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mbed library sources. Supersedes mbed-src.

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cmsis/BUILD/mbed/platform/SingletonPtr.h@189:f392fc9709a3, 2019-02-20 (annotated)

Committer:
AnnaBridge
Date:
Wed Feb 20 22:31:08 2019 +0000
Revision:
189:f392fc9709a3
mbed library release version 165

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 189:f392fc9709a3 1
AnnaBridge 189:f392fc9709a3 2 /** \addtogroup platform */
AnnaBridge 189:f392fc9709a3 3 /** @{*/
AnnaBridge 189:f392fc9709a3 4 /**
AnnaBridge 189:f392fc9709a3 5 * \defgroup platform_SingletonPtr SingletonPtr class
AnnaBridge 189:f392fc9709a3 6 * @{
AnnaBridge 189:f392fc9709a3 7 */
AnnaBridge 189:f392fc9709a3 8 /* mbed Microcontroller Library
AnnaBridge 189:f392fc9709a3 9 * Copyright (c) 2006-2013 ARM Limited
AnnaBridge 189:f392fc9709a3 10 * SPDX-License-Identifier: Apache-2.0
AnnaBridge 189:f392fc9709a3 11 *
AnnaBridge 189:f392fc9709a3 12 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 189:f392fc9709a3 13 * you may not use this file except in compliance with the License.
AnnaBridge 189:f392fc9709a3 14 * You may obtain a copy of the License at
AnnaBridge 189:f392fc9709a3 15 *
AnnaBridge 189:f392fc9709a3 16 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 189:f392fc9709a3 17 *
AnnaBridge 189:f392fc9709a3 18 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 189:f392fc9709a3 19 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 189:f392fc9709a3 20 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 189:f392fc9709a3 21 * See the License for the specific language governing permissions and
AnnaBridge 189:f392fc9709a3 22 * limitations under the License.
AnnaBridge 189:f392fc9709a3 23 */
AnnaBridge 189:f392fc9709a3 24 #ifndef SINGLETONPTR_H
AnnaBridge 189:f392fc9709a3 25 #define SINGLETONPTR_H
AnnaBridge 189:f392fc9709a3 26
AnnaBridge 189:f392fc9709a3 27 #include <stdlib.h>
AnnaBridge 189:f392fc9709a3 28 #include <stdint.h>
AnnaBridge 189:f392fc9709a3 29 #include <new>
AnnaBridge 189:f392fc9709a3 30 #include "platform/mbed_assert.h"
AnnaBridge 189:f392fc9709a3 31 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 189:f392fc9709a3 32 #include "cmsis_os2.h"
AnnaBridge 189:f392fc9709a3 33 #endif
AnnaBridge 189:f392fc9709a3 34
AnnaBridge 189:f392fc9709a3 35 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 189:f392fc9709a3 36 extern osMutexId_t singleton_mutex_id;
AnnaBridge 189:f392fc9709a3 37 #endif
AnnaBridge 189:f392fc9709a3 38
AnnaBridge 189:f392fc9709a3 39 /** Lock the singleton mutex
AnnaBridge 189:f392fc9709a3 40 *
AnnaBridge 189:f392fc9709a3 41 * This function is typically used to provide
AnnaBridge 189:f392fc9709a3 42 * exclusive access when initializing a
AnnaBridge 189:f392fc9709a3 43 * global object.
AnnaBridge 189:f392fc9709a3 44 */
AnnaBridge 189:f392fc9709a3 45 inline static void singleton_lock(void)
AnnaBridge 189:f392fc9709a3 46 {
AnnaBridge 189:f392fc9709a3 47 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 189:f392fc9709a3 48 if (!singleton_mutex_id) {
AnnaBridge 189:f392fc9709a3 49 // RTOS has not booted yet so no mutex is needed
AnnaBridge 189:f392fc9709a3 50 return;
AnnaBridge 189:f392fc9709a3 51 }
AnnaBridge 189:f392fc9709a3 52 osMutexAcquire(singleton_mutex_id, osWaitForever);
AnnaBridge 189:f392fc9709a3 53 #endif
AnnaBridge 189:f392fc9709a3 54 }
AnnaBridge 189:f392fc9709a3 55
AnnaBridge 189:f392fc9709a3 56 /** Unlock the singleton mutex
AnnaBridge 189:f392fc9709a3 57 *
AnnaBridge 189:f392fc9709a3 58 * This function is typically used to provide
AnnaBridge 189:f392fc9709a3 59 * exclusive access when initializing a
AnnaBridge 189:f392fc9709a3 60 * global object.
AnnaBridge 189:f392fc9709a3 61 */
AnnaBridge 189:f392fc9709a3 62 inline static void singleton_unlock(void)
AnnaBridge 189:f392fc9709a3 63 {
AnnaBridge 189:f392fc9709a3 64 #ifdef MBED_CONF_RTOS_PRESENT
