diff --git a/libs/util/include/psemek/util/bits.hpp b/libs/util/include/psemek/util/bits.hpp
index 9f17bf9d..38d7343b 100644
--- a/libs/util/include/psemek/util/bits.hpp
+++ b/libs/util/include/psemek/util/bits.hpp
@@ -5,6 +5,20 @@
 namespace psemek::util
 {
 
+	// log2 rounded down
+
+	template <typename T>
+	T log2(T x)
+	{
+		T result = 0;
+		while (x > 1)
+		{
+			++result;
+			x /= 2;
+		}
+		return result;
+	}
+
 	// round up to power of 2
 	template <typename T>
 	T round_pow2(T x)