X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=e3c9140dfaad0b02b49b12b5462dc7f00f10a111;hp=c67c01a62ff258dfaa0438152cb1d2e45304d8e6;hb=c0cb713a000ef176cdad16defe640b7b6432a4a9;hpb=099b5e45e6fb84c0c6ac9c867e0902e0195d97a5 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index c67c01a6..e3c9140d 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) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2015-2017 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 @@ -18,226 +19,207 @@ */ #include -#include -#include #include "bitboard.h" -#include "bitcount.h" -#include "rkiss.h" - -CACHE_LINE_ALIGNMENT - -Bitboard RMasks[64]; -Bitboard RMagics[64]; -Bitboard* RAttacks[64]; -unsigned RShifts[64]; - -Bitboard BMasks[64]; -Bitboard BMagics[64]; -Bitboard* BAttacks[64]; -unsigned BShifts[64]; - -Bitboard SquareBB[64]; -Bitboard FileBB[8]; -Bitboard RankBB[8]; -Bitboard AdjacentFilesBB[8]; -Bitboard ThisAndAdjacentFilesBB[8]; -Bitboard InFrontBB[2][8]; -Bitboard StepAttacksBB[16][64]; -Bitboard BetweenBB[64][64]; -Bitboard SquaresInFrontMask[2][64]; -Bitboard PassedPawnMask[2][64]; -Bitboard AttackSpanMask[2][64]; -Bitboard PseudoAttacks[6][64]; - -uint8_t BitCount8Bit[256]; -int SquareDistance[64][64]; +#include "misc.h" + +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 ForwardRanksBB[COLOR_NB][RANK_NB]; +Bitboard BetweenBB[SQUARE_NB][SQUARE_NB]; +Bitboard LineBB[SQUARE_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]; + +Magic RookMagics[SQUARE_NB]; +Magic BishopMagics[SQUARE_NB]; namespace { - CACHE_LINE_ALIGNMENT + // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan + const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL; + const uint32_t DeBruijn32 = 0x783A9B23; - int BSFTable[64]; - Bitboard RTable[0x19000]; // Storage space for rook attacks - Bitboard BTable[0x1480]; // Storage space for bishop attacks + int MSBTable[256]; // To implement software msb() + Square BSFTable[SQUARE_NB]; // To implement software bitscan + Bitboard RookTable[0x19000]; // To store rook attacks + Bitboard BishopTable[0x1480]; // To store bishop attacks - typedef unsigned (Fn)(Square, Bitboard); - - void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], unsigned shifts[], Square deltas[], Fn get_index); -} + void init_magics(Bitboard table[], Magic magics[], Square deltas[]); + // 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. -/// print_bitboard() prints a bitboard in an easily readable format to the -/// standard output. This is sometimes useful for debugging. + unsigned bsf_index(Bitboard b) { + b ^= b - 1; + return Is64Bit ? (b * DeBruijn64) >> 58 + : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26; + } -void print_bitboard(Bitboard b) { - for (Rank r = RANK_8; r >= RANK_1; r--) - { - std::cout << "+---+---+---+---+---+---+---+---+" << '\n'; - for (File f = FILE_A; f <= FILE_H; f++) - std::cout << "| " << ((b & make_square(f, r)) ? "X " : " "); + // popcount16() counts the non-zero bits using SWAR-Popcount algorithm - std::cout << "|\n"; + unsigned popcount16(unsigned u) { + u -= (u >> 1) & 0x5555U; + u = ((u >> 2) & 0x3333U) + (u & 0x3333U); + u = ((u >> 4) + u) & 0x0F0FU; + return (u * 0x0101U) >> 8; } - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl; } +#ifdef NO_BSF -/// first_1() finds the least significant nonzero bit in a nonzero bitboard. -/// pop_1st_bit() finds and clears the least significant nonzero bit in a -/// nonzero bitboard. +/// Software fall-back of lsb() and msb() for CPU lacking hardware support -#if defined(IS_64BIT) && !defined(USE_BSFQ) - -Square first_1(Bitboard b) { - return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]); +Square lsb(Bitboard b) { + assert(b); + return