/*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* MESSAGE QUEUE MANAGEMENT
*
* (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
* All Rights Reserved
*
* File : OS_Q.C
* By : Jean J. Labrosse
*********************************************************************************************************
*/
#ifndef OS_MASTER_FILE//防止编译器包含一些代码
#include "includes.h"
#endif
#if (OS_Q_EN > 0) && (OS_MAX_QS > 0)
/*
*********************************************************************************************************
* ACCEPT MESSAGE FROM QUEUE
*
* Description: This function checks the queue to see if a message is available. Unlike OSQPend(),
* OSQAccept() does not suspend the calling task if a message is not available.
*
* Arguments : pevent is a pointer to the event control block
*
* Returns : != (void *)0 is the message in the queue if one is available. The message is removed
* from the so the next time OSQAccept() is called, the queue will contain
* one less entry.
* == (void *)0 if the queue is empty or,
* if 'pevent' is a NULL pointer or,
* if you passed an invalid event type
*********************************************************************************************************
*/
#if OS_Q_ACCEPT_EN > 0
void *OSQAccept (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
void *msg;
OS_Q *pq;
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return ((void *)0);
}
if (pevent->OSEventType != OS_EVENT_TYPE_Q) {/* Validate event block type */
return ((void *)0);
}
#endif
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point at queue control block */
if (pq->OSQEntries > 0) { /* See if any messages in the queue */
msg = *pq->OSQOut++; /* Yes, extract oldest message from the queue */
pq->OSQEntries--; /* Update the number of entries in the queue */
if (pq->OSQOut == pq->OSQEnd) { /* Wrap OUT pointer if we are at the end of the queue */
pq->OSQOut = pq->OSQStart;
}
} else {
msg = (void *)0; /* Queue is empty */
}
OS_EXIT_CRITICAL();
return (msg); /* Return message received (or NULL) */
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A MESSAGE QUEUE
*
* Description: This function creates a message queue if free event control blocks are available.
*
* Arguments : start is a pointer to the base address of the message queue storage area. The
* storage area MUST be declared as an array of pointers to 'void' as follows
*
* void *MessageStorage[size]
*
* size is the number of elements in the storage area
*
* Returns : != (OS_EVENT *)0 is a pointer to the event control clock (OS_EVENT) associated with the
* created queue
* == (OS_EVENT *)0 if no event control blocks were available or an error was detected
建立一个消息队列
描述：如果有空余事件控制块，就建立一个消息队列
参数：start：指向消息队列存储空间基地址。存储空间必须定义成void 型的
一系列指针，形式如右：void *MessageStorage[size]
size：存储空间内单元的数目
返回：!= (OS_EVENT *)0 是指向结合建立的队列的事件控制时钟(OS_EVENT)的指针
== (OS_EVENT *)0如果没有适合的事件控制块或者有错误
*********************************************************************************************************
*/
OS_EVENT *OSQCreate (void **start, INT16U size)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;//分配名为cpu_sr 的局部变量，用于支持OS_CRITICAL_METHOD方法3
#endif
OS_EVENT *pevent;
OS_Q *pq;
if (OSIntNesting > 0) { /* See if called from ISR ... */
return ((OS_EVENT *)0); /* ... can't CREATE from an ISR */
}//不能在ISR中建立消息队列
OS_ENTER_CRITICAL();
pevent = OSEventFreeList; /* Get next free event control block */
//从空余的ECB链表中取得一个事件控制块。对剩下的作相应调整
//ECB是单向链表
if (OSEventFreeList != (OS_EVENT *)0) { /* See if pool of free ECB pool was empty */
OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
}//对剩下的进行相应的调整
OS_EXIT_CRITICAL();
if (pevent != (OS_EVENT *)0) { /* See if we have an event control block */
//如果我们得到了事件控制块
OS_ENTER_CRITICAL();
pq = OSQFreeList; /* Get a free queue control block */
//得到一块新的队列控制块
if (pq != (OS_Q *)0) { /* Were we able to get a queue control block ? */
//如果得到的不为空，即真正得到了。
OSQFreeList = OSQFreeList->OSQPtr; /* Yes, Adjust free list pointer to next free*/
//调整表头
OS_EXIT_CRITICAL();
//初始化新得到的队列控制块
pq->OSQStart = start; /* Initialize the queue */
pq->OSQEnd = &start[size];
pq->OSQIn = start;
pq->OSQOut = start;
pq->OSQSize = size;
pq->OSQEntries = 0;//初始化消息数为零
pevent->OSEventType = OS_EVENT_TYPE_Q;//设置事件控制块类型
pevent->OSEventCnt = 0;//信号量
pevent->OSEventPtr = pq;//将此块指向消息队列结构指针
OS_EventWaitListInit(pevent); /* Initalize the wait list *///初始化等待列表
} else {//如果没有得到队列控制块
pevent->OSEventPtr = (void *)OSEventFreeList; /* No, Return event control block on error */
//以错误形式返回队列控制块
OSEventFreeList = pevent;//退回事件控制块，不用了。
OS_EXIT_CRITICAL();
pevent = (OS_EVENT *)0;//清零，给下一次使用。
}
}
return (pevent);//如果消息队列建立成功，则会返回一个指针，否则，就返回空指针。
//消息队列成功后返回的这个指针用于以后对消息队列的操作因此，该指针
//可以看作是相应消息队列的句柄。
}
/*$PAGE*/
/*
*********************************************************************************************************
* DELETE A MESSAGE QUEUE
*
* Description: This function deletes a message queue and readies all tasks pending on the queue.
*
* Arguments : pevent is a pointer to the event control block associated with the desired
* queue.
