Simplify a condition in is_KXK()

[stockfish] / src / pawns.cpp

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 64c8e4b6182f2133108e69d1e3bf6bdb87ee1a82..aa3139e27a7b65fe7af7b986437134d93e0ca5de 100644 (file)
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -57,6 +57,11 @@ namespace {
     S( 0, 0), S( 6, 13), S(6,13), S(14,29),
     S(34,68), S(83,166), S(0, 0), S( 0, 0) };
 
+    // Levers bonus by rank
+  const Score Lever[RANK_NB] = {
+    S( 0, 0), S( 0, 0), S(0, 0), S(0, 0),
+    S(20,20), S(40,40), S(0, 0), S(0, 0) };
+
   // Bonus for file distance of the two outermost pawns
   const Score PawnsFileSpan = S(0, 15);
 
@@ -72,7 +77,7 @@ namespace {
   const Value StormDanger[3][RANK_NB] = {
   { V( 0),  V(64), V(128), V(51), V(26) },
   { V(26),  V(32), V( 96), V(38), V(20) },
-  { V( 0),  V( 0), V( 64), V(25), V(13) } };
+  { V( 0),  V( 0), V(160), V(25), V(13) } };
 
   // Max bonus for king safety. Corresponds to start position with all the pawns
   // in front of the king and no enemy pawn on the horizon.
@@ -92,9 +97,10 @@ namespace {
     Bitboard b, p, doubled;
     Square s;
     File f;
-    bool passed, isolated, opposed, connected, backward, candidate, unsupported;
+    bool passed, isolated, opposed, connected, backward, candidate, unsupported, lever;
     Score value = SCORE_ZERO;
     const Square* pl = pos.list<PAWN>(Us);
+    const Bitboard* pawnAttacksBB = StepAttacksBB[make_piece(Us, PAWN)];
 
     Bitboard ourPawns = pos.pieces(Us, PAWN);
     Bitboard theirPawns = pos.pieces(Them, PAWN);
@@ -130,6 +136,7 @@ namespace {
         doubled     =   ourPawns   & forward_bb(Us, s);
         opposed     =   theirPawns & forward_bb(Us, s);
         passed      = !(theirPawns & passed_pawn_mask(Us, s));
+        lever       =   theirPawns & pawnAttacksBB[s];
 
         // Test for backward pawn.
         // If the pawn is passed, isolated, or connected it cannot be
@@ -185,6 +192,9 @@ namespace {
         if (connected)
             value += Connected[f][relative_rank(Us, s)];
 
+        if (lever)
+           value += Lever[relative_rank(Us, s)];
+
         if (candidate)
         {
             value += CandidatePassed[relative_rank(Us, s)];
@@ -270,7 +280,7 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
       if (   (MiddleEdges & make_square(f, rkThem))
           && file_of(ksq) == f
           && relative_rank(Us, ksq) == rkThem - 1)
-          safety += Value(200);
+          safety += 200;
       else
           safety -= ShelterWeakness[rkUs]
                   + StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem];