X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fbitboard.h;h=b0e272338c0f536f95067a4f34747ba6e714b22f;hb=e7c1c8c1abd85a71fd8190e0c1af49214625904b;hp=440de1ea1ee0be74befddbac703a15d91b900bbf;hpb=09bef14c76e119103cc1a9404cbde7e249205deb;p=stockfish

diff --git a/src/bitboard.h b/src/bitboard.h
index 440de1ea..b0e27233 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -129,8 +129,8 @@ 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);
+constexpr bool opposite_colors(Square s1, Square s2) {
+  return (s1 + rank_of(s1) + s2 + rank_of(s2)) & 1;
 }
 
 
@@ -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
 }