www.pudn.com > ucos.rar > os_sem.c, change:2010-06-03,size:29519b


/* 
********************************************************************************************************* 
*                                                uC/OS-II 
*                                          The Real-Time Kernel 
*                                          SEMAPHORE MANAGEMENT 
* 
*                              (c) Copyright 1992-2009, Micrium, Weston, FL 
*                                           All Rights Reserved 
* 
* File    : OS_SEM.C 
* By      : Jean J. Labrosse 
* Version : V2.91 
* 
* LICENSING TERMS: 
* --------------- 
*   uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research. 
* If you plan on using  uC/OS-II  in a commercial product you need to contact Micriµm to properly license 
* its use in your product. We provide ALL the source code for your convenience and to help you experience 
* uC/OS-II.   The fact that the  source is provided does  NOT  mean that you can use it without  paying a 
* licensing fee. 
********************************************************************************************************* 
*/ 
 
#ifndef  OS_MASTER_FILE 
#include <ucos_ii.h> 
#endif 
 
#if OS_SEM_EN > 0u 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                           ACCEPT SEMAPHORE 
* 
* Description: This function checks the semaphore to see if a resource is available or, if an event 
*              occurred.  Unlike OSSemPend(), OSSemAccept() does not suspend the calling task if the 
*              resource is not available or the event did not occur. 
* 
* Arguments  : pevent     is a pointer to the event control block 
* 
* Returns    : >  0       if the resource is available or the event did not occur the semaphore is 
*                         decremented to obtain the resource. 
*              == 0       if the resource is not available or the event did not occur or, 
*                         if 'pevent' is a NULL pointer or, 
*                         if you didn't pass a pointer to a semaphore 
********************************************************************************************************* 
*/ 
 
#if OS_SEM_ACCEPT_EN > 0u 
INT16U  OSSemAccept (OS_EVENT *pevent) 
{ 
    INT16U     cnt; 
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#if OS_ARG_CHK_EN > 0u 
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */ 
        return (0u); 
    } 
#endif 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */ 
        return (0u); 
    } 
    OS_ENTER_CRITICAL(); 
    cnt = pevent->OSEventCnt; 
    if (cnt > 0u) {                                   /* See if resource is available                  */ 
        pevent->OSEventCnt--;                         /* Yes, decrement semaphore and notify caller    */ 
    } 
    OS_EXIT_CRITICAL(); 
    return (cnt);                                     /* Return semaphore count                        */ 
} 
#endif 
 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                           CREATE A SEMAPHORE 
* 
* Description: This function creates a semaphore. 
* 
* Arguments  : cnt           is the initial value for the semaphore.  If the value is 0, no resource is 
*                            available (or no event has occurred).  You initialize the semaphore to a 
*                            non-zero value to specify how many resources are available (e.g. if you have 
*                            10 resources, you would initialize the semaphore to 10). 
* 
* Returns    : != (void *)0  is a pointer to the event control block (OS_EVENT) associated with the 
*                            created semaphore 
*              == (void *)0  if no event control blocks were available 
********************************************************************************************************* 
*/ 
 
OS_EVENT  *OSSemCreate (INT16U cnt) 
{ 
    OS_EVENT  *pevent; 
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#ifdef OS_SAFETY_CRITICAL_IEC61508 
    if (OSSafetyCriticalStartFlag == OS_TRUE) { 
        OS_SAFETY_CRITICAL_EXCEPTION(); 
    } 
#endif 
 
