os_mutex.c

avr ucos 代码 测试环境：source insight WINAVR 4个进程

        if (rdy == TRUE) {                                 /* If task was ready at owner's priority ...*/
			//确定占用mutex的任务是否应在PIP优先级上进入就绪态
            OSRdyGrp               |= ptcb->OSTCBBitY;     /* ... make it ready at new priority.       */
            OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX;//保证在新优先级上就绪
        }
        OSTCBPrioTbl[pip]       = (OS_TCB *)ptcb;
    }
    OSTCBCur->OSTCBStat |= OS_STAT_MUTEX;             /* Mutex not available, pend current task        */
	//为了让调用本函数的任务进入休眠态，就将任务的TCB置位，表明等待的任务已经挂起
    OSTCBCur->OSTCBDly   = timeout;                   /* Store timeout in current task's TCB           */
	//保存超时时间
    OS_EventTaskWait(pevent);                         /* Suspend task until event or timeout occurs    */
	//挂起任务直到超时或者事件发生
    OS_EXIT_CRITICAL();
    OS_Sched();                                        /* Find next highest priority task ready         */
	//找另一优先级最高任务运行
    OS_ENTER_CRITICAL();
    if (OSTCBCur->OSTCBStat & OS_STAT_MUTEX) {        /* Must have timed out if still waiting for event*/
		//看是否还在等待mutex，如果还在等待，说明一定是没有从OSMutexPost()
      //中得到mutex，而是由于OSTimeTick（）函数进入就绪态，出现等待超时
        OS_EventTO(pevent);//让等待超时的任务运行
        OS_EXIT_CRITICAL();
        *err = OS_TIMEOUT;                            /* Indicate that we didn't get mutex within TO   */
        return;
    }
    OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0;//释放事件控制块指针
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                  POST TO A MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function signals a mutual exclusion semaphore
*
* Arguments  : pevent              is a pointer to the event control block associated with the desired
*                                  mutex.
*
* Returns    : OS_NO_ERR               The call was successful and the mutex was signaled.
*              OS_ERR_EVENT_TYPE       If you didn't pass a pointer to a mutex
*              OS_ERR_PEVENT_NULL      'pevent' is a NULL pointer
*              OS_ERR_POST_ISR         Attempted to post from an ISR (not valid for MUTEXes)
*              OS_ERR_NOT_MUTEX_OWNER  The task that did the post is NOT the owner of the MUTEX.
                                          释放一个互斥型信号量
描述：释放一个互斥型信号量
参数：pevent：指向事件控制块结合目标mutex的指针
返回：OS_NO_ERR               调用成功，mutex成功释放
*              OS_ERR_EVENT_TYPE       如果没有传递指针到mutex
*              OS_ERR_PEVENT_NULL      'pevent' 是空指针
*              OS_ERR_POST_ISR        想从ISR中释放
*              OS_ERR_NOT_MUTEX_OWNER  想释放的任务并没有占有此mutex
*********************************************************************************************************
*/

INT8U  OSMutexPost (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3                           /* Allocate storage for CPU status register      */
    OS_CPU_SR  cpu_sr;
#endif    
    INT8U      pip;                                   /* Priority inheritance priority                 */
//优先级继承优先级
    INT8U      prio;


