X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=80206b58af93c512c56dc841f0af82ba6f7579d8;hp=70114f20fadd3485e2c30d93f2760038ea50c61d;hb=32edb1d009e09a9442cb7393920e072ffd08005d;hpb=7f623206f413b96170d432b401fe3c647325d01a diff --git a/src/bitboard.cpp b/src/bitboard.cpp index 70114f20..80206b58 100644 --- a/src/bitboard.cpp +++ b/src/bitboard.cpp @@ -1,8 +1,6 @@ /* 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) 2015-2020 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad + Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file) Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -40,7 +38,17 @@ namespace { Bitboard RookTable[0x19000]; // To store rook attacks Bitboard BishopTable[0x1480]; // To store bishop attacks - void init_magics(Bitboard table[], Magic magics[], Direction directions[]); + void init_magics(PieceType pt, Bitboard table[], Magic magics[]); + +} + + +/// safe_destination() returns the bitboard of target square for the given step +/// from the given square. If the step is off the board, returns empty bitboard. + +inline Bitboard safe_destination(Square s, int step) { + Square to = Square(s + step); + return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0); } @@ -56,8 +64,9 @@ 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; } @@ -69,7 +78,7 @@ const std::string Bitboards::pretty(Bitboard b) { void Bitboards::init() { for (unsigned i = 0; i < (1 << 16); ++i) - PopCnt16[i] = std::bitset<16>(i).count(); + PopCnt16[i] = uint8_t(std::bitset<16>(i).count()); for (Square s = SQ_A1; s <= SQ_H8; ++s) SquareBB[s] = (1ULL << s); @@ -78,36 +87,20 @@ void Bitboards::init() { for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2) SquareDistance[s1][s2] = std::max(distance(s1, s2), distance(s1, s2)); - for (Square s = SQ_A1; s <= SQ_H8; ++s) - { - PawnAttacks[WHITE][s] = pawn_attacks_bb(square_bb(s)); - PawnAttacks[BLACK][s] = pawn_attacks_bb(square_bb(s)); - } + init_magics(ROOK, RookTable, RookMagics); + init_magics(BISHOP, BishopTable, BishopMagics); - // Helper returning the target bitboard of a step from a square - auto landing_square_bb = [&](Square s, int step) + for (Square s1 = SQ_A1; s1 <= SQ_H8; ++s1) { - Square to = Square(s + step); - return is_ok(to) && distance(s, to) <= 2 ? square_bb(to) : Bitboard(0); - }; + PawnAttacks[WHITE][s1] = pawn_attacks_bb(square_bb(s1)); + PawnAttacks[BLACK][s1] = pawn_attacks_bb(square_bb(s1)); - for (Square s = SQ_A1; s <= SQ_H8; ++s) - { for (int step : {-9, -8, -7, -1, 1, 7, 8, 9} ) - PseudoAttacks[KING][s] |= landing_square_bb(s, step); + PseudoAttacks[KING][s1] |= safe_destination(s1, step); for (int step : {-17, -15, -10, -6, 6, 10, 15, 17} ) - PseudoAttacks[KNIGHT][s] |= landing_square_bb(s, step); - } - - Direction RookDirections[] = { NORTH, EAST, SOUTH, WEST }; - Direction BishopDirections[] = { NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST }; - - init_magics(RookTable, RookMagics, RookDirections); - init_magics(BishopTable, BishopMagics, BishopDirections); + 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); @@ -121,22 +114,20 @@ void Bitboards::init() { namespace { - Bitboard sliding_attack(Direction directions[], Square sq, Bitboard occupied) { + Bitboard sliding_attack(PieceType pt, Square sq, Bitboard occupied) { - Bitboard attack = 0; + Bitboard attacks = 0; + Direction RookDirections[4] = {NORTH, SOUTH, EAST, WEST}; + Direction BishopDirections[4] = {NORTH_EAST, SOUTH_EAST, SOUTH_WEST, NORTH_WEST}; - for (int i = 0; i < 4; ++i) - for (Square s = sq + directions[i]; - is_ok(s) && distance(s, s - directions[i]) == 1; - s += directions[i]) - { - attack |= s; - - if (occupied & s) - break; - } + for (Direction d : (pt == ROOK ? RookDirections : BishopDirections)) + { + Square s = sq; + while(safe_destination(s, d) && !(occupied & s)) + attacks |= (s += d); + } - return attack; + return attacks; } @@ -145,7 +136,7 @@ namespace { // www.chessprogramming.org/Magic_Bitboards. In particular, here we use the so // called "fancy" approach. - void init_magics(Bitboard table[], Magic magics[], Direction directions[]) { + void init_magics(PieceType pt, Bitboard table[], Magic magics[]) { // Optimal PRNG seeds to pick the correct magics in the shortest time int seeds[][RANK_NB] = { { 8977, 44560, 54343, 38998, 5731, 95205, 104912, 17020 }, @@ -165,7 +156,7 @@ 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(directions, s, 0) & ~edges; + m.mask = sliding_attack(pt, s, 0) & ~edges; m.shift = (Is64Bit ? 64 : 32) - popcount(m.mask); // Set the offset for the attacks table of the square. We have individual @@ -177,7 +168,7 @@ namespace { b = size = 0; do { occupancy[size] = b; - reference[size] = sliding_attack(directions, s, b); + reference[size] = sliding_attack(pt, s, b); if (HasPext) m.attacks[pext(b, m.mask)] = reference[size];