Introduce concept of double pawn protection.

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index f1bb861dcca629e08de695df7bb0c8ff4ccf0b2f..d6239594d9165cb91578311a353e801851ac724e 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -309,7 +309,7 @@ namespace {
         attackedBy[Us][Pt] |= b;
         attackedBy[Us][ALL_PIECES] |= b;
 
-        if (b & kingRing[Them])
+        if (b & kingRing[Them] & ~double_pawn_attacks_bb<Them>(pos.pieces(Them, PAWN)))
         {
             kingAttackersCount[Us]++;
             kingAttackersWeight[Us] += KingAttackWeights[Pt];