?? os_q.c
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//任務的TCB中。
if (msg != (void *)0) { /* Did we get a message? */
//如果消息確實存在。
OSTCBCur->OSTCBMsg = (void *)0; /* Extract message from TCB (Put there by QPost) */
//清除此消息？
OSTCBCur->OSTCBStat = OS_STAT_RDY;//就緒
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 */
//超時了。
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
向消息隊列發(fā)送一則消息（FIFO）
描述：發(fā)送一則消息到隊列
參數：pevent：指向事件控制塊聯合目標隊列的指針
msg：指向要發(fā)送的消息。不能發(fā)送NULL
返回：OS_NO_ERR 消息成功發(fā)送
* OS_Q_FULL 如果隊列滿了，不能接收消息了
* OS_ERR_EVENT_TYPE 如果沒有發(fā)送消息到隊列
* OS_ERR_PEVENT_NULL 如果 'pevent' 是空指針
* OS_ERR_POST_NULL_PTR 如果你發(fā)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);
}//保證沒有發(fā)送空指針
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//非法的事件塊類型
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any task pending on queue */
//如果有任務在等
OS_EventTaskRdy(pevent, msg, OS_STAT_Q); /* Ready highest priority task waiting on event */
//使在事件中等待的最高優(yōu)先級任務就緒
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
//任務調度
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 */
//將消息插入
pq->OSQEntries++; /* Update the nbr of entries in the queue */
//更新總消息數
if (pq->OSQIn == pq->OSQEnd) { /* Wrap IN ptr if we are at end of queue */
pq->OSQIn = pq->OSQStart;//調節(jié)消息隊列循環(huán)緩沖區(qū)，當越界時，重新指向新的開頭
}
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.
向消息隊列發(fā)送一則消息（LIFO）
描述：發(fā)送一則消息，但與OSQPost()不同，消息是指向前端而不是隊列的后端，
//用此函數允許你發(fā)送優(yōu)先級消息。
參數：pevent：指向事件控制塊聯合目標隊列的指針
smg:指向你要發(fā)送的消息，不能發(fā)送空指針
返回：OS_NO_ERR 調用成功，消息成功發(fā)送
* OS_Q_FULL 如果隊列滿了，不能接收消息了
* OS_ERR_EVENT_TYPE 如果沒有發(fā)送消息到隊列
* OS_ERR_PEVENT_NULL 如果 'pevent' 是空指針
* OS_ERR_POST_NULL_PTR 如果你想發(fā)送到的不是隊列
*********************************************************************************************************
*/
#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);
}//保證沒有發(fā)送空指針
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//非法的事件塊類型
#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);//解釋見上個函數
}
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue control block */
//裝載隊列控制塊指針
if (pq->OSQEntries >= pq->OSQSize) { /* Make sure queue is not full */
//保證隊列還沒有滿
OS_EXIT_CRITICAL();
return (OS_Q_FULL);
}//OSQOut指針指向的是已經插入了消息指針的單元，所以在插入新的消息指針前，
//要將OSQOut指針在消息隊列中前移一個單元，
if (pq->OSQOut == pq->OSQStart) { /* Wrap OUT ptr if we are at the 1st queue entry */
pq->OSQOut = pq->OSQEnd;//更新循環(huán)緩沖鏈。如果pq->OSQOut指向的當前單無是隊
//列中的第一個單元，再向前移的話就意味著指向了隊列的末尾
}
pq->OSQOut--;//OSQEnd指向的是消息隊列中最后一個單元的下一個單元，所以，
//要求將其調整到指向隊列的有效范圍內。因為OSQPend（）函數取出的消息
//是由此函數剛剛插入的，這樣，就實現了后進先出。
*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.
向消息隊列發(fā)送一則消息（LIFO或者FIFO）
描述：以可以替代的，更靈活的方式給消息隊列發(fā)消息，可以代替LIFO或者FIFO
允許發(fā)送消息給所有消息隊列中等待消息的任務（廣播方式）
參數：pevent：指向事件控制塊聯合目標隊列的指針
smg:指向你要發(fā)送的消息，不能發(fā)送空指針
opt:確定發(fā)送方式：
* OS_POST_OPT_NONE 發(fā)送給單個任務，相當于OSQPost()
* OS_POST_OPT_BROADCAST 發(fā)送給隊列中所有等待的任務
* OS_POST_OPT_FRONT 以LIFO 發(fā)送(與 OSQPostFront()相似)
下面是所有標志可能的結合情況：
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