uint8_t PopCnt16[1 << 16];
int SquareDistance[SQUARE_NB][SQUARE_NB];
-Bitboard RookMasks [SQUARE_NB];
-Bitboard RookMagics [SQUARE_NB];
-Bitboard* RookAttacks[SQUARE_NB];
-unsigned RookShifts [SQUARE_NB];
-
-Bitboard BishopMasks [SQUARE_NB];
-Bitboard BishopMagics [SQUARE_NB];
-Bitboard* BishopAttacks[SQUARE_NB];
-unsigned BishopShifts [SQUARE_NB];
-
Bitboard SquareBB[SQUARE_NB];
Bitboard FileBB[FILE_NB];
Bitboard RankBB[RANK_NB];
Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
Bitboard PawnAttacks[COLOR_NB][SQUARE_NB];
+Magic RookMagics[SQUARE_NB];
+Magic BishopMagics[SQUARE_NB];
+
namespace {
// De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan
Bitboard RookTable[0x19000]; // To store rook attacks
Bitboard BishopTable[0x1480]; // To store bishop attacks
- typedef unsigned (Fn)(Square, Bitboard);
+ typedef unsigned (Fn)(const Magic&, Bitboard);
- void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], unsigned shifts[], Square deltas[], Fn index);
+ void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index);
// 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, RookAttacks, RookMagics, RookMasks, RookShifts, RookDeltas, magic_index<ROOK>);
- init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index<BISHOP>);
+ init_magics(RookTable, RookMagics, RookDeltas, magic_index);
+ init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index);
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[], Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) {
+ void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index) {
int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 },
{ 728, 10316, 55013, 32803, 12281, 15100, 16645, 255 } };
Bitboard occupancy[4096], reference[4096], edges, b;
- int age[4096] = {0}, current = 0, i, size;
-
- // attacks[s] is a pointer to the beginning of the attacks table for square 's'
- attacks[SQ_A1] = table;
+ int epoch[4096] = {}, cnt = 0, size = 0;
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
// all the attacks for each possible subset of the mask and so is 2 power
// the number of 1s of the mask. Hence we deduce the size of the shift to
// apply to the 64 or 32 bits word to get the index.
- masks[s] = sliding_attack(deltas, s, 0) & ~edges;
- shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]);
+ Magic& m = magics[s];
+ m.mask = sliding_attack(deltas, s, 0) & ~edges;
+ m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask);
+
+ // Set the offset for the attacks table of the square. We have individual
+ // table sizes for each square with "Fancy Magic Bitboards".
+ m.attacks = s == SQ_A1 ? table : magics[s - 1].attacks + size;
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
reference[size] = sliding_attack(deltas, s, b);
if (HasPext)
- attacks[s][pext(b, masks[s])] = reference[size];
+ m.attacks[pext(b, m.mask)] = reference[size];
size++;
- b = (b - masks[s]) & masks[s];
+ b = (b - m.mask) & m.mask;
} while (b);
- // Set the offset for the table of the next square. We have individual
- // table sizes for each square with "Fancy Magic Bitboards".
- if (s < SQ_H8)
- attacks[s + 1] = attacks[s] + size;
-
if (HasPext)
continue;
// Find a magic for square 's' picking up an (almost) random number
// until we find the one that passes the verification test.
- do {
- do
- magics[s] = rng.sparse_rand<Bitboard>();
- while (popcount((magics[s] * masks[s]) >> 56) < 6);
+ for (int i = 0; i < size; )
+ {
+ for (m.magic = 0; popcount((m.magic * m.mask) >> 56) < 6; )
+ m.magic = rng.sparse_rand<Bitboard>();
// A good magic must map every possible occupancy to an index that
// looks up the correct sliding attack in the attacks[s] database.
// Note that we build up the database for square 's' as a side
- // effect of verifying the magic.
- for (++current, i = 0; i < size; ++i)
+ // effect of verifying the magic. Keep track of the attempt count
+ // and save it in epoch[], little speed-up trick to avoid resetting
+ // m.attacks[] after every failed attempt.
+ for (++cnt, i = 0; i < size; ++i)
{
- unsigned idx = index(s, occupancy[i]);
+ unsigned idx = index(m, occupancy[i]);
- if (age[idx] < current)
+ if (epoch[idx] < cnt)
{
- age[idx] = current;
- attacks[s][idx] = reference[i];
+ epoch[idx] = cnt;
+ m.attacks[idx] = reference[i];
}
- else if (attacks[s][idx] != reference[i])
+ else if (m.attacks[idx] != reference[i])
break;
}
- } while (i < size);
+ }
}
}
}
projects / stockfish / blobdiff