From: protonspring <mike@whiteley.org>
Date: Fri, 5 Apr 2019 03:45:52 +0000 (-0600)
Subject: Remove BetweenBB Array #2076
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=f98c77413b68d506977bc078de7a47455968a926

Remove BetweenBB Array #2076

Non functional change.
---

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 2adf2779..94dfa70f 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -27,7 +27,6 @@
 uint8_t PopCnt16[1 << 16];
 uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
-Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 Bitboard DistanceRingBB[SQUARE_NB][8];
 Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
@@ -121,10 +120,7 @@ void Bitboards::init() {
       for (PieceType pt : { BISHOP, ROOK })
           for (Square s2 = SQ_A1; s2 <= SQ_H8; ++s2)
               if (PseudoAttacks[pt][s1] & s2)
-              {
                   LineBB[s1][s2] = (attacks_bb(pt, s1, 0) & attacks_bb(pt, s2, 0)) | s1 | s2;
-                  BetweenBB[s1][s2] = attacks_bb(pt, s1, square_bb(s2)) & attacks_bb(pt, s2, square_bb(s1));
-              }
   }
 }
 
diff --git a/src/bitboard.h b/src/bitboard.h
index 77986638..b1d961f4 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -68,7 +68,6 @@ constexpr Bitboard Center      = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
 extern uint8_t PopCnt16[1 << 16];
 extern uint8_t SquareDistance[SQUARE_NB][SQUARE_NB];
 
-extern Bitboard BetweenBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard LineBB[SQUARE_NB][SQUARE_NB];
 extern Bitboard DistanceRingBB[SQUARE_NB][8];
 extern Bitboard PseudoAttacks[PIECE_TYPE_NB][SQUARE_NB];
@@ -185,13 +184,12 @@ inline Bitboard adjacent_files_bb(File f) {
 }
 
 
-/// between_bb() returns a bitboard representing all the squares between the two
-/// given ones. For instance, between_bb(SQ_C4, SQ_F7) returns a bitboard with
-/// the bits for square d5 and e6 set. If s1 and s2 are not on the same rank,
-/// file or diagonal, 0 is returned.
+/// between_bb() returns squares that are linearly between the given squares
+/// If the given squares are not on a same file/rank/diagonal, return 0.
 
 inline Bitboard between_bb(Square s1, Square s2) {
-  return BetweenBB[s1][s2];
+  return LineBB[s1][s2] & ( (AllSquares << (s1 +  (s1 < s2)))
+                           ^(AllSquares << (s2 + !(s1 < s2))));
 }