/***********************************************************************************************************                                                uC/OS-II*                                          The Real-Time Kernel*                                       MESSAGE MAILBOX MANAGEMENT**                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL*                                           All Rights Reserved**                                                  V2.00** File : OS_MBOX.C* By   : Jean J. Labrosse**********************************************************************************************************/#ifndef  OS_MASTER_FILE#include "includes.h"#endif#if OS_MBOX_EN/***********************************************************************************************************                                     ACCEPT MESSAGE FROM MAILBOX** Description: This function checks the mailbox to see if a message is available.  Unlike OSMboxPend(),*              OSMboxAccept() does not suspend the calling task if a message is not available.** Arguments  : pevent        is a pointer to the event control block** Returns    : != (void *)0  is the message in the mailbox if one is available.  The mailbox is cleared*                            so the next time OSMboxAccept() is called, the mailbox will be empty.*              == (void *)0  if the mailbox is empty or if you didn't pass the proper event pointer.**********************************************************************************************************/void *OSMboxAccept (OS_EVENT *pevent){    void  *msg;    OS_ENTER_CRITICAL();    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {      /* Validate event block type                 */        OS_EXIT_CRITICAL();        return ((void *)0);    }    msg = pevent->OSEventPtr;     if (msg != (void *)0) {                               /* See if there is already a message         */        pevent->OSEventPtr = (void *)0;                   /* Clear the mailbox                         */    }    OS_EXIT_CRITICAL();    return (msg);                                         /* Return the message received (or NULL)     */}/*$PAGE*//***********************************************************************************************************                                        CREATE A MESSAGE MAILBOX** Description: This function creates a message mailbox if free event control blocks are available.** Arguments  : msg           is a pointer to a message that you wish to deposit in the mailbox.  If*                            you set this value to the NULL pointer (i.e. (void *)0) then the mailbox*                            will be considered empty.** Returns    : != (void *)0  is a pointer to the event control clock (OS_EVENT) associated with the*                            created mailbox*              == (void *)0  if no event control blocks were available**********************************************************************************************************/OS_EVENT *OSMboxCreate (void *msg){    OS_EVENT *pevent;    OS_ENTER_CRITICAL();    pevent = OSEventFreeList;                    /* Get next free event control block                  */    if (OSEventFreeList != (OS_EVENT *)0) {      /* See if pool of free ECB pool was empty             */        OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;    }    OS_EXIT_CRITICAL();    if (pevent != (OS_EVENT *)0) {        pevent->OSEventType = OS_EVENT_TYPE_MBOX;        pevent->OSEventPtr  = msg;               /* Deposit message in event control block             */        OSEventWaitListInit(pevent);    }    return (pevent);                             /* Return pointer to event control block              */}/*$PAGE*//***********************************************************************************************************                                      PEND ON MAILBOX FOR A MESSAGE** Description: This function waits for a message to be sent to a mailbox** Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox**              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will*                            wait for a message to arrive at the mailbox up to the amount of time *                            specified by this argument.  If you specify 0, however, your task will wait *                            forever at the specified mailbox 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 Invalid event type*                            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 no message was received or you didn't pass the proper pointer to the*                            event control block.**********************************************************************************************************/void *OSMboxPend (OS_EVENT *pevent, INT16U timeout, INT8U *err){    void  *msg;    OS_ENTER_CRITICAL();    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */        OS_EXIT_CRITICAL();        *err = OS_ERR_EVENT_TYPE;        return ((void *)0);    }    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;    } else if (OSIntNesting > 0) {                    /* See if called from ISR ...                    */        OS_EXIT_CRITICAL();                           /* ... can't PEND from an ISR                    */        *err = OS_ERR_PEND_ISR;    } else {        OSTCBCur->OSTCBStat |= OS_STAT_MBOX;          /* Message not available, task will pend         */        OSTCBCur->OSTCBDly   = timeout;               /* Load timeout in TCB                           */        OSEventTaskWait(pevent);                      /* Suspend task until event or timeout occurs    */        OS_EXIT_CRITICAL();        OSSched();                                    /* Find next highest priority task ready to run  */        OS_ENTER_CRITICAL();        if ((msg = OSTCBCur->OSTCBMsg) != (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;        } else if (OSTCBCur->OSTCBStat & OS_STAT_MBOX) {   /* If status is not OS_STAT_RDY, timed out  */            OSEventTO(pevent);                             /* Make task ready                          */            OS_EXIT_CRITICAL();            msg                     = (void *)0;           /* Set message contents to NULL             */            *err                    = OS_TIMEOUT;          /* Indicate that a timeout occured          */        } else {            msg                     = pevent->OSEventPtr;  /* Message received                         */            pevent->OSEventPtr      = (void *)0;           /* Clear the mailbox                        */            OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;            OS_EXIT_CRITICAL();            *err                    = OS_NO_ERR;        }    }    return (msg);                                          /* Return the message received (or NULL)    */}/*$PAGE*//***********************************************************************************************************                                       POST MESSAGE TO A MAILBOX** Description: This function sends a message to a mailbox** Arguments  : pevent        is a pointer to the event control block associated with the desired mailbox**              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.  ** Returns    : OS_NO_ERR          The call was successful and the message was sent*              OS_MBOX_FULL       If the mailbox already contains a message.  You can can only send one*                                 message at a time and thus, the message MUST be consumed before you are*                                 allowed to send another one.*              OS_ERR_EVENT_TYPE  If you are attempting to post to a non mailbox.**********************************************************************************************************/INT8U OSMboxPost (OS_EVENT *pevent, void *msg){    OS_ENTER_CRITICAL();    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {  /* Validate event block type                     */        OS_EXIT_CRITICAL();        return (OS_ERR_EVENT_TYPE);    }    if (pevent->OSEventGrp) {                         /* See if any task pending on mailbox            */        OSEventTaskRdy(pevent, msg, OS_STAT_MBOX);    /* Ready highest priority task waiting on event  */        OS_EXIT_CRITICAL();        OSSched();                                    /* Find highest priority task ready to run       */        return (OS_NO_ERR);    } else {        if (pevent->OSEventPtr != (void *)0) {        /* Make sure mailbox doesn't already have a msg  */            OS_EXIT_CRITICAL();            return (OS_MBOX_FULL);        } else {            pevent->OSEventPtr = msg;                 /* Place message in mailbox                      */            OS_EXIT_CRITICAL();            return (OS_NO_ERR);        }    }}/*$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.**********************************************************************************************************/INT8U OSMboxQuery (OS_EVENT *pevent, OS_MBOX_DATA *pdata){    INT8U  i;    INT8U *psrc;    INT8U *pdest;            OS_ENTER_CRITICAL();    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {       /* Validate event block type                */        OS_EXIT_CRITICAL();        return (OS_ERR_EVENT_TYPE);    }    pdata->OSEventGrp = pevent->OSEventGrp;                /* Copy message mailbox wait list           */    psrc              = &pevent->OSEventTbl[0];    pdest             = &pdata->OSEventTbl[0];    for (i = 0; i < OS_EVENT_TBL_SIZE; i++) {        *pdest++ = *psrc++;       }    pdata->OSMsg = pevent->OSEventPtr;                     /* Get message from mailbox                 */    OS_EXIT_CRITICAL();    return (OS_NO_ERR);}#endif