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The official Mbed 2 C/C++ SDK provides the software platform and libraries to build your applications.

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mbed 2

This is the mbed 2 library. If you'd like to learn about Mbed OS please see the mbed-os docs.

platform/SingletonPtr.h@147:a97add6d7e64, 2017-07-19 (annotated)

Committer:
Kojto
Date:
Wed Jul 19 16:46:19 2017 +0100
Revision:
147:a97add6d7e64
Parent:
145:64910690c574 
Release 147 of the mbed library.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 128:9bcdf88f62b0 1
<> 128:9bcdf88f62b0 2 /** \addtogroup platform */
<> 128:9bcdf88f62b0 3 /** @{*/
<> 128:9bcdf88f62b0 4 /* mbed Microcontroller Library
<> 128:9bcdf88f62b0 5 * Copyright (c) 2006-2013 ARM Limited
<> 128:9bcdf88f62b0 6 *
<> 128:9bcdf88f62b0 7 * Licensed under the Apache License, Version 2.0 (the "License");
<> 128:9bcdf88f62b0 8 * you may not use this file except in compliance with the License.
<> 128:9bcdf88f62b0 9 * You may obtain a copy of the License at
<> 128:9bcdf88f62b0 10 *
<> 128:9bcdf88f62b0 11 * http://www.apache.org/licenses/LICENSE-2.0
<> 128:9bcdf88f62b0 12 *
<> 128:9bcdf88f62b0 13 * Unless required by applicable law or agreed to in writing, software
<> 128:9bcdf88f62b0 14 * distributed under the License is distributed on an "AS IS" BASIS,
<> 128:9bcdf88f62b0 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 128:9bcdf88f62b0 16 * See the License for the specific language governing permissions and
<> 128:9bcdf88f62b0 17 * limitations under the License.
<> 128:9bcdf88f62b0 18 */
<> 128:9bcdf88f62b0 19 #ifndef SINGLETONPTR_H
<> 128:9bcdf88f62b0 20 #define SINGLETONPTR_H
<> 128:9bcdf88f62b0 21
<> 128:9bcdf88f62b0 22 #include <stdint.h>
<> 128:9bcdf88f62b0 23 #include <new>
<> 128:9bcdf88f62b0 24 #include "platform/mbed_assert.h"
<> 128:9bcdf88f62b0 25 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 145:64910690c574 26 #include "cmsis_os2.h"
<> 128:9bcdf88f62b0 27 #endif
<> 128:9bcdf88f62b0 28
<> 128:9bcdf88f62b0 29 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 145:64910690c574 30 extern osMutexId_t singleton_mutex_id;
<> 128:9bcdf88f62b0 31 #endif
<> 128:9bcdf88f62b0 32
<> 128:9bcdf88f62b0 33 /** Lock the singleton mutex
<> 128:9bcdf88f62b0 34 *
<> 128:9bcdf88f62b0 35 * This function is typically used to provide
<> 128:9bcdf88f62b0 36 * exclusive access when initializing a
<> 128:9bcdf88f62b0 37 * global object.
<> 128:9bcdf88f62b0 38 */
<> 128:9bcdf88f62b0 39 inline static void singleton_lock(void)
<> 128:9bcdf88f62b0 40 {
<> 128:9bcdf88f62b0 41 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 145:64910690c574 42 osMutexAcquire(singleton_mutex_id, osWaitForever);
<> 128:9bcdf88f62b0 43 #endif
<> 128:9bcdf88f62b0 44 }
<> 128:9bcdf88f62b0 45
<> 128:9bcdf88f62b0 46 /** Unlock the singleton mutex