    if (OSIntNesting > 0u) {                               /* See if called from ISR ...               */ 
        return ((OS_EVENT *)0);                            /* ... can't CREATE from an ISR             */ 
    } 
    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                      */ 
        pevent->OSEventPtr     = (void *)0;                /* Unlink from ECB free list                */ 
#if OS_EVENT_NAME_EN > 0u 
        pevent->OSEventName    = (INT8U *)(void *)"?"; 
#endif 
        OS_EventWaitListInit(pevent);                      /* Initialize to 'nobody waiting' on sem.   */ 
    } 
    return (pevent); 
} 
 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                         DELETE A SEMAPHORE 
* 
* Description: This function deletes a semaphore and readies all tasks pending on the semaphore. 
* 
* Arguments  : pevent        is a pointer to the event control block associated with the desired 
*                            semaphore. 
* 
*              opt           determines delete options as follows: 
*                            opt == OS_DEL_NO_PEND   Delete semaphore ONLY if no task pending 
*                            opt == OS_DEL_ALWAYS    Deletes the semaphore even if tasks are waiting. 
*                                                    In this case, all the tasks pending will be readied. 
* 
*              perr          is a pointer to an error code that can contain one of the following values: 
*                            OS_ERR_NONE             The call was successful and the semaphore was deleted 
*                            OS_ERR_DEL_ISR          If you attempted to delete the semaphore from an ISR 
*                            OS_ERR_INVALID_OPT      An invalid option was specified 
*                            OS_ERR_TASK_WAITING     One or more tasks were waiting on the semaphore 
*                            OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a semaphore 
*                            OS_ERR_PEVENT_NULL      If 'pevent' is a NULL pointer. 
* 
* Returns    : pevent        upon error 
*              (OS_EVENT *)0 if the semaphore was successfully deleted. 
* 
* Note(s)    : 1) This function must be used with care.  Tasks that would normally expect the presence of 
*                 the semaphore MUST check the return code of OSSemPend(). 
*              2) OSSemAccept() callers will not know that the intended semaphore has been deleted unless 
*                 they check 'pevent' to see that it's a NULL pointer. 
*              3) This call can potentially disable interrupts for a long time.  The interrupt disable 
*                 time is directly proportional to the number of tasks waiting on the semaphore. 
*              4) Because ALL tasks pending on the semaphore will be readied, you MUST be careful in 
*                 applications where the semaphore is used for mutual exclusion because the resource(s) 
*                 will no longer be guarded by the semaphore. 
********************************************************************************************************* 
*/ 
 
#if OS_SEM_DEL_EN > 0u 
OS_EVENT  *OSSemDel (OS_EVENT  *pevent, 
                     INT8U      opt, 
                     INT8U     *perr) 
{ 
    BOOLEAN    tasks_waiting; 
    OS_EVENT  *pevent_return; 
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#ifdef OS_SAFETY_CRITICAL 
    if (perr == (INT8U *)0) { 
        OS_SAFETY_CRITICAL_EXCEPTION(); 
    } 
#endif 
 
#if OS_ARG_CHK_EN > 0u 
    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */ 
        *perr = OS_ERR_PEVENT_NULL; 
        return (pevent); 
    } 
#endif 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {        /* Validate event block type                */ 
        *perr = OS_ERR_EVENT_TYPE; 
        return (pevent); 
    } 
    if (OSIntNesting > 0u) {                               /* See if called from ISR ...               */ 
        *perr = OS_ERR_DEL_ISR;                            /* ... can't DELETE from an ISR             */ 
        return (pevent); 
    } 
    OS_ENTER_CRITICAL(); 
    if (pevent->OSEventGrp != 0u) {                        /* See if any tasks waiting on semaphore    */ 
        tasks_waiting = OS_TRUE;                           /* Yes                                      */ 
    } else { 
        tasks_waiting = OS_FALSE;                          /* No                                       */ 
    } 
    switch (opt) { 
        case OS_DEL_NO_PEND:                               /* Delete semaphore only if no task waiting */ 
             if (tasks_waiting == OS_FALSE) { 
#if OS_EVENT_NAME_EN > 0u 
                 pevent->OSEventName    = (INT8U *)(void *)"?"; 
#endif 
                 pevent->OSEventType    = OS_EVENT_TYPE_UNUSED; 
                 pevent->OSEventPtr     = OSEventFreeList; /* Return Event Control Block to free list  */ 
                 pevent->OSEventCnt     = 0u; 
                 OSEventFreeList        = pevent;          /* Get next free event control block        */ 
                 OS_EXIT_CRITICAL(); 
                 *perr                  = OS_ERR_NONE; 
                 pevent_return          = (OS_EVENT *)0;   /* Semaphore has been deleted               */ 
             } else { 
                 OS_EXIT_CRITICAL(); 
                 *perr                  = OS_ERR_TASK_WAITING; 
                 pevent_return          = pevent; 
             } 
             break; 
 
