*err                   = OS_ERR_TASK_WAITING;
                 pevent_return          = pevent;
             }
             break;

        case OS_DEL_ALWAYS:                                /* Always delete the queue                  */
             while (pevent->OSEventGrp != 0) {             /* Ready ALL tasks waiting for queue        */
                 (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_Q);
             }
#if OS_EVENT_NAME_SIZE > 1
             pevent->OSEventName[0] = '?';                 /* Unknown name                             */
             pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
             pq                     = (OS_Q *)pevent->OSEventPtr;   /* Return OS_Q to free list        */
             pq->OSQPtr             = OSQFreeList;
             OSQFreeList            = pq;
             pevent->OSEventType    = OS_EVENT_TYPE_UNUSED;
             pevent->OSEventPtr     = OSEventFreeList;     /* Return Event Control Block to free list  */
             pevent->OSEventCnt     = 0;
             OSEventFreeList        = pevent;              /* Get next free event control block        */
             OS_EXIT_CRITICAL();
             if (tasks_waiting == TRUE) {                  /* Reschedule only if task(s) were waiting  */
                 OS_Sched();                               /* Find highest priority task ready to run  */
             }
             *err                   = OS_NO_ERR;
             pevent_return          = (OS_EVENT *)0;       /* Queue has been deleted                   */
             break;

        default:
             OS_EXIT_CRITICAL();
             *err                   = OS_ERR_INVALID_OPT;
             pevent_return          = pevent;
             break;
    }
    return (pevent_return);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                             FLUSH QUEUE
*
* Description : This function is used to flush the contents of the message queue.
*
* Arguments   : none
*
* Returns     : OS_NO_ERR           upon success
*               OS_ERR_EVENT_TYPE   If you didn't pass a pointer to a queue
*               OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer
*
* WARNING     : You should use this function with great care because, when to flush the queue, you LOOSE
*               the references to what the queue entries are pointing to and thus, you could cause
*               'memory leaks'.  In other words, the data you are pointing to that's being referenced
*               by the queue entries should, most likely, need to be de-allocated (i.e. freed).
*********************************************************************************************************
*/

#if OS_Q_FLUSH_EN > 0
INT8U  OSQFlush (OS_EVENT *pevent)
{
    OS_Q      *pq;
#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 (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_Q) {     /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }
#endif
    OS_ENTER_CRITICAL();
    pq             = (OS_Q *)pevent->OSEventPtr;      /* Point to queue storage structure              */
    pq->OSQIn      = pq->OSQStart;
    pq->OSQOut     = pq->OSQStart;
    pq->OSQEntries = 0;
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                     PEND ON A QUEUE FOR A MESSAGE
*
* Description: This function waits for a message to be sent to a queue
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will
*                            wait for a message to arrive at the queue up to the amount of time
*                            specified by this argument.  If you specify 0, however, your task will wait
*                            forever at the specified queue or, until a message arrives.
*
*              err           is a pointer to where an error message will be deposited.  Possible error
*                            messages are:
*
*                            OS_NO_ERR           The call was successful and your task received a
*                                                message.
*                            OS_TIMEOUT          A message was not received within the specified timeout
*                            OS_ERR_EVENT_TYPE   You didn't pass a pointer to a queue
*                            OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer
*                            OS_ERR_PEND_ISR     If you called this function from an ISR and the result
*                                                would lead to a suspension.
*
* Returns    : != (void *)0  is a pointer to the message received
*              == (void *)0  if you received a NULL pointer message or,
*                            if no message was received or,
*                            if 'pevent' is a NULL pointer or,
*                            if you didn't pass a pointer to a queue.
*
* Note(s)    : As of V2.60, this function allows you to receive NULL pointer messages.
*********************************************************************************************************
*/

