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mbed library sources. Supersedes mbed-src.

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api/SingletonPtr.h@148:4802eb17e82b, 2016-10-17 (annotated)

Committer:
rodriguise
Date:
Mon Oct 17 18:47:01 2016 +0000
Revision:
148:4802eb17e82b
Parent:
144:ef7eb2e8f9f7 
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<> 144:ef7eb2e8f9f7 1 /* mbed Microcontroller Library
<> 144:ef7eb2e8f9f7 2 * Copyright (c) 2006-2013 ARM Limited
<> 144:ef7eb2e8f9f7 3 *
<> 144:ef7eb2e8f9f7 4 * Licensed under the Apache License, Version 2.0 (the "License");
<> 144:ef7eb2e8f9f7 5 * you may not use this file except in compliance with the License.
<> 144:ef7eb2e8f9f7 6 * You may obtain a copy of the License at
<> 144:ef7eb2e8f9f7 7 *
<> 144:ef7eb2e8f9f7 8 * http://www.apache.org/licenses/LICENSE-2.0
<> 144:ef7eb2e8f9f7 9 *
<> 144:ef7eb2e8f9f7 10 * Unless required by applicable law or agreed to in writing, software
<> 144:ef7eb2e8f9f7 11 * distributed under the License is distributed on an "AS IS" BASIS,
<> 144:ef7eb2e8f9f7 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
<> 144:ef7eb2e8f9f7 13 * See the License for the specific language governing permissions and
<> 144:ef7eb2e8f9f7 14 * limitations under the License.
<> 144:ef7eb2e8f9f7 15 */
<> 144:ef7eb2e8f9f7 16 #ifndef SINGLETONPTR_H
<> 144:ef7eb2e8f9f7 17 #define SINGLETONPTR_H
<> 144:ef7eb2e8f9f7 18
<> 144:ef7eb2e8f9f7 19 #include <stdint.h>
<> 144:ef7eb2e8f9f7 20 #include <new>
<> 144:ef7eb2e8f9f7 21 #include "mbed_assert.h"
<> 144:ef7eb2e8f9f7 22 #ifdef MBED_CONF_RTOS_PRESENT
<> 144:ef7eb2e8f9f7 23 #include "cmsis_os.h"
<> 144:ef7eb2e8f9f7 24 #endif
<> 144:ef7eb2e8f9f7 25
<> 144:ef7eb2e8f9f7 26 #ifdef MBED_CONF_RTOS_PRESENT
<> 144:ef7eb2e8f9f7 27 extern osMutexId singleton_mutex_id;
<> 144:ef7eb2e8f9f7 28 #endif
<> 144:ef7eb2e8f9f7 29
<> 144:ef7eb2e8f9f7 30 /** Lock the singleton mutex
<> 144:ef7eb2e8f9f7 31 *
<> 144:ef7eb2e8f9f7 32 * This function is typically used to provide
<> 144:ef7eb2e8f9f7 33 * exclusive access when initializing a
<> 144:ef7eb2e8f9f7 34 * global object.
<> 144:ef7eb2e8f9f7 35 */
<> 144:ef7eb2e8f9f7 36 inline static void singleton_lock(void)
<> 144:ef7eb2e8f9f7 37 {
<> 144:ef7eb2e8f9f7 38 #ifdef MBED_CONF_RTOS_PRESENT
<> 144:ef7eb2e8f9f7 39 osMutexWait(singleton_mutex_id, osWaitForever);
<> 144:ef7eb2e8f9f7 40 #endif
<> 144:ef7eb2e8f9f7 41 }
<> 144:ef7eb2e8f9f7 42
<> 144:ef7eb2e8f9f7 43 /** Unlock the singleton mutex
<> 144:ef7eb2e8f9f7 44 *
<> 144:ef7eb2e8f9f7 45 * This function is typically used to provide
<> 144:ef7eb2e8f9f7 46 * exclusive access when initializing a
<> 144:ef7eb2e8f9f7 47 * global object.
