Simplify futility equation

[stockfish] / src / tt.cpp

diff --git a/src/tt.cpp b/src/tt.cpp
index 33768ca4117d099e8fc0a46284a14ea803c60195..6121b3ad771b24bd40410e8e5f6bff6004fdccc7 100644 (file)
--- a/src/tt.cpp
+++ b/src/tt.cpp
@@ -43,14 +43,16 @@ void TTEntry::save(Key k, Value v, bool pv, Bound b, Depth d, Move m, Value ev)
 
   // Overwrite less valuable entries
   if (  (k >> 48) != key16
-      || d / ONE_PLY > depth8 - 4
+      ||(d - DEPTH_OFFSET) / ONE_PLY > depth8 - 4
       || b == BOUND_EXACT)
   {
+      assert((d - DEPTH_OFFSET) / ONE_PLY >= 0);
+
       key16     = (uint16_t)(k >> 48);
       value16   = (int16_t)v;
       eval16    = (int16_t)ev;
       genBound8 = (uint8_t)(TT.generation8 | uint8_t(pv) << 2 | b);
-      depth8    = (int8_t)(d / ONE_PLY);
+      depth8    = (uint8_t)((d - DEPTH_OFFSET) / ONE_PLY);
   }
 }