X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=de28e03a05c4ef345ab0d89db30d206046811637;hp=8c70a8e27b10820e27f288f28febfced33f91657;hb=bc54a44010e7a7fb55ee55afba65be029a9e423a;hpb=d632e77058114e87a6d7c02fda3a40768546e1d6 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 8c70a8e2..de28e03a 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -65,8 +65,8 @@ namespace { Bitboard RAttacksTable[0x19000]; Bitboard BAttacksTable[0x1480]; - void do_magics(Bitboard magic[], Bitboard* attack[], Bitboard attTabl[], - Bitboard mask[], int shift[], Square deltas[]); + void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[], + Bitboard mask[], int shift[], Square delta[]); } @@ -79,7 +79,7 @@ void print_bitboard(Bitboard b) { { std::cout << "+---+---+---+---+---+---+---+---+" << '\n'; for (File f = FILE_A; f <= FILE_H; f++) - std::cout << "| " << (bit_is_set(b, make_square(f, r)) ? 'X' : ' ') << ' '; + std::cout << "| " << (bit_is_set(b, make_square(f, r)) ? "X " : " "); std::cout << "|\n"; } @@ -159,7 +159,7 @@ void init_bitboards() { for (Square s = SQ_A1; s <= SQ_H8; s++) { - SetMaskBB[s] = (1ULL << s); + SetMaskBB[s] = 1ULL << s; ClearMaskBB[s] = ~SetMaskBB[s]; } @@ -195,9 +195,9 @@ void init_bitboards() { } for (Bitboard b = 0; b < 256; b++) - BitCount8Bit[b] = (uint8_t)count_1s(b); + BitCount8Bit[b] = (uint8_t)count_1s(b); - for (int i = 1; i < 64; i++) + for (int i = 0; i < 64; i++) if (!CpuIs64Bit) // Matt Taylor's folding trick for 32 bit systems { Bitboard b = 1ULL << i; @@ -208,13 +208,12 @@ void init_bitboards() { else BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i; - int steps[][9] = { - {0}, {7,9,0}, {17,15,10,6,-6,-10,-15,-17,0}, {0}, {0}, {0}, {9,7,-7,-9,8,1,-1,-8,0} - }; + int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 }, + {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } }; for (Color c = WHITE; c <= BLACK; c++) - for (Square s = SQ_A1; s <= SQ_H8; s++) - for (PieceType pt = PAWN; pt <= KING; pt++) + for (PieceType pt = PAWN; pt <= KING; pt++) + for (Square s = SQ_A1; s <= SQ_H8; s++) for (int k = 0; steps[pt][k]; k++) { Square to = s + Square(c == WHITE ? steps[pt][k] : -steps[pt][k]); @@ -223,11 +222,11 @@ void init_bitboards() { 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 }; + Square RDelta[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; + Square BDelta[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; - do_magics(BMult, BAttacks, BAttacksTable, BMask, BShift, BDeltas); - do_magics(RMult, RAttacks, RAttacksTable, RMask, RShift, RDeltas); + init_sliding_attacks(BMult, BAttacks, BAttacksTable, BMask, BShift, BDelta); + init_sliding_attacks(RMult, RAttacks, RAttacksTable, RMask, RShift, RDelta); for (Square s = SQ_A1; s <= SQ_H8; s++) { @@ -253,98 +252,79 @@ void init_bitboards() { namespace { - Bitboard submask(Bitboard mask, int key) { - - Bitboard subMask = 0; - int bitNum = -1; - - // Extract an unique submask out of a mask according to the given key - for (Square s = SQ_A1; s <= SQ_H8; s++) - if (bit_is_set(mask, s) && bit_is_set(key, Square(++bitNum))) - set_bit(&subMask, s); - - return subMask; - } - - Bitboard sliding_attacks(Square sq, Bitboard occupied, Square deltas[], Bitboard excluded) { + Bitboard sliding_attacks(Square sq, Bitboard occupied, Square delta[]) { Bitboard attacks = 0; 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 - && !bit_is_set(excluded, s)) + 