X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=555cd13ca78960895e22f84a1a47f03830deca2d;hp=1f6dab9df64de1394d6784b6d84983cd378d5ead;hb=27ba611a3da37423a3502e49beeebe11c9a11d8e;hpb=e06a117d5e78ec4edc051f2b161d36559f784d37 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 1f6dab9d..555cd13c 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -26,16 +26,6 @@ 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]; @@ -50,6 +40,9 @@ Bitboard PawnAttackSpan[COLOR_NB][SQUARE_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 @@ -61,10 +54,9 @@ namespace { 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. @@ -212,8 +204,8 @@ void Bitboards::init() { 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); - init_magics(BishopTable, BishopAttacks, BishopMagics, BishopMasks, BishopShifts, BishopDeltas, magic_index); + init_magics(RookTable, RookMagics, RookDeltas, magic_index); + init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index); for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { @@ -259,17 +251,13 @@ namespace { // 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) { @@ -281,8 +269,13 @@ namespace { // 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[]. @@ -292,17 +285,12 @@ namespace { 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; @@ -310,28 +298,30 @@ namespace { // 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(); - 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(); // 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); + } } } }