X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=de28e03a05c4ef345ab0d89db30d206046811637;hp=0e31d5d69adccca37458c0ca8b9ddf9b9d44d49f;hb=bc54a44010e7a7fb55ee55afba65be029a9e423a;hpb=3dfff5bdae8447fad085558d3f3a729e52963f7a diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 0e31d5d6..de28e03a 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -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 }; - init_sliding_attacks(BMult, BAttacks, BAttacksTable, BMask, BShift, BDeltas); - init_sliding_attacks(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++) { @@ -253,56 +252,42 @@ 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; - // 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) return magic; @@ -312,34 +297,34 @@ namespace { void init_sliding_attacks(Bitboard magic[], Bitboard* attack[], Bitboard attTable[], Bitboard mask[], int shift[], Square delta[]) { - const int MagicBoosters[][8] = { { 55, 11, 17, 2, 39, 3, 31, 44 }, - { 26, 21, 21, 32, 31, 9, 5, 11 } }; + 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], reference[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] = &attTable[offset]; - mask[s] = sliding_attacks(s, EmptyBoardBB, delta, excluded); - shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s(mask[s]); + mask[s] = sliding_attacks(s, EmptyBoardBB, delta) & ~edges; + shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s(mask[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); - maxKey = 1 << count_1s(mask[s]); offset += maxKey; booster = MagicBoosters[CpuIs64Bit][square_rank(s)]; - // First compute occupancy and attacks for square 's' - for (key = 0; key < maxKey; key++) - { - occupancy[key] = submask(mask[s], key); - reference[key] = sliding_attacks(s, occupancy[key], delta, EmptyBoardBB); - } - // 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++)