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; } - template Bitboard pick_magic(Bitboard mask, RKISS& rk, int booster) { Bitboard magic; - int lsb; - - if (!Is64) - lsb = first_1(mask); - // Advance PRNG state of a quantity known to be the optimal to - // quickly retrieve all the magics. - for (int i = 0; i < booster; i++) - rk.rand(); + // Values s1 and s2 are used to rotate the candidate magic of a + // quantity known to be the optimal to quickly find the magics. + int s1 = booster & 63, s2 = (booster >> 6) & 63; while (true) { - magic = rk.rand() & rk.rand(); - magic &= Is64 ? rk.rand() : (rk.rand() | rk.rand()); + magic = rk.rand(); + magic = (magic >> s1) | (magic << (64 - s1)); + magic &= rk.rand(); + magic = (magic >> s2) | (magic << (64 - s2)); + magic &= rk.rand(); - if ( BitCount8Bit[(mask * magic) >> 56] >= 6 - && (Is64 || BitCount8Bit[(lsb * magic) >> 56])) + if (BitCount8Bit[(mask * magic) >> 56] >= 6) return magic; } } - void do_magics(Bitboard magic[], Bitboard* attack[], Bitboard attTabl[], - Bitboard mask[], int shift[], Square deltas[]) { - - const int MagicBoosters32[] = { 43, 53, 76, 17, 51, 65, 55, 23 }; - const int MagicBoosters64[] = { 26, 21, 21, 32, 31, 9, 5, 11 }; + void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[], + Bitboard mask[], int shift[], Square delta[]) { + const int MagicBoosters[][8] = { { 3191, 2184, 1310, 3618, 2091, 1308, 2452, 3996 }, + { 1059, 3608, 605, 3234, 3326, 38, 2029, 3043 } }; RKISS rk; - Bitboard occupancy[4096], proofs[4096], excluded; + Bitboard occupancy[4096], reference[4096], edges, b; int key, maxKey, index, booster, offset = 0; for (Square s = SQ_A1; s <= SQ_H8; s++) { - excluded = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s)); + edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s)); - attack[s] = &attTabl[offset]; - mask[s] = sliding_attacks(s, EmptyBoardBB, deltas, excluded); - shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s(mask[s]); + attack[s] = &attTable[offset]; + mask[s] = sliding_attacks(s, EmptyBoardBB, delta) & ~edges; + shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s(mask[s]); - maxKey = 1 << count_1s(mask[s]); - booster = CpuIs64Bit ? MagicBoosters64[square_rank(s)] : MagicBoosters32[square_rank(s)]; + // Use Carry-Rippler trick to enumerate all subsets of mask[s] + b = maxKey = 0; + do { + occupancy[maxKey] = b; + reference[maxKey++] = sliding_attacks(s, b, delta); + b = (b - mask[s]) & mask[s]; + } while (b); - // First compute occupancy and attacks for square 's' - for (key = 0; key < maxKey; key++) - { - occupancy[key] = submask(mask[s], key); - proofs[key] = sliding_attacks(s, occupancy[key], deltas, EmptyBoardBB); - } + offset += maxKey; + booster = MagicBoosters[CpuIs64Bit][square_rank(s)]; - // Then find a possible magic and corresponding attacks + // Then find a possible magic and the corresponding attacks do { - magic[s] = pick_magic(mask[s], rk, booster); + magic[s] = pick_magic(mask[s], rk, booster); memset(attack[s], 0, maxKey * sizeof(Bitboard)); for (key = 0; key < maxKey; key++) @@ -353,14 +333,12 @@ namespace { : unsigned(occupancy[key] * magic[s] ^ (occupancy[key] >> 32) * (magic[s] >> 32)) >> shift[s]; if (!attack[s][index]) - attack[s][index] = proofs[key]; + attack[s][index] = reference[key]; - else if (attack[s][index] != proofs[key]) + else if (attack[s][index] != reference[key]) break; } } while (key != maxKey); - - offset += maxKey; } } }