os_sem.c

DSP RTOS源代码

#ifndef  OS_MASTER_FILE
#include "..\EX1\includes.h"
#endif

#if OS_SEM_EN

INT16U OSSemAccept (OS_EVENT *pevent)
{
    INT16U cnt;


    OS_ENTER_CRITICAL();
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */
        OS_EXIT_CRITICAL();
        return (0);
    }
    cnt = pevent->OSEventCnt;
    if (cnt > 0) {                                    /* See if resource is available                  */
        pevent->OSEventCnt--;                         /* Yes, decrement semaphore and notify caller    */
    }
    OS_EXIT_CRITICAL();
    return (cnt);                                     /* Return semaphore count                        */
}


OS_EVENT *OSSemCreate (INT16U cnt)
{
    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) {                         /* Get an event control block               */
        pevent->OSEventType = OS_EVENT_TYPE_SEM;
        pevent->OSEventCnt  = cnt;                         /* Set semaphore value                      */
        OSEventWaitListInit(pevent);
    }
    return (pevent);
}

void OSSemPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
    OS_ENTER_CRITICAL();
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */
        OS_EXIT_CRITICAL();
        *err = OS_ERR_EVENT_TYPE;
    }
    if (pevent->OSEventCnt > 0) {                     /* If sem. is positive, resource available ...   */
        pevent->OSEventCnt--;                         /* ... decrement semaphore only if positive.     */
        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 {                                          /* 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                     */
        OSEventTaskWait(pevent);                      /* Suspend task until event or timeout occurs    */
        OS_EXIT_CRITICAL();
        OSSched();                                    /* Find next highest priority task ready         */
        OS_ENTER_CRITICAL();
        if (OSTCBCur->OSTCBStat & OS_STAT_SEM) {      /* Must have timed out if still waiting for event*/
            OSEventTO(pevent);
            OS_EXIT_CRITICAL();
            *err = OS_TIMEOUT;                        /* Indicate that didn't get event within TO      */
        } else {
            OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;
            OS_EXIT_CRITICAL();
            *err = OS_NO_ERR;
        }
    }
}

INT8U OSSemPost (OS_EVENT *pevent)
{
    OS_ENTER_CRITICAL();
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {        /* Validate event block type                */
        OS_EXIT_CRITICAL();
        return (OS_ERR_EVENT_TYPE);
    }
    if (pevent->OSEventGrp) {                              /* See if any task waiting for semaphore    */
        OSEventTaskRdy(pevent, (void *)0, OS_STAT_SEM);    /* Ready highest prio task waiting on event */
        OS_EXIT_CRITICAL();
        OSSched();                                    /* Find highest priority task ready to run       */
        return (OS_NO_ERR);
    } else {
        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);
        } else {                                      /* Semaphore value has reached its maximum       */
            OS_EXIT_CRITICAL();
            return (OS_SEM_OVF);
        }
    }
}

INT8U OSSemQuery (OS_EVENT *pevent, OS_SEM_DATA *pdata)
{
    INT8U  i;
    INT8U *psrc;
    INT8U *pdest;
    
    
    OS_ENTER_CRITICAL();
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {        /* 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->OSCnt      = pevent->OSEventCnt;                /* Get semaphore count                      */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif