/*
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
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.
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, Square s2) { return square_bb(s) | s2; }
+inline Bitboard operator|(Square s1, Square s2) { return square_bb(s1) | s2; }
constexpr bool more_than_one(Bitboard b) {
return b & (b - 1);
}
+
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));
}
/// adjacent_files_bb() returns a bitboard representing all the squares on the
-/// adjacent files of the given one.
+/// adjacent files of a given square.
-inline Bitboard adjacent_files_bb(Square s) {
+constexpr Bitboard adjacent_files_bb(Square s) {
return shift<EAST>(file_bb(s)) | shift<WEST>(file_bb(s));
}
-/// line_bb(Square, Square) returns a Bitboard representing an entire line
-/// (from board edge to board edge) that intersects the given squares.
-/// If the given squares are not on a same file/rank/diagonal, return 0.
-/// Ex. line_bb(SQ_C4, SQ_F7) returns a bitboard with the A2-G8 diagonal.
+
+/// 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) {
return LineBB[s1][s2];
}
-/// between_bb() returns a Bitboard representing squares that are linearly
-/// between the given squares (excluding the given squares).
-/// If the given squares are not on a same file/rank/diagonal, return 0.
-/// Ex. between_bb(SQ_C4, SQ_F7) returns a bitboard with squares D5 and E6.
+
+/// 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) {
Bitboard b = line_bb(s1, s2) & ((AllSquares << s1) ^ (AllSquares << 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) {
+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) {
+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) {
+constexpr Bitboard passed_pawn_span(Color c, Square s) {
return pawn_attack_span(c, s) | forward_file_bb(c, s);
}
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)); }
-/// Return the target square bitboard if we do not step off the board, empty otherwise
+
+/// 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)
{
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.
return PseudoAttacks[Pt][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.
projects / stockfish / blobdiff