os_sem.c

操作系统ucosii的源码

*                            wait for the resource up to the amount of time specified by this argument.
*                            If you specify 0, however, your task will wait forever at the specified
*                            semaphore or, until the resource becomes available (or the event occurs).
*
*              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 owns the resource
*                                                or, the event you are waiting for occurred.
*                            OS_TIMEOUT          The semaphore was not received within the specified
*                                                timeout.
*                            OS_ERR_EVENT_TYPE   If you didn't pass a pointer to a semaphore.
*                            OS_ERR_PEND_ISR     If you called this function from an ISR and the result
*                                                would lead to a suspension.
*                            OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer.
*
* Returns    : none
*********************************************************************************************************
*/

void  OSSemPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
#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;
    }
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        *err = OS_ERR_PEVENT_NULL;
        return;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */
        *err = OS_ERR_EVENT_TYPE;
        return;
    }
    if (OSIntNesting > 0) {                           /* See if called from ISR ...                    */
        *err = OS_ERR_PEND_ISR;                       /* ... can't PEND from an ISR                    */
        return;
    }
    if (OSLockNesting > 0) {                          /* See if called with scheduler locked ...       */
        *err = OS_ERR_PEND_LOCKED;                    /* ... can't PEND when locked                    */
        return;
    }
    OS_ENTER_CRITICAL();
    if (pevent->OSEventCnt > 0) {                     /* If sem. is positive, resource available ...   */
        pevent->OSEventCnt--;                         /* ... decrement semaphore only if positive.     */
        OS_EXIT_CRITICAL();
        *err = OS_NO_ERR;
        return;
    }
                                                      /* Otherwise, must wait until event occurs       */
    OSTCBCur->OSTCBStat   |= OS_STAT_SEM;             /* Resource not available, pend on semaphore     */
    OSTCBCur->OSTCBPendTO  = OS_FALSE;
    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();
    if (OSTCBCur->OSTCBPendTO == OS_TRUE) {           /* See if we timedout                            */
        OS_EventTO(pevent);
        OS_EXIT_CRITICAL();
        *err = OS_TIMEOUT;                            /* Indicate that didn't get event within TO      */
        return;
    }
    OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                         POST TO A SEMAPHORE
*
* Description: This function signals a semaphore
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired
*                            semaphore.
*
* Returns    : OS_NO_ERR           The call was successful and the semaphore was signaled.
*              OS_SEM_OVF          If the semaphore count exceeded its limit.  In other words, you have
*                                  signalled the semaphore more often than you waited on it with either
*                                  OSSemAccept() or OSSemPend().
*              OS_ERR_EVENT_TYPE   If you didn't pass a pointer to a semaphore
*              OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer.
*********************************************************************************************************
*/

INT8U  OSSemPost (OS_EVENT *pevent)
{
#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_SEM) {        /* Validate event block type                */
        return (OS_ERR_EVENT_TYPE);
    }
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0) {                             /* See if any task waiting for semaphore*/
        (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM); /* Ready HPT waiting on event           */
        OS_EXIT_CRITICAL();
        OS_Sched();                                            /* Find HPT ready to run                */
        return (OS_NO_ERR);
    }
    if (pevent->OSEventCnt < 65535u) {                /* Make sure semaphore will not overflow         */
        pevent->OSEventCnt++;                         /* Increment semaphore count to register event   */
        OS_EXIT_CRITICAL();
        return (OS_NO_ERR);
    }
    OS_EXIT_CRITICAL();                               /* Semaphore value has reached its maximum       */
    return (OS_SEM_OVF);
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                          QUERY A SEMAPHORE
*
* Description: This function obtains information about a semaphore
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired
*                            semaphore
*
*              p_sem_data    is a pointer to a structure that will contain information about the
*                            semaphore.
*
* 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 semaphore.
*              OS_ERR_PEVENT_NULL  If 'pevent'     is a NULL pointer.
*              OS_ERR_PDATA_NULL   If 'p_sem_data' is a NULL pointer
*********************************************************************************************************
*/

#if OS_SEM_QUERY_EN > 0
INT8U  OSSemQuery (OS_EVENT *pevent, OS_SEM_DATA *p_sem_data)
{
#if OS_LOWEST_PRIO <= 63
    INT8U     *psrc;
    INT8U     *pdest;
#else
    INT16U    *psrc;
    INT16U    *pdest;
#endif
    INT8U      i;
#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 (p_sem_data == (OS_SEM_DATA *)0) {                  /* Validate 'p_sem_data'                    */
        return (OS_ERR_PDATA_NULL);
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {        /* Validate event block type                */
        return (OS_ERR_EVENT_TYPE);
    }
    OS_ENTER_CRITICAL();
    p_sem_data->OSEventGrp = pevent->OSEventGrp;           /* Copy message mailbox wait list           */
    psrc                   = &pevent->OSEventTbl[0];
    pdest                  = &p_sem_data->OSEventTbl[0];
    for (i = 0; i < OS_EVENT_TBL_SIZE; i++) {
        *pdest++ = *psrc++;
    }
    p_sem_data->OSCnt = pevent->OSEventCnt;                /* Get semaphore count                      */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif                                                     /* OS_SEM_QUERY_EN                          */

/*$PAGE*/
/*
*********************************************************************************************************
*                                              SET SEMAPHORE
*
* Description: This function sets the semaphore count to the value specified as an argument.  Typically,
*              this value would be 0.
*
*              You would typically use this function when a semaphore is used as a signaling mechanism
*              and, you want to reset the count value.
*
* Arguments  : pevent     is a pointer to the event control block
*
*              cnt        is the new value for the semaphore count.  You would pass 0 to reset the
*                         semaphore count.
*
*              err        is a pointer to an error code returned by the function as follows:
*
*                            OS_NO_ERR            The call was successful and the semaphore value was set.
*                            OS_ERR_EVENT_TYPE    If you didn't pass a pointer to a semaphore.
*                            OS_ERR_PEVENT_NULL   If 'pevent' is a NULL pointer.
*                            OS_ERR_TASK_WAITING  If tasks are waiting on the semaphore.
*********************************************************************************************************
*/

#if OS_SEM_SET_EN > 0
void  OSSemSet (OS_EVENT *pevent, INT16U cnt, INT8U *err)
{
#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;
    }
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        *err = OS_ERR_PEVENT_NULL;
        return;
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */
        *err = OS_ERR_EVENT_TYPE;
        return;
    }
    OS_ENTER_CRITICAL();
    *err = OS_NO_ERR;
    if (pevent->OSEventCnt > 0) {                     /* See if semaphore already has a count          */
        pevent->OSEventCnt = cnt;                     /* Yes, set it to the new value specified.       */
    } else {                                          /* No                                            */
        if (pevent->OSEventGrp == 0) {                /*      See if task(s) waiting?                  */
            pevent->OSEventCnt = cnt;                 /*      No, OK to set the value                  */
        } else {
            *err               = OS_ERR_TASK_WAITING;
        }
    }
    OS_EXIT_CRITICAL();
}
#endif

#endif                                                /* OS_SEM_EN                                     */