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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@169:a7c7b631e539, 2018-06-22 (annotated)

Committer:
Anna Bridge
Date:
Fri Jun 22 15:38:59 2018 +0100
Revision:
169:a7c7b631e539
Parent:
158:1c57384330a6
Child:
170:e95d10626187
mbed library. Release version 162

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 156:ff21514d8981 1
AnnaBridge 156:ff21514d8981 2 /** \addtogroup platform */
AnnaBridge 156:ff21514d8981 3 /** @{*/
AnnaBridge 158:1c57384330a6 4 /**
AnnaBridge 158:1c57384330a6 5 * \defgroup platform_SingletonPtr SingletonPtr class
AnnaBridge 158:1c57384330a6 6 * @{
AnnaBridge 158:1c57384330a6 7 */
AnnaBridge 156:ff21514d8981 8 /* mbed Microcontroller Library
AnnaBridge 156:ff21514d8981 9 * Copyright (c) 2006-2013 ARM Limited
AnnaBridge 156:ff21514d8981 10 *
AnnaBridge 156:ff21514d8981 11 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 156:ff21514d8981 12 * you may not use this file except in compliance with the License.
AnnaBridge 156:ff21514d8981 13 * You may obtain a copy of the License at
AnnaBridge 156:ff21514d8981 14 *
AnnaBridge 156:ff21514d8981 15 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 156:ff21514d8981 16 *
AnnaBridge 156:ff21514d8981 17 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 156:ff21514d8981 18 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 156:ff21514d8981 19 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 156:ff21514d8981 20 * See the License for the specific language governing permissions and
AnnaBridge 156:ff21514d8981 21 * limitations under the License.
AnnaBridge 156:ff21514d8981 22 */
AnnaBridge 156:ff21514d8981 23 #ifndef SINGLETONPTR_H
AnnaBridge 156:ff21514d8981 24 #define SINGLETONPTR_H
AnnaBridge 156:ff21514d8981 25
AnnaBridge 156:ff21514d8981 26 #include <stdint.h>
AnnaBridge 156:ff21514d8981 27 #include <new>
AnnaBridge 156:ff21514d8981 28 #include "platform/mbed_assert.h"
AnnaBridge 156:ff21514d8981 29 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 156:ff21514d8981 30 #include "cmsis_os2.h"
AnnaBridge 156:ff21514d8981 31 #endif
AnnaBridge 156:ff21514d8981 32
AnnaBridge 156:ff21514d8981 33 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 156:ff21514d8981 34 extern osMutexId_t singleton_mutex_id;
AnnaBridge 156:ff21514d8981 35 #endif
AnnaBridge 156:ff21514d8981 36
AnnaBridge 156:ff21514d8981 37 /** Lock the singleton mutex
AnnaBridge 156:ff21514d8981 38 *
AnnaBridge 156:ff21514d8981 39 * This function is typically used to provide
AnnaBridge 156:ff21514d8981 40 * exclusive access when initializing a
AnnaBridge 156:ff21514d8981 41 * global object.
AnnaBridge 156:ff21514d8981 42 */
AnnaBridge 156:ff21514d8981 43 inline static void singleton_lock(void)
AnnaBridge 156:ff21514d8981 44 {
AnnaBridge 156:ff21514d8981 45 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 156:ff21514d8981 46 osMutexAcquire(singleton_mutex_id, osWaitForever);
AnnaBridge 156:ff21514d8981 47 #endif
AnnaBridge 156:ff21514d8981 48 }
AnnaBridge 156:ff21514d8981 49
AnnaBridge 156:ff21514d8981 50 /** Unlock the singleton mutex
AnnaBridge 156:ff21514d8981 51 *
AnnaBridge 156:ff21514d8981 52 * This function is typically used to provide
AnnaBridge 156:ff21514d8981 53 * exclusive access when initializing a
AnnaBridge 156:ff21514d8981 54 * global object.
