Add library for critical section entry/exit

os/sys/critical.h

@@ -0,0 +1,92 @@
+/*
+ * 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 critical Critical sections
+ * @{
+ *
+ * Platform-independent functions for critical section entry and exit
+ */
+/*---------------------------------------------------------------------------*/
+#ifndef CRITICAL_H_
+#define CRITICAL_H_
+/*---------------------------------------------------------------------------*/
+#include "contiki.h"
+#include "sys/memory-barrier.h"
+#include "sys/int-master.h"
+
+#include <stdint.h>
+/*---------------------------------------------------------------------------*/
+/**
+ * \brief Enter a critical section
+ * \return The status of the master interrupt before entering the critical
+ *
+ * This function will return the status of the master interrupt as it was
+ * before entering the critical section.
+ *
+ * The semantics of the return value are entirely platform-specific. The
+ * calling code should not try to determine whether the master interrupt was
+ * previously enabled/disabled by interpreting the return value of this
+ * function. The return value should only be used as an argument to
+ * critical_exit().
+ */
+static inline int_master_status_t
+critical_enter()
+{
+  int_master_status_t status = int_master_read_and_disable();
+  memory_barrier();
+  return status;
+}
+/*---------------------------------------------------------------------------*/
+/**
+ * \brief Exit a critical section and restore the master interrupt
+ * \param status The new status of the master interrupt
+ *
+ * The semantics of \e status are platform-dependent. Normally, the argument
+ * provided to this function will be a value previously retrieved through a
+ * call to critical_enter().
+ */
+static inline void
+critical_exit(int_master_status_t status)
+{
+  memory_barrier();
+  int_master_status_set(status);
+}
+/*---------------------------------------------------------------------------*/
+#endif /* CRITICAL_H_ */
+/*---------------------------------------------------------------------------*/
+/**
+ * @}
+ * @}
+ */