ucos 任务的挂起与恢复

最新推荐文章于 2024-02-27 19:04:27 发布

原创最新推荐文章于 2024-02-27 19:04:27 发布 · 3.3k 阅读

2 ·

CC 4.0 BY-SA版权

ucos 专栏收录该内容

9 篇文章

订阅专栏

本文详细介绍了任务挂起和恢复的实现过程，包括挂起函数和恢复函数的内部逻辑，以及如何在任务就绪表中更改任务状态。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

1：任务的挂起

看看任务挂起的函数
#if OS_TASK_SUSPEND_EN > 0
INT8U OSTaskSuspend (INT8U prio)
{
BOOLEAN self;
OS_TCB *ptcb;
INT8U y;
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0;
#endif

#if OS_ARG_CHK_EN > 0
if (prio == OS_TASK_IDLE_PRIO) { /* Not allowed to suspend idle task */
return (OS_ERR_TASK_SUSPEND_IDLE);
}
if (prio >= OS_LOWEST_PRIO) { /* Task priority valid ? */
if (prio != OS_PRIO_SELF) {
return (OS_ERR_PRIO_INVALID);
}
}
#endif
OS_ENTER_CRITICAL();
if (prio == OS_PRIO_SELF) { /* See if suspend SELF */
prio = OSTCBCur->OSTCBPrio;
self = OS_TRUE;
} else if (prio == OSTCBCur->OSTCBPrio) { /* See if suspending self */
self = OS_TRUE;
} else {
self = OS_FALSE; /* No suspending another task */
}
ptcb = OSTCBPrioTbl[prio];
if (ptcb == (OS_TCB *)0) { /* Task to suspend must exist */
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_SUSPEND_PRIO);
}
if (ptcb == OS_TCB_RESERVED) { /* See if assigned to Mutex */
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NOT_EXIST);
}
y = ptcb->OSTCBY;
OSRdyTbl[y] &= ~ptcb->OSTCBBitX; /* Make task not ready */
if (OSRdyTbl[y] == 0) {
OSRdyGrp &= ~ptcb->OSTCBBitY;
}
ptcb->OSTCBStat |= OS_STAT_SUSPEND; /* Status of task is 'SUSPENDED' */
OS_EXIT_CRITICAL();
if (self == OS_TRUE) { /* Context switch only if SELF */
OS_Sched(); /* Find new highest priority task */
}
return (OS_ERR_NONE);
}
#endif
首先是判断传入的优先级是否为：OS_PRIO_SELF即是否需要挂起任务本身，或者挂起当前正在运行的任务(prio == OSTCBCur->OSTCBPrio)。
之后根据任务优先级prio得到任务TCB指针判断是否合法的TCB，有了TCB就可以会的当前任务有关就绪表及OSRdyGrp信息。使
此任务在任务就绪表及OSRdyGrp中挂起，并将任务的饿状态设置为：OS_STAT_SUSPEND。并且当挂起的任务为本身时，进行一次任务切换。

总之主要工作就是：在任务就绪表中更改prio优先级对应的任务状态。

2：任务的恢复

#if OS_TASK_SUSPEND_EN > 0
INT8U OSTaskResume (INT8U prio)
{
OS_TCB *ptcb;
#if OS_CRITICAL_METHOD == 3 /* Storage for CPU status register */
OS_CPU_SR cpu_sr = 0;
#endif

#if OS_ARG_CHK_EN > 0
if (prio >= OS_LOWEST_PRIO) { /* Make sure task priority is valid */
return (OS_ERR_PRIO_INVALID);
}
#endif
OS_ENTER_CRITICAL();
ptcb = OSTCBPrioTbl[prio];
if (ptcb == (OS_TCB *)0) { /* Task to suspend must exist */
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_RESUME_PRIO);
}
if (ptcb == OS_TCB_RESERVED) { /* See if assigned to Mutex */
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NOT_EXIST);
}
if ((ptcb->OSTCBStat & OS_STAT_SUSPEND) != OS_STAT_RDY) { /* Task must be suspended */
ptcb->OSTCBStat &= ~(INT8U)OS_STAT_SUSPEND; /* Remove suspension */
if (ptcb->OSTCBStat == OS_STAT_RDY) { /* See if task is now ready */
if (ptcb->OSTCBDly == 0) {
OSRdyGrp |= ptcb->OSTCBBitY; /* Yes, Make task ready to run */
OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
OS_EXIT_CRITICAL();
if (OSRunning == OS_TRUE) {
OS_Sched(); /* Find new highest priority task */
}
} else {
OS_EXIT_CRITICAL();
}
} else { /* Must be pending on event */
OS_EXIT_CRITICAL();
}
return (OS_ERR_NONE);
}
OS_EXIT_CRITICAL();
return (OS_ERR_TASK_NOT_SUSPENDED);
}
#endif
其中主要的代码如下：
if ((ptcb->OSTCBStat & OS_STAT_SUSPEND) != OS_STAT_RDY) { /* Task must be suspended */
ptcb->OSTCBStat &= ~(INT8U)OS_STAT_SUSPEND; /* Remove suspension */
if (ptcb->OSTCBStat == OS_STAT_RDY) { /* See if task is now ready */
if (ptcb->OSTCBDly == 0) {
OSRdyGrp |= ptcb->OSTCBBitY; /* Yes, Make task ready to run */
OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;
OS_EXIT_CRITICAL();
if (OSRunning == OS_TRUE) {
OS_Sched(); /* Find new highest priority task */
}
} else {
OS_EXIT_CRITICAL();
}
} else { /* Must be pending on event */
OS_EXIT_CRITICAL();
}
return (OS_ERR_NONE);
}
看之前复习一下几个变量的值：
#if OS_LOWEST_PRIO <= 63
ptcb->OSTCBY = (INT8U)(prio >> 3); /* Pre-compute X, Y, BitX and BitY */
ptcb->OSTCBX = (INT8U)(prio & 0x07);
ptcb->OSTCBBitY = (INT8U)(1 << ptcb->OSTCBY);
ptcb->OSTCBBitX = (INT8U)(1 << ptcb->OSTCBX);
#else
ptcb->OSTCBY = (INT8U)((prio >> 4) & 0xFF); /* Pre-compute X, Y, BitX and BitY */
ptcb->OSTCBX = (INT8U) (prio & 0x0F);
ptcb->OSTCBBitY = (INT16U)(1 << ptcb->OSTCBY);
ptcb->OSTCBBitX = (INT16U)(1 << ptcb->OSTCBX);
#endif
在OS_LOWEST_PRIO <= 63时，ptcb->OSTCY和ptcb->OSTCBX的最大值为：8。
ptcb->OSTCY表示的是就绪表中的下标，ptcb->OSTCBX表示的是：OSRdyTbl[ptcb->OSTCBY]中的第ptcb->OSTCBXbit位的值。
在明确一下就用：ptcb->OSTCBBitY和ptcb->OSTCBBitX。这俩个分别表示的是某一bit位。
有了上面的值，函数OSTaskResume()很好理解，设置就绪表，是任务处于就绪状态，并进行一次任务调度。