Simplify doubled pawn

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index c5c42ff14a593bc08caf2d914c0cdda6846ce0b0..1ccc0958ca432e870629231b9676651f4765710b 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -44,10 +44,8 @@ namespace {
   // Connected pawn bonus by opposed, phalanx, twice supported and rank
   Score Connected[2][2][2][RANK_NB];
 
-  // Doubled pawn penalty by file
-  const Score Doubled[FILE_NB] = {
-    S(11, 34), S(17, 38), S(19, 38), S(19, 38),
-    S(19, 38), S(19, 38), S(17, 38), S(11, 34) };
+  // Doubled pawn penalty
+  const Score Doubled = S(18,38);
 
   // Lever bonus by rank
   const Score Lever[RANK_NB] = {
@@ -126,7 +124,7 @@ namespace {
         opposed    = theirPawns & forward_bb(Us, s);
         stoppers   = theirPawns & passed_pawn_mask(Us, s);
         lever      = theirPawns & pawnAttacksBB[s];
-        doubled    = ourPawns   & forward_bb(Us, s);
+        doubled    = ourPawns   & (s + Up);
         neighbours = ourPawns   & adjacent_files_bb(f);
         phalanx    = neighbours & rank_bb(s);
         supported  = neighbours & rank_bb(s - Up);
@@ -145,14 +143,14 @@ namespace {
             // either there is a stopper in the way on this rank, or there is a
             // stopper on adjacent file which controls the way to that rank.
             backward = (b | shift_bb<Up>(b & adjacent_files_bb(f))) & stoppers;
-            
+
             assert(!backward || !(pawn_attack_span(Them, s + Up) & neighbours));
         }
 
         // Passed pawns will be properly scored in evaluation because we need
         // full attack info to evaluate them. Only the frontmost passed
         // pawn on each file is considered a true passed pawn.
-        if (!(stoppers | doubled))
+        if (!(stoppers | doubled)) // FIXME this is just doubled by adjacent pawn
             e->passedPawns[Us] |= s;
 
         // Score this pawn
@@ -169,7 +167,7 @@ namespace {
             score += Connected[opposed][!!phalanx][more_than_one(supported)][relative_rank(Us, s)];
 
         if (doubled)
-            score -= Doubled[f] / distance<Rank>(s, frontmost_sq(Us, doubled));
+            score -= Doubled;
 
         if (lever)
             score += Lever[relative_rank(Us, s)];