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Editing: lowest_bit.hpp
// ----------------------------------------------------------- // lowest_bit.hpp // // Position of the lowest bit 'on' // // Copyright (c) 2003-2004, 2008 Gennaro Prota // // Distributed under the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) // // ----------------------------------------------------------- #ifndef BOOST_LOWEST_BIT_HPP_GP_20030301 #define BOOST_LOWEST_BIT_HPP_GP_20030301 #include "boost/integer/integer_log2.hpp" #include "boost/assert.hpp" namespace boost { namespace detail { template <typename T> int lowest_bit(T x) { BOOST_ASSERT(x >= 1); // PRE // clear all bits on except the rightmost one, // then calculate the logarithm base 2 // return boost::integer_log2<T>( x - ( x & (x-1) ) ); } } } #endif // include guard
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