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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
/** @}*/
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