sl@0: // -------------------------------------
sl@0: // lowest_bit.hpp
sl@0: //
sl@0: //           Position of the lowest bit 'on'
sl@0: //
sl@0: //       (C) Copyright Gennaro Prota 2003 - 2004.
sl@0: //
sl@0: // Distributed under the Boost Software License, Version 1.0.
sl@0: //    (See accompanying file LICENSE_1_0.txt or copy at
sl@0: //          http://www.boost.org/LICENSE_1_0.txt)
sl@0: //
sl@0: // ------------------------------------------------------
sl@0: 
sl@0: #ifndef BOOST_LOWEST_BIT_HPP_GP_20030301
sl@0: #define BOOST_LOWEST_BIT_HPP_GP_20030301
sl@0: 
sl@0: #include <cassert>
sl@0: #include "boost/pending/integer_log2.hpp"
sl@0: 
sl@0: 
sl@0: namespace boost {
sl@0: 
sl@0:     template <typename T>
sl@0:     int lowest_bit(T x) {
sl@0: 
sl@0:         assert(x >= 1); // PRE
sl@0: 
sl@0:         // clear all bits on except the rightmost one,
sl@0:         // then calculate the logarithm base 2
sl@0:         //
sl@0:         return boost::integer_log2<T>( x - ( x & (x-1) ) );
sl@0: 
sl@0:     }
sl@0: 
sl@0: 
sl@0: }
sl@0: 
sl@0: 
sl@0: #endif // include guard