        case OS_DEL_ALWAYS:                                /* Always delete the semaphore              */ 
             while (pevent->OSEventGrp != 0u) {            /* Ready ALL tasks waiting for semaphore    */ 
                 (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_OK); 
             } 
#if OS_EVENT_NAME_EN > 0u 
             pevent->OSEventName    = (INT8U *)(void *)"?"; 
#endif 
             pevent->OSEventType    = OS_EVENT_TYPE_UNUSED; 
             pevent->OSEventPtr     = OSEventFreeList;     /* Return Event Control Block to free list  */ 
             pevent->OSEventCnt     = 0u; 
             OSEventFreeList        = pevent;              /* Get next free event control block        */ 
             OS_EXIT_CRITICAL(); 
             if (tasks_waiting == OS_TRUE) {               /* Reschedule only if task(s) were waiting  */ 
                 OS_Sched();                               /* Find highest priority task ready to run  */ 
             } 
             *perr                  = OS_ERR_NONE; 
             pevent_return          = (OS_EVENT *)0;       /* Semaphore has been deleted               */ 
             break; 
 
        default: 
             OS_EXIT_CRITICAL(); 
             *perr                  = OS_ERR_INVALID_OPT; 
             pevent_return          = pevent; 
             break; 
    } 
    return (pevent_return); 
} 
#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). 
* 
*              perr          is a pointer to where an error message will be deposited.  Possible error 
*                            messages are: 
* 
*                            OS_ERR_NONE         The call was successful and your task owns the resource 
*                                                or, the event you are waiting for occurred. 
*                            OS_ERR_TIMEOUT      The semaphore was not received within the specified 
*                                                'timeout'. 
*                            OS_ERR_PEND_ABORT   The wait on the semaphore was aborted. 
*                            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. 
*                            OS_ERR_PEND_LOCKED  If you called this function when the scheduler is locked 
* 
* Returns    : none 
********************************************************************************************************* 
*/ 
/*$PAGE*/ 
void  OSSemPend (OS_EVENT  *pevent, 
                 INT32U     timeout, 
                 INT8U     *perr) 
{ 
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#ifdef OS_SAFETY_CRITICAL 
    if (perr == (INT8U *)0) { 
        OS_SAFETY_CRITICAL_EXCEPTION(); 
    } 
#endif 
 
#if OS_ARG_CHK_EN > 0u 
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */ 
        *perr = OS_ERR_PEVENT_NULL; 
        return; 
    } 
#endif 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */ 
        *perr = OS_ERR_EVENT_TYPE; 
        return; 
    } 
    if (OSIntNesting > 0u) {                          /* See if called from ISR ...                    */ 
        *perr = OS_ERR_PEND_ISR;                      /* ... can't PEND from an ISR                    */ 
        return; 
    } 
    if (OSLockNesting > 0u) {                         /* See if called with scheduler locked ...       */ 
        *perr = OS_ERR_PEND_LOCKED;                   /* ... can't PEND when locked                    */ 
        return; 
    } 
    OS_ENTER_CRITICAL(); 
    if (pevent->OSEventCnt > 0u) {                    /* If sem. is positive, resource available ...   */ 
        pevent->OSEventCnt--;                         /* ... decrement semaphore only if positive.     */ 
        OS_EXIT_CRITICAL(); 
        *perr = OS_ERR_NONE; 
        return; 
    } 
                                                      /* Otherwise, must wait until event occurs       */ 
    OSTCBCur->OSTCBStat     |= OS_STAT_SEM;           /* Resource not available, pend on semaphore     */ 
    OSTCBCur->OSTCBStatPend  = OS_STAT_PEND_OK; 
    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(); 
    switch (OSTCBCur->OSTCBStatPend) {                /* See if we timed-out or aborted                */ 
        case OS_STAT_PEND_OK: 
             *perr = OS_ERR_NONE; 
             break; 
 
