Simplify unstoppable pawns evaluation
authorReuven Peleg <reuvenpe2005@gmail.com>
Tue, 10 Sep 2013 18:39:48 +0000 (21:39 +0300)
committerMarco Costalba <mcostalba@gmail.com>
Tue, 10 Sep 2013 21:02:05 +0000 (23:02 +0200)
No functional change

src/evaluate.cpp

index e693b2a8e3f4fb6ae9724ad62ee5d65a72ccdb86..42f7addfcce822b478da9fedf8b3db04b772eee7 100644 (file)
@@ -1002,19 +1002,19 @@ Value do_evaluate(const Position& pos, Value& margin) {
             {
                 b2 = supporters & in_front_bb(winnerSide, rank_of(blockSq + pawn_push(winnerSide)));
 
             {
                 b2 = supporters & in_front_bb(winnerSide, rank_of(blockSq + pawn_push(winnerSide)));
 
-                while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
+                if (b2)
                 {
                 {
-                    d = square_distance(blockSq, pop_lsb(&b2)) - 2;
+                    d = square_distance(blockSq, backmost_sq(winnerSide, b2)) - 2;
                     movesToGo = std::min(movesToGo, d);
                 }
             }
 
             // Check pawns that can be sacrificed against the blocking pawn
                     movesToGo = std::min(movesToGo, d);
                 }
             }
 
             // Check pawns that can be sacrificed against the blocking pawn
-            b2 = pawn_attack_span(winnerSide, blockSq) & candidates & ~(1ULL << s);
+            b2 = pawn_attack_span(winnerSide, blockSq) & candidates & ~SquareBB[s];
 
 
-            while (b2) // This while-loop could be replaced with LSB/MSB (depending on color)
+            if (b2)
             {
             {
-                d = square_distance(blockSq, pop_lsb(&b2)) - 2;
+                d = square_distance(blockSq, backmost_sq(winnerSide, b2)) - 2;
                 movesToGo = std::min(movesToGo, d);
             }
 
                 movesToGo = std::min(movesToGo, d);
             }
 
@@ -1033,12 +1033,8 @@ Value do_evaluate(const Position& pos, Value& margin) {
             kingptg = (minKingDist + blockersCount) * 2;
         }
 
             kingptg = (minKingDist + blockersCount) * 2;
         }
 
-        // Check if pawn sacrifice plan _may_ save the day
-        if (pliesToQueen[winnerSide] + 3 > pliesToGo + sacptg)
-            return SCORE_ZERO;
-
-        // Check if king capture plan _may_ save the day (contains some false positives)
-        if (pliesToQueen[winnerSide] + 3 > pliesToGo + kingptg)
+        // Check if pawn sacrifice or king capture plan _may_ save the day
+        if (pliesToQueen[winnerSide] + 3 > pliesToGo + std::min(kingptg, sacptg))
             return SCORE_ZERO;
     }
 
             return SCORE_ZERO;
     }