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Fork of OmniWheels by Gustav Atmel

mbed-os/rtos/ConditionVariable.cpp@2:798925c9e4a8, 2018-05-01 (annotated)

Committer:
gustavatmel
Date:
Tue May 01 15:55:34 2018 +0000
Revision:
2:798925c9e4a8
Parent:
1:9c5af431a1f1 
bluetooth

Who changed what in which revision?

UserRevisionLine numberNew contents of line
gustavatmel 1:9c5af431a1f1 1 /* mbed Microcontroller Library
gustavatmel 1:9c5af431a1f1 2 * Copyright (c) 2017-2017 ARM Limited
gustavatmel 1:9c5af431a1f1 3 *
gustavatmel 1:9c5af431a1f1 4 * Permission is hereby granted, free of charge, to any person obtaining a copy
gustavatmel 1:9c5af431a1f1 5 * of this software and associated documentation files (the "Software"), to deal
gustavatmel 1:9c5af431a1f1 6 * in the Software without restriction, including without limitation the rights
gustavatmel 1:9c5af431a1f1 7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
gustavatmel 1:9c5af431a1f1 8 * copies of the Software, and to permit persons to whom the Software is
gustavatmel 1:9c5af431a1f1 9 * furnished to do so, subject to the following conditions:
gustavatmel 1:9c5af431a1f1 10 *
gustavatmel 1:9c5af431a1f1 11 * The above copyright notice and this permission notice shall be included in
gustavatmel 1:9c5af431a1f1 12 * all copies or substantial portions of the Software.
gustavatmel 1:9c5af431a1f1 13 *
gustavatmel 1:9c5af431a1f1 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
gustavatmel 1:9c5af431a1f1 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
gustavatmel 1:9c5af431a1f1 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
gustavatmel 1:9c5af431a1f1 17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
gustavatmel 1:9c5af431a1f1 18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
gustavatmel 1:9c5af431a1f1 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
gustavatmel 1:9c5af431a1f1 20 * SOFTWARE.
gustavatmel 1:9c5af431a1f1 21 */
gustavatmel 1:9c5af431a1f1 22 #include "rtos/ConditionVariable.h"
gustavatmel 1:9c5af431a1f1 23 #include "rtos/Kernel.h"
gustavatmel 1:9c5af431a1f1 24 #include "rtos/Thread.h"
gustavatmel 1:9c5af431a1f1 25
gustavatmel 1:9c5af431a1f1 26 #include "mbed_error.h"
gustavatmel 1:9c5af431a1f1 27 #include "mbed_assert.h"
gustavatmel 1:9c5af431a1f1 28
gustavatmel 1:9c5af431a1f1 29 namespace rtos {
gustavatmel 1:9c5af431a1f1 30
gustavatmel 1:9c5af431a1f1 31 ConditionVariable::Waiter::Waiter(): sem(0), prev(NULL), next(NULL), in_list(false)
gustavatmel 1:9c5af431a1f1 32 {
gustavatmel 1:9c5af431a1f1 33 // No initialization to do
gustavatmel 1:9c5af431a1f1 34 }
gustavatmel 1:9c5af431a1f1 35
gustavatmel 1:9c5af431a1f1 36 ConditionVariable::ConditionVariable(Mutex &mutex): _mutex(mutex), _wait_list(NULL)
gustavatmel 1:9c5af431a1f1 37 {
gustavatmel 1:9c5af431a1f1 38 // No initialization to do
gustavatmel 1:9c5af431a1f1 39 }
gustavatmel 1:9c5af431a1f1 40
gustavatmel 1:9c5af431a1f1 41 void ConditionVariable::wait()
gustavatmel 1:9c5af431a1f1 42 {
gustavatmel 1:9c5af431a1f1 43 wait_for(osWaitForever);
gustavatmel 1:9c5af431a1f1 44 }
gustavatmel 1:9c5af431a1f1 45
gustavatmel 1:9c5af431a1f1 46 bool ConditionVariable::wait_for(uint32_t millisec)
