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// Copyright Oliver Kowalke 2014.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
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#define BOOST_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
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#include <cstddef>
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#include <memory>
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#include <utility>
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#include <boost/assert.hpp>
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#include <boost/config.hpp>
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#include <boost/context/preallocated.hpp>
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#include <boost/context/stack_context.hpp>
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#include <boost/coroutine2/detail/config.hpp>
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_PREFIX
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#endif
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namespace boost {
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namespace coroutines2 {
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namespace detail {
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template< typename ControlBlock, typename StackAllocator, typename Fn >
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ControlBlock * create_control_block( StackAllocator && salloc, Fn && fn) {
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auto sctx = salloc.allocate();
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// reserve space for control structure
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#if defined(BOOST_NO_CXX11_CONSTEXPR) || defined(BOOST_NO_CXX11_STD_ALIGN)
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void * sp = static_cast< char * >( sctx.sp) - sizeof( ControlBlock);
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const std::size_t size = sctx.size - sizeof( ControlBlock);
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#else
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constexpr std::size_t func_alignment = 64; // alignof( ControlBlock);
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constexpr std::size_t func_size = sizeof( ControlBlock);
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// reserve space on stack
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void * sp = static_cast< char * >( sctx.sp) - func_size - func_alignment;
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// align sp pointer
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std::size_t space = func_size + func_alignment;
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sp = std::align( func_alignment, func_size, sp, space);
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BOOST_ASSERT( nullptr != sp);
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// calculate remaining size
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const std::size_t size = sctx.size - ( static_cast< char * >( sctx.sp) - static_cast< char * >( sp) );
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#endif
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// placment new for control structure on coroutine stack
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return new ( sp) ControlBlock{ context::preallocated( sp, size, sctx),
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std::forward< StackAllocator >( salloc), std::forward< Fn >( fn) };
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}
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}}}
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#ifdef BOOST_HAS_ABI_HEADERS
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# include BOOST_ABI_SUFFIX
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#endif
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#endif // BOOST_COROUTINES2_DETAIL_CREATE_CONTROLBLOCK_IPP
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