X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=4e2778a946b89a282d83ba51f774d8b21fe2ecee;hp=3597e7d830fe4d79cc0f1da4ebce5bbb78748548;hb=8a4821923ac6860c791185a6d25c60ad0391739f;hpb=b71418defa4e7b0475fe9e16afdfdfefeab31e0f diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 3597e7d8..4e2778a9 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -1,7 +1,8 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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 @@ -18,227 +19,158 @@ */ #include -#include -#include #include "bitboard.h" -#include "bitcount.h" -#include "rkiss.h" +#include "misc.h" -CACHE_LINE_ALIGNMENT - -Bitboard RMasks[SQUARE_NB]; -Bitboard RMagics[SQUARE_NB]; -Bitboard* RAttacks[SQUARE_NB]; -unsigned RShifts[SQUARE_NB]; - -Bitboard BMasks[SQUARE_NB]; -Bitboard BMagics[SQUARE_NB]; -Bitboard* BAttacks[SQUARE_NB]; -unsigned BShifts[SQUARE_NB]; +uint8_t PopCnt16[1 << 16]; +int SquareDistance[SQUARE_NB][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 StepAttacksBB[PIECE_NB][SQUARE_NB]; +Bitboard ForwardRanksBB[COLOR_NB][RANK_NB]; Bitboard BetweenBB[SQUARE_NB][SQUARE_NB]; Bitboard LineBB[SQUARE_NB][SQUARE_NB]; -Bitboard DistanceRingsBB[SQUARE_NB][8]; -Bitboard ForwardBB[COLOR_NB][SQUARE_NB]; +Bitboard DistanceRingBB[SQUARE_NB][8]; +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]; -int SquareDistance[SQUARE_NB][SQUARE_NB]; +Magic RookMagics[SQUARE_NB]; +Magic BishopMagics[SQUARE_NB]; namespace { - // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan - const uint64_t DeBruijn_64 = 0x3F79D71B4CB0A89ULL; - const uint32_t DeBruijn_32 = 0x783A9B23; - - CACHE_LINE_ALIGNMENT - - int MS1BTable[256]; - Square BSFTable[SQUARE_NB]; - Bitboard RTable[0x19000]; // Storage space for rook attacks - Bitboard BTable[0x1480]; // Storage space for bishop attacks - - typedef unsigned (Fn)(Square, Bitboard); - - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn index); - - FORCE_INLINE unsigned bsf_index(Bitboard b) { - - // Matt Taylor's folding for 32 bit systems, extended to 64 bits by Kim Walisch - b ^= (b - 1); - return Is64Bit ? (b * DeBruijn_64) >> 58 - : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn_32) >> 26; - } -} - -/// lsb()/msb() finds the least/most significant bit in a non-zero bitboard. -/// pop_lsb() finds and clears the least significant bit in a non-zero bitboard. - -#ifndef USE_BSFQ - -Square lsb(Bitboard b) { return BSFTable[bsf_index(b)]; } + Bitboard RookTable[0x19000]; // To store rook attacks + Bitboard BishopTable[0x1480]; // To store bishop attacks -Square pop_lsb(Bitboard* b) { + void init_magics(Bitboard table[], Magic magics[], Direction directions[]); - Bitboard bb = *b; - *b = bb & (bb - 1); - return BSFTable[bsf_index(bb)]; -} - -Square msb(Bitboard b) { - - unsigned b32; - int result = 0; - - if (b > 0xFFFFFFFF) - { - b >>= 32; - result = 32; - } + // popcount16() counts the non-zero bits using SWAR-Popcount algorithm - b32 = unsigned(b); - - if (b32 > 0xFFFF) - { - b32 >>= 16; - result += 16; + unsigned popcount16(unsigned u) { + u -= (u >> 1) & 0x5555U; + u = ((u >> 2) & 0x3333U) + (u & 0x3333U); + u = ((u >> 4) + u) & 0x0F0FU; + return (u * 0x0101U) >> 8; } - - if (b32 > 0xFF) - { - b32 >>= 8; - result += 8; - } - - return (Square)(result + MS1BTable[b32]); } -#endif // ifndef USE_BSFQ - -/// Bitboards::pretty() returns an ASCII representation of a bitboard to be -/// printed to standard output. This is sometimes useful for debugging. +/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable +/// to be printed to standard output. Useful for debugging. const std::string Bitboards::pretty(Bitboard b) { - std::ostringstream ss; + std::string s = "+---+---+---+---+---+---+---+---+\n"; - for (Rank rank = RANK_8; rank >= RANK_1; --rank) + for (Rank r = RANK_8; r >= RANK_1; --r) { - ss << "+---+---+---+---+---+---+---+---+" << '\n'; - - for (File file = FILE_A; file <= FILE_H; ++file) - ss << "| " << (b & (file | rank) ? "X " : " "); + for (File f = FILE_A; f <= FILE_H; ++f) + s += b & make_square(f, r) ? "| X " : "| "; - ss << "|\n"; + s += "|\n+---+---+---+---+---+---+---+---+\n"; } - ss << "+---+---+---+---+---+---+---+---+"; - return ss.str(); + + return s; } -/// Bitboards::init() initializes various bitboard arrays. It is called during -/// program initialization. +/// Bitboards::init() initializes various bitboard tables. It is called at +/// startup and relies on global objects to be already zero-initialized. void Bitboards::init() { - for (int k = 0, i = 0; i < 8; ++i) - while (k < (2 << i)) - MS1BTable[k++] = i; + for (unsigned i = 0; i < (1 << 16); ++i) + PopCnt16[i] = (uint8_t) popcount16(i); for (Square s = SQ_A1; s <= SQ_H8; ++s) - BSFTable[bsf_index(SquareBB[s] = 1ULL << s)] = s; + SquareBB[s] = (1ULL << s); - FileBB[FILE_A] = FileABB; - RankBB[RANK_1] = Rank1BB; + for (File f = FILE_A; f <= FILE_H; ++f) + FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB; - for (int i = 1; i < 8; ++i) - { - FileBB[i] = FileBB[i - 1] << 1; - RankBB[i] = RankBB[i - 1] << 8; - } + for (Rank r = RANK_1; r <= RANK_8; ++r) + RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB; for (File f = FILE_A; f <= FILE_H; ++f) 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) for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - { - SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2)); if (s1 != s2) - DistanceRingsBB[s1][SquareDistance[s1][s2] - 1] |= s2; - } + { + SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2)); + DistanceRingBB[s1][SquareDistance[s1][s2]] |= s2; + } - int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 }, - {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } }; + int steps[][5] = { {}, { 7, 9 }, { 6, 10, 15, 17 }, {}, {}, {}, { 1, 7, 8, 9 } }; for (Color c = WHITE; c <= BLACK; ++c) - for (PieceType pt = PAWN; pt <= KING; ++pt) + for (PieceType pt : { PAWN, KNIGHT, KING }) 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]); - - if (is_ok(to) && square_distance(s, to) < 3) - StepAttacksBB[make_piece(c, pt)][s] |= to; + Square to = s + Direction(c == WHITE ? steps[pt][i] : -steps[pt][i]); + + if (is_ok(to) && distance(s, to) < 3) + { + if (pt == PAWN) + PawnAttacks[c][s] |= to; + else + PseudoAttacks[pt][s] |= to; + } } - Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; - Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; + Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST }; + Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index); - init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index); + init_magics(RookTable, RookMagics, RookDirections); + init_magics(BishopTable, BishopMagics, BishopDirections); for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb(s1, 0); PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0); - for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - { - Piece pc = (PseudoAttacks[BISHOP][s1] & s2) ? W_BISHOP : - (PseudoAttacks[ROOK][s1] & s2) ? W_ROOK : NO_PIECE; + for (PieceType pt : { BISHOP, ROOK }) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) + { + if (!(PseudoAttacks[pt][s1] & s2)) + continue; - if (pc == NO_PIECE) - continue; - - LineBB[s1][s2] = (attacks_bb(pc, s1, 0) & attacks_bb(pc, s2, 0)) | s1 | s2; - BetweenBB[s1][s2] = attacks_bb(pc, s1, SquareBB[s2]) & attacks_bb(pc, s2, SquareBB[s1]); - } + LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2; + BetweenBB[s1][s2] = attacks_bb(pt, s1, SquareBB[s2]) & attacks_bb(pt, s2, SquareBB[s1]); + } } } 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) && square_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; @@ -250,36 +182,19 @@ namespace { } - Bitboard pick_random(RKISS& rk, int booster) { - - // Values s1 and s2 are used to rotate the candidate magic of a - // quantity known to be optimal to quickly find the magics. - int s1 = booster & 63, s2 = (booster >> 6) & 63; - - Bitboard m = rk.rand(); - m = (m >> s1) | (m << (64 - s1)); - m &= rk.rand(); - m = (m >> s2) | (m << (64 - s2)); - return m & rk.rand(); - } - - // init_magics() computes all rook and bishop attacks at startup. Magic // bitboards are used to look up attacks of sliding pieces. As a reference see // 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[], Direction directions[]) { - 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], edges, b; - int i, size, booster; + // 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 } }; - // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = table; + Bitboard occupancy[4096], reference[4096], edges, b; + int epoch[4096] = {}, cnt = 0, size = 0; for (Square s = SQ_A1; s <= SQ_H8; ++s) { @@ -291,49 +206,59 @@ 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(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); - b = (b - masks[s]) & masks[s]; + reference[size] = sliding_attack(directions, s, b); + + if (HasPext) + m.attacks[pext(b, m.mask)] = reference[size]; + + size++; + 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; - booster = MagicBoosters[Is64Bit][rank_of(s)]; + PRNG rng(seeds[Is64Bit][rank_of(s)]); // 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] = pick_random(rk, booster); - while (popcount((magics[s] * masks[s]) >> 56) < 6); - - std::memset(attacks[s], 0, size * sizeof(Bitboard)); + 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 (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) { - Bitboard& attack = attacks[s][index(s, occupancy[i])]; - - if (attack && attack != reference[i]) + unsigned idx = m.index(occupancy[i]); + + if (epoch[idx] < cnt) + { + epoch[idx] = cnt; + m.attacks[idx] = reference[i]; + } + else if (m.attacks[idx] != reference[i]) break; - - assert(reference[i] != 0); - - attack = reference[i]; } - } while (i != size); + } } } }