整理

include/boost/atomic/detail/cas_based_exchange.hpp

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+/*
+ * 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)
+ *
+ * Copyright (c) 2014-2025 Andrey Semashev
+ */
+/*!
+ * \file   atomic/detail/cas_based_exchange.hpp
+ *
+ * This header contains CAS-based implementation of exchange operation.
+ */
+
+#ifndef BOOST_ATOMIC_DETAIL_CAS_BASED_EXCHANGE_HPP_INCLUDED_
+#define BOOST_ATOMIC_DETAIL_CAS_BASED_EXCHANGE_HPP_INCLUDED_
+
+#include <boost/memory_order.hpp>
+#include <boost/atomic/detail/config.hpp>
+#include <boost/atomic/detail/header.hpp>
+
+#ifdef BOOST_HAS_PRAGMA_ONCE
+#pragma once
+#endif
+
+namespace boost {
+namespace atomics {
+namespace detail {
+
+template< typename Base >
+struct cas_based_exchange :
+    public Base
+{
+    using storage_type = typename Base::storage_type;
+
+    static BOOST_FORCEINLINE storage_type exchange(storage_type volatile& storage, storage_type v, memory_order order) noexcept
+    {
+        storage_type old_val;
+        atomics::detail::non_atomic_load(storage, old_val);
+        while (!Base::compare_exchange_weak(storage, old_val, v, order, memory_order_relaxed)) {}
+        return old_val;
+    }
+};
+
+} // namespace detail
+} // namespace atomics
+} // namespace boost
+
+#include <boost/atomic/detail/footer.hpp>
+
+#endif // BOOST_ATOMIC_DETAIL_CAS_BASED_EXCHANGE_HPP_INCLUDED_