Small cleanups

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index d11b7e732b66227515d83c54647daed57a5937c3..529e3dfe5f44e31e18099dfa85e372a11e31c76e 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -154,7 +154,7 @@ inline Bitboard file_bb(Square 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<Direction D>
 constexpr Bitboard shift(Bitboard b) {
@@ -199,8 +199,8 @@ inline Bitboard adjacent_files_bb(Square s) {
 /// If the given squares are not on a same file/rank/diagonal, return 0.
 
 inline Bitboard between_bb(Square s1, Square s2) {
-  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
-                           ^(AllSquares << (s2 + !(s1 < s2))));
+  Bitboard b = LineBB[s1][s2] & ((AllSquares << s1) ^ (AllSquares << s2));
+  return b & (b - 1); //exclude lsb
 }
 
 
@@ -255,9 +255,8 @@ template<> inline int distance<File>(Square x, Square y) { return std::abs(file_
 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]; }
 
-template<class T> constexpr const T& clamp(const T& v, const T& lo, const T&  hi) {
-  return v < lo ? lo : v > hi ? hi : v;
-}
+inline File edge_distance(File f) { return std::min(f, File(FILE_H - f)); }
+inline Rank edge_distance(Rank r) { return std::min(r, Rank(RANK_8 - r)); }
 
 /// attacks_bb() returns a bitboard representing all the squares attacked by a
 /// piece of type Pt (bishop or rook) placed on 's'.
@@ -376,14 +375,17 @@ 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() returns the most advanced square for the given color
+/// 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);
 }