X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fsearch.cpp;h=0ee25bca1b421a159e60071e2d0d482fb3903b91;hb=77341f67f30456dc456177062309ad5e73e2e1a4;hp=d59fc521eedcba2815ae3cdeaf92f4bdb6e80730;hpb=53ab32ef0b6e47d8d962f8c1fccd32d3c22f138c;p=stockfish

diff --git a/src/search.cpp b/src/search.cpp
index d59fc521..0ee25bca 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -628,12 +628,12 @@ namespace {
     {
         ss->currentMove = MOVE_NULL;
 
-        // Null move dynamic reduction based on depth
-        Depth R = 3 * ONE_PLY + depth / 4;
+        assert(eval - beta >= 0);
 
-        // Null move dynamic reduction based on value
-        if (eval - PawnValueMg > beta)
-            R += ONE_PLY;
+        // Null move dynamic reduction based on depth and value
+        Depth R =  3 * ONE_PLY
+                 + depth / 4
+                 + int(eval - beta) / PawnValueMg * ONE_PLY;
 
         pos.do_null_move(st);
         (ss+1)->skipNullMove = true;
@@ -653,7 +653,8 @@ namespace {
 
             // Do verification search at high depths
             ss->skipNullMove = true;
-            Value v = search<NonPV>(pos, ss, alpha, beta, depth-R, false);
+            Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO)
+                                        :  search<NonPV>(pos, ss, alpha, beta, depth-R, false);
             ss->skipNullMove = false;
 
             if (v >= beta)