1 // -----------------------------------------------------------
4 // Position of the lowest bit 'on'
6 // Copyright (c) 2003-2004, 2008 Gennaro Prota
8 // Distributed under the Boost Software License, Version 1.0.
9 // (See accompanying file LICENSE_1_0.txt or copy at
10 // http://www.boost.org/LICENSE_1_0.txt)
12 // -----------------------------------------------------------
14 #ifndef BOOST_LOWEST_BIT_HPP_GP_20030301
15 #define BOOST_LOWEST_BIT_HPP_GP_20030301
17 #include "boost/integer/integer_log2.hpp"
18 #include "boost/assert.hpp"
26 BOOST_ASSERT(x >= 1); // PRE
28 // clear all bits on except the rightmost one,
29 // then calculate the logarithm base 2
31 return boost::integer_log2<T>( x - ( x & (x-1) ) );
39 #endif // include guard