From a6dbc589a14a8538b594465b8f875c31d355cf51 Mon Sep 17 00:00:00 2001
From: George Oikonomou <george@contiki-ng.org>
Date: Sun, 3 Dec 2017 17:46:48 +0000
Subject: [PATCH] Add an API for memory barriers

---
 os/sys/memory-barrier.h | 67 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 os/sys/memory-barrier.h

diff --git a/os/sys/memory-barrier.h b/os/sys/memory-barrier.h
new file mode 100644
index 000000000..a89b4384b
--- /dev/null
+++ b/os/sys/memory-barrier.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2017, George Oikonomou - http://www.spd.gr
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*---------------------------------------------------------------------------*/
+/**
+ * \addtogroup sys
+ * @{
+ *
+ * \defgroup memory-barrier CPU/Compiler memory barriers
+ * @{
+ *
+ * API for CPU/Compiler memory barriers
+ */
+/*---------------------------------------------------------------------------*/
+#ifndef MEMORY_BARRIER_H_
+#define MEMORY_BARRIER_H_
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+/*---------------------------------------------------------------------------*/
+#ifdef MEMORY_BARRIER_CONF_ARCH_HEADER_PATH
+#include MEMORY_BARRIER_CONF_ARCH_HEADER_PATH
+#endif /* MEMORY_BARRIER_CONF_ARCH_HEADER_PATH */
+/*---------------------------------------------------------------------------*/
+#ifndef memory_barrier
+/**
+ * \brief Insert a memory barrier
+ *
+ * It is the platform/CPU developer's responsibility to expand this macro to
+ * a function that creates a memory barrier. Calling this macro will otherwise
+ * not generate any code.
+ */
+#define memory_barrier()
+#endif
+/*---------------------------------------------------------------------------*/
+#endif /* MEMORY_BARRIER_H_ */
+/*---------------------------------------------------------------------------*/
+/**
+ * @}
+ * @}
+ */