        case OS_STAT_PEND_ABORT: 
             *perr = OS_ERR_PEND_ABORT;               /* Indicate that we aborted                      */ 
             break; 
 
        case OS_STAT_PEND_TO: 
        default: 
             OS_EventTaskRemove(OSTCBCur, pevent); 
             *perr = OS_ERR_TIMEOUT;                  /* Indicate that we didn't get event within TO   */ 
             break; 
    } 
    OSTCBCur->OSTCBStat          =  OS_STAT_RDY;      /* Set   task  status to ready                   */ 
    OSTCBCur->OSTCBStatPend      =  OS_STAT_PEND_OK;  /* Clear pend  status                            */ 
    OSTCBCur->OSTCBEventPtr      = (OS_EVENT  *)0;    /* Clear event pointers                          */ 
#if (OS_EVENT_MULTI_EN > 0u) 
    OSTCBCur->OSTCBEventMultiPtr = (OS_EVENT **)0; 
#endif 
    OS_EXIT_CRITICAL(); 
} 
 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                      ABORT WAITING ON A SEMAPHORE 
* 
* Description: This function aborts & readies any tasks currently waiting on a semaphore.  This function 
*              should be used to fault-abort the wait on the semaphore, rather than to normally signal 
*              the semaphore via OSSemPost(). 
* 
* Arguments  : pevent        is a pointer to the event control block associated with the desired 
*                            semaphore. 
* 
*              opt           determines the type of ABORT performed: 
*                            OS_PEND_OPT_NONE         ABORT wait for a single task (HPT) waiting on the 
*                                                     semaphore 
*                            OS_PEND_OPT_BROADCAST    ABORT wait for ALL tasks that are  waiting on the 
*                                                     semaphore 
* 
*              perr          is a pointer to where an error message will be deposited.  Possible error 
*                            messages are: 
* 
*                            OS_ERR_NONE         No tasks were     waiting on the semaphore. 
*                            OS_ERR_PEND_ABORT   At least one task waiting on the semaphore was readied 
*                                                and informed of the aborted wait; check return value 
*                                                for the number of tasks whose wait on the semaphore 
*                                                was aborted. 
*                            OS_ERR_EVENT_TYPE   If you didn't pass a pointer to a semaphore. 
*                            OS_ERR_PEVENT_NULL  If 'pevent' is a NULL pointer. 
* 
* Returns    : == 0          if no tasks were waiting on the semaphore, or upon error. 
*              >  0          if one or more tasks waiting on the semaphore are now readied and informed. 
********************************************************************************************************* 
*/ 
 
#if OS_SEM_PEND_ABORT_EN > 0u 
INT8U  OSSemPendAbort (OS_EVENT  *pevent, 
                       INT8U      opt, 
                       INT8U     *perr) 
{ 
    INT8U      nbr_tasks; 
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#ifdef OS_SAFETY_CRITICAL 
    if (perr == (INT8U *)0) { 
        OS_SAFETY_CRITICAL_EXCEPTION(); 
    } 
#endif 
 
#if OS_ARG_CHK_EN > 0u 
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */ 
        *perr = OS_ERR_PEVENT_NULL; 
        return (0u); 
    } 
#endif 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */ 
        *perr = OS_ERR_EVENT_TYPE; 
        return (0u); 
    } 
    OS_ENTER_CRITICAL(); 
    if (pevent->OSEventGrp != 0u) {                   /* See if any task waiting on semaphore?         */ 
        nbr_tasks = 0u; 
        switch (opt) { 
            case OS_PEND_OPT_BROADCAST:               /* Do we need to abort ALL waiting tasks?        */ 
                 while (pevent->OSEventGrp != 0u) {   /* Yes, ready ALL tasks waiting on semaphore     */ 
                     (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_ABORT); 
                     nbr_tasks++; 
                 } 
                 break; 
 
            case OS_PEND_OPT_NONE: 
            default:                                  /* No,  ready HPT       waiting on semaphore     */ 
                 (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_ABORT); 
                 nbr_tasks++; 
                 break; 
        } 
        OS_EXIT_CRITICAL(); 
        OS_Sched();                                   /* Find HPT ready to run                         */ 
        *perr = OS_ERR_PEND_ABORT; 
        return (nbr_tasks); 
    } 
    OS_EXIT_CRITICAL(); 
    *perr = OS_ERR_NONE; 
    return (0u);                                      /* No tasks waiting on semaphore                 */ 
} 
#endif 
 