    if (OSIntNesting > 0) {                           /* See if called from ISR ...                    */
        return (OS_ERR_POST_ISR);                     /* ... can't POST mutex from an ISR              */
    }
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }                                                 
#endif
    OS_ENTER_CRITICAL();
    pip  = (INT8U)(pevent->OSEventCnt >> 8);          /* Get priority inheritance priority of mutex    */
	//得到PIP的优先级值
    prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);  /* Get owner's original priority      */
	//得到占有任务的原始优先级
    if (OSTCBCur->OSTCBPrio != pip && 
        OSTCBCur->OSTCBPrio != prio) {                /* See if posting task owns the MUTEX            */
        //看看释放的任务是否占有此mutex
        OS_EXIT_CRITICAL();
        return (OS_ERR_NOT_MUTEX_OWNER);
    }
    if (OSTCBCur->OSTCBPrio == pip) {                 /* Did we have to raise current task's priority? */
                                                      /* Yes, Return to original priority              */
                                                      /*      Remove owner from ready list at 'pip'    */
        if ((OSRdyTbl[OSTCBCur->OSTCBY] &= ~OSTCBCur->OSTCBBitX) == 0) {
//将调用本函数的任务从任务就绪表中PIP位置删去，放回任务就绪表原来的优先
//级位置上。原来任务优先级的TCB将被重新处置
            OSRdyGrp &= ~OSTCBCur->OSTCBBitY;
        }
        OSTCBCur->OSTCBPrio         = prio;
        OSTCBCur->OSTCBY            = prio >> 3;
        OSTCBCur->OSTCBBitY         = OSMapTbl[OSTCBCur->OSTCBY];
        OSTCBCur->OSTCBX            = prio & 0x07;
        OSTCBCur->OSTCBBitX         = OSMapTbl[OSTCBCur->OSTCBX];
        OSRdyGrp                   |= OSTCBCur->OSTCBBitY;
        OSRdyTbl[OSTCBCur->OSTCBY] |= OSTCBCur->OSTCBBitX;
        OSTCBPrioTbl[prio]          = (OS_TCB *)OSTCBCur;
    }
    OSTCBPrioTbl[pip] = (OS_TCB *)1;                  /* Reserve table entry                           */
	//保留入口
    if (pevent->OSEventGrp != 0x00) {                 /* Any task waiting for the mutex?               */
                                                      /* Yes, Make HPT waiting for mutex ready         */
	//是的，让等待的高优先级任务就绪
        prio                = OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX);
        pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8;  /*      Save priority of mutex's new owner       */
		//保存新占有者的优先级
        pevent->OSEventCnt |= prio;//新的占有mutex任务的优先级保存在mutex的ECB中
        pevent->OSEventPtr  = OSTCBPrioTbl[prio];     /*      Link to mutex owner's OS_TCB             */
		//加到单向链表中去
        OS_EXIT_CRITICAL();
        OS_Sched();                                   /*      Find highest priority task ready to run  */
		//任务调度
        return (OS_NO_ERR);
    }
    pevent->OSEventCnt |= OS_MUTEX_AVAILABLE;         /* No,  Mutex is now available                   */
    pevent->OSEventPtr  = (void *)0;
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                     QUERY A MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function obtains information about a mutex
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired mutex
*
*              pdata         is a pointer to a structure that will contain information about the mutex
*
* Returns    : OS_NO_ERR            The call was successful and the message was sent
*              OS_ERR_QUERY_ISR     If you called this function from an ISR
*              OS_ERR_PEVENT_NULL   'pevent' is a NULL pointer
*              OS_ERR_EVENT_TYPE    If you are attempting to obtain data from a non mutex.
                                                获取互斥型信号量的当前状态
描述： 获取互斥型信号量的当前状态
参数：pevent：指向事件控制块结合目标mutex的指针
                 pdata：指向包含mutex信息的结构指针
*********************************************************************************************************
*/

#if OS_MUTEX_QUERY_EN > 0
INT8U  OSMutexQuery (OS_EVENT *pevent, OS_MUTEX_DATA *pdata)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif    
    INT8U     *psrc;
    INT8U     *pdest;


    if (OSIntNesting > 0) {                                /* See if called from ISR ...               */
        return (OS_ERR_QUERY_ISR);                         /* ... can't QUERY mutex from an ISR        */
    }//不能从ISR中调用
#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                         /* Validate 'pevent'                        */
        return (OS_ERR_PEVENT_NULL);
    }//非法的pevent
    if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) {      /* Validate event block type                */
        return (OS_ERR_EVENT_TYPE);
    }//非法的事件控制块类型
#endif
    OS_ENTER_CRITICAL();
    pdata->OSMutexPIP  = (INT8U)(pevent->OSEventCnt >> 8);//将相应的参数传给OS_MUTE_DATA,mutex的PIP
//由OSEnentCnt的高八位得到。
    pdata->OSOwnerPrio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8);
    if (pdata->OSOwnerPrio == 0xFF) {
        pdata->OSValue = 1;//从.OSEventCnt的低八位得到mutex的值，如果mutex有效（低八位是0XFF）.
       //将mutex的值设为一
    } else {//否则设置为零
        pdata->OSValue = 0;
    }
    pdata->OSEventGrp  = pevent->OSEventGrp;           //  复制链表
    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
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif                                                     /* OS_MUTEX_QUERY_EN                        */
#endif                                                     /* OS_MUTEX_EN                              */