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+
+/** \addtogroup platform */
+/** @{*/
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * 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 SINGLETONPTR_H
+#define SINGLETONPTR_H
+
+#include <stdint.h>
+#include <new>
+#include "platform/mbed_assert.h"
+#ifdef MBED_CONF_RTOS_PRESENT
+#include "cmsis_os.h"
+#endif
+
+#ifdef MBED_CONF_RTOS_PRESENT
+extern osMutexId singleton_mutex_id;
+#endif
+
+/** Lock the singleton mutex
+ *
+ * This function is typically used to provide
+ * exclusive access when initializing a
+ * global object.
+ */
+inline static void singleton_lock(void)
+{
+#ifdef MBED_CONF_RTOS_PRESENT
+ osMutexWait(singleton_mutex_id, osWaitForever);
+#endif
+}
+
+/** Unlock the singleton mutex
+ *
+ * This function is typically used to provide
+ * exclusive access when initializing a
+ * global object.
+ */
+inline static void singleton_unlock(void)
+{
+#ifdef MBED_CONF_RTOS_PRESENT
+ osMutexRelease (singleton_mutex_id);
+#endif
+}
+
+/** Utility class for creating an using a singleton
+ *
+ * @Note Synchronization level: Thread safe
+ *
+ * @Note: This class must only be used in a static context -
+ * this class must never be allocated or created on the
+ * stack.
+ *
+ * @Note: This class is lazily initialized on first use.
+ * This class is a POD type so if it is not used it will
+ * be garbage collected.
+ */
+template <class T>
+struct SingletonPtr {
+
+ /** Get a pointer to the underlying singleton
+ *
+ * @returns
+ * A pointer to the singleton
+ */
+ T* get() {
+ if (NULL == _ptr) {
+ singleton_lock();
+ if (NULL == _ptr) {
+ _ptr = new (_data) T();
+ }
+ singleton_unlock();
+ }
+ // _ptr was not zero initialized or was
+ // corrupted if this assert is hit
+ MBED_ASSERT(_ptr == (T *)&_data);
+ return _ptr;
+ }
+
+ /** Get a pointer to the underlying singleton
+ *
+ * @returns
+ * A pointer to the singleton
+ */
+ T* operator->() {
+ return get();
+ }
+
+ // This is zero initialized when in global scope
+ T *_ptr;
+ // Force data to be 4 byte aligned
+ uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
+};
+
+#endif
+
+/** @}*/