X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=ba00c78d876fb23fa0ebe3becf58185deb40429f;hp=99070ef2c0a6f9e606781517af9a4a213c91cb35;hb=cad300cfab869a4e8dcc6b286f9b2e60d2827bed;hpb=659990b43ff1a089be9878561048fa4c60ba2705 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 99070ef2..ba00c78d 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -2,7 +2,7 @@ Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad - Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -26,23 +26,23 @@ uint8_t PopCnt16[1 << 16]; int SquareDistance[SQUARE_NB][SQUARE_NB]; -Magic RookMagics[SQUARE_NB]; -Magic BishopMagics[SQUARE_NB]; - Bitboard SquareBB[SQUARE_NB]; Bitboard FileBB[FILE_NB]; Bitboard RankBB[RANK_NB]; Bitboard AdjacentFilesBB[FILE_NB]; -Bitboard InFrontBB[COLOR_NB][RANK_NB]; +Bitboard ForwardRanksBB[COLOR_NB][RANK_NB]; Bitboard BetweenBB[SQUARE_NB][SQUARE_NB]; Bitboard LineBB[SQUARE_NB][SQUARE_NB]; Bitboard DistanceRingBB[SQUARE_NB][8]; -Bitboard ForwardBB[COLOR_NB][SQUARE_NB]; +Bitboard ForwardFileBB[COLOR_NB][SQUARE_NB]; Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB]; 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 @@ -54,9 +54,7 @@ namespace { Bitboard RookTable[0x19000]; // To store rook attacks Bitboard BishopTable[0x1480]; // To store bishop attacks - typedef unsigned (Fn)(Square, Bitboard); - - void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index); + void init_magics(Bitboard table[], Magic magics[], Direction directions[]); // 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. @@ -165,14 +163,14 @@ void Bitboards::init() { AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); for (Rank r = RANK_1; r < RANK_8; ++r) - InFrontBB[WHITE][r] = ~(InFrontBB[BLACK][r + 1] = InFrontBB[BLACK][r] | RankBB[r]); + ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]); for (Color c = WHITE; c <= BLACK; ++c) for (Square s = SQ_A1; s <= SQ_H8; ++s) { - ForwardBB[c][s] = InFrontBB[c][rank_of(s)] & FileBB[file_of(s)]; - PawnAttackSpan[c][s] = InFrontBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)]; - PassedPawnMask[c][s] = ForwardBB[c][s] | PawnAttackSpan[c][s]; + ForwardFileBB [c][s] = ForwardRanksBB[c][rank_of(s)] & FileBB[file_of(s)]; + PawnAttackSpan[c][s] = ForwardRanksBB[c][rank_of(s)] & AdjacentFilesBB[file_of(s)]; + PassedPawnMask[c][s] = ForwardFileBB [c][s] | PawnAttackSpan[c][s]; } for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) @@ -190,7 +188,7 @@ void Bitboards::init() { for (Square s = SQ_A1; s <= SQ_H8; ++s) for (int i = 0; steps[pt][i]; ++i) { - Square to = s + Square(c == WHITE ? steps[pt][i] : -steps[pt][i]); + Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]); if (is_ok(to) && distance(s, to) < 3) { @@ -201,11 +199,11 @@ void Bitboards::init() { } } - Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST }; - Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; + Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST }; + Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - init_magics(RookTable, RookMagics, RookDeltas, magic_index); - init_magics(BishopTable, BishopMagics, BishopDeltas, magic_index); + init_magics(RookTable, RookMagics, RookDirections); + init_magics(BishopTable, BishopMagics, BishopDirections); for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { @@ -227,14 +225,14 @@ void Bitboards::init() { namespace { - Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) { + Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) { Bitboard attack = 0; for (int i = 0; i < 4; ++i) - for (Square s = sq + deltas[i]; - is_ok(s) && distance(s, s - deltas[i]) == 1; - s += deltas[i]) + for (Square s = sq + directions[i]; + is_ok(s) && distance(s, s - directions[i]) == 1; + s += directions[i]) { attack |= s; @@ -251,16 +249,14 @@ namespace { // chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we // use the so called "fancy" approach. - void init_magics(Bitboard table[], Magic magics[], Square deltas[], Fn index) { + void init_magics(Bitboard table[], Magic magics[], Direction directions[]) { + // Optimal PRNG seeds to pick the correct magics in the shortest time 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' - magics[SQ_A1].attacks = table; + int epoch[4096] = {}, cnt = 0, size = 0; for (Square s = SQ_A1; s <= SQ_H8; ++s) { @@ -272,28 +268,28 @@ 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. - magics[s].mask = sliding_attack(deltas, s, 0) & ~edges; - magics[s].shift = (Is64Bit ? 64 : 32) - popcount(magics[s].mask); + Magic& m = magics[s]; + m.mask = sliding_attack(directions, 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[]. b = size = 0; do { occupancy[size] = b; - reference[size] = sliding_attack(deltas, s, b); + reference[size] = sliding_attack(directions, s, b); if (HasPext) - magics[s].attacks[pext(b, magics[s].mask)] = reference[size]; + m.attacks[pext(b, m.mask)] = reference[size]; size++; - b = (b - magics[s].mask) & magics[s].mask; + 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) - magics[s + 1].attacks = magics[s].attacks + size; - if (HasPext) continue; @@ -301,28 +297,30 @@ 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].magic = rng.sparse_rand(); - while (popcount((magics[s].magic * magics[s].mask) >> 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 = m.index(occupancy[i]); - if (age[idx] < current) + if (epoch[idx] < cnt) { - age[idx] = current; - magics[s].attacks[idx] = reference[i]; + epoch[idx] = cnt; + m.attacks[idx] = reference[i]; } - else if (magics[s].attacks[idx] != reference[i]) + else if (m.attacks[idx] != reference[i]) break; } - } while (i < size); + } } } }