Simplify bonus for bishop on long diagonal

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index f34c01b6c3e15cc8072e60d40c55c0f80626e964..aadde25a19472a3791d20197bfd80060bfca1a44 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -31,11 +31,10 @@
 
 namespace {
 
-  const Bitboard LongDiagonals = 0x8142241818244281ULL; // A1..H8 | H1..A8
-  const Bitboard Center        = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
-  const Bitboard QueenSide     = FileABB | FileBBB | FileCBB | FileDBB;
-  const Bitboard CenterFiles   = FileCBB | FileDBB | FileEBB | FileFBB;
-  const Bitboard KingSide      = FileEBB | FileFBB | FileGBB | FileHBB;
+  const Bitboard Center      = (FileDBB | FileEBB) & (Rank4BB | Rank5BB);
+  const Bitboard QueenSide   = FileABB | FileBBB | FileCBB | FileDBB;
+  const Bitboard CenterFiles = FileCBB | FileDBB | FileEBB | FileFBB;
+  const Bitboard KingSide    = FileEBB | FileFBB | FileGBB | FileHBB;
 
   const Bitboard KingFlank[FILE_NB] = {
     QueenSide, QueenSide, QueenSide, CenterFiles, CenterFiles, KingSide, KingSide, KingSide
@@ -222,7 +221,7 @@ namespace {
   const Score CloseEnemies        = S(  7,  0);
   const Score PawnlessFlank       = S( 20, 80);
   const Score ThreatByHangingPawn = S( 71, 61);
-  const Score ThreatBySafePawn    = S(182,175);
+  const Score ThreatBySafePawn    = S(192,175);
   const Score ThreatByRank        = S( 16,  3);
   const Score Hanging             = S( 48, 27);
   const Score WeakUnopposedPawn   = S(  5, 25);
@@ -354,10 +353,8 @@ namespace {
                 // Penalty for pawns on the same color square as the bishop
                 score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s);
 
-                // Bonus for bishop on a long diagonal without pawns in the center
-                if (    (LongDiagonals & s)
-                    && !(attackedBy[Them][PAWN] & s)
-                    && !(Center & PseudoAttacks[BISHOP][s] & pos.pieces(PAWN)))
+                // Bonus for bishop on a long diagonal which can "see" both center squares
+                if (more_than_one(Center & (attacks_bb<BISHOP>(s, pos.pieces(PAWN)) | s)))
                     score += LongRangedBishop;
             }