<> 144:ef7eb2e8f9f7 48 */
<> 144:ef7eb2e8f9f7 49 inline static void singleton_unlock(void)
<> 144:ef7eb2e8f9f7 50 {
<> 144:ef7eb2e8f9f7 51 #ifdef MBED_CONF_RTOS_PRESENT
<> 144:ef7eb2e8f9f7 52 osMutexRelease (singleton_mutex_id);
<> 144:ef7eb2e8f9f7 53 #endif
<> 144:ef7eb2e8f9f7 54 }
<> 144:ef7eb2e8f9f7 55
<> 144:ef7eb2e8f9f7 56 /** Utility class for creating an using a singleton
<> 144:ef7eb2e8f9f7 57 *
<> 144:ef7eb2e8f9f7 58 * @Note Synchronization level: Thread safe
<> 144:ef7eb2e8f9f7 59 *
<> 144:ef7eb2e8f9f7 60 * @Note: This class must only be used in a static context -
<> 144:ef7eb2e8f9f7 61 * this class must never be allocated or created on the
<> 144:ef7eb2e8f9f7 62 * stack.
<> 144:ef7eb2e8f9f7 63 *
<> 144:ef7eb2e8f9f7 64 * @Note: This class is lazily initialized on first use.
<> 144:ef7eb2e8f9f7 65 * This class is a POD type so if it is not used it will
<> 144:ef7eb2e8f9f7 66 * be garbage collected.
<> 144:ef7eb2e8f9f7 67 */
<> 144:ef7eb2e8f9f7 68 template <class T>
<> 144:ef7eb2e8f9f7 69 struct SingletonPtr {
<> 144:ef7eb2e8f9f7 70
<> 144:ef7eb2e8f9f7 71 /** Get a pointer to the underlying singleton
<> 144:ef7eb2e8f9f7 72 *
<> 144:ef7eb2e8f9f7 73 * @returns
<> 144:ef7eb2e8f9f7 74 * A pointer to the singleton
<> 144:ef7eb2e8f9f7 75 */
<> 144:ef7eb2e8f9f7 76 T* get() {
<> 144:ef7eb2e8f9f7 77 if (NULL == _ptr) {
<> 144:ef7eb2e8f9f7 78 singleton_lock();
<> 144:ef7eb2e8f9f7 79 if (NULL == _ptr) {
<> 144:ef7eb2e8f9f7 80 _ptr = new (_data) T();
<> 144:ef7eb2e8f9f7 81 }
<> 144:ef7eb2e8f9f7 82 singleton_unlock();
<> 144:ef7eb2e8f9f7 83 }
<> 144:ef7eb2e8f9f7 84 // _ptr was not zero initialized or was
<> 144:ef7eb2e8f9f7 85 // corrupted if this assert is hit
<> 144:ef7eb2e8f9f7 86 MBED_ASSERT(_ptr == (T *)&_data);
<> 144:ef7eb2e8f9f7 87 return _ptr;
<> 144:ef7eb2e8f9f7 88 }
<> 144:ef7eb2e8f9f7 89
<> 144:ef7eb2e8f9f7 90 /** Get a pointer to the underlying singleton
<> 144:ef7eb2e8f9f7 91 *
<> 144:ef7eb2e8f9f7 92 * @returns
<> 144:ef7eb2e8f9f7 93 * A pointer to the singleton
<> 144:ef7eb2e8f9f7 94 */
<> 144:ef7eb2e8f9f7 95 T* operator->() {
<> 144:ef7eb2e8f9f7 96 return get();
<> 144:ef7eb2e8f9f7 97 }
<> 144:ef7eb2e8f9f7 98
<> 144:ef7eb2e8f9f7 99 // This is zero initialized when in global scope
<> 144:ef7eb2e8f9f7 100 T *_ptr;
<> 144:ef7eb2e8f9f7 101 // Force data to be 4 byte aligned
<> 144:ef7eb2e8f9f7 102 uint32_t _data[(sizeof(T) + sizeof(uint32_t) - 1) / sizeof(uint32_t)];
<> 144:ef7eb2e8f9f7 103 };
<> 144:ef7eb2e8f9f7 104
<> 144:ef7eb2e8f9f7 105 #endif