2009-05-13 声明：本篇文章主要参考了http://blog.ednchina.com/bluehacker<?XML:NAMESPACE PREFIX = O />

 

它把所有挂起的任务加到xSuspendedTaskList中，而且一旦调用vTaskSuspend()函数挂起一个任务，该任务就将从所有它原先连入的链表中删除（包括就绪表，延时表和它等待的事件链表），也就是说，一旦一个任务被挂起，它将取消先前它的延时和对事件的等待。<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

void vTaskSuspend( xTaskHandle pxTaskToSuspend )

{

        tskTCB *pxTCB;

 

        taskENTER_CRITICAL();

        {

            /* Ensure a yield is performed if the current task is being

            suspended. */

            if( pxTaskToSuspend == pxCurrentTCB )

            {

                pxTaskToSuspend = NULL;//token

            }

 

            /* 得到对应任务tcb */

            pxTCB = prvGetTCBFromHandle( pxTaskToSuspend );

 

            traceTASK_SUSPEND( pxTaskToSuspend );

 

            /* 把任务从就绪表或者延时链表中删除 */

            vListRemove( &( pxTCB->xGenericListItem ) );

 

            /* 如果任务也在等待某事件，则取消等待 */

            if( pxTCB->xEventListItem.pvContainer )

            {

                vListRemove( &( pxTCB->xEventListItem ) );

            }

           //插到xSuspendedTaskList

            vListInsertEnd( ( xList * ) &xSuspendedTaskList, &( pxTCB->xGenericListItem ) );

        }

        taskEXIT_CRITICAL();

 

        /* 如果挂起的是当前任务，则调度 */

        if( ( void * ) pxTaskToSuspend == NULL )

        {

            taskYIELD();

        }

    }

 

相反的唤醒就是把任务从xSuspendedTaskList中删除，加到对应的就绪链表中（根据任务的优先级），然后如果唤醒的任务优先级高于当前任务优先级，则调度。

void vTaskResume( xTaskHandle pxTaskToResume )

{

        tskTCB *pxTCB;

 

        /* Remove the task from whichever list it is currently in, and place

        it in the ready list. */

        pxTCB = ( tskTCB * ) pxTaskToResume;

 

        /* The parameter cannot be NULL as it is impossible to resume the

        currently executing task. */

        if( pxTCB != NULL )

        {

            taskENTER_CRITICAL();

            {

                if( prvIsTaskSuspended( pxTCB ) == pdTRUE )

                {

                    traceTASK_RESUME( pxTCB );

 

                    /* As we are in a critical section we can access the ready

                    lists even if the scheduler is suspended. */

                    vListRemove(  &( pxTCB->xGenericListItem ) );

                    prvAddTaskToReadyQueue( pxTCB );

 

                    /* We may have just resumed a higher priority task. */

                    if( pxTCB->uxPriority >= pxCurrentTCB->uxPriority )

                    {

                        /* This yield may not cause the task just resumed to run, butwill leave the lists in the correct state for the next yield. */

                        taskYIELD();

                    }

                }

            }

            taskEXIT_CRITICAL();

        }

    }