X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.h;h=15ec4153362d82d1339e9657e19190cf2e118005;hp=53e96f4455478e176f79b2c98b28799a5e7f6bee;hb=1f3bd968bb194a1f42af661cca9ec445c13978e8;hpb=a858b5a84e8702390adee4388034c57570e65fee diff --git a/src/bitboard.h b/src/bitboard.h index 53e96f44..15ec4153 100644 --- a/src/bitboard.h +++ b/src/bitboard.h @@ -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) 2015-2019 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 @@ -65,14 +65,19 @@ constexpr Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB; constexpr Bitboard KingSide = FileEBB | FileFBB | FileGBB | FileHBB; constexpr Bitboard Center = (FileDBB | FileEBB) & (Rank4BB | Rank5BB); +constexpr Bitboard KingFlank[FILE_NB] = { + QueenSide ^ FileDBB, QueenSide, QueenSide, + CenterFiles, CenterFiles, + KingSide, KingSide, KingSide ^ FileEBB +}; + extern uint8_t PopCnt16[1 << 16]; extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB]; +extern Bitboard SquareBB[SQUARE_NB]; extern Bitboard LineBB[SQUARE_NB][SQUARE_NB]; extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB]; extern Bitboard PawnAttacks[COLOR_NB][SQUARE_NB]; -extern Bitboard KingFlank[FILE_NB]; -extern Bitboard SquareBB[SQUARE_NB]; /// Magic holds all magic bitboards relevant data for a single square @@ -101,10 +106,11 @@ extern Magic RookMagics[SQUARE_NB]; extern Magic BishopMagics[SQUARE_NB]; inline Bitboard square_bb(Square s) { - assert(s >= SQ_A1 && s <= SQ_H8); + assert(is_ok(s)); return SquareBB[s]; } + /// Overloads of bitwise operators between a Bitboard and a Square for testing /// whether a given bit is set in a bitboard, and for setting and clearing bits. @@ -114,40 +120,54 @@ inline Bitboard operator^( Bitboard b, Square s) { return b ^ square_bb(s); } inline Bitboard& operator|=(Bitboard& b, Square s) { return b |= square_bb(s); } inline Bitboard& operator^=(Bitboard& b, Square s) { return b ^= square_bb(s); } +inline Bitboard operator&(Square s, Bitboard b) { return b & s; } +inline Bitboard operator|(Square s, Bitboard b) { return b | s; } +inline Bitboard operator^(Square s, Bitboard b) { return b ^ s; } + +inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; } + constexpr bool more_than_one(Bitboard b) { return b & (b - 1); } -inline bool opposite_colors(Square s1, Square s2) { - return bool(DarkSquares & s1) != bool(DarkSquares & s2); +/// Counts the occupation of the bitboard depending on the occupation of SQ_A1 +/// as in `b & (1ULL << SQ_A1) ? more_than_two(b) : more_than_one(b)` + +constexpr bool conditional_more_than_two(Bitboard b) { + return b & (b - 1) & (b - 2); +} + +constexpr bool opposite_colors(Square s1, Square s2) { + return (s1 + rank_of(s1) + s2 + rank_of(s2)) & 1; } /// rank_bb() and file_bb() return a bitboard representing all the squares on /// the given file or rank. -inline Bitboard rank_bb(Rank r) { +constexpr Bitboard rank_bb(Rank r) { return Rank1BB << (8 * r); } -inline Bitboard rank_bb(Square s) { +constexpr Bitboard rank_bb(Square s) { return rank_bb(rank_of(s)); } -inline Bitboard file_bb(File f) { +constexpr Bitboard file_bb(File f) { return FileABB << f; } -inline Bitboard file_bb(Square s) { +constexpr Bitboard file_bb(Square s) { return file_bb(file_of(s)); } -/// shift() moves a bitboard one step along direction D +/// shift() moves a bitboard one or two steps as specified by the direction D template constexpr Bitboard shift(Bitboard b) { return D == NORTH ? b << 8 : D == SOUTH ? b >> 8 + : D == NORTH+NORTH? b <<16 : D == SOUTH+SOUTH? b >>16 : D == EAST ? (b & ~FileHBB) << 1 : D == WEST ? (b & ~FileABB) >> 1 : D == NORTH_EAST ? (b & ~FileHBB) << 9 : D == NORTH_WEST ? (b & ~FileABB) << 7 : D == SOUTH_EAST ? (b & ~FileHBB) >> 7 : D == SOUTH_WEST ? (b & ~FileABB) >> 9 @@ -164,6 +184,12 @@ constexpr Bitboard pawn_attacks_bb(Bitboard b) { : shift(b) | shift(b); } +inline Bitboard pawn_attacks_bb(Color c, Square s) { + + assert(is_ok(s)); + return PawnAttacks[c][s]; +} + /// pawn_double_attacks_bb() returns the squares doubly attacked by pawns of the /// given color from the squares in the given bitboard. @@ -176,19 +202,33 @@ constexpr Bitboard pawn_double_attacks_bb(Bitboard b) { /// adjacent_files_bb() returns a bitboard representing all the squares on the -/// adjacent files of the given one. +/// adjacent files of a given square. + +constexpr Bitboard adjacent_files_bb(Square s) { + return shift(file_bb(s)) | shift(file_bb(s)); +} + + +/// line_bb() returns a bitboard representing an entire line (from board edge +/// to board edge) that intersects the two given squares. If the given squares +/// are not on a same file/rank/diagonal, the function returns 0. For instance, +/// line_bb(SQ_C4, SQ_F7) will return a bitboard with the A2-G8 diagonal. + +inline Bitboard line_bb(Square s1, Square s2) { -inline Bitboard adjacent_files_bb(File f) { - return shift(file_bb(f)) | shift(file_bb(f)); + assert(is_ok(s1) && is_ok(s2)); + return LineBB[s1][s2]; } -/// between_bb() returns squares that are linearly between the given squares -/// If the given squares are not on a same file/rank/diagonal, return 0. +/// between_bb() returns a bitboard representing squares that are linearly +/// between the two given squares (excluding the given squares). If the given +/// squares are not on a same file/rank/diagonal, we return 0. For instance, +/// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5 and E6. inline Bitboard between_bb(Square s1, Square s2) { - return LineBB[s1][s2] & ( (AllSquares << (s1 + (s1 < s2))) - ^(AllSquares << (s2 + !(s1 < s2)))); + Bitboard b = line_bb(s1, s2) & ((AllSquares << s1) ^ (AllSquares << s2)); + return b & (b - 1); //exclude lsb } @@ -196,34 +236,34 @@ inline Bitboard between_bb(Square s1, Square s2) { /// in front of the given one, from the point of view of the given color. For instance, /// forward_ranks_bb(BLACK, SQ_D3) will return the 16 squares on ranks 1 and 2. -inline Bitboard forward_ranks_bb(Color c, Square s) { - return c == WHITE ? ~Rank1BB << 8 * (rank_of(s) - RANK_1) - : ~Rank8BB >> 8 * (RANK_8 - rank_of(s)); +constexpr Bitboard forward_ranks_bb(Color c, Square s) { + return c == WHITE ? ~Rank1BB << 8 * relative_rank(WHITE, s) + : ~Rank8BB >> 8 * relative_rank(BLACK, s); } /// forward_file_bb() returns a bitboard representing all the squares along the /// line in front of the given one, from the point of view of the given color. -inline Bitboard forward_file_bb(Color c, Square s) { +constexpr Bitboard forward_file_bb(Color c, Square s) { return forward_ranks_bb(c, s) & file_bb(s); } /// pawn_attack_span() returns a bitboard representing all the squares that can -/// be attacked by a pawn of the given color when it moves along its file, -/// starting from the given square. +/// be attacked by a pawn of the given color when it moves along its file, starting +/// from the given square. -inline Bitboard pawn_attack_span(Color