AnnaBridge 189:f392fc9709a3 65 if (!singleton_mutex_id) {
AnnaBridge 189:f392fc9709a3 66 // RTOS has not booted yet so no mutex is needed
AnnaBridge 189:f392fc9709a3 67 return;
AnnaBridge 189:f392fc9709a3 68 }
AnnaBridge 189:f392fc9709a3 69 osMutexRelease(singleton_mutex_id);
AnnaBridge 189:f392fc9709a3 70 #endif
AnnaBridge 189:f392fc9709a3 71 }
AnnaBridge 189:f392fc9709a3 72
AnnaBridge 189:f392fc9709a3 73 /** Utility class for creating an using a singleton
AnnaBridge 189:f392fc9709a3 74 *
AnnaBridge 189:f392fc9709a3 75 * @note Synchronization level: Thread safe
AnnaBridge 189:f392fc9709a3 76 *
AnnaBridge 189:f392fc9709a3 77 * @note: This class must only be used in a static context -
AnnaBridge 189:f392fc9709a3 78 * this class must never be allocated or created on the
AnnaBridge 189:f392fc9709a3 79 * stack.
AnnaBridge 189:f392fc9709a3 80 *
AnnaBridge 189:f392fc9709a3 81 * @note: This class is lazily initialized on first use.
AnnaBridge 189:f392fc9709a3 82 * This class is a POD type so if it is not used it will
AnnaBridge 189:f392fc9709a3 83 * be garbage collected.
AnnaBridge 189:f392fc9709a3 84 */
AnnaBridge 189:f392fc9709a3 85 template <class T>
AnnaBridge 189:f392fc9709a3 86 struct SingletonPtr {
AnnaBridge 189:f392fc9709a3 87
AnnaBridge 189:f392fc9709a3 88 /** Get a pointer to the underlying singleton
AnnaBridge 189:f392fc9709a3 89 *
AnnaBridge 189:f392fc9709a3 90 * @returns
AnnaBridge 189:f392fc9709a3 91 * A pointer to the singleton
AnnaBridge 189:f392fc9709a3 92 */
AnnaBridge 189:f392fc9709a3 93 T *get() const
AnnaBridge 189:f392fc9709a3 94 {
AnnaBridge 189:f392fc9709a3 95 if (NULL == _ptr) {
AnnaBridge 189:f392fc9709a3 96 singleton_lock();
AnnaBridge 189:f392fc9709a3 97 if (NULL == _ptr) {
AnnaBridge 189:f392fc9709a3 98 _ptr = new (_data) T();
AnnaBridge 189:f392fc9709a3 99 }
AnnaBridge 189:f392fc9709a3 100 singleton_unlock();
AnnaBridge 189:f392fc9709a3 101 }
AnnaBridge 189:f392fc9709a3 102 // _ptr was not zero initialized or was
AnnaBridge 189:f392fc9709a3 103 // corrupted if this assert is hit
AnnaBridge 189:f392fc9709a3 104 MBED_ASSERT(_ptr == (T *)&_data);
AnnaBridge 189:f392fc9709a3 105 return _ptr;
AnnaBridge 189:f392fc9709a3 106 }
AnnaBridge 189:f392fc9709a3 107
AnnaBridge 189:f392fc9709a3 108 /** Get a pointer to the underlying singleton
AnnaBridge 189:f392fc9709a3 109 *
AnnaBridge 189:f392fc9709a3 110 * @returns
AnnaBridge 189:f392fc9709a3 111 * A pointer to the singleton
AnnaBridge 189:f392fc9709a3 112 */
AnnaBridge 189:f392fc9709a3 113 T *operator->() const
AnnaBridge 189:f392fc9709a3 114 {
AnnaBridge 189:f392fc9709a3 115 return get();
AnnaBridge 189:f392fc9709a3 116 }
AnnaBridge 189:f392fc9709a3 117
AnnaBridge 189:f392fc9709a3 118 /** Get a reference to the underlying singleton
AnnaBridge 189:f392fc9709a3 119 *
AnnaBridge 189:f392fc9709a3 120 * @returns
AnnaBridge 189:f392fc9709a3 121 * A reference to the singleton
AnnaBridge 189:f392fc9709a3 122 */
AnnaBridge 189:f392fc9709a3 123 T &operator*() const
AnnaBridge 189:f392fc9709a3 124 {
AnnaBridge 189:f392fc9709a3 125 return *get();
AnnaBridge 189:f392fc9709a3 126 }
AnnaBridge 189:f392fc9709a3 127
AnnaBridge 189:f392fc9709a3 128 // This is zero initialized when in global scope
AnnaBridge 189:f392fc9709a3 129 mutable T *_ptr;
AnnaBridge 189:f392fc9709a3 130 #if __cplusplus >= 201103L
AnnaBridge 189:f392fc9709a3 131 // Align data appropriately
AnnaBridge 189:f392fc9709a3 132 alignas(T) mutable char _data[sizeof(T)];
AnnaBridge 189:f392fc9709a3 133 #else
AnnaBridge 189:f392fc9709a3 134 // Force data to be 8 byte aligned
AnnaBridge 189:f392fc9709a3 135 mutable uint64_t _data[(sizeof(T) + sizeof(uint64_t) - 1) / sizeof(uint64_t)];
AnnaBridge 189:f392fc9709a3 136 #endif
AnnaBridge 189:f392fc9709a3 137 };
AnnaBridge 189:f392fc9709a3 138
AnnaBridge 189:f392fc9709a3 139 #endif
AnnaBridge 189:f392fc9709a3 140 /**@}*/
AnnaBridge 189:f392fc9709a3 141
AnnaBridge 189:f392fc9709a3 142 /**@}*/