/*$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_ERR_NONE         The call was successful and the semaphore was signaled. 
*              OS_ERR_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 == 3u                          /* Allocate storage for CPU status register      */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#if OS_ARG_CHK_EN > 0u 
    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 != 0u) {                   /* See if any task waiting for semaphore         */ 
                                                      /* Ready HPT waiting on event                    */ 
        (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_SEM, OS_STAT_PEND_OK); 
        OS_EXIT_CRITICAL(); 
        OS_Sched();                                   /* Find HPT ready to run                         */ 
        return (OS_ERR_NONE); 
    } 
    if (pevent->OSEventCnt < 65535u) {                /* Make sure semaphore will not overflow         */ 
        pevent->OSEventCnt++;                         /* Increment semaphore count to register event   */ 
        OS_EXIT_CRITICAL(); 
        return (OS_ERR_NONE); 
    } 
    OS_EXIT_CRITICAL();                               /* Semaphore value has reached its maximum       */ 
    return (OS_ERR_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_ERR_NONE         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 > 0u 
INT8U  OSSemQuery (OS_EVENT     *pevent, 
                   OS_SEM_DATA  *p_sem_data) 
{ 
    INT8U       i; 
    OS_PRIO    *psrc; 
    OS_PRIO    *pdest; 
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */ 
    OS_CPU_SR   cpu_sr = 0u; 
#endif 
 
 
 
#if OS_ARG_CHK_EN > 0u 
    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 = 0u; i < OS_EVENT_TBL_SIZE; i++) { 
        *pdest++ = *psrc++; 
    } 
    p_sem_data->OSCnt = pevent->OSEventCnt;                /* Get semaphore count                      */ 
    OS_EXIT_CRITICAL(); 
    return (OS_ERR_NONE); 
} 
#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. 
* 
*              perr       is a pointer to an error code returned by the function as follows: 
* 
*                            OS_ERR_NONE          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 > 0u 
void  OSSemSet (OS_EVENT  *pevent, 
                INT16U     cnt, 
                INT8U     *perr) 
{ 
#if OS_CRITICAL_METHOD == 3u                          /* Allocate storage for CPU status register      */ 
    OS_CPU_SR  cpu_sr = 0u; 
#endif 
 
 
 
#ifdef OS_SAFETY_CRITICAL 
    if (perr == (INT8U *)0) { 
        OS_SAFETY_CRITICAL_EXCEPTION(); 
    } 
#endif 
 
#if OS_ARG_CHK_EN > 0u 
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */ 
        *perr = OS_ERR_PEVENT_NULL; 
        return; 
    } 
#endif 
    if (pevent->OSEventType != OS_EVENT_TYPE_SEM) {   /* Validate event block type                     */ 
        *perr = OS_ERR_EVENT_TYPE; 
        return; 
    } 
    OS_ENTER_CRITICAL(); 
    *perr = OS_ERR_NONE; 
    if (pevent->OSEventCnt > 0u) {                    /* See if semaphore already has a count          */ 
        pevent->OSEventCnt = cnt;                     /* Yes, set it to the new value specified.       */ 
    } else {                                          /* No                                            */ 
        if (pevent->OSEventGrp == 0u) {               /*      See if task(s) waiting?                  */ 
            pevent->OSEventCnt = cnt;                 /*      No, OK to set the value                  */ 
        } else { 
            *perr              = OS_ERR_TASK_WAITING; 
        } 
    } 
    OS_EXIT_CRITICAL(); 
} 
#endif 
 
#endif                                                /* OS_SEM_EN                                     */