<> 128:9bcdf88f62b0 47 *
<> 128:9bcdf88f62b0 48 * This function is typically used to provide
<> 128:9bcdf88f62b0 49 * exclusive access when initializing a
<> 128:9bcdf88f62b0 50 * global object.
<> 128:9bcdf88f62b0 51 */
<> 128:9bcdf88f62b0 52 inline static void singleton_unlock(void)
<> 128:9bcdf88f62b0 53 {
<> 128:9bcdf88f62b0 54 #ifdef MBED_CONF_RTOS_PRESENT
<> 128:9bcdf88f62b0 55 osMutexRelease (singleton_mutex_id);
<> 128:9bcdf88f62b0 56 #endif
<> 128:9bcdf88f62b0 57 }
AnnaBridge 145:64910690c574 58 /** @}*/
<> 128:9bcdf88f62b0 59
<> 128:9bcdf88f62b0 60 /** Utility class for creating an using a singleton
<> 128:9bcdf88f62b0 61 *
AnnaBridge 145:64910690c574 62 * @note Synchronization level: Thread safe
<> 128:9bcdf88f62b0 63 *
AnnaBridge 145:64910690c574 64 * @note: This class must only be used in a static context -
<> 128:9bcdf88f62b0 65 * this class must never be allocated or created on the
<> 128:9bcdf88f62b0 66 * stack.
<> 128:9bcdf88f62b0 67 *
AnnaBridge 145:64910690c574 68 * @note: This class is lazily initialized on first use.
<> 128:9bcdf88f62b0 69 * This class is a POD type so if it is not used it will
<> 128:9bcdf88f62b0 70 * be garbage collected.
AnnaBridge 145:64910690c574 71 * @ingroup platform
<> 128:9bcdf88f62b0 72 */
<> 128:9bcdf88f62b0 73 template <class T>
<> 128:9bcdf88f62b0 74 struct SingletonPtr {
<> 128:9bcdf88f62b0 75
<> 128:9bcdf88f62b0 76 /** Get a pointer to the underlying singleton
<> 128:9bcdf88f62b0 77 *
<> 128:9bcdf88f62b0 78 * @returns
<> 128:9bcdf88f62b0 79 * A pointer to the singleton
<> 128:9bcdf88f62b0 80 */
<> 128:9bcdf88f62b0 81 T* get() {
<> 128:9bcdf88f62b0 82 if (NULL == _ptr) {
<> 128:9bcdf88f62b0 83 singleton_lock();
<> 128:9bcdf88f62b0 84 if (NULL == _ptr) {
<> 128:9bcdf88f62b0 85 _ptr = new (_data) T();
<> 128:9bcdf88f62b0 86 }
<> 128:9bcdf88f62b0 87 singleton_unlock();
<> 128:9bcdf88f62b0 88 }
<> 128:9bcdf88f62b0 89 // _ptr was not zero initialized or was
<> 128:9bcdf88f62b0 90 // corrupted if this assert is hit
<> 128:9bcdf88f62b0 91 MBED_ASSERT(_ptr == (T *)&_data);
<> 128:9bcdf88f62b0 92 return _ptr;
<> 128:9bcdf88f62b0 93 }
<> 128:9bcdf88f62b0 94
<> 128:9bcdf88f62b0 95 /** Get a pointer to the underlying singleton
<> 128:9bcdf88f62b0 96 *
<> 128:9bcdf88f62b0 97 * @returns
<> 128:9bcdf88f62b0 98 * A pointer to the singleton
<> 128:9bcdf88f62b0 99 */
<> 128:9bcdf88f62b0 100 T* operator->() {
<> 128:9bcdf88f62b0 101 return get();
<> 128:9bcdf88f62b0 102 }
<> 128:9bcdf88f62b0 103
<> 128:9bcdf88f62b0 104 // This is zero initialized when in global scope
<> 128:9bcdf88f62b0 105 T *_ptr;
<> 128:9bcdf88f62b0 106 // Force data to be 4 byte aligned
<> 128:9bcdf88f62b0 107 uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
<> 128:9bcdf88f62b0 108 };
<> 128:9bcdf88f62b0 109
<> 128:9bcdf88f62b0 110 #endif
<> 128:9bcdf88f62b0 111