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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),
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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