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_IEC61508if (OSSafetyCriticalStartFlag == OS_TRUE){OS_SAFETY_CRITICAL_EXCEPTION();return ((OS_EVENT *)0);}#endifif (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 > 0upevent->OSEventName    = (INT8U *) (void *)"?";
#endifOS_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_CRITICALif (perr == (INT8U *)0){OS_SAFETY_CRITICAL_EXCEPTION();return ((OS_EVENT *)0);}#endif
#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0)                           /* Validate 'pevent'                        */{*perr = OS_ERR_PEVENT_NULL;return (pevent);}#endifif (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 > 0upevent->OSEventName    = (INT8U *) (void *)"?";
#endifpevent->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 > 0upevent->OSEventName    = (INT8U *) (void *)"?";
#endifpevent->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_CRITICALif (perr == (INT8U *)0){OS_SAFETY_CRITICAL_EXCEPTION();return;}#endif
#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0)                      /* Validate 'pevent'                             */{*perr = OS_ERR_PEVENT_NULL;return;}#endifif (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;
#endifOS_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 > 0uif (pevent == (OS_EVENT *)0)                      /* Validate 'pevent'                             */{return (OS_ERR_PEVENT_NULL);}#endifif (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);
}