Count only the most advanced passed pawn for each file.

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 560fd76b171fc80306f92aee1716ae9cbcd15997..3023021d408a853a93c2294c73f4bec74b01aa50 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -124,6 +124,8 @@ namespace {
                 || (   stoppers == blocked && r >= RANK_5
                     && (shift<Up>(support) & ~(theirPawns | doubleAttackThem)));
 
+        passed &= !(forward_file_bb(Us, s) & ourPawns);
+
         // Passed pawns will be properly scored later in evaluation when we have
         // full attack info.
         if (passed)