X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=7687cbb4441cb5cf66c40277c39a5532be4f8178;hp=8c7bb9ebfe5e4060d89fa4d5e16a28ece3c40b9d;hb=091aff044516fcd8700a8a194f9e9ffaabed8bb4;hpb=0a6532a39d2e2cfd92ba0a2c4fa8c6ad6c29b581 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 8c7bb9eb..7687cbb4 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, 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 @@ -23,294 +23,269 @@ #include "bitboard.h" #include "bitcount.h" +#include "misc.h" #include "rkiss.h" -Bitboard RMasks[64]; -Bitboard RMagics[64]; -Bitboard* RAttacks[64]; -int RShifts[64]; - -Bitboard BMasks[64]; -Bitboard BMagics[64]; -Bitboard* BAttacks[64]; -int BShifts[64]; - -Bitboard SetMaskBB[65]; -Bitboard ClearMaskBB[65]; - -Bitboard FileBB[8]; -Bitboard RankBB[8]; -Bitboard NeighboringFilesBB[8]; -Bitboard ThisAndNeighboringFilesBB[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 BishopPseudoAttacks[64]; -Bitboard RookPseudoAttacks[64]; -Bitboard QueenPseudoAttacks[64]; - -uint8_t BitCount8Bit[256]; -int SquareDistance[64][64]; +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]; + +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 BetweenBB[SQUARE_NB][SQUARE_NB]; +Bitboard LineBB[SQUARE_NB][SQUARE_NB]; +Bitboard DistanceRingsBB[SQUARE_NB][8]; +Bitboard ForwardBB[COLOR_NB][SQUARE_NB]; +Bitboard PassedPawnMask[COLOR_NB][SQUARE_NB]; +Bitboard PawnAttackSpan[COLOR_NB][SQUARE_NB]; +Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB]; + +int SquareDistance[SQUARE_NB][SQUARE_NB]; namespace { - CACHE_LINE_ALIGNMENT + // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan + const uint64_t DeBruijn_64 = 0x3F79D71B4CB0A89ULL; + const uint32_t DeBruijn_32 = 0x783A9B23; - int BSFTable[64]; - Bitboard RookTable[0x19000]; // Storage space for rook attacks - Bitboard BishopTable[0x1480]; // Storage space for bishop attacks + CACHE_LINE_ALIGNMENT - void init_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]); -} + 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); -/// print_bitboard() prints a bitboard in an easily readable format to the -/// standard output. This is sometimes useful for debugging. + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], unsigned shifts[], Square deltas[], Fn index); -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 << "| " << (bit_is_set(b, make_square(f, r)) ? "X " : " "); + FORCE_INLINE unsigned bsf_index(Bitboard b) { - std::cout << "|\n"; + // 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; } - std::cout << "+---+---+---+---+---+---+---+---+" << std::endl; } +/// lsb()/msb() finds the least/most significant bit in a nonzero bitboard. +/// pop_lsb() finds and clears the least significant bit in a nonzero bitboard. -/// 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. +#ifndef USE_BSFQ -#if defined(IS_64BIT) && !defined(USE_BSFQ) +Square lsb(Bitboard b) { return BSFTable[bsf_index(b)]; } -Square first_1(Bitboard b) { - return Square(BSFTable[((b & -b) * 0x218A392CD3D5DBFULL) >> 58]); -} +Square pop_lsb(Bitboard* b) { -Square pop_1st_bit(Bitboard* b) { Bitboard bb = *b; - *b &= (*b - 1); - return Square(BSFTable[((bb & -bb) * 0x218A392CD3D5DBFULL) >> 58]); + *b = bb & (bb - 1); + return BSFTable[bsf_index(bb)]; } -#elif !defined(USE_BSFQ) +Square msb(Bitboard b) { -Square first_1(Bitboard b) { - b ^= (b - 1); - uint32_t fold = unsigned(b) ^ unsigned(b >> 32); - return Square(BSFTable[(fold * 0x783A9B23) >> 26]); -} + unsigned b32; + int result = 0; + + if (b > 0xFFFFFFFF) + { + b >>= 32; + result = 32; + } + + b32 = unsigned(b); -// 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; + if (b32 > 0xFFFF) + { + b32 >>= 16; + result += 16; + } + + if (b32 > 0xFF) + { + b32 >>= 8; + result += 8; + } + + return (Square)(result + MS1BTable[b32]); } -#endif // !defined(USE_BSFQ) +#endif // ifndef USE_BSFQ -/// bitboards_init() initializes various bitboard arrays. It