void  *OSQPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
    void      *msg;
    OS_Q      *pq;
#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 (err == (INT8U *)0) {                     /* Validate 'err'                                     */
        return ((void *)0);
    }
    if (pevent == (OS_EVENT *)0) {               /* Validate 'pevent'                                  */
        *err = OS_ERR_PEVENT_NULL;
        return ((void *)0);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_Q) {/* Validate event block type                          */
        *err = OS_ERR_EVENT_TYPE;
        return ((void *)0);
    }
#endif
    if (OSIntNesting > 0) {                      /* See if called from ISR ...                         */
        *err = OS_ERR_PEND_ISR;                  /* ... can't PEND from an ISR                         */
        return ((void *)0);
    }
    OS_ENTER_CRITICAL();
    pq = (OS_Q *)pevent->OSEventPtr;             /* Point at queue control block                       */
    if (pq->OSQEntries > 0) {                    /* See if any messages in the queue                   */
        msg = *pq->OSQOut++;                     /* Yes, extract oldest message from the queue         */
        pq->OSQEntries--;                        /* Update the number of entries in the queue          */
        if (pq->OSQOut == pq->OSQEnd) {          /* Wrap OUT pointer if we are at the end of the queue */
            pq->OSQOut = pq->OSQStart;
        }
        OS_EXIT_CRITICAL();
        *err = OS_NO_ERR;
        return (msg);                            /* Return message received                            */
    }
    OSTCBCur->OSTCBStat   |= OS_STAT_Q;          /* Task will have to pend for a message to be posted  */
    OSTCBCur->OSTCBPendTO  = FALSE;
    OSTCBCur->OSTCBDly     = timeout;            /* Load timeout into TCB                              */
    OS_EventTaskWait(pevent);                    /* Suspend task until event or timeout occurs         */
    OS_EXIT_CRITICAL();
    OS_Sched();                                  /* Find next highest priority task ready to run       */
    OS_ENTER_CRITICAL();
    if (OSTCBCur->OSTCBPendTO == TRUE) {         /* Was task readied because of a timeout?             */
        OS_EventTO(pevent);                      /* Yes                                                */
        OS_EXIT_CRITICAL();
        *err = OS_TIMEOUT;                       /*     Indicate a timeout occured                     */
        return ((void *)0);                      /*     No message received                            */
    }
    msg                     = OSTCBCur->OSTCBMsg;/* No, Extract message from TCB (Put there by QPost)  */
    OSTCBCur->OSTCBMsg      = (void *)0;
    OSTCBCur->OSTCBStat     = OS_STAT_RDY;
    OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;     /*     No longer waiting for event                    */
    OS_EXIT_CRITICAL();
    *err                    = OS_NO_ERR;
    return (msg);                                /*     Return message received                        */
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                        POST MESSAGE TO A QUEUE
*
* Description: This function sends a message to a queue
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              msg           is a pointer to the message to send.
*
* Returns    : OS_NO_ERR             The call was successful and the message was sent
*              OS_Q_FULL             If the queue cannot accept any more messages because it is full.
*              OS_ERR_EVENT_TYPE     If you didn't pass a pointer to a queue.
*              OS_ERR_PEVENT_NULL    If 'pevent' is a NULL pointer
*
* Note(s)    : As of V2.60, this function allows you to send NULL pointer messages.
*********************************************************************************************************
*/

#if OS_Q_POST_EN > 0
INT8U  OSQPost (OS_EVENT *pevent, void *msg)
{
    OS_Q      *pq;
#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 (pevent == (OS_EVENT *)0) {                     /* Validate 'pevent'                            */
        return (OS_ERR_PEVENT_NULL);
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_Q) {      /* Validate event block type                    */
        return (OS_ERR_EVENT_TYPE);
    }
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0) {                     /* See if any task pending on queue             */
        (void)OS_EventTaskRdy(pevent, msg, OS_STAT_Q); /* Ready highest priority task waiting on event */
        OS_EXIT_CRITICAL();
        OS_Sched();                                    /* Find highest priority task ready to run      */
        return (OS_NO_ERR);
    }
    pq = (OS_Q *)pevent->OSEventPtr;                   /* Point to queue control block                 */
    if (pq->OSQEntries >= pq->OSQSize) {               /* Make sure queue is not full                  */
        OS_EXIT_CRITICAL();
        return (OS_Q_FULL);
    }
    *pq->OSQIn++ = msg;                                /* Insert message into queue                    */
    pq->OSQEntries++;                                  /* Update the nbr of entries in the queue       */
    if (pq->OSQIn == pq->OSQEnd) {                     /* Wrap IN ptr if we are at end of queue        */
        pq->OSQIn = pq->OSQStart;
    }
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                   POST MESSAGE TO THE FRONT OF A QUEUE
*
* Description: This function sends a message to a queue but unlike OSQPost(), the message is posted at
*              the front instead of the end of the queue.  Using OSQPostFront() allows you to send
*              'priority' messages.
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              msg           is a pointer to the message to send.
*
* Returns    : OS_NO_ERR             The call was successful and the message was sent
*              OS_Q_FULL             If the queue cannot accept any more messages because it is full.
*              OS_ERR_EVENT_TYPE     If you didn't pass a pointer to a queue.