align/detail/align.hpp

0001 /*
0002 Copyright 2014-2020 Glen Joseph Fernandes
0003 (glenjofe@gmail.com)
0004
0005 Distributed under the Boost Software License, Version 1.0.
0006 (http://www.boost.org/LICENSE_1_0.txt)
0007 */
0008 #ifndef BOOST_ALIGN_DETAIL_ALIGN_HPP
0009 #define BOOST_ALIGN_DETAIL_ALIGN_HPP
0010
0011 #include <boost/align/detail/is_alignment.hpp>
0012 #include <boost/assert.hpp>
0013
0014 namespace boost {
0015 namespace alignment {
0016
0017 inline void*
0018 align(std::size_t alignment, std::size_t size, void*& ptr,
0019     std::size_t& space)
0020 {
0021     BOOST_ASSERT(boost::alignment::detail::is_alignment(alignment));
0022     if (size <= space) {
0023         char* p = reinterpret_cast<char*>(~(alignment - 1) &
0024             (reinterpret_cast<std::size_t>(ptr) + alignment - 1));
0025         std::size_t n = p - static_cast<char*>(ptr);
0026         if (n <= space - size) {
0027             ptr = p;
0028             space -= n;
0029             return p;
0030         }
0031     }
0032     return 0;
0033 }
0034
0035 } /* alignment */
0036 } /* boost */
0037
0038 #endif