libalgebra-demo/libalgebra/ConstLog2.h

/* *************************************************************

Copyright 2010 Terry Lyons, Stephen Buckley, Djalil Chafai, 
Greg Gyurkó and Arend Janssen. 

Distributed under the terms of the GNU General Public License, 
Version 3. (See accompanying file License.txt)

************************************************************* */




#pragma once
#ifndef ConstLog2_h__
#define ConstLog2_h__



template <unsigned exp>
struct ConstLog2
{
        static  enum
        {
                ans = ConstLog2 < exp /2 >::ans+1
        };
};

template <>
struct ConstLog2<1>
{
        static  enum
        {
                ans = 0
        };
};

template <>
struct ConstLog2<0>
{
        static  enum
        {
                ans = 0
        };
};
template <unsigned RANGE>
struct TestConstLog2
{
        static enum
        {
                ans = ((RANGE >> ConstLog2<RANGE>::ans) == 1) && TestConstLog2< RANGE - 1 >::ans
        };
};

template <>
struct TestConstLog2<1>
{
        static enum
        {
                ans = ((1 >> ConstLog2<1>::ans) == 1) && (ConstLog2<0>::ans == 0)
        };
};


#endif // ConstLog2_h__