From: protonspring <mike@whiteley.org>
Date: Tue, 3 Mar 2020 23:35:45 +0000 (-0700)
Subject: Small speed-up in BetweenBB
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=0424273d0b20ae7ad65143b530b2db8b94de0338

Small speed-up in BetweenBB

A speed-up removing some comparisons.

closes https://github.com/official-stockfish/Stockfish/pull/2571

No functional change.
---

diff --git a/src/bitboard.h b/src/bitboard.h
index ca161481..b0e27233 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -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
 }