os_q.c

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

    //任务的TCB中。
    if (msg != (void *)0) {                      /* Did we get a message?                              */
		//如果消息确实存在。
        OSTCBCur->OSTCBMsg      = (void *)0;     /* Extract message from TCB (Put there by QPost)      */
		//清除此消息？
        OSTCBCur->OSTCBStat     = OS_STAT_RDY;//就绪
        OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0; /* No longer waiting for event                        */
		//不再等待事件了
        OS_EXIT_CRITICAL();
        *err                    = OS_NO_ERR;
        return (msg);                            /* Return message received                            */
    }
    OS_EventTO(pevent);                          /* Timed out                                          */
	//超时了。
    OS_EXIT_CRITICAL();
    *err = OS_TIMEOUT;                           /* Indicate a timeout occured       */
    return ((void *)0);                          /* No message received      */
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                        POST MESSAGE TO A QUEUE
*
* Description: This function sends a message to a queue
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.
*
* Returns    : OS_NO_ERR             The call was successful and the message was sent
*              OS_Q_FULL             If the queue cannot accept any more messages because it is full.
*              OS_ERR_EVENT_TYPE     If you didn't pass a pointer to a queue.
*              OS_ERR_PEVENT_NULL    If 'pevent' is a NULL pointer
*              OS_ERR_POST_NULL_PTR  If you are attempting to post a NULL pointer
                                             向消息队列发送一则消息（FIFO）
描述：发送一则消息到队列
参数：pevent：指向事件控制块联合目标队列的指针
                msg：指向要发送的消息。不能发送NULL
返回：OS_NO_ERR            消息成功发送
*              OS_Q_FULL             如果队列满了，不能接收消息了
*              OS_ERR_EVENT_TYPE     如果没有发送消息到队列
*              OS_ERR_PEVENT_NULL    如果 'pevent' 是空指针
*              OS_ERR_POST_NULL_PTR  如果你发送空消息
*********************************************************************************************************
*/

#if OS_Q_POST_EN > 0
INT8U  OSQPost (OS_EVENT *pevent, void *msg)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif
    OS_Q      *pq;


#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }//不合理的pevent
    if (msg == (void *)0) {                           /* Make sure we are not posting a NULL pointer   */
        return (OS_ERR_POST_NULL_PTR);
    }//保证没有发送空指针
    if (pevent->OSEventType != OS_EVENT_TYPE_Q) {     /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }//非法的事件块类型
#endif
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0x00) {                 /* See if any task pending on queue              */
//如果有任务在等
        OS_EventTaskRdy(pevent, msg, OS_STAT_Q);      /* Ready highest priority task waiting on event  */
//使在事件中等待的最高优先级任务就绪
        OS_EXIT_CRITICAL();
        OS_Sched();                                   /* Find highest priority task ready to run       */
		//任务调度
        return (OS_NO_ERR);
    }
    pq = (OS_Q *)pevent->OSEventPtr;                  /* Point to queue control block                  */
    if (pq->OSQEntries >= pq->OSQSize) {              /* Make sure queue is not full                   */
        OS_EXIT_CRITICAL();
        return (OS_Q_FULL);
    }
    *pq->OSQIn++ = msg;                               /* Insert message into queue                     */
	//将消息插入
    pq->OSQEntries++;                                 /* Update the nbr of entries in the queue        */
	//更新总消息数
    if (pq->OSQIn == pq->OSQEnd) {                    /* Wrap IN ptr if we are at end of queue         */
        pq->OSQIn = pq->OSQStart;//调节消息队列循环缓冲区，当越界时，重新指向新的开头
    }
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                   POST MESSAGE TO THE FRONT OF A QUEUE
*
* Description: This function sends a message to a queue but unlike OSQPost(), the message is posted at
*              the front instead of the end of the queue.  Using OSQPostFront() allows you to send
*              'priority' messages.
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.
*
* Returns    : OS_NO_ERR             The call was successful and the message was sent
*              OS_Q_FULL             If the queue cannot accept any more messages because it is full.
*              OS_ERR_EVENT_TYPE     If you didn't pass a pointer to a queue.
*              OS_ERR_PEVENT_NULL    If 'pevent' is a NULL pointer
*              OS_ERR_POST_NULL_PTR  If you are attempting to post to a non queue.
                             向消息队列发送一则消息（LIFO）
描述：发送一则消息，但与OSQPost()不同，消息是指向前端而不是队列的后端，
                //用此函数允许你发送优先级消息。
参数：pevent：指向事件控制块联合目标队列的指针
                smg:指向你要发送的消息，不能发送空指针
返回：OS_NO_ERR             调用成功，消息成功发送
*              OS_Q_FULL             如果队列满了，不能接收消息了
*              OS_ERR_EVENT_TYPE     如果没有发送消息到队列
*              OS_ERR_PEVENT_NULL   如果 'pevent' 是空指针
*              OS_ERR_POST_NULL_PTR  如果你想发送到的不是队列
*********************************************************************************************************
*/

