X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=5474850494cbb98036b2c307e172791b3ca3f099;hp=d7848fbd2f33364cc63232c11646701dc47f1a5a;hb=d889bb47185e33012b45cab63359952247bc86e2;hpb=53d197b841731840891c783bb7e044f012db4aa7

diff --git a/src/pawns.cpp b/src/pawns.cpp
index d7848fbd..54748504 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -36,6 +36,7 @@ namespace {
   constexpr Score Doubled  = S(11, 56);
   constexpr Score Isolated = S( 5, 15);
   constexpr Score WeakUnopposed = S( 13, 27);
+  constexpr Score Attacked2Unsupported = S( 0, 20);
 
   // Connected pawn bonus
   constexpr int Connected[RANK_NB] = { 0, 7, 8, 12, 29, 48, 86 };
@@ -79,8 +80,13 @@ namespace {
     Bitboard theirPawns = pos.pieces(Them, PAWN);
 
     e->passedPawns[Us] = e->pawnAttacksSpan[Us] = 0;
-    e->kingSquares[Us]   = SQ_NONE;
-    e->pawnAttacks[Us]   = pawn_attacks_bb<Us>(ourPawns);
+    e->kingSquares[Us] = SQ_NONE;
+    e->pawnAttacks[Us] = pawn_attacks_bb<Us>(ourPawns);
+
+    // Unsupported enemy pawns attacked twice by us
+    score += Attacked2Unsupported * popcount(  theirPawns
+                                             & pawn_double_attacks_bb<Us>(ourPawns)
+                                             & ~pawn_attacks_bb<Them>(theirPawns));
 
     // Loop through all pawns of the current color and score each pawn
     while ((s = *pl++) != SQ_NONE)
@@ -190,7 +196,7 @@ void Entry::evaluate_shelter(const Position& pos, Square ksq, Score& shelter) {
   for (File f = File(center - 1); f <= File(center + 1); ++f)
   {
       b = ourPawns & file_bb(f);
-      Rank ourRank = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
+      Rank ourRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
 
       b = theirPawns & file_bb(f);
       Rank theirRank = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;