BSFTable[bsf_index(b)]; } -Square pop_1st_bit(Bitboard* b) { - Bitboard bb = *b; - *b &= (*b - 1); - return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]); -} +Square msb(Bitboard b) { -#elif !defined(USE_BSFQ) + assert(b); + unsigned b32; + int result = 0; -Square first_1(Bitboard b) { - b ^= (b - 1); - uint32_t fold = unsigned(b) ^ unsigned(b >> 32); - return Square(BSFTable[(fold * 0x783A9B23) >> 26]); -} + if (b > 0xFFFFFFFF) + { + b >>= 32; + result = 32; + } -// Use type-punning -union b_union { - - Bitboard b; - struct { -#if defined (BIGENDIAN) - uint32_t h; - uint32_t l; -#else - uint32_t l; - uint32_t h; -#endif - } dw; -}; - -Square pop_1st_bit(Bitboard* bb) { - - b_union u; - Square ret; - - u.b = *bb; - - if (u.dw.l) - { - ret = Square(BSFTable[((u.dw.l ^ (u.dw.l - 1)) * 0x783A9B23) >> 26]); - u.dw.l &= (u.dw.l - 1); - *bb = u.b; - return ret; - } - ret = Square(BSFTable[((~(u.dw.h ^ (u.dw.h - 1))) * 0x783A9B23) >> 26]); - u.dw.h &= (u.dw.h - 1); - *bb = u.b; - return ret; -} + b32 = unsigned(b); -#endif // !defined(USE_BSFQ) + if (b32 > 0xFFFF) + { + b32 >>= 16; + result += 16; + } + + if (b32 > 0xFF) + { + b32 >>= 8; + result += 8; + } + return Square(result + MSBTable[b32]); +} -/// bitboards_init() initializes various bitboard arrays. It is called during -/// program initialization. +#endif // ifdef NO_BSF -void bitboards_init() { - for (Bitboard b = 0; b < 256; b++) - BitCount8Bit[b] = (uint8_t)popcount(b); +/// Bitboards::pretty() returns an ASCII representation of a bitboard suitable +/// to be printed to standard output. Useful for debugging. - for (Square s = SQ_A1; s <= SQ_H8; s++) - SquareBB[s] = 1ULL << s; +const std::string Bitboards::pretty(Bitboard b) { - FileBB[FILE_A] = FileABB; - RankBB[RANK_1] = Rank1BB; + std::string s = "+---+---+---+---+---+---+---+---+\n"; - for (int f = FILE_B; f <= FILE_H; f++) + for (Rank r = RANK_8; r >= RANK_1; --r) { - FileBB[f] = FileBB[f - 1] << 1; - RankBB[f] = RankBB[f - 1] << 8; - } + for (File f = FILE_A; f <= FILE_H; ++f) + s += b & make_square(f, r) ? "| X " : "| "; - for (int f = FILE_A; f <= FILE_H; f++) - { - AdjacentFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); - ThisAndAdjacentFilesBB[f] = FileBB[f] | AdjacentFilesBB[f]; + s += "|\n+---+---+---+---+---+---+---+---+\n"; } - for (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++) + return s; +} + + +/// 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 (unsigned i = 0; i < (1 << 16); ++i) + PopCnt16[i] = (uint8_t) popcount16(i); + + for (Square s = SQ_A1; s <= SQ_H8; ++s) { - InFrontBB[WHITE][rw] = InFrontBB[WHITE][rw + 1] | RankBB[rw + 1]; - InFrontBB[BLACK][rb] = InFrontBB[BLACK][rb - 1] | RankBB[rb - 1]; + SquareBB[s] = 1ULL << s; + BSFTable[bsf_index(SquareBB[s])] = s; } - for (Color c = WHITE; c <= BLACK; c++) - for (Square s = SQ_A1; s <= SQ_H8; s++) - { - SquaresInFrontMask[c][s] = in_front_bb(c, s) & file_bb(s); - PassedPawnMask[c][s] = in_front_bb(c, s) & this_and_adjacent_files_bb(file_of(s)); - AttackSpanMask[c][s] = in_front_bb(c, s) & adjacent_files_bb(file_of(s)); - } + for (Bitboard b = 2; b < 256; ++b) + MSBTable[b] = MSBTable[b - 1] + !more_than_one(b); + + for (File f = FILE_A; f <= FILE_H; ++f) + FileBB[f] = f > FILE_A ? FileBB[f - 1] << 1 : FileABB; - 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)); + for (Rank r = RANK_1; r <= RANK_8; ++r) + RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB; - for (int i = 0; i < 64; i++) - if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems + 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) + 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) { - Bitboard b = 1ULL << i; - b ^= b - 1; - b ^= b >> 32; - BSFTable[(uint32_t)(b * 0x783A9B23) >> 26] = i; + 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]; } - else - BSFTable[((1ULL << i) * 0x218A392CD3D5DBFULL) >> 58] = i; - int steps[][9] = { {}, { 7, 9 }, { 17, 15, 10, 6, -6, -10, -15, -17 }, - {}, {}, {}, { 9, 7, -7, -9, 8, 1, -1, -8 } }; + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) + if (s1 != s2) + { + SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2)); + DistanceRingBB[s1][SquareDistance[s1][s2] - 1] |= s2; + } + + 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 (Square s = SQ_A1; s <= SQ_H8; s++) - for (int k = 0; steps[pt][k]; k++) + for (Color c = WHITE; c <= BLACK; ++c) + 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][k] : -steps[pt][k]); - - if (square_is_ok(to) && square_distance(s, to) < 3) - StepAttacksBB[make_piece(c, pt)][s] |= to; + Square to = s + Square(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 }; + Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST }; + Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, r_index); - init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, b_index); + init_magics(RookTable, RookMagics, RookDeltas); + init_magics(BishopTable, BishopMagics, BishopDeltas); - for (Square s = SQ_A1; s <= SQ_H8; s++) + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { - PseudoAttacks[BISHOP][s] = bishop_attacks_bb(s, 0); - PseudoAttacks[ROOK][s] = rook_attacks_bb(s, 0); - PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] | PseudoAttacks[ROOK][s]; - } + PseudoAttacks[QUEEN][s1] = PseudoAttacks[BISHOP][s1] = attacks_bb(s1, 0); + PseudoAttacks[QUEEN][s1] |= PseudoAttacks[ ROOK][s1] = attacks_bb< ROOK>(s1, 0); - for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) - for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++) - if (PseudoAttacks[QUEEN][s1] & s2) + for (PieceType pt : { BISHOP, ROOK }) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) { - Square delta = (s2 - s1) / square_distance(s1, s2); + if (!(PseudoAttacks[pt][s1] & s2)) + continue; - for (Square s = s1 + delta; s != s2; s += delta) - BetweenBB[s1][s2] |= s; + 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]); } + } } @@ -247,9 +229,9 @@ namespace { Bitboard attack = 0; - for (int i = 0; i < 4; i++) + for (int i = 0; i < 4; ++i) for (Square s = sq + deltas[i]; - square_is_ok(s) && square_distance(s, s - deltas[i]) == 1; + is_ok(s) && distance(s, s - deltas[i]) == 1; s += deltas[i]) { attack |= s; @@ -262,46 +244,21 @@ namespace { } - Bitboard pick_random(Bitboard mask, RKISS& rk, int booster) { - - 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. - int s1 = booster & 63, s2 = (booster >> 6) & 63; - - while (true) - { - 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; - } - } - - // 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 get_index) { + void init_magics(Bitboard table[], Magic magics[], Square deltas[]) { - 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++) + for (Square s = SQ_A1; s <= SQ_H8; ++s) { // Board edges are not considered in the relevant occupancies edges = ((Rank1BB | Rank8BB) & ~rank_bb(s)) | ((FileABB | FileHBB) & ~file_bb(s)); @@ -311,45 +268,59 @@ 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(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[]. b = size = 0; do { occupancy[size] = b; - reference[size++] = sliding_attack(deltas, s, b); - b = (b - masks[s]) & masks[s]; + reference[size] = sliding_attack(deltas, 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 { - magics[s] = pick_random(masks[s], rk, booster); - 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][get_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; - - attack = reference[i]; } - } while (i != size); + } } } }