Added original SDK code for Alien Swarm.

public/bittools.h

@@ -0,0 +1,46 @@
+//===== Copyright <20> 1996-2009, Valve Corporation, All rights reserved. ======//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//===========================================================================//
+
+#ifndef BITTOOLS_H
+#define BITTOOLS_H
+#ifdef _WIN32
+#pragma once
+#endif
+
+namespace bittools
+{
+	template<int N, int C = 0>
+	struct RecurseBit
+	{
+		enum {result = RecurseBit<N/2, C+1>::result};
+	};
+	
+	template<int C>
+	struct RecurseBit<0, C>
+	{
+		enum {result = C};
+	};
+	
+	template<int N, int C = 1>
+	struct RecursePow2
+	{
+		enum {result = RecursePow2<N/2, C*2>::result};
+	};
+
+	template<int C>
+	struct RecursePow2<0, C>
+	{
+		enum {result = C};
+	};
+	
+}
+
+#define ROUND_TO_POWER_OF_2( n ) ( bittools::RecursePow2< (n) - 1 >::result )
+#define MINIMUM_BITS_NEEDED( n ) ( bittools::RecurseBit< (n) - 1 >::result )
+
+#endif //BITTOOLS_H
+