Simplify WeakUnopposedPawn #2181

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 8d6f812a6d56cf5607e06f51c903f96cad0fc01f..47c89ed4c076c73d6be4647ba1cd16f960438cec 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -35,9 +35,10 @@ namespace {
   constexpr Score Backward = S( 9, 24);
   constexpr Score Doubled  = S(11, 56);
   constexpr Score Isolated = S( 5, 15);
+  constexpr Score WeakUnopposed = S( 13, 27);
 
   // Connected pawn bonus
-  constexpr int Connected[RANK_NB] = { 0, 13, 17, 24, 59, 96, 171 };
+  constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
 
   // Strength of pawn shelter for our king by [distance from edge][rank].
   // RANK_1 = 0 is used for files where we have no pawn, or pawn is behind our king.
@@ -77,7 +78,7 @@ namespace {
     Bitboard ourPawns   = pos.pieces(  Us, PAWN);
     Bitboard theirPawns = pos.pieces(Them, PAWN);
 
-    e->passedPawns[Us] = e->pawnAttacksSpan[Us] = e->weakUnopposed[Us] = 0;
+    e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
     e->kingSquares[Us]   = SQ_NONE;
     e->pawnAttacks[Us]   = pawn_attacks_bb<Us>(ourPawns);
 
@@ -126,15 +127,16 @@ namespace {
         // Score this pawn
         if (support | phalanx)
         {
-            int v = (phalanx ? 3 : 2) * Connected[r];
-            v = 17 * popcount(support) + (v >> (opposed + 1));
+            int v =  Connected[r] * (phalanx ? 3 : 2) / (opposed ? 2 : 1)
+                   + 17 * popcount(support);
+
             score += make_score(v, v * (r - 2) / 4);
         }
         else if (!neighbours)
-            score -= Isolated, e->weakUnopposed[Us] += !opposed;
+            score -= Isolated + WeakUnopposed * int(!opposed);
 
         else if (backward)
-            score -= Backward, e->weakUnopposed[Us] += !opposed;
+            score -= Backward + WeakUnopposed * int(!opposed);
 
         if (doubled && !support)
             score -= Doubled;