is called during -/// program initialization. +/// Bitboards::print() prints a bitboard in an easily readable format to the +/// standard output. This is sometimes useful for debugging. -void bitboards_init() { +void Bitboards::print(Bitboard b) { - for (Bitboard b = 0; b < 256; b++) - BitCount8Bit[b] = (uint8_t)count_1s(b); + sync_cout; - for (Square s = SQ_A1; s <= SQ_H8; s++) + for (Rank rank = RANK_8; rank >= RANK_1; --rank) { - SetMaskBB[s] = 1ULL << s; - ClearMaskBB[s] = ~SetMaskBB[s]; + std::cout << "+---+---+---+---+---+---+---+---+" << '\n'; + + for (File file = FILE_A; file <= FILE_H; ++file) + std::cout << "| " << (b & (file | rank) ? "X " : " "); + + std::cout << "|\n"; } + std::cout << "+---+---+---+---+---+---+---+---+" << sync_endl; +} - ClearMaskBB[SQ_NONE] = ~0ULL; + +/// Bitboards::init() initializes various bitboard arrays. It is called during +/// program initialization. + +void Bitboards::init() { + + for (int k = 0, i = 0; i < 8; ++i) + while (k < (2 << i)) + MS1BTable[k++] = i; + + for (int i = 0; i < 64; ++i) + BSFTable[bsf_index(1ULL << i)] = Square(i); + + for (Square s = SQ_A1; s <= SQ_H8; ++s) + SquareBB[s] = 1ULL << s; FileBB[FILE_A] = FileABB; RankBB[RANK_1] = Rank1BB; - for (int f = FILE_B; f <= FILE_H; f++) + for (int i = 1; i < 8; ++i) { - FileBB[f] = FileBB[f - 1] << 1; - RankBB[f] = RankBB[f - 1] << 8; + FileBB[i] = FileBB[i - 1] << 1; + RankBB[i] = RankBB[i - 1] << 8; } - for (int f = FILE_A; f <= FILE_H; f++) - { - NeighboringFilesBB[f] = (f > FILE_A ? FileBB[f - 1] : 0) | (f < FILE_H ? FileBB[f + 1] : 0); - ThisAndNeighboringFilesBB[f] = FileBB[f] | NeighboringFilesBB[f]; - } + 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 (int rw = RANK_7, rb = RANK_2; rw >= RANK_1; rw--, rb++) - { - InFrontBB[WHITE][rw] = InFrontBB[WHITE][rw + 1] | RankBB[rw + 1]; - InFrontBB[BLACK][rb] = InFrontBB[BLACK][rb - 1] | RankBB[rb - 1]; - } + for (Rank r = RANK_1; r < RANK_8; ++r) + InFrontBB[WHITE][r] = ~(InFrontBB[BLACK][r + 1] = InFrontBB[BLACK][r] | RankBB[r]); - for (Color c = WHITE; c <= BLACK; c++) - for (Square s = SQ_A1; s <= SQ_H8; 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_neighboring_files_bb(file_of(s)); - AttackSpanMask[c][s] = in_front_bb(c, s) & neighboring_files_bb(file_of(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]; } - 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 (int i = 0; i < 64; i++) - if (!Is64Bit) // Matt Taylor's folding trick for 32 bit systems + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) { - Bitboard b = 1ULL << i; - b ^= b - 1; - b ^= b >> 32; - BSFTable[uint32_t(b * 0x783A9B23) >> 26] = i; + SquareDistance[s1][s2] = std::max(file_distance(s1, s2), rank_distance(s1, s2)); + if (s1 != s2) + DistanceRingsBB[s1][SquareDistance[s1][s2] - 1] |= s2; } - 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 (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; 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]); - if (square_is_ok(to) && square_distance(s, to) < 3) - set_bit(&StepAttacksBB[make_piece(c, pt)][s], to); + if (is_ok(to) && square_distance(s, to) < 3) + StepAttacksBB[make_piece(c, pt)][s] |= to; } - init_magic_bitboards(ROOK, RAttacks, RMagics, RMasks, RShifts); - init_magic_bitboards(BISHOP, BAttacks, BMagics, BMasks, BShifts); + Square RDeltas[] = { DELTA_N, DELTA_E, DELTA_S, DELTA_W }; + Square BDeltas[] = { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW }; + + init_magics(RTable, RAttacks, RMagics, RMasks, RShifts, RDeltas, magic_index); + init_magics(BTable, BAttacks, BMagics, BMasks, BShifts, BDeltas, magic_index); - for (Square s = SQ_A1; s <= SQ_H8; s++) + for (Square s = SQ_A1; s <= SQ_H8; ++s) { - BishopPseudoAttacks[s] = bishop_attacks_bb(s, 0); - RookPseudoAttacks[s] = rook_attacks_bb(s, 0); - QueenPseudoAttacks[s] = queen_attacks_bb(s, 0); + PseudoAttacks[QUEEN][s] = PseudoAttacks[BISHOP][s] = attacks_bb(s, 