Bitboard RookTable[0x19000]; // Storage space for rook attacks
Bitboard BishopTable[0x1480]; // Storage space for bishop attacks
- void init_magic_bitboards(Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[], Square deltas[]);
+ void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[],
+ Bitboard masks[], int shifts[]);
}
set_bit(&StepAttacksBB[make_piece(c, pt)][s], to);
}
- Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W };
- Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW };
-
- RAttacks[0] = RookTable;
- BAttacks[0] = BishopTable;
-
- init_magic_bitboards(RAttacks, RMagics, RMasks, RShifts, RDeltas);
- init_magic_bitboards(BAttacks, BMagics, BMasks, BShifts, BDeltas);
+ init_magic_bitboards(ROOK, RAttacks, RMagics, RMasks, RShifts);
+ init_magic_bitboards(BISHOP, BAttacks, BMagics, BMasks, BShifts);
for (Square s = SQ_A1; s <= SQ_H8; s++)
{
for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++)
if (bit_is_set(QueenPseudoAttacks[s1], s2))
{
- int f = file_distance(s1, s2);
- int r = rank_distance(s1, s2);
+ Square delta = (s2 - s1) / square_distance(s1, s2);
- Square d = (s2 - s1) / std::max(f, r);
-
- for (Square s3 = s1 + d; s3 != s2; s3 += d)
- set_bit(&BetweenBB[s1][s2], s3);
+ for (Square s = s1 + delta; s != s2; s += delta)
+ set_bit(&BetweenBB[s1][s2], s);
}
}
namespace {
- Bitboard sliding_attacks(Square sq, Bitboard occupied, Square deltas[]) {
+ Bitboard sliding_attacks(PieceType pt, Square sq, Bitboard occupied) {
+ Square deltas[][4] = { { DELTA_N, DELTA_E, DELTA_S, DELTA_W },
+ { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW } };
Bitboard attacks = 0;
+ Square* delta = (pt == ROOK ? deltas[0] : deltas[1]);
for (int i = 0; i < 4; i++)
{
- Square s = sq + deltas[i];
+ Square s = sq + delta[i];
- while (square_is_ok(s) && square_distance(s, s - deltas[i]) == 1)
+ while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1)
{
set_bit(&attacks, s);
if (bit_is_set(occupied, s))
break;
- s += deltas[i];
+ s += delta[i];
}
}
return attacks;
// see chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we
// use the so called "fancy" approach.
- void init_magic_bitboards(Bitboard* attacks[], Bitboard magics[],
- Bitboard masks[], int shifts[], Square deltas[]) {
+ void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[],
+ Bitboard masks[], int shifts[]) {
- const int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
- { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
+ int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 },
+ { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } };
RKISS rk;
Bitboard occupancy[4096], reference[4096], edges, b;
- int key, maxKey, index, booster;
+ int i, size, index, booster;
+
+ // attacks[s] is a pointer to the beginning of the attacks table for square 's'
+ attacks[SQ_A1] = (pt == ROOK ? RookTable : BishopTable);
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_attacks(s, EmptyBoardBB, deltas) & ~edges;
+ masks[s] = sliding_attacks(pt, s, EmptyBoardBB) & ~edges;
shifts[s] = (CpuIs64Bit ? 64 : 32) - count_1s<CNT32_MAX15>(masks[s]);
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
- // store the corresponding sliding attacks in reference[].
- b = maxKey = 0;
+ // store the corresponding sliding attacks bitboard in reference[].
+ b = size = 0;
do {
- occupancy[maxKey] = b;
- reference[maxKey++] = sliding_attacks(s, b, deltas);
+ occupancy[size] = b;
+ reference[size++] = sliding_attacks(pt, s, b);
b = (b - masks[s]) & masks[s];
} 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] + maxKey;
+ attacks[s + 1] = attacks[s] + size;
booster = MagicBoosters[CpuIs64Bit][rank_of(s)];
// until we find the one that passes the verification test.
do {
magics[s] = pick_random(masks[s], rk, booster);
- memset(attacks[s], 0, maxKey * sizeof(Bitboard));
+ memset(attacks[s], 0, size * sizeof(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 (key = 0; key < maxKey; key++)
+ for (i = 0; i < size; i++)
{
- index = CpuIs64Bit ? unsigned((occupancy[key] * magics[s]) >> shifts[s])
- : unsigned(occupancy[key] * magics[s] ^ (occupancy[key] >> 32) * (magics[s] >> 32)) >> shifts[s];
+ index = (pt == ROOK ? rook_index(s, occupancy[i])
+ : bishop_index(s, occupancy[i]));
if (!attacks[s][index])
- attacks[s][index] = reference[key];
+ attacks[s][index] = reference[i];
- else if (attacks[s][index] != reference[key])
+ else if (attacks[s][index] != reference[i])
break;
}
- } while (key != maxKey);
+ } while (i != size);
}
}
}
projects / stockfish / blobdiff