if (OSIntNesting > 0) {                           /* See if called from ISR ...                    */
        *err = OS_ERR_PEND_ISR;                       /* ... can't PEND from an ISR                    */
        return ((void *)0);
    }
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        *err = OS_ERR_PEVENT_NULL;
        return ((void *)0);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */
        *err = OS_ERR_EVENT_TYPE;
        return ((void *)0);
    }
#endif
    OS_ENTER_CRITICAL();
    msg = pevent->OSEventPtr;
    if (msg != (void *)0) {                           /* See if there is already a message             */
        pevent->OSEventPtr = (void *)0;               /* Clear the mailbox                             */
        OS_EXIT_CRITICAL();
        *err = OS_NO_ERR;
        return (msg);                                 /* Return the message received (or NULL)         */
    }
    OSTCBCur->OSTCBStat |= OS_STAT_MBOX;              /* Message not available, task will pend         */
    OSTCBCur->OSTCBDly   = timeout;                   /* Load timeout in 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();
    msg = OSTCBCur->OSTCBMsg;
    if (msg != (void *)0) {                           /* See if we were given the message              */
        OSTCBCur->OSTCBMsg      = (void *)0;          /* Yes, clear message received                   */
        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 the message received                   */
    }
    OS_EventTO(pevent);                               /* Timed out, Make task ready                    */
    OS_EXIT_CRITICAL();
    *err = OS_TIMEOUT;                                /* Indicate that a timeout occured               */
    return ((void *)0);                               /* Return a NULL message                         */
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                       POST MESSAGE TO A MAILBOX
*
* Description: This function sends a message to a mailbox
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
*
*              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.
*
* Returns    : OS_NO_ERR            The call was successful and the message was sent
*              OS_MBOX_FULL         If the mailbox already contains a message.  You can can only send one
*                                   message at a time and thus, the message MUST be consumed before you
*                                   are allowed to send another one.
*              OS_ERR_EVENT_TYPE    If you are attempting to post to a non mailbox.
*              OS_ERR_PEVENT_NULL   If 'pevent' is a NULL pointer
*              OS_ERR_POST_NULL_PTR If you are attempting to post a NULL pointer
*********************************************************************************************************
*/

#if OS_MBOX_POST_EN > 0
INT8U  OSMboxPost (OS_EVENT *pevent, void *msg)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    
    
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }
    if (msg == (void *)0) {                           /* Make sure we are not posting a NULL pointer   */
        return (OS_ERR_POST_NULL_PTR);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }
#endif
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0x00) {                 /* See if any task pending on mailbox            */
        OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX);   /* Ready highest priority task waiting on event  */
        OS_EXIT_CRITICAL();
        OS_Sched();                                   /* Find highest priority task ready to run       */
        return (OS_NO_ERR);
    }
    if (pevent->OSEventPtr != (void *)0) {            /* Make sure mailbox doesn't already have a msg  */
        OS_EXIT_CRITICAL();
        return (OS_MBOX_FULL);
    }
    pevent->OSEventPtr = msg;                         /* Place message in mailbox                      */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                       POST MESSAGE TO A MAILBOX
*
* Description: This function sends a message to a mailbox
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
*
*              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.
*
*              opt           determines the type of POST performed:
*                            OS_POST_OPT_NONE         POST to a single waiting task 
*                                                     (Identical to OSMboxPost())
*                            OS_POST_OPT_BROADCAST    POST to ALL tasks that are waiting on the mailbox
*
* Returns    : OS_NO_ERR            The call was successful and the message was sent
*              OS_MBOX_FULL         If the mailbox already contains a message.  You can can only send one
*                                   message at a time and thus, the message MUST be consumed before you
*                                   are allowed to send another one.
*              OS_ERR_EVENT_TYPE    If you are attempting to post to a non mailbox.
*              OS_ERR_PEVENT_NULL   If 'pevent' is a NULL pointer
*              OS_ERR_POST_NULL_PTR If you are attempting to post a NULL pointer
*
* Warning    : Interrupts can be disabled for a long time if you do a 'broadcast'.  In fact, the 
*              interrupt disable time is proportional to the number of tasks waiting on the mailbox.
*********************************************************************************************************
*/

#if OS_MBOX_POST_OPT_EN > 0
INT8U  OSMboxPostOpt (OS_EVENT *pevent, void *msg, INT8U opt)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    
    
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }
    if (msg == (void *)0) {                           /* Make sure we are not posting a NULL pointer   */
        return (OS_ERR_POST_NULL_PTR);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }
#endif
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0x00) {                 /* See if any task pending on mailbox            */
        if ((opt & OS_POST_OPT_BROADCAST) != 0x00) {  /* Do we need to post msg to ALL waiting tasks ? */
            while (pevent->OSEventGrp != 0x00) {      /* Yes, Post to ALL tasks waiting on mailbox     */           
                OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX);    
            }
        } else {
            OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX);    /* No,  Post to HPT waiting on mbox         */
        }
        OS_EXIT_CRITICAL();
        OS_Sched();                                        /* Find highest priority task ready to run  */
        return (OS_NO_ERR);
    }
    if (pevent->OSEventPtr != (void *)0) {            /* Make sure mailbox doesn't already have a msg  */
        OS_EXIT_CRITICAL();
        return (OS_MBOX_FULL);
    }
    pevent->OSEventPtr = msg;                         /* Place message in mailbox                      */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif

/*$PAGE*/
/*
*********************************************************************************************************
*                                        QUERY A MESSAGE MAILBOX
*
* Description: This function obtains information about a message mailbox.
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox
*
*              pdata         is a pointer to a structure that will contain information about the message
*                            mailbox.
*
* Returns    : OS_NO_ERR           The call was successful and the message was sent
*              OS_ERR_EVENT_TYPE   If you are attempting to obtain data from a non mailbox.
*              OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer
*********************************************************************************************************
*/

#if OS_MBOX_QUERY_EN > 0
INT8U  OSMboxQuery (OS_EVENT *pevent, OS_MBOX_DATA *pdata)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    INT8U     *psrc;
    INT8U     *pdest;


#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */
        return (OS_ERR_PEVENT_NULL);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {       /* Validate event block type                */
        return (OS_ERR_EVENT_TYPE);
    }
#endif
    OS_ENTER_CRITICAL();
    pdata->OSEventGrp = pevent->OSEventGrp;                /* Copy message mailbox wait list           */
    psrc              = &pevent->OSEventTbl[0];
    pdest             = &pdata->OSEventTbl[0];

#if OS_EVENT_TBL_SIZE > 0
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 1
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 2
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 3
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 4
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 5
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 6
    *pdest++          = *psrc++;
#endif

#if OS_EVENT_TBL_SIZE > 7
    *pdest            = *psrc;
#endif
    pdata->OSMsg = pevent->OSEventPtr;                     /* Get message from mailbox                 */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif                                                     /* OS_MBOX_QUERY_EN                         */
#endif                                                     /* OS_MBOX_EN                               */