X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fevaluate.cpp;h=434ebd6241249f21869fe6b6b58211a61febe325;hp=d1799d6064810e3d58e6d8a380740d9504377f93;hb=0d669be76cadd33c801ba9e07410c789d2c7b364;hpb=7ae3c05795e79c9bd945607cdcfb08198f4c4b45

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index d1799d60..434ebd62 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -198,6 +198,8 @@ namespace {
   const Score Hanging             = S(48, 27);
   const Score ThreatByPawnPush    = S(38, 22);
   const Score Unstoppable         = S( 0, 20);
+  const Score PawnlessFlank       = S(20, 80);
+  const Score HinderPassedPawn    = S( 7,  0);
 
   // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
   // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
@@ -482,7 +484,8 @@ namespace {
     }
 
     // King tropism: firstly, find squares that opponent attacks in our king flank
-    b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][file_of(ksq)];
+    File kf = file_of(ksq);
+    b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][kf];
 
     assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
     assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
@@ -494,6 +497,10 @@ namespace {
 
     score -= CloseEnemies * popcount(b);
 
+    // Penalty when our king is on a pawnless flank
+    if (!(pos.pieces(PAWN) & (KingFlank[WHITE][kf] | KingFlank[BLACK][kf])))
+        score -= PawnlessFlank;
+
     if (DoTrace)
         Trace::add(KING, Us, score);
 
@@ -595,7 +602,7 @@ namespace {
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
-    Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+    Bitboard b, bb, squaresToQueen, defendedSquares, unsafeSquares;
     Score score = SCORE_ZERO;
 
     b = ei.pi->passed_pawns(Us);
@@ -607,6 +614,9 @@ namespace {
         assert(pos.pawn_passed(Us, s));
         assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
 
+        bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
+        score -= HinderPassedPawn * popcount(bb);
+
         int r = relative_rank(Us, s) - RANK_2;
         int rr = r * (r - 1);
 
@@ -632,7 +642,7 @@ namespace {
                 // in the pawn's path attacked or occupied by the enemy.
                 defendedSquares = unsafeSquares = squaresToQueen = forward_bb(Us, s);
 
-                Bitboard bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
+                bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
 
                 if (!(pos.pieces(Us) & bb))
                     defendedSquares &= ei.attackedBy[Us][ALL_PIECES];