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- // Copyright Oliver Kowalke 2014.
- // 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_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
- #define BOOST_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
- #include <cstddef>
- #include <memory>
- #include <utility>
- #include <boost/assert.hpp>
- #include <boost/config.hpp>
- #include <boost/context/preallocated.hpp>
- #include <boost/context/stack_context.hpp>
- #include <boost/coroutine2/detail/config.hpp>
- #ifdef BOOST_HAS_ABI_HEADERS
- # include BOOST_ABI_PREFIX
- #endif
- namespace boost {
- namespace coroutines2 {
- namespace detail {
- template< typename ControlBlock, typename StackAllocator, typename Fn >
- ControlBlock * create_control_block( StackAllocator && salloc, Fn && fn) {
- auto sctx = salloc.allocate();
- // reserve space for control structure
- #if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN)
- void * sp = static_cast< char * >( sctx.sp) - sizeof( ControlBlock);
- const std::size_t size = sctx.size - sizeof( ControlBlock);
- #else
- constexpr std::size_t func_alignment = 64; // alignof( ControlBlock);
- constexpr std::size_t func_size = sizeof( ControlBlock);
- // reserve space on stack
- void * sp = static_cast< char * >( sctx.sp) - func_size - func_alignment;
- // align sp pointer
- std::size_t space = func_size + func_alignment;
- sp = std::align( func_alignment, func_size, sp, space);
- BOOST_ASSERT( nullptr != sp);
- // calculate remaining size
- const std::size_t size = sctx.size - ( static_cast< char * >( sctx.sp) - static_cast< char * >( sp) );
- #endif
- // placment new for control structure on coroutine stack
- return new ( sp) ControlBlock{ context::preallocated( sp, size, sctx),
- std::forward< StackAllocator >( salloc), std::forward< Fn >( fn) };
- }
- }}}
- #ifdef BOOST_HAS_ABI_HEADERS
- # include BOOST_ABI_SUFFIX
- #endif
- #endif // BOOST_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
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