gustavatmel 1:9c5af431a1f1 47 {
gustavatmel 1:9c5af431a1f1 48 Waiter current_thread;
gustavatmel 1:9c5af431a1f1 49 MBED_ASSERT(_mutex.get_owner() == Thread::gettid());
gustavatmel 1:9c5af431a1f1 50 MBED_ASSERT(_mutex._count == 1);
gustavatmel 1:9c5af431a1f1 51 _add_wait_list(&_wait_list, &current_thread);
gustavatmel 1:9c5af431a1f1 52
gustavatmel 1:9c5af431a1f1 53 _mutex.unlock();
gustavatmel 1:9c5af431a1f1 54
gustavatmel 1:9c5af431a1f1 55 int32_t sem_count = current_thread.sem.wait(millisec);
gustavatmel 1:9c5af431a1f1 56 bool timeout = (sem_count > 0) ? false : true;
gustavatmel 1:9c5af431a1f1 57
gustavatmel 1:9c5af431a1f1 58 _mutex.lock();
gustavatmel 1:9c5af431a1f1 59
gustavatmel 1:9c5af431a1f1 60 if (current_thread.in_list) {
gustavatmel 1:9c5af431a1f1 61 _remove_wait_list(&_wait_list, &current_thread);
gustavatmel 1:9c5af431a1f1 62 }
gustavatmel 1:9c5af431a1f1 63
gustavatmel 1:9c5af431a1f1 64 return timeout;
gustavatmel 1:9c5af431a1f1 65 }
gustavatmel 1:9c5af431a1f1 66
gustavatmel 1:9c5af431a1f1 67 bool ConditionVariable::wait_until(uint64_t millisec)
gustavatmel 1:9c5af431a1f1 68 {
gustavatmel 1:9c5af431a1f1 69 uint64_t now = Kernel::get_ms_count();
gustavatmel 1:9c5af431a1f1 70
gustavatmel 1:9c5af431a1f1 71 if (now >= millisec) {
gustavatmel 1:9c5af431a1f1 72 // Time has already passed - standard behaviour is to
gustavatmel 1:9c5af431a1f1 73 // treat as a "try".
gustavatmel 1:9c5af431a1f1 74 return wait_for(0);
gustavatmel 1:9c5af431a1f1 75 } else if (millisec - now >= osWaitForever) {
gustavatmel 1:9c5af431a1f1 76 // Exceeds maximum delay of underlying wait_for -
gustavatmel 1:9c5af431a1f1 77 // spuriously wake after 49 days, indicating no timeout.
gustavatmel 1:9c5af431a1f1 78 wait_for(osWaitForever - 1);
gustavatmel 1:9c5af431a1f1 79 return false;
gustavatmel 1:9c5af431a1f1 80 } else {
gustavatmel 1:9c5af431a1f1 81 return wait_for(millisec - now);
gustavatmel 1:9c5af431a1f1 82 }
gustavatmel 1:9c5af431a1f1 83 }
gustavatmel 1:9c5af431a1f1 84
gustavatmel 1:9c5af431a1f1 85 void ConditionVariable::notify_one()
gustavatmel 1:9c5af431a1f1 86 {
gustavatmel 1:9c5af431a1f1 87 MBED_ASSERT(_mutex.get_owner() == Thread::gettid());
gustavatmel 1:9c5af431a1f1 88 if (_wait_list != NULL) {
gustavatmel 1:9c5af431a1f1 89 _wait_list->sem.release();
gustavatmel 1:9c5af431a1f1 90 _remove_wait_list(&_wait_list, _wait_list);
gustavatmel 1:9c5af431a1f1 91 }
gustavatmel 1:9c5af431a1f1 92 }
gustavatmel 1:9c5af431a1f1 93
gustavatmel 1:9c5af431a1f1 94 void ConditionVariable::notify_all()
gustavatmel 1:9c5af431a1f1 95 {
gustavatmel 1:9c5af431a1f1 96 MBED_ASSERT(_mutex.get_owner() == Thread::gettid());
gustavatmel 1:9c5af431a1f1 97 while (_wait_list != NULL) {
gustavatmel 1:9c5af431a1f1 98 _wait_list->sem.release();
gustavatmel 1:9c5af431a1f1 99 _remove_wait_list(&_wait_list, _wait_list);
gustavatmel 1:9c5af431a1f1 100 }
gustavatmel 1:9c5af431a1f1 101 }
gustavatmel 1:9c5af431a1f1 102
gustavatmel 1:9c5af431a1f1 103 void ConditionVariable::_add_wait_list(Waiter **wait_list, Waiter *waiter)
gustavatmel 1:9c5af431a1f1 104 {
gustavatmel 1:9c5af431a1f1 105 if (NULL == *wait_list) {
gustavatmel 1:9c5af431a1f1 106 // Nothing in the list so add it directly.
