Add a rank based bonus for blocked pawns.

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index d741b2ef1b3ef0078cd550e010ba58c94924d3ba..f18e03155042112dc71e89472b55120ad26c312b 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -38,7 +38,12 @@ namespace {
   constexpr Score WeakLever     = S( 0, 56);
   constexpr Score WeakUnopposed = S(13, 27);
 
-  constexpr Score BlockedStorm[RANK_NB]  = {S( 0, 0), S( 0, 0), S( 76, 78), S(-10, 15), S(-7, 10), S(-4, 6), S(-1, 2)};
+  // Bonus for blocked pawns at 5th or 6th rank
+  constexpr Score BlockedPawn[2] = { S(-10, -3), S(-3, 3) };
+
+  constexpr Score BlockedStorm[RANK_NB] = {
+    S(0, 0), S(0, 0), S(76, 78), S(-10, 15), S(-7, 10), S(-4, 6), S(-1, 2)
+  };
 
   // Connected pawn bonus
   constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
@@ -167,6 +172,9 @@ namespace {
         if (!support)
             score -=  Doubled * doubled
                     + WeakLever * more_than_one(lever);
+
+        if (blocked && r > RANK_4)
+            score += BlockedPawn[r-4];
     }
 
     return score;