mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

Dependents:   Nucleo_Hello_Encoder BLE_iBeaconScan AM1805_DEMO DISCO-F429ZI_ExportTemplate1 ... more

platform/SingletonPtr.h@187:0387e8f68319, 2018-09-06 (annotated)

Committer:
AnnaBridge
Date:
Thu Sep 06 13:40:20 2018 +0100
Revision:
187:0387e8f68319
Parent:
178:79309dc6340a
Child:
188:bcfe06ba3d64
mbed-dev library. Release version 163

Who changed what in which revision?

UserRevisionLine numberNew contents of line
<> 149:156823d33999 1
<> 149:156823d33999 2 /** \addtogroup platform */
<> 149:156823d33999 3 /** @{*/
AnnaBridge 178:79309dc6340a 4 /**
AnnaBridge 178:79309dc6340a 5 * \defgroup platform_SingletonPtr SingletonPtr class
AnnaBridge 178:79309dc6340a 6 * @{
AnnaBridge 178:79309dc6340a 7 */
<> 149:156823d33999 8 /* mbed Microcontroller Library
<> 149:156823d33999 9 * Copyright (c) 2006-2013 ARM Limited
<> 149:156823d33999 10 *
<> 149:156823d33999 11 * Licensed under the Apache License, Version 2.0 (the "License");
<> 149:156823d33999 12 * you may not use this file except in compliance with the License.
<> 149:156823d33999 13 * You may obtain a copy of the License at
<> 149:156823d33999 14 *
<> 149:156823d33999 15 * http://www.apache.org/licenses/LICENSE-2.0
<> 149:156823d33999 16 *
<> 149:156823d33999 17 * Unless required by applicable law or agreed to in writing, software
<> 149:156823d33999 18 * distributed under the License is distributed on an "AS IS" BASIS,
<> 149:156823d33999 19 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 149:156823d33999 20 * See the License for the specific language governing permissions and
<> 149:156823d33999 21 * limitations under the License.
<> 149:156823d33999 22 */
<> 149:156823d33999 23 #ifndef SINGLETONPTR_H
<> 149:156823d33999 24 #define SINGLETONPTR_H
<> 149:156823d33999 25
<> 149:156823d33999 26 #include <stdint.h>
<> 149:156823d33999 27 #include <new>
<> 149:156823d33999 28 #include "platform/mbed_assert.h"
<> 149:156823d33999 29 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 167:e84263d55307 30 #include "cmsis_os2.h"
<> 149:156823d33999 31 #endif
<> 149:156823d33999 32
<> 149:156823d33999 33 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 167:e84263d55307 34 extern osMutexId_t singleton_mutex_id;
<> 149:156823d33999 35 #endif
<> 149:156823d33999 36
<> 149:156823d33999 37 /** Lock the singleton mutex
<> 149:156823d33999 38 *
<> 149:156823d33999 39 * This function is typically used to provide
<> 149:156823d33999 40 * exclusive access when initializing a
<> 149:156823d33999 41 * global object.
<> 149:156823d33999 42 */
<> 149:156823d33999 43 inline static void singleton_lock(void)
<> 149:156823d33999 44 {
<> 149:156823d33999 45 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 167:e84263d55307 46 osMutexAcquire(singleton_mutex_id, osWaitForever);
<> 149:156823d33999 47 #endif
<> 149:156823d33999 48 }
<> 149:156823d33999 49
<> 149:156823d33999 50 /** Unlock the singleton mutex
<> 149:156823d33999 51 *
<> 149:156823d33999 52 * This function is typically used to provide
<> 149:156823d33999 53 * exclusive access when initializing a
<> 149:156823d33999 54 * global object.
<> 149:156823d33999 55 */
<> 149:156823d33999 56 inline static void singleton_unlock(void)
<> 149:156823d33999 57 {
<> 149:156823d33999 58 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 187:0387e8f68319 59 osMutexRelease(singleton_mutex_id);
<> 149:156823d33999 60 #endif
<> 149:156823d33999 61 }
<> 149:156823d33999 62
<> 149:156823d33999 63 /** Utility class for creating an using a singleton
<> 149:156823d33999 64 *
AnnaBridge 167:e84263d55307 65 * @note Synchronization level: Thread safe
<> 149:156823d33999 66 *
AnnaBridge 167:e84263d55307 67 * @note: This class must only be used in a static context -
<> 149:156823d33999 68 * this class must never be allocated or created on the
<> 149:156823d33999 69 * stack.
<> 149:156823d33999 70 *
AnnaBridge 167:e84263d55307 71 * @note: This class is lazily initialized on first use.
<> 149:156823d33999 72 * This class is a POD type so if it is not used it will
<> 149:156823d33999 73 * be garbage collected.
<> 149:156823d33999 74 */
<> 149:156823d33999 75 template <class T>
<> 149:156823d33999 76 struct SingletonPtr {
<> 149:156823d33999 77
<> 149:156823d33999 78 /** Get a pointer to the underlying singleton
<> 149:156823d33999 79 *
<> 149:156823d33999 80 * @returns
<> 149:156823d33999 81 * A pointer to the singleton
<> 149:156823d33999 82 */
AnnaBridge 187:0387e8f68319 83 T *get()
AnnaBridge 187:0387e8f68319 84 {
<> 149:156823d33999 85 if (NULL == _ptr) {
<> 149:156823d33999 86 singleton_lock();
<> 149:156823d33999 87 if (NULL == _ptr) {
<> 149:156823d33999 88 _ptr = new (_data) T();
<> 149:156823d33999 89 }
<> 149:156823d33999 90 singleton_unlock();
<> 149:156823d33999 91 }
<> 149:156823d33999 92 // _ptr was not zero initialized or was
<> 149:156823d33999 93 // corrupted if this assert is hit
<> 149:156823d33999 94 MBED_ASSERT(_ptr == (T *)&_data);
<> 149:156823d33999 95 return _ptr;
<> 149:156823d33999 96 }
<> 149:156823d33999 97
<> 149:156823d33999 98 /** Get a pointer to the underlying singleton
<> 149:156823d33999 99 *
<> 149:156823d33999 100 * @returns
<> 149:156823d33999 101 * A pointer to the singleton
<> 149:156823d33999 102 */
AnnaBridge 187:0387e8f68319 103 T *operator->()
AnnaBridge 187:0387e8f68319 104 {
<> 149:156823d33999 105 return get();
<> 149:156823d33999 106 }
<> 149:156823d33999 107
<> 149:156823d33999 108 // This is zero initialized when in global scope
<> 149:156823d33999 109 T *_ptr;
<> 149:156823d33999 110 // Force data to be 4 byte aligned
<> 149:156823d33999 111 uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
<> 149:156823d33999 112 };
<> 149:156823d33999 113
<> 149:156823d33999 114 #endif
AnnaBridge 178:79309dc6340a 115 /**@}*/
<> 149:156823d33999 116
AnnaBridge 178:79309dc6340a 117 /**@}*/