μC/OS-II---信号量管理1（os_sem.c）

信号量管理

信号量创建

OS_EVENT  *OSSemCreate (INT16U cnt)
{
	OS_EVENT  *pevent;
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */
	OS_CPU_SR  cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL_IEC61508
	
	if (OSSafetyCriticalStartFlag == OS_TRUE)
	{
		OS_SAFETY_CRITICAL_EXCEPTION();
		return ((OS_EVENT *)0);
	}
	
#endif
	
	if (OSIntNesting > 0u)                                 /* See if called from ISR ...               */
	{
		return ((OS_EVENT *)0);                            /* ... can't CREATE from an ISR             */
	}
	
	OS_ENTER_CRITICAL();
	pevent = OSEventFreeList;                              /* Get next free event control block        */
	
	if (OSEventFreeList != (OS_EVENT *)0)                  /* See if pool of free ECB pool was empty   */
	{
		OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
	}
	
	OS_EXIT_CRITICAL();
	
	if (pevent != (OS_EVENT *)0)                           /* Get an event control block               */
	{
		pevent->OSEventType    = OS_EVENT_TYPE_SEM;
		pevent->OSEventCnt     = cnt;                      /* Set semaphore value                      */
		pevent->OSEventPtr     = (void *)0;                /* Unlink from ECB free list                */
#if OS_EVENT_NAME_EN > 0u
		pevent->OSEventName    = (INT8U *) (void *)"?";
#endif
		OS_EventWaitListInit (pevent);                     /* Initialize to 'nobody waiting' on sem.   */
	}
	
	return (pevent);
}

信号量删除

#if OS_SEM_DEL_EN > 0u
OS_EVENT  *OSSemDel (OS_EVENT  *pevent,
										 INT8U      opt,
										 INT8U     *perr)
{
	BOOLEAN    tasks_waiting;
	OS_EVENT  *pevent_return;
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */
	OS_CPU_SR  cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL
	
	if (perr == (INT8U *)0)
	{
		OS_SAFETY_CRITICAL_EXCEPTION();
		return ((OS_EVENT *)0);
	}
	
#endif
#if OS_ARG_CHK_EN > 0u
	
	if (pevent == (OS_EVENT *)0)                           /* Validate 'pevent'                        */
	{
		*perr = OS_ERR_PEVENT_NULL;
		return (pevent);
	}
	
#endif
	
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)          /* Validate event block type                */
	{
		*perr = OS_ERR_EVENT_TYPE;
		return (pevent);
	}
	
	if (OSIntNesting > 0u)                                 /* See if called from ISR ...               */
	{
		*perr = OS_ERR_DEL_ISR;                            /* ... can't DELETE from an ISR             */
		return (pevent);
	}
	
	OS_ENTER_CRITICAL();
	
	if (pevent->OSEventGrp != 0u)                          /* See if any tasks waiting on semaphore    */
	{
		tasks_waiting = OS_TRUE;                           /* Yes                                      */
	}
	
	else
	{
		tasks_waiting = OS_FALSE;                          /* No                                       */
	}
	
	switch (opt)
	{
		case OS_DEL_NO_PEND:                               /* Delete semaphore only if no task waiting */
			if (tasks_waiting == OS_FALSE)
			{
#if OS_EVENT_NAME_EN > 0u
				pevent->OSEventName    = (INT8U *) (void *)"?";
#endif
				pevent->OSEventType    = OS_EVENT_TYPE_UNUSED;
				pevent->OSEventPtr     = OSEventFreeList; /* Return Event Control Block to free list  */
				pevent->OSEventCnt     = 0u;
				OSEventFreeList        = pevent;          /* Get next free event control block        */
				OS_EXIT_CRITICAL();
				*perr                  = OS_ERR_NONE;
				pevent_return          = (OS_EVENT *)0;   /* Semaphore has been deleted               */
			}
			
			else
			{
				OS_EXIT_CRITICAL();
				*perr                  = OS_ERR_TASK_WAITING;
				pevent_return          = pevent;
			}
			
			break;
			
		case OS_DEL_ALWAYS:                                /* Always delete the semaphore              */
			while (pevent->OSEventGrp != 0u)              /* Ready ALL tasks waiting for semaphore    */
			{
				(void)OS_EventTaskRdy (pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_ABORT);
			}
			
#if OS_EVENT_NAME_EN > 0u
			pevent->OSEventName    = (INT8U *) (void *)"?";
#endif
			pevent->OSEventType    = OS_EVENT_TYPE_UNUSED;
			pevent->OSEventPtr     = OSEventFreeList;     /* Return Event Control Block to free list  */
			pevent->OSEventCnt     = 0u;
			OSEventFreeList        = pevent;              /* Get next free event control block        */
			OS_EXIT_CRITICAL();
			
			if (tasks_waiting == OS_TRUE)                 /* Reschedule only if task(s) were waiting  */
			{
				OS_Sched();                               /* Find highest priority task ready to run  */
			}
			