0); + PseudoAttacks[QUEEN][s] |= PseudoAttacks[ ROOK][s] = attacks_bb< ROOK>(s, 0); } - for (Square s1 = SQ_A1; s1 <= SQ_H8; s1++) - for (Square s2 = SQ_A1; s2 <= SQ_H8; s2++) - if (bit_is_set(QueenPseudoAttacks[s1], s2)) + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) + if (PseudoAttacks[QUEEN][s1] & s2) { Square delta = (s2 - s1) / square_distance(s1, s2); for (Square s = s1 + delta; s != s2; s += delta) - set_bit(&BetweenBB[s1][s2], s); + BetweenBB[s1][s2] |= s; + + PieceType pc = (PseudoAttacks[BISHOP][s1] & s2) ? BISHOP : ROOK; + LineBB[s1][s2] = (PseudoAttacks[pc][s1] & PseudoAttacks[pc][s2]) | s1 | s2; } } namespace { - Bitboard sliding_attacks(PieceType pt, Square sq, Bitboard occupied) { - - Square deltas[][4] = { { DELTA_N, DELTA_E, DELTA_S, DELTA_W }, - { DELTA_NE, DELTA_SE, DELTA_SW, DELTA_NW } }; - Bitboard attacks = 0; - Square* delta = (pt == ROOK ? deltas[0] : deltas[1]); + Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) { - for (int i = 0; i < 4; i++) - { - Square s = sq + delta[i]; + Bitboard attack = 0; - while (square_is_ok(s) && square_distance(s, s - delta[i]) == 1) + 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]) { - set_bit(&attacks, s); + attack |= s; - if (bit_is_set(occupied, s)) + if (occupied & s) break; - - s += delta[i]; } - } - return attacks; - } + return attack; + } - Bitboard pick_random(Bitboard mask, RKISS& rk, int booster) { - Bitboard magic; + Bitboard pick_random(RKISS& rk, int booster) { // 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; - } + Bitboard m = rk.rand(); + m = (m >> s1) | (m << (64 - s1)); + m &= rk.rand(); + m = (m >> s2) | (m << (64 - s2)); + return m & rk.rand(); } - // init_magic_bitboards() computes all rook and bishop magics at startup. - // Magic bitboards are used to look up attacks of sliding pieces. As reference - // see chessprogramming.wikispaces.com/Magic+Bitboards. In particular, here we + // 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_magic_bitboards(PieceType pt, Bitboard* attacks[], Bitboard magics[], - Bitboard masks[], int shifts[]) { + void init_magics(Bitboard table[], Bitboard* attacks[], Bitboard magics[], + Bitboard masks[], unsigned shifts[], Square deltas[], Fn index) { 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, index, booster; + int i, size, booster; // attacks[s] is a pointer to the beginning of the attacks table for square 's' - attacks[SQ_A1] = (pt == ROOK ? RookTable : BishopTable); + attacks[SQ_A1] = table; - 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)); @@ -320,15 +295,15 @@ 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_attacks(pt, s, 0) & ~edges; - shifts[s] = (Is64Bit ? 64 : 32) - count_1s(masks[s]); + masks[s] = sliding_attack(deltas, s, 0) & ~edges; + shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]); // Use Carry-Rippler trick to enumerate all subsets of masks[s] and - // store the corresponding sliding attacks bitboard in reference[]. + // store the corresponding sliding attack bitboard in reference[]. b = size = 0; do { occupancy[size] = b; - reference[size++] = sliding_attacks(pt, s, b); + reference[size++] = sliding_attack(deltas, s, b); b = (b - masks[s]) & masks[s]; } while (b); @@ -342,23 +317,25 @@ namespace { // 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)); + do magics[s] = pick_random(rk, booster); + while (popcount((magics[s] * masks[s]) >> 56) < 6); + + std::memset(attacks[s], 0, size * sizeof(Bitboard)); // 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++) + for (i = 0; i < size; ++i) { - index = (pt == ROOK ? rook_index(s, occupancy[i]) - : bishop_index(s, occupancy[i])); + Bitboard& attack = attacks[s][index(s, occupancy[i])]; - if (!attacks[s][index]) - attacks[s][index] = reference[i]; - - else if (attacks[s][index] != reference[i]) + if (attack && attack != reference[i]) break; + + assert(reference[i] != 0); + + attack = reference[i]; } } while (i != size); }