gustavatmel 1:9c5af431a1f1 107 // Update prev and next pointer to reference self
gustavatmel 1:9c5af431a1f1 108 *wait_list = waiter;
gustavatmel 1:9c5af431a1f1 109 waiter->next = waiter;
gustavatmel 1:9c5af431a1f1 110 waiter->prev = waiter;
gustavatmel 1:9c5af431a1f1 111 } else {
gustavatmel 1:9c5af431a1f1 112 // Add after the last element
gustavatmel 1:9c5af431a1f1 113 Waiter *first = *wait_list;
gustavatmel 1:9c5af431a1f1 114 Waiter *last = (*wait_list)->prev;
gustavatmel 1:9c5af431a1f1 115
gustavatmel 1:9c5af431a1f1 116 // Update new entry
gustavatmel 1:9c5af431a1f1 117 waiter->next = first;
gustavatmel 1:9c5af431a1f1 118 waiter->prev = last;
gustavatmel 1:9c5af431a1f1 119
gustavatmel 1:9c5af431a1f1 120 // Insert into the list
gustavatmel 1:9c5af431a1f1 121 first->prev = waiter;
gustavatmel 1:9c5af431a1f1 122 last->next = waiter;
gustavatmel 1:9c5af431a1f1 123 }
gustavatmel 1:9c5af431a1f1 124 waiter->in_list = true;
gustavatmel 1:9c5af431a1f1 125 }
gustavatmel 1:9c5af431a1f1 126
gustavatmel 1:9c5af431a1f1 127 void ConditionVariable::_remove_wait_list(Waiter **wait_list, Waiter *waiter)
gustavatmel 1:9c5af431a1f1 128 {
gustavatmel 1:9c5af431a1f1 129 Waiter *prev = waiter->prev;
gustavatmel 1:9c5af431a1f1 130 Waiter *next = waiter->next;
gustavatmel 1:9c5af431a1f1 131
gustavatmel 1:9c5af431a1f1 132 // Remove from list
gustavatmel 1:9c5af431a1f1 133 prev->next = waiter->next;
gustavatmel 1:9c5af431a1f1 134 next->prev = waiter->prev;
gustavatmel 1:9c5af431a1f1 135 *wait_list = waiter->next;
gustavatmel 1:9c5af431a1f1 136
gustavatmel 1:9c5af431a1f1 137 if (*wait_list == waiter) {
gustavatmel 1:9c5af431a1f1 138 // This was the last element in the list
gustavatmel 1:9c5af431a1f1 139 *wait_list = NULL;
gustavatmel 1:9c5af431a1f1 140 }
gustavatmel 1:9c5af431a1f1 141
gustavatmel 1:9c5af431a1f1 142 // Invalidate pointers
gustavatmel 1:9c5af431a1f1 143 waiter->next = NULL;
gustavatmel 1:9c5af431a1f1 144 waiter->prev = NULL;
gustavatmel 1:9c5af431a1f1 145 waiter->in_list = false;
gustavatmel 1:9c5af431a1f1 146 }
gustavatmel 1:9c5af431a1f1 147
gustavatmel 1:9c5af431a1f1 148 ConditionVariable::~ConditionVariable()
gustavatmel 1:9c5af431a1f1 149 {
gustavatmel 1:9c5af431a1f1 150 MBED_ASSERT(NULL == _wait_list);
gustavatmel 1:9c5af431a1f1 151 }
gustavatmel 1:9c5af431a1f1 152
gustavatmel 1:9c5af431a1f1 153 }