Scale down eval for drawish rook endgames.

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index c1119a4102ca59a8459a1977d6c48699d1c59dff..d741b2ef1b3ef0078cd550e010ba58c94924d3ba 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -66,6 +66,12 @@ namespace {
   #undef S
   #undef V
 
+
+  /// evaluate() calculates a score for the static pawn structure of the given position.
+  /// We cannot use the location of pieces or king in this function, as the evaluation
+  /// of the pawn structure will be stored in a small cache for speed reasons, and will
+  /// be re-used even when the pieces have moved.
+
   template<Color Us>
   Score evaluate(const Position& pos, Pawns::Entry* e) {
 
@@ -150,17 +156,17 @@ namespace {
                 && !(theirPawns & adjacent_files_bb(s)))
                 score -= Doubled;
             else
-                score -=   Isolated
-                         + WeakUnopposed * !opposed;
+                score -=  Isolated
+                        + WeakUnopposed * !opposed;
         }
 
         else if (backward)
-            score -=   Backward
-                     + WeakUnopposed * !opposed;
+            score -=  Backward
+                    + WeakUnopposed * !opposed;
 
         if (!support)
-            score -=   Doubled * doubled
-                     + WeakLever * more_than_one(lever);
+            score -=  Doubled * doubled
+                    + WeakLever * more_than_one(lever);
     }
 
     return score;
@@ -170,6 +176,7 @@ namespace {
 
 namespace Pawns {
 
+
 /// Pawns::probe() looks up the current position's pawns configuration in
 /// the pawns hash table. It returns a pointer to the Entry if the position
 /// is found. Otherwise a new Entry is computed and stored there, so we don't
@@ -196,7 +203,7 @@ Entry* probe(const Position& pos) {
 /// penalty for a king, looking at the king file and the two closest files.
 
 template<Color Us>
-Score Entry::evaluate_shelter(const Position& pos, Square ksq) {
+Score Entry::evaluate_shelter(const Position& pos, Square ksq) const {
 
   constexpr Color Them = ~Us;