#if OS_Q_POST_FRONT_EN > 0
INT8U  OSQPostFront (OS_EVENT *pevent, void *msg)
{
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;
#endif
    OS_Q      *pq;


#if OS_ARG_CHK_EN > 0
    if (pevent == (OS_EVENT *)0) {                    /* Validate 'pevent'                             */
        return (OS_ERR_PEVENT_NULL);
    }}//不合理的pevent
    if (msg == (void *)0) {                           /* Make sure we are not posting a NULL pointer   */
        return (OS_ERR_POST_NULL_PTR);
    }//保证没有发送空指针
    if (pevent->OSEventType != OS_EVENT_TYPE_Q) {     /* Validate event block type                     */
        return (OS_ERR_EVENT_TYPE);
    }//非法的事件块类型
#endif
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0x00) {                 /* See if any task pending on queue              */
        OS_EventTaskRdy(pevent, msg, OS_STAT_Q);      /* Ready highest priority task waiting on event  */
        OS_EXIT_CRITICAL();
        OS_Sched();                                   /* Find highest priority task ready to run       */
        return (OS_NO_ERR);//解释见上个函数
    }
    pq = (OS_Q *)pevent->OSEventPtr;                  /* Point to queue control block                  */
	//装载队列控制块指针
    if (pq->OSQEntries >= pq->OSQSize) {  /* Make sure queue is not full                   */
		//保证队列还没有满
        OS_EXIT_CRITICAL();
        return (OS_Q_FULL);
    }//OSQOut指针指向的是已经插入了消息指针的单元，所以在插入新的消息指针前，
    //要将OSQOut指针在消息队列中前移一个单元，
    if (pq->OSQOut == pq->OSQStart) {                 /* Wrap OUT ptr if we are at the 1st queue entry */
        pq->OSQOut = pq->OSQEnd;//更新循环缓冲链。如果pq->OSQOut指向的当前单无是队
        //列中的第一个单元，再向前移的话就意味着指向了队列的末尾
    }
    pq->OSQOut--;//OSQEnd指向的是消息队列中最后一个单元的下一个单元，所以，
    //要求将其调整到指向队列的有效范围内。因为OSQPend（）函数取出的消息
    //是由此函数刚刚插入的，这样，就实现了后进先出。
    *pq->OSQOut = msg;                                /* Insert message into queue                     */
    pq->OSQEntries++;                                 /* Update the nbr of entries in the queue        */
    OS_EXIT_CRITICAL();
    return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                        POST MESSAGE TO A QUEUE
*
* Description: This function sends a message to a queue.  This call has been added to reduce code size
*              since it can replace both OSQPost() and OSQPostFront().  Also, this function adds the
*              capability to broadcast a message to ALL tasks waiting on the message queue.
*
* Arguments  : pevent        is a pointer to the event control block associated with the desired queue
*
*              msg           is a pointer to the message to send.  You MUST NOT send a NULL pointer.
*
*              opt           determines the type of POST performed:
*                            OS_POST_OPT_NONE         POST to a single waiting task
*                                                     (Identical to OSQPost())
*                            OS_POST_OPT_BROADCAST    POST to ALL tasks that are waiting on the queue
*                            OS_POST_OPT_FRONT        POST as LIFO (Simulates OSQPostFront())
*
*                            Below is a list of ALL the possible combination of these flags:
*
*                                 1) OS_POST_OPT_NONE
*                                    identical to OSQPost()
*
*                                 2) OS_POST_OPT_FRONT
*                                    identical to OSQPostFront()
*
*                                 3) OS_POST_OPT_BROADCAST
*                                    identical to OSQPost() but will broadcast 'msg' to ALL waiting tasks
*
*                                 4) OS_POST_OPT_FRONT + OS_POST_OPT_BROADCAST  is identical to
*                                    OSQPostFront() except that will broadcast 'msg' to ALL waiting tasks
*
* Returns    : OS_NO_ERR             The call was successful and the message was sent
*              OS_Q_FULL             If the queue cannot accept any more messages because it is full.
*              OS_ERR_EVENT_TYPE     If you didn't pass a pointer to a queue.
*              OS_ERR_PEVENT_NULL    If 'pevent' is a NULL pointer
*              OS_ERR_POST_NULL_PTR  If you are attempting to post a NULL pointer
*
* Warning    : Interrupts can be disabled for a long time if you do a 'broadcast'.  In fact, the
*              interrupt disable time is proportional to the number of tasks waiting on the queue.
                              向消息队列发送一则消息（LIFO或者FIFO）   
描述：以可以替代的，更灵活的方式给消息队列发消息，可以代替LIFO或者FIFO
               允许发送消息给所有消息队列中等待消息的任务（广播方式）
参数：pevent：指向事件控制块联合目标队列的指针
                smg:指向你要发送的消息，不能发送空指针
                opt:确定发送方式：
*                            OS_POST_OPT_NONE        发送给单个任务，相当于OSQPost()
*                            OS_POST_OPT_BROADCAST   发送给队列中所有等待的任务
*                            OS_POST_OPT_FRONT        以LIFO 发送(与 OSQPostFront()相似)
                 下面是所有标志可能的结合情况：