Fix GrainSize rounding error

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 25ee79ead4df1ca94f1ddbe95d62a36b49496c84..147a1b3e90b5eb788fcbcdbb359f08792b91c293 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1083,7 +1083,7 @@ Value do_evaluate(const Position& pos, Value& margin) {
 
     int ev = (eg_value(v) * int(sf)) / SCALE_FACTOR_NORMAL;
     int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
-    return Value((result + GrainSize / 2) & ~(GrainSize - 1));
+    return Value((result / GrainSize) * GrainSize); // Sign independent
   }
 
   // apply_weight() weights score v by score w trying to prevent overflow