boost/align/detail/align.hpp

/*
 (c) 2014 Glen Joseph Fernandes
 glenjofe at gmail dot com

 Distributed under the Boost Software
 License, Version 1.0.
 http://boost.org/LICENSE_1_0.txt
*/
#ifndef BOOST_ALIGN_DETAIL_ALIGN_HPP
#define BOOST_ALIGN_DETAIL_ALIGN_HPP

#include <boost/assert.hpp>
#include <boost/align/detail/address.hpp>
#include <boost/align/detail/is_alignment.hpp>
#include <cstddef>

namespace boost {
    namespace alignment {
        inline void* align(std::size_t alignment, std::size_t size,
            void*& ptr, std::size_t& space)
        {
            BOOST_ASSERT(detail::is_alignment(alignment));
            std::size_t n = detail::address_t(ptr) & (alignment - 1);
            if (n != 0) {
                n = alignment - n;
            }
            void* p = 0;
            if (n <= space && size <= space - n) {
                p = static_cast<char*>(ptr) + n;
                ptr = p;
                space -= n;
            }
            return p;
        }
    }
}

#endif

Boost C++ Libraries

boost/align/detail/align.hpp