AnnaBridge 156:ff21514d8981 55 */
AnnaBridge 156:ff21514d8981 56 inline static void singleton_unlock(void)
AnnaBridge 156:ff21514d8981 57 {
AnnaBridge 156:ff21514d8981 58 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 156:ff21514d8981 59 osMutexRelease (singleton_mutex_id);
AnnaBridge 156:ff21514d8981 60 #endif
AnnaBridge 156:ff21514d8981 61 }
AnnaBridge 156:ff21514d8981 62
AnnaBridge 156:ff21514d8981 63 /** Utility class for creating an using a singleton
AnnaBridge 156:ff21514d8981 64 *
AnnaBridge 156:ff21514d8981 65 * @note Synchronization level: Thread safe
AnnaBridge 156:ff21514d8981 66 *
AnnaBridge 156:ff21514d8981 67 * @note: This class must only be used in a static context -
AnnaBridge 156:ff21514d8981 68 * this class must never be allocated or created on the
AnnaBridge 156:ff21514d8981 69 * stack.
AnnaBridge 156:ff21514d8981 70 *
AnnaBridge 156:ff21514d8981 71 * @note: This class is lazily initialized on first use.
AnnaBridge 156:ff21514d8981 72 * This class is a POD type so if it is not used it will
AnnaBridge 156:ff21514d8981 73 * be garbage collected.
AnnaBridge 156:ff21514d8981 74 */
AnnaBridge 156:ff21514d8981 75 template <class T>
AnnaBridge 156:ff21514d8981 76 struct SingletonPtr {
AnnaBridge 156:ff21514d8981 77
AnnaBridge 156:ff21514d8981 78 /** Get a pointer to the underlying singleton
AnnaBridge 156:ff21514d8981 79 *
AnnaBridge 156:ff21514d8981 80 * @returns
AnnaBridge 156:ff21514d8981 81 * A pointer to the singleton
AnnaBridge 156:ff21514d8981 82 */
AnnaBridge 156:ff21514d8981 83 T* get() {
AnnaBridge 156:ff21514d8981 84 if (NULL == _ptr) {
AnnaBridge 156:ff21514d8981 85 singleton_lock();
AnnaBridge 156:ff21514d8981 86 if (NULL == _ptr) {
AnnaBridge 156:ff21514d8981 87 _ptr = new (_data) T();
AnnaBridge 156:ff21514d8981 88 }
AnnaBridge 156:ff21514d8981 89 singleton_unlock();
AnnaBridge 156:ff21514d8981 90 }
AnnaBridge 156:ff21514d8981 91 // _ptr was not zero initialized or was
AnnaBridge 156:ff21514d8981 92 // corrupted if this assert is hit
AnnaBridge 156:ff21514d8981 93 MBED_ASSERT(_ptr == (T *)&_data);
AnnaBridge 156:ff21514d8981 94 return _ptr;
AnnaBridge 156:ff21514d8981 95 }
AnnaBridge 156:ff21514d8981 96
AnnaBridge 156:ff21514d8981 97 /** Get a pointer to the underlying singleton
AnnaBridge 156:ff21514d8981 98 *
AnnaBridge 156:ff21514d8981 99 * @returns
AnnaBridge 156:ff21514d8981 100 * A pointer to the singleton
AnnaBridge 156:ff21514d8981 101 */
AnnaBridge 156:ff21514d8981 102 T* operator->() {
AnnaBridge 156:ff21514d8981 103 return get();
AnnaBridge 156:ff21514d8981 104 }
AnnaBridge 156:ff21514d8981 105
AnnaBridge 156:ff21514d8981 106 // This is zero initialized when in global scope
AnnaBridge 156:ff21514d8981 107 T *_ptr;
AnnaBridge 156:ff21514d8981 108 // Force data to be 4 byte aligned
AnnaBridge 156:ff21514d8981 109 uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
AnnaBridge 156:ff21514d8981 110 };
AnnaBridge 156:ff21514d8981 111
AnnaBridge 156:ff21514d8981 112 #endif
AnnaBridge 158:1c57384330a6 113 /**@}*/
AnnaBridge 156:ff21514d8981 114
AnnaBridge 158:1c57384330a6 115 /**@}*/