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remove blank line between function and it's description

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- remove the blank line between the declaration of the function and it's
  comment, leads to better IDE support when hovering over a function to see it's
  description
- remove the unnecessary duplication of the function name in the functions
  description
- slightly refactored code for lsb, msb in bitboard.h There are still a few
  things we can be improved later on, move the description of a function where
  it was declared (instead of implemented) and add descriptions to functions
  which are behind macros ifdefs

closes https://github.com/official-stockfish/Stockfish/pull/4840

No functional change
This commit is contained in:
Disservin
2023-10-22 20:20:53 +02:00
parent b187622233
commit a105978bbd
24 changed files with 175 additions and 271 deletions
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96
src/bitboard.h
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@@ -125,8 +125,7 @@ constexpr Bitboard file_bb(File f) { return FileABB << f; }
constexpr Bitboard file_bb(Square s) { return file_bb(file_of(s)); }
// shift() moves a bitboard one or two steps as specified by the direction D
// Moves a bitboard one or two steps as specified by the direction D
template<Direction D>
constexpr Bitboard shift(Bitboard b) {
return D == NORTH ? b << 8
@@ -143,9 +142,8 @@ constexpr Bitboard shift(Bitboard b) {
}
// pawn_attacks_bb() returns the squares attacked by pawns of the given color
// Returns the squares attacked by pawns of the given color
// from the squares in the given bitboard.
template<Color C>
constexpr Bitboard pawn_attacks_bb(Bitboard b) {
return C == WHITE ? shift<NORTH_WEST>(b) | shift<NORTH_EAST>(b)
@@ -158,11 +156,10 @@ inline Bitboard pawn_attacks_bb(Color c, Square s) {
return PawnAttacks[c][s];
}
// line_bb() returns a bitboard representing an entire line (from board edge
// 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) {
assert(is_ok(s1) && is_ok(s2));
@@ -171,14 +168,13 @@ inline Bitboard line_bb(Square s1, Square s2) {
}
// between_bb(s1, s2) returns a bitboard representing the squares in the semi-open
// Returns a bitboard representing the squares in the semi-open
// segment between the squares s1 and s2 (excluding s1 but including s2). If the
// given squares are not on a same file/rank/diagonal, it returns s2. For instance,
// between_bb(SQ_C4, SQ_F7) will return a bitboard with squares D5, E6 and F7, but
// between_bb(SQ_E6, SQ_F8) will return a bitboard with the square F8. This trick
// allows to generate non-king evasion moves faster: the defending piece must either
// interpose itself to cover the check or capture the checking piece.
inline Bitboard between_bb(Square s1, Square s2) {
assert(is_ok(s1) && is_ok(s2));
@@ -186,9 +182,8 @@ inline Bitboard between_bb(Square s1, Square s2) {
return BetweenBB[s1][s2];
}
// aligned() returns true if the squares s1, s2 and s3 are aligned either on a
// Returns true if the squares s1, s2 and s3 are aligned either on a
// straight or on a diagonal line.
inline bool aligned(Square s1, Square s2, Square s3) { return line_bb(s1, s2) & s3; }
@@ -197,14 +192,17 @@ inline bool aligned(Square s1, Square s2, Square s3) { return line_bb(s1, s2) &
template<typename T1 = Square>
inline int distance(Square x, Square y);
template<>
inline int distance<File>(Square x, Square y) {
return std::abs(file_of(x) - file_of(y));
}
template<>
inline int distance<Rank>(Square x, Square y) {
return std::abs(rank_of(x) - rank_of(y));
}
template<>
inline int distance<Square>(Square x, Square y) {
return SquareDistance[x][y];
@@ -212,9 +210,8 @@ inline int distance<Square>(Square x, Square y) {
inline int edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
// attacks_bb(Square) returns the pseudo attacks of the given piece type
// Returns the pseudo attacks of the given piece type
// assuming an empty board.
template<PieceType Pt>
inline Bitboard attacks_bb(Square s) {
@@ -224,10 +221,9 @@ inline Bitboard attacks_bb(Square s) {
}
// attacks_bb(Square, Bitboard) returns the attacks by the given piece
// 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<PieceType Pt>
inline Bitboard attacks_bb(Square s, Bitboard occupied) {
@@ -246,6 +242,9 @@ inline Bitboard attacks_bb(Square s, Bitboard occupied) {
}
}
// 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.
inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
assert((pt != PAWN) && (is_ok(s)));
@@ -264,8 +263,7 @@ inline Bitboard attacks_bb(PieceType pt, Square s, Bitboard occupied) {
}
// popcount() counts the number of non-zero bits in a bitboard
// Counts the number of non-zero bits in a bitboard.
inline int popcount(Bitboard b) {
#ifndef USE_POPCNT
@@ -287,43 +285,22 @@ inline int popcount(Bitboard b) {
#endif
}
// lsb() and msb() return the least/most significant bit in a non-zero bitboard
// Returns the least significant bit in a non-zero bitboard.
inline Square lsb(Bitboard b) {
assert(b);
#if defined(__GNUC__) // GCC, Clang, ICX
inline Square lsb(Bitboard b) {
assert(b);
return Square(__builtin_ctzll(b));
}
inline Square msb(Bitboard b) {
assert(b);
return Square(63 ^ __builtin_clzll(b));
}
#elif defined(_MSC_VER) // MSVC
#elif defined(_MSC_VER)
#ifdef _WIN64 // MSVC, WIN64
inline Square lsb(Bitboard b) {
assert(b);
unsigned long idx;
_BitScanForward64(&idx, b);
return (Square) idx;
}
inline Square msb(Bitboard b) {
assert(b);
unsigned long idx;
_BitScanReverse64(&idx, b);
return (Square) idx;
}
#else // MSVC, WIN32
inline Square lsb(Bitboard b) {
assert(b);
unsigned long idx;
if (b & 0xffffffff)
@@ -336,10 +313,29 @@ inline Square lsb(Bitboard b) {
_BitScanForward(&idx, int32_t(b >> 32));
return Square(idx + 32);
}
#endif
#else // Compiler is neither GCC nor MSVC compatible
#error "Compiler not supported."
#endif
}
// Returns the most significant bit in a non-zero bitboard.
inline Square msb(Bitboard b) {
assert(b);
#if defined(__GNUC__) // GCC, Clang, ICX
return Square(63 ^ __builtin_clzll(b));
#elif defined(_MSC_VER)
#ifdef _WIN64 // MSVC, WIN64
unsigned long idx;
_BitScanReverse64(&idx, b);
return (Square) idx;
#else // MSVC, WIN32
unsigned long idx;
if (b >> 32)
@@ -352,26 +348,20 @@ inline Square msb(Bitboard b) {
_BitScanReverse(&idx, int32_t(b));
return Square(idx);
}
#endif
#else // Compiler is neither GCC nor MSVC compatible
#error "Compiler not supported."
#endif
}
#endif
#else // Compiler is neither GCC nor MSVC compatible
#error "Compiler not supported."
#endif
// least_significant_square_bb() returns the bitboard of the least significant
// Returns the bitboard of the least significant
// square of a non-zero bitboard. It is equivalent to square_bb(lsb(bb)).
inline Bitboard least_significant_square_bb(Bitboard b) {
assert(b);
return b & -b;
}
// pop_lsb() finds and clears the least significant bit in a non-zero bitboard
// 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);