X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=3bb3ff8f8d5777ab0aa9ccf9e3928d3e94280051;hp=e3c9140dfaad0b02b49b12b5462dc7f00f10a111;hb=d0cb9b286f4d7415be002855201e75340c8adef0;hpb=c0cb713a000ef176cdad16defe640b7b6432a4a9 diff --git a/src/bitboard.cpp b/src/bitboard.cpp index e3c9140d..3bb3ff8f 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) 2015-2020 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 @@ -19,24 +19,16 @@ */ #include +#include #include "bitboard.h" #include "misc.h" uint8_t PopCnt16[1 << 16]; -int SquareDistance[SQUARE_NB][SQUARE_NB]; +uint8_t 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]; @@ -45,77 +37,12 @@ Magic BishopMagics[SQUARE_NB]; namespace { - // De Bruijn sequences. See chessprogramming.wikispaces.com/BitScan - const uint64_t DeBruijn64 = 0x3F79D71B4CB0A89ULL; - const uint32_t DeBruijn32 = 0x783A9B23; - - 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 - 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. - - unsigned bsf_index(Bitboard b) { - b ^= b - 1; - return Is64Bit ? (b * DeBruijn64) >> 58 - : ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26; - } - - - // popcount16() counts the non-zero bits using SWAR-Popcount algorithm - - unsigned popcount16(unsigned u) { - u -= (u >> 1) & 0x5555U; - u = ((u >> 2) & 0x3333U) + (u & 0x3333U); - u = ((u >> 4) + u) & 0x0F0FU; - return (u * 0x0101U) >> 8; - } -} - -#ifdef NO_BSF - -/// Software fall-back of lsb() and msb() for CPU lacking hardware support - -Square lsb(Bitboard b) { - assert(b); - return BSFTable[bsf_index(b)]; -} - -Square msb(Bitboard b) { - - assert(b); - unsigned b32; - int result = 0; - - if (b > 0xFFFFFFFF) - { - b >>= 32; - result = 32; - } - - b32 = unsigned(b); - - if (b32 > 0xFFFF) - { - b32 >>= 16; - result += 16; - } - - if (b32 > 0xFF) - { - b32 >>= 8; - result += 8; - } - - return Square(result + MSBTable[b32]); + void init_magics(Bitboard table[], Magic magics[], Direction directions[]); } -#endif // ifdef NO_BSF - /// Bitboards::pretty() returns an ASCII representation of a bitboard suitable /// to be printed to standard output. Useful for debugging. @@ -129,8 +56,9 @@ const std::string Bitboards::pretty(Bitboard b) { for (File f = FILE_A; f <= FILE_H; ++f) s += b & make_square(f, r) ? "| X " : "| "; - s += "|\n+---+---+---+---+---+---+---+---+\n"; + s += "| " + std::to_string(1 + r) + "\n+---+---+---+---+---+---+---+---+\n"; } + s += " a b c d e f g h\n"; return s; } @@ -142,114 +70,66 @@ const std::string Bitboards::pretty(Bitboard b) { void Bitboards::init() { for (unsigned i = 0; i < (1 << 16); ++i) - PopCnt16[i] = (uint8_t) popcount16(i); + PopCnt16[i] = uint8_t(std::bitset<16>(i).count()); for (Square s = SQ_A1; s <= SQ_H8; ++s) - { - SquareBB[s] = 1ULL << s; - BSFTable[bsf_index(SquareBB[s])] = s; - } - - for (Bitboard b = 2; b < 256; ++b) - MSBTable[b] = MSBTable[b - 1] + !more_than_one(b); + SquareBB[s] = (1ULL << s); - 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(distance(s1, s2), distance(s1, s2)); - for (Rank r = RANK_1; r <= RANK_8; ++r) - RankBB[r] = r > RANK_1 ? RankBB[r - 1] << 8 : Rank1BB; + Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST }; + Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - 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); + init_magics(RookTable, RookMagics, RookDirections); + init_magics(BishopTable, BishopMagics, BishopDirections); - for (Rank r = RANK_1; r < RANK_8; ++r) - ForwardRanksBB[WHITE][r] = ~(ForwardRanksBB[BLACK][r + 1] = ForwardRanksBB[BLACK][r] | RankBB[r]); + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) + { + PawnAttacks[WHITE][s1] = pawn_attacks_bb(square_bb(s1)); + PawnAttacks[BLACK][s1] = pawn_attacks_bb(square_bb(s1)); - for (Color c = WHITE; c <= BLACK; ++c) - for (Square s = SQ_A1; s <= SQ_H8; ++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 (int step : {-9, -8, -7, -1, 1, 7, 8, 9} ) + PseudoAttacks[KING][s1] |= safe_destination(s1, step); - 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, 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) && distance(s, to) < 3) - { - if (pt == PAWN) - PawnAttacks[c][s] |= to; - else - PseudoAttacks[pt][s] |= to; - } - } - - Square RookDeltas[] = { NORTH, EAST, SOUTH, WEST }; - Square BishopDeltas[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - - init_magics(RookTable, RookMagics, RookDeltas); - init_magics(BishopTable, BishopMagics, BishopDeltas); + for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} ) + PseudoAttacks[KNIGHT][s1] |= safe_destination(s1, step); - 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 (PieceType pt : { BISHOP, ROOK }) for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) - { - if (!(PseudoAttacks[pt][s1] & s2)) - continue; - - 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]); - } + if (PseudoAttacks[pt][s1] & s2) + LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2; } } namespace { - Bitboard sliding_attack(Square deltas[], Square sq, Bitboard occupied) { + Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) { - Bitboard attack = 0; + Bitboard attacks = 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]) - { - attack |= s; - - if (occupied & s) - break; - } + { + Square s = sq; + while(safe_destination(s, directions[i]) && !(occupied & s)) + attacks |= (s += directions[i]); + } - return attack; + return attacks; } // 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. + // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so + // called "fancy" approach. - void init_magics(Bitboard table[], Magic magics[], Square deltas[]) { + 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 }, @@ -269,7 +149,7 @@ namespace { // 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. Magic& m = magics[s]; - m.mask = sliding_attack(deltas, s, 0) & ~edges; + 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 @@ -281,7 +161,7 @@ namespace { b = size = 0; do { occupancy[size] = b; - reference[size] = sliding_attack(deltas, s, b); + reference[size] = sliding_attack(directions, s, b); if (HasPext) m.attacks[pext(b, m.mask)] = reference[size];