FreeRTOS的任务挂起和恢复

1.任务的挂起

c 复制代码
void vTaskSuspend( TaskHandle_t xTaskToSuspend )
	{
	TCB_t *pxTCB;

        /* 进入临界区 */
		taskENTER_CRITICAL();
		{
			/* If null is passed in here then it is the running task that is
			being suspended. */
			 /* 获取任务控制块,若为NULL则挂起自身 */
			pxTCB = prvGetTCBFromHandle( xTaskToSuspend );

			traceTASK_SUSPEND( pxTCB );

			/* Remove task from the ready/delayed list and place in the
			suspended list. */

			/*从就绪/延迟列表中删除任务 */
			if( uxListRemove( &( pxTCB->xGenericListItem ) ) == ( UBaseType_t ) 0 )
			{
				taskRESET_READY_PRIORITY( pxTCB->uxPriority );
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}

			/* Is the task waiting on an event also? */
			/*任务是否也在等待事件,从事件链表中删除*/
			if( listLIST_ITEM_CONTAINER( &( pxTCB->xEventListItem ) ) != NULL )
			{
				( void ) uxListRemove( &( pxTCB->xEventListItem ) );
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}
			/* 将任务放在挂起链表中 */
			vListInsertEnd( &xSuspendedTaskList, &( pxTCB->xGenericListItem ) );
		}
		taskEXIT_CRITICAL();  /* 退出临界区 */

		if( pxTCB == pxCurrentTCB )  /*若刚挂起的是正在运行的任务 */
		{
			if( xSchedulerRunning != pdFALSE )  /* 调度器正常运行 */
			{
				/* The current task has just been suspended. */
				configASSERT( uxSchedulerSuspended == 0 );
				portYIELD_WITHIN_API();  /* 直接发起任务切换 */
			}
			else
			{
				/* The scheduler is not running, but the task that was pointed
				to by pxCurrentTCB has just been suspended and pxCurrentTCB
				must be adjusted to point to a different task. */
				 /* 若任务调度器没有开启,则读取当前任务挂起列表的长度,判断所有任务是否都被挂起*/
				if( listCURRENT_LIST_LENGTH( &xSuspendedTaskList ) == uxCurrentNumberOfTasks )
				{
					/* No other tasks are ready, so set pxCurrentTCB back to
					NULL so when the next task is created pxCurrentTCB will
					be set to point to it no matter what its relative priority
					is. */
					/*没有其他任务准备就绪,因此将pxCurrentTCB设置回NULL*/
					pxCurrentTCB = NULL;
				}
				else
				{
					/* 若还有没被挂起的任务,则获取下一个要运行的任务 */
					vTaskSwitchContext();
				}
			}
		}
		else
		{
			if( xSchedulerRunning != pdFALSE )  /* 调度器正常运行 */
			{
				/* A task other than the currently running task was suspended,
				reset the next expected unblock time in case it referred to the
				task that is now in the Suspended state. */
				taskENTER_CRITICAL();
				{
					prvResetNextTaskUnblockTime();  /* 重置下一个预期的解锁时间 */
				}
				taskEXIT_CRITICAL();
			}
			else
			{
				mtCOVERAGE_TEST_MARKER();
			}
		}
	}

2.任务的恢复

c 复制代码
	void vTaskResume( TaskHandle_t xTaskToResume )
	{
	TCB_t * const pxTCB = ( TCB_t * ) xTaskToResume;

		/* It does not make sense to resume the calling task. */
		configASSERT( xTaskToResume );

		/* The parameter cannot be NULL as it is impossible to resume the
		currently executing task. */
		if( ( pxTCB != NULL ) && ( pxTCB != pxCurrentTCB ) )    /* 任务控制块不能为NULL和当前任务	*/
		{
			taskENTER_CRITICAL();
			{
				if( prvTaskIsTaskSuspended( pxTCB ) == pdTRUE )  /* 判断任务是否被挂起 */
				{
					traceTASK_RESUME( pxTCB );

					/* As we are in a critical section we can access the ready
					lists even if the scheduler is suspended. */
					( void ) uxListRemove(  &( pxTCB->xGenericListItem ) );  /* 从挂起列表中移除 */
					prvAddTaskToReadyList( pxTCB );   /* 添加到就绪列表中 */

					/* We may have just resumed a higher priority task. */
					if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )  /* 恢复的任务优先级更高 */
					{
						/* This yield may not cause the task just resumed to run,
						but will leave the lists in the correct state for the
						next yield. */
						taskYIELD_IF_USING_PREEMPTION();  /* 发起任务调度切换 */
					}
					else
					{
						mtCOVERAGE_TEST_MARKER();
					}
				}
				else
				{
					mtCOVERAGE_TEST_MARKER();
				}
			}
			taskEXIT_CRITICAL();
		}
		else
		{
			mtCOVERAGE_TEST_MARKER();
		}
	}
相关推荐
Ronin-Lotus3 小时前
嵌入式硬件篇---有线串口通信问题解决
单片机·嵌入式硬件·ttl·rs232·rs485·有线串口
GalaxySinCos5 小时前
08 51单片机之串口通信
单片机·嵌入式硬件·51单片机
悠哉悠哉愿意5 小时前
【电赛学习笔记】MaxiCAM 项目实践——与单片机的串口通信
笔记·python·单片机·嵌入式硬件·学习·视觉检测
李某学编程7 小时前
Cortex-M内核SysTick定时器介绍
stm32·单片机
李永奉7 小时前
STM32-定时器的基本定时/计数功能实现配置教程(寄存器版)
c语言·开发语言·stm32·单片机·嵌入式硬件
糖糖单片机设计8 小时前
硬件开发_基于STM32单片机的电脑底座系统
stm32·单片机·嵌入式硬件·物联网·51单片机
IT项目分享11 小时前
ESP32入门实战:PC远程控制LED灯完整指南
单片机·嵌入式硬件·micropython·it项目网
Electrical_IT13 小时前
STM32-PWM输入捕获的配置
stm32·单片机
风吹花中花吹风14 小时前
原创-锐能微82xx系列电能计量芯片软件驱动开发与精度校准流程完全指南
驱动开发·单片机·嵌入式硬件·锐能微·计量芯片·精度校准·电能表校准
嵌入式小白牙17 小时前
ARM-DMA
arm开发·stm32·单片机