			*perr                  = OS_ERR_NONE;
			pevent_return          = (OS_EVENT *)0;       /* Semaphore has been deleted               */
			break;
			
		default:
			OS_EXIT_CRITICAL();
			*perr                  = OS_ERR_INVALID_OPT;
			pevent_return          = pevent;
			break;
	}
	
	return (pevent_return);
}
#endif

获取/等待信号量

void  OSSemPend (OS_EVENT  *pevent,
								 INT32U     timeout,
								 INT8U     *perr)
{
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */
	OS_CPU_SR  cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL
	
	if (perr == (INT8U *)0)
	{
		OS_SAFETY_CRITICAL_EXCEPTION();
		return;
	}
	
#endif
#if OS_ARG_CHK_EN > 0u
	
	if (pevent == (OS_EVENT *)0)                      /* Validate 'pevent'                             */
	{
		*perr = OS_ERR_PEVENT_NULL;
		return;
	}
	
#endif
	
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)     /* Validate event block type                     */
	{
		*perr = OS_ERR_EVENT_TYPE;
		return;
	}
	
	if (OSIntNesting > 0u)                            /* See if called from ISR ...                    */
	{
		*perr = OS_ERR_PEND_ISR;                      /* ... can't PEND from an ISR                    */
		return;
	}
	
	if (OSLockNesting > 0u)                           /* See if called with scheduler locked ...       */
	{
		*perr = OS_ERR_PEND_LOCKED;                   /* ... can't PEND when locked                    */
		return;
	}
	
	OS_ENTER_CRITICAL();
	
	if (pevent->OSEventCnt > 0u)                      /* If sem. is positive, resource available ...   */
	{
		pevent->OSEventCnt--;                         /* ... decrement semaphore only if positive.     */
		OS_EXIT_CRITICAL();
		*perr = OS_ERR_NONE;
		return;
	}
	
	/* Otherwise, must wait until event occurs       */
	OSTCBCur->OSTCBStat     |= OS_STAT_SEM;           /* Resource not available, pend on semaphore     */
	OSTCBCur->OSTCBStatPend  = OS_STAT_PEND_OK;
	OSTCBCur->OSTCBDly       = timeout;               /* Store pend timeout in TCB                     */
	OS_EventTaskWait (pevent);                        /* Suspend task until event or timeout occurs    */
	OS_EXIT_CRITICAL();
	OS_Sched();                                       /* Find next highest priority task ready         */
	OS_ENTER_CRITICAL();
	
	switch (OSTCBCur->OSTCBStatPend)                  /* See if we timed-out or aborted                */
	{
		case OS_STAT_PEND_OK:
			*perr = OS_ERR_NONE;
			break;
			
		case OS_STAT_PEND_ABORT:
			*perr = OS_ERR_PEND_ABORT;               /* Indicate that we aborted                      */
			break;
			
		case OS_STAT_PEND_TO:
		default:
			OS_EventTaskRemove (OSTCBCur, pevent);
			*perr = OS_ERR_TIMEOUT;                  /* Indicate that we didn't get event within TO   */
			break;
	}
	
	OSTCBCur->OSTCBStat          =  OS_STAT_RDY;      /* Set   task  status to ready                   */
	OSTCBCur->OSTCBStatPend      =  OS_STAT_PEND_OK;  /* Clear pend  status                            */
	OSTCBCur->OSTCBEventPtr      = (OS_EVENT  *)0;    /* Clear event pointers                          */
#if (OS_EVENT_MULTI_EN > 0u)
	OSTCBCur->OSTCBEventMultiPtr = (OS_EVENT **)0;
#endif
	OS_EXIT_CRITICAL();
}

发出信号量

INT8U  OSSemPost (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */
	OS_CPU_SR  cpu_sr = 0u;
#endif
#if OS_ARG_CHK_EN > 0u
	
	if (pevent == (OS_EVENT *)0)                      /* Validate 'pevent'                             */
	{
		return (OS_ERR_PEVENT_NULL);
	}
	
#endif
	
	if (pevent->OSEventType != OS_EVENT_TYPE_SEM)     /* Validate event block type                     */
	{
		return (OS_ERR_EVENT_TYPE);
	}
	
	OS_ENTER_CRITICAL();
	
	if (pevent->OSEventGrp != 0u)                     /* See if any task waiting for semaphore         */
	{
		/* Ready HPT waiting on event                    */
		(void)OS_EventTaskRdy (pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_OK);
		OS_EXIT_CRITICAL();
		OS_Sched();                                   /* Find HPT ready to run                         */
		return (OS_ERR_NONE);
	}
	
	if (pevent->OSEventCnt < 65535u)                  /* Make sure semaphore will not overflow         */
	{
		pevent->OSEventCnt++;                         /* Increment semaphore count to register event   */
		OS_EXIT_CRITICAL();
		return (OS_ERR_NONE);
	}
	
	OS_EXIT_CRITICAL();                               /* Semaphore value has reached its maximum       */
	return (OS_ERR_SEM_OVF);
}