X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=3bed69bead7665dc9a51e53f29008d67ab8fda9e;hp=b9071ea8bab0beb0323e1b597e27097c6ce7a732;hb=fd5d6c53402517cf8277641a8e37af153b7540c5;hpb=bc4f3155ae3937d32a3ebaae77ee4f7be355aa60 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index b9071ea8..3bed69be 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -56,6 +56,7 @@ Bitboard RookPseudoAttacks[64]; Bitboard QueenPseudoAttacks[64]; uint8_t BitCount8Bit[256]; +int SquareDistance[64][64]; namespace { @@ -154,12 +155,19 @@ Square pop_1st_bit(Bitboard* bb) { void init_bitboards() { + for (Bitboard b = 0; b < 256; b++) + BitCount8Bit[b] = (uint8_t)count_1s(b); + + for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) + for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++) + SquareDistance[s1][s2] = Max(file_distance(s1, s2), rank_distance(s1, s2)); + SquaresByColorBB[DARK] = 0xAA55AA55AA55AA55ULL; SquaresByColorBB[LIGHT] = ~SquaresByColorBB[DARK]; for (Square s = SQ_A1; s <= SQ_H8; s++) { - SetMaskBB[s] = (1ULL << s); + SetMaskBB[s] = 1ULL << s; ClearMaskBB[s] = ~SetMaskBB[s]; } @@ -194,10 +202,7 @@ void init_bitboards() { AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(s); } - for (Bitboard b = 0; b < 256; 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 +213,12 @@ 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 +227,11 @@ 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++) { @@ -253,44 +257,22 @@ void init_bitboards() { namespace { - Bitboard submask(Bitboard mask, int key) { - - Bitboard b, subMask = 0; - int bitProbe = 1; - - // Extract an unique submask out of a mask according to the given key - while (mask) - { - b = mask & -mask; - mask ^= b; - - if (key & bitProbe) - subMask |= b; - - bitProbe <<= 1; - } - - 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; @@ -300,8 +282,8 @@ namespace { Bitboard magic; - // Values s1 and s2 are used to rotate the candidate magic of - // a quantity known to be the optimal to quickly find the magics. + // 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) @@ -323,27 +305,27 @@ namespace { 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); + mask[s] = sliding_attacks(s, EmptyBoardBB, delta) & ~edges; shift[s] = (CpuIs64Bit ? 64 : 32) - count_1s(mask[s]); - maxKey = 1 << count_1s(mask[s]); - offset += maxKey; - booster = MagicBoosters[CpuIs64Bit][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); - reference[key] = sliding_attacks(s, occupancy[key], delta, EmptyBoardBB); - } + offset += maxKey; + booster = MagicBoosters[CpuIs64Bit][rank_of(s)]; // Then find a possible magic and the corresponding attacks do {