os_sem.c

完整的ucos实例

    } 
} 
#endif 
 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                           PEND ON SEMAPHORE 
* 
* Description: This function waits for a semaphore. 
* 
* Arguments  : pevent        is a pointer to the event control block associated with the desired 
*                            semaphore. 
* 
*              timeout       is an optional timeout period (in clock ticks).  If non-zero, your task will 
*                            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; 
#endif     
 
 
    if (OSIntNesting > 0) {                           /* See if called from ISR ...                    */ 
        *err = OS_ERR_PEND_ISR;                       /* ... can't PEND from an ISR                    */ 
        return; 
    } 
#if OS_ARG_CHK_EN > 0 
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */ 
        *err = OS_ERR_PEVENT_NULL; 
        return; 
    } 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */ 
        *err = OS_ERR_EVENT_TYPE; 
        return; 
    } 
#endif 
    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->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->OSTCBStat & OS_STAT_SEM) {          /* Must have timed out if still waiting for event*/ 
        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;                                
#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_SEM) {        /* Validate event block type                */ 
        return (OS_ERR_EVENT_TYPE); 
    } 
#endif 
    OS_ENTER_CRITICAL(); 
    if (pevent->OSEventGrp != 0x00) {                      /* See if any task waiting for semaphore    */ 
        OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM);   /* Ready highest prio task waiting on event */ 
        OS_EXIT_CRITICAL(); 
        OS_Sched();                                        /* Find highest priority task ready to run  */ 
        return (OS_NO_ERR); 
    } 
    if (pevent->OSEventCnt < 65535) {                 /* 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 
* 
*              pdata         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. 
********************************************************************************************************* 
*/ 
 
#if OS_SEM_QUERY_EN > 0 
INT8U  OSSemQuery (OS_EVENT *pevent, OS_SEM_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_SEM) {        /* 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->OSCnt      = pevent->OSEventCnt;                /* Get semaphore count                      */ 
    OS_EXIT_CRITICAL(); 
    return (OS_NO_ERR); 
} 
#endif                                                     /* OS_SEM_QUERY_EN                          */ 
#endif                                                     /* OS_SEM_EN                                */