c, Square s) { - return forward_ranks_bb(c, s) & adjacent_files_bb(file_of(s)); +constexpr Bitboard pawn_attack_span(Color c, Square s) { + return forward_ranks_bb(c, s) & adjacent_files_bb(s); } /// passed_pawn_span() returns a bitboard which can be used to test if a pawn of /// the given color and on the given square is a passed pawn. -inline Bitboard passed_pawn_span(Color c, Square s) { - return forward_ranks_bb(c, s) & (adjacent_files_bb(file_of(s)) | file_bb(s)); +constexpr Bitboard passed_pawn_span(Color c, Square s) { + return pawn_attack_span(c, s) | forward_file_bb(c, s); } @@ -231,7 +271,7 @@ inline Bitboard passed_pawn_span(Color c, Square s) { /// straight or on a diagonal line. inline bool aligned(Square s1, Square s2, Square s3) { - return LineBB[s1][s2] & s3; + return line_bb(s1, s2) & s3; } @@ -243,23 +283,53 @@ template<> inline int distance(Square x, Square y) { return std::abs(file_ template<> inline int distance(Square x, Square y) { return std::abs(rank_of(x) - rank_of(y)); } template<> inline int distance(Square x, Square y) { return SquareDistance[x][y]; } -template constexpr const T& clamp(const T& v, const T& lo, const T& hi) { - return v < lo ? lo : v > hi ? hi : v; +inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); } +inline int edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); } + + +/// 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); +} + + +/// attacks_bb(Square) returns the pseudo attacks of the give piece type +/// assuming an empty board. + +template +inline Bitboard attacks_bb(Square s) { + + assert((Pt != PAWN) && (is_ok(s))); + + return PseudoAttacks[Pt][s]; } -/// attacks_bb() returns a bitboard representing all the squares attacked by a -/// piece of type Pt (bishop or rook) placed on 's'. + +/// attacks_bb(Square, Bitboard) returns the attacks by the given piece +/// assuming the board is occupied according to the passed Bitboard. +/// Sliding piece attacks do not continue passed an occupied square. template inline Bitboard attacks_bb(Square s, Bitboard occupied) { - const Magic& m = Pt == ROOK ? RookMagics[s] : BishopMagics[s]; - return m.attacks[m.index(occupied)]; + assert((Pt != PAWN) && (is_ok(s))); + + switch (Pt) + { + case BISHOP: return BishopMagics[s].attacks[BishopMagics[s].index(occupied)]; + case ROOK : return RookMagics[s].attacks[ RookMagics[s].index(occupied)]; + case QUEEN : return attacks_bb(s, occupied) | attacks_bb(s, occupied); + default : return PseudoAttacks[Pt][s]; + } } inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) { - assert(pt != PAWN); + assert((pt != PAWN) && (is_ok(s))); switch (pt) { @@ -364,16 +434,18 @@ inline Square msb(Bitboard b) { /// pop_lsb() finds and clears the least significant bit in a non-zero bitboard inline Square pop_lsb(Bitboard* b) { + assert(*b); const Square s = lsb(*b); *b &= *b - 1; return s; } -/// frontmost_sq() and backmost_sq() return the square corresponding to the -/// most/least advanced bit relative to the given color. - -inline Square frontmost_sq(Color c, Bitboard b) { return c == WHITE ? msb(b) : lsb(b); } -inline Square backmost_sq(Color c, Bitboard b) { return c == WHITE ? lsb(b) : msb(b); } +/// frontmost_sq() returns the most advanced square for the given color, +/// requires a non-zero bitboard. +inline Square frontmost_sq(Color c, Bitboard b) { + assert(b); + return c == WHITE ? msb(b) : lsb(b); +} #endif // #ifndef BITBOARD_H_INCLUDED