RookMagics, RookDeltas, magic_index);
- init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index);
+ init_magics(RookTable, RookMagics, RookDeltas);
+ init_magics(BishopTable, BishopMagics, BishopDeltas);
for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1)
{
// chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
// use the so called "fancy" approach.
- void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index) {
+ void init_magics(Bitboard table[], Magic magics[], Square deltas[]) {
int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 },
{ 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
// m.attacks[] after every failed attempt.
for (++cnt, i = 0; i < size; ++i)
{
- unsigned idx = index(m, occupancy[i]);
+ unsigned idx = m.index(occupancy[i]);
if (epoch[idx] < cnt)
{
Bitboard magic;
Bitboard* attacks;
unsigned shift;
+
+ /// looks up the index using the 'magic bitboards' approach.
+ unsigned index(Bitboard occupied) const {
+
+ if (HasPext)
+ return unsigned(pext(occupied, mask));
+
+ if (Is64Bit)
+ return unsigned(((occupied & mask) * magic) >> shift);
+
+ unsigned lo = unsigned(occupied) & unsigned(mask);
+ unsigned hi = unsigned(occupied >> 32) & unsigned(mask >> 32);
+ return (lo * unsigned(magic) ^ hi * unsigned(magic >> 32)) >> shift;
+ }
};
extern Magic RookMagics[SQUARE_NB];
/// 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.
-inline unsigned magic_index(const Magic& m, Bitboard occupied) {
-
- if (HasPext)
- return unsigned(pext(occupied, m.mask));
-
- if (Is64Bit)
- return unsigned(((occupied & m.mask) * m.magic) >> m.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;
-}
+/// piece of type Pt (bishop or rook) placed on 's'.
template<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
const Magic& M = Pt == ROOK ? RookMagics[s] : BishopMagics[s];
- return M.attacks[magic_index(M, occupied)];
+ return M.attacks[M.index(occupied)];
}
inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {