Move stdatomic helper to rcutils (#126)

* initial migration of stdatomic_helper.h to rcutils from rcl

Signed-off-by: William Woodall <william@osrfoundation.org>

* refactor namespaces after moving files

Signed-off-by: William Woodall <william@osrfoundation.org>

* address line length linter warning

Signed-off-by: William Woodall <william@osrfoundation.org>

include/rcutils/stdatomic_helper.h

@@ -0,0 +1,130 @@
+// Copyright 2015 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCUTILS__STDATOMIC_HELPER_H_
+#define RCUTILS__STDATOMIC_HELPER_H_
+
+#if !defined(_WIN32)
+
+#if defined(__GNUC__) && __GNUC__ <= 4 && __GNUC_MINOR__ <= 9
+// If GCC and below GCC-4.9, use the compatability header.
+#include "stdatomic_helper/gcc/stdatomic.h"
+#elif defined(__clang__) && defined(__has_feature)
+#if !__has_feature(c_atomic)
+// If Clang and no c_atomics (true for some older versions), use the compatability header.
+#include "stdatomic_helper/gcc/stdatomic.h"
+#endif
+#else
+#include <stdatomic.h>
+#endif
+
+#define rcutils_atomic_load(object, out) (out) = atomic_load(object)
+
+#define rcutils_atomic_compare_exchange_strong(object, out, expected, desired) \
+  (out) = atomic_compare_exchange_strong(object, expected, desired)
+
+#define rcutils_atomic_exchange(object, out, desired) (out) = atomic_exchange(object, desired)
+
+#define rcutils_atomic_store(object, desired) atomic_store(object, desired)
+
+#else  // !defined(_WIN32)
+
+#include "./stdatomic_helper/win32/stdatomic.h"
+
+#define rcutils_atomic_load(object, out) rcutils_win32_atomic_load(object, out)
+
+#define rcutils_atomic_compare_exchange_strong(object, out, expected, desired) \
+  rcutils_win32_atomic_compare_exchange_strong(object, out, expected, desired)
+
+#define rcutils_atomic_exchange(object, out, desired) \
+  rcutils_win32_atomic_exchange(object, out, desired)
+
+#define rcutils_atomic_store(object, desired) rcutils_win32_atomic_store(object, desired)
+
+#endif  // !defined(_WIN32)
+
+static inline bool
+rcutils_atomic_load_bool(atomic_bool * a_bool)
+{
+  bool result = false;
+  rcutils_atomic_load(a_bool, result);
+  return result;
+}
+
+static inline int64_t
+rcutils_atomic_load_int64_t(atomic_int_least64_t * a_int64_t)
+{
+  int64_t result = 0;
+  rcutils_atomic_load(a_int64_t, result);
+  return result;
+}
+
+static inline uint64_t
+rcutils_atomic_load_uint64_t(atomic_uint_least64_t * a_uint64_t)
+{
+  uint64_t result = 0;
+  rcutils_atomic_load(a_uint64_t, result);
+  return result;
+}
+
+static inline uintptr_t
+rcutils_atomic_load_uintptr_t(atomic_uintptr_t * a_uintptr_t)
+{
+  uintptr_t result = 0;
+  rcutils_atomic_load(a_uintptr_t, result);
+  return result;
+}
+
+static inline bool
+rcutils_atomic_compare_exchange_strong_uint_least64_t(
+  atomic_uint_least64_t * a_uint_least64_t, uint64_t * expected, uint64_t desired)
+{
+  bool result;
+  rcutils_atomic_compare_exchange_strong(a_uint_least64_t, result, expected, desired);
+  return result;
+}
+
+static inline bool
+rcutils_atomic_exchange_bool(atomic_bool * a_bool, bool desired)
+{
+  bool result;
+  rcutils_atomic_exchange(a_bool, result, desired);
+  return result;
+}
+
+static inline int64_t
+rcutils_atomic_exchange_int64_t(atomic_int_least64_t * a_int64_t, int64_t desired)
+{
+  int64_t result;
+  rcutils_atomic_exchange(a_int64_t, result, desired);
+  return result;
+}
+
+static inline uint64_t
+rcutils_atomic_exchange_uint64_t(atomic_uint_least64_t * a_uint64_t, uint64_t desired)
+{
+  uint64_t result;
+  rcutils_atomic_exchange(a_uint64_t, result, desired);
+  return result;
+}
+
+static inline uintptr_t
+rcutils_atomic_exchange_uintptr_t(atomic_uintptr_t * a_uintptr_t, uintptr_t desired)
+{
+  uintptr_t result;
+  rcutils_atomic_exchange(a_uintptr_t, result, desired);
+  return result;
+}
+
+#endif  // RCUTILS__STDATOMIC_HELPER_H_