X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fbitboard.h;h=529e3dfe5f44e31e18099dfa85e372a11e31c76e;hb=fbc7a328c67092799547f93e684323e2c1a6226e;hp=3ea18dd88d6f09bb31c9a0f9813b8a6c44f24214;hpb=37e38639279bf58558b92932739da57e7c2e3bdc;p=stockfish

diff --git a/src/bitboard.h b/src/bitboard.h
index 3ea18dd8..529e3dfe 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -255,6 +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]; }
 
+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'.
@@ -373,14 +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);
 }