*
* opt determines delete options as follows:
* opt == OS_DEL_NO_PEND Delete the queue ONLY if no task pending
* opt == OS_DEL_ALWAYS Deletes the queue even if tasks are waiting.
* In this case, all the tasks pending will be readied.
*
* err is a pointer to an error code that can contain one of the following values:
* OS_NO_ERR The call was successful and the queue was deleted
* OS_ERR_DEL_ISR If you tried to delete the queue from an ISR
* OS_ERR_INVALID_OPT An invalid option was specified
* OS_ERR_TASK_WAITING One or more tasks were waiting on the queue
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer.
*
* Returns : pevent upon error
* (OS_EVENT *)0 if the queue was successfully deleted.
*
* Note(s) : 1) This function must be used with care. Tasks that would normally expect the presence of
* the queue MUST check the return code of OSQPend().
* 2) OSQAccept() callers will not know that the intended queue 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 queue.
* 4) Because ALL tasks pending on the queue will be readied, you MUST be careful in
* applications where the queue is used for mutual exclusion because the resource(s)
* will no longer be guarded by the queue.
* 5) If the storage for the message queue was allocated dynamically (i.e. using a malloc()
* type call) then your application MUST release the memory storage by call the counterpart
* call of the dynamic allocation scheme used. If the queue storage was created statically
* then, the storage can be reused.
删除一个消息队列
描述：删除一个队列，使在队列上挂起的任务全部就绪
参数：pevent ：指向事件控制块和目标队列的指针
opt:决定删除选项，如下：
* opt == OS_DEL_NO_PEND 没有任务挂起才删除
* opt == OS_DEL_ALWAYS 有任务挂起也删，挂起的任务全部就绪
* err 指向包含如下错误信息的指针
* OS_NO_ERR 调用成功，队列删除
* OS_ERR_DEL_ISR 如果想从ISR中删除
* OS_ERR_INVALID_OPT 指定了非法选项
* OS_ERR_TASK_WAITING 有任务在队列中等待
* OS_ERR_EVENT_TYPE 如果你没有传递消息给队列
* OS_ERR_PEVENT_NULL 如果pevent是一个空指针
返回：pevent；有错
(OS_EVENT *)0如果队列成功删除
备注：1、此函数要小心使用，任务希望现场队列检查OSQPend()的返回代码，什么意思，不知道
2、OSQAccept()的调用者不知道目标队列是否删除了，除非检查pevent'是否为空指针
3、此调用将潜在关中断一段时间，时间长短与队列中任务多少成正比
4、因为所有队列中挂起的任务就绪，在多任务的时候要小心，因为这些资源
队列不再看管（因为删除了）。
5、如果消息存储用动态分配（比如用malloc()），那么应用程序必须通过
调用相应的动态配置去释放内存空间，如果队列存储是静态建立，则可以再次
利用
*********************************************************************************************************
*/
#if OS_Q_DEL_EN > 0
OS_EVENT *OSQDel (OS_EVENT *pevent, INT8U opt, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
BOOLEAN tasks_waiting;
OS_Q *pq;
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_DEL_ISR; /* ... can't DELETE from an ISR */
return ((OS_EVENT *)0);
}//不能在中断服务程序中删除
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return (pevent);//pevent不合理
}
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return (pevent);//非法的事件块模式
}
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any tasks waiting on queue */
//如果有任务在队列中等待
tasks_waiting = TRUE; /* Yes */
} else {
tasks_waiting = FALSE; /* No */
}
switch (opt) {
case OS_DEL_NO_PEND: /* Delete queue only if no task waiting */
//如果只在无任务等待的情况下删除
if (tasks_waiting == FALSE) {//无任务等待
pq = (OS_Q *)pevent->OSEventPtr; /* Return OS_Q to free list */
pq->OSQPtr = OSQFreeList;
OSQFreeList = pq;//将它加入了空闲链表
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;//标记未用
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
OSEventFreeList = pevent; /* Get next free event control block *///将事件控制块放入空闲链表中
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;//无错
return ((OS_EVENT *)0); /* Queue has been deleted */
} else {//有任务等待
OS_EXIT_CRITICAL();
*err = OS_ERR_TASK_WAITING;
return (pevent);
}
case OS_DEL_ALWAYS: /* Always delete the queue */
//始终要删除队列
while (pevent->OSEventGrp != 0x00) { /* Ready ALL tasks waiting for queue */
//真有任务等待
OS_EventTaskRdy(pevent, (void *)0, OS_STAT_Q);//将挂起的任务就绪
}
pq = (OS_Q *)pevent->OSEventPtr; /* Return OS_Q to free list */
pq->OSQPtr = OSQFreeList;
OSQFreeList = pq;//同上，将队列控制块放入空闲链表
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;//标记为未用
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
OSEventFreeList = pevent; /* Get next free event control block */
//将事件控制块放入空闲链表
OS_EXIT_CRITICAL();
if (tasks_waiting == TRUE) { /* Reschedule only if task(s) were waiting */
OS_Sched(); /* Find highest priority task ready to run */
//因为新任务就绪，所以要重新调度
}
*err = OS_NO_ERR;
return ((OS_EVENT *)0); /* Queue has been deleted */
default://其它异常情况
OS_EXIT_CRITICAL();
*err = OS_ERR_INVALID_OPT;
return (pevent);
}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* FLUSH QUEUE
*
* Description : This function is used to flush the contents of the message queue.
*
* Arguments : none
*
* Returns : OS_NO_ERR upon success
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
清空消息队列
描述：清空消息队列中内容
参数：无
返回：
OS_NO_ERR 成功
* OS_ERR_EVENT_TYPE 没有传递指针给队列
* OS_ERR_PEVENT_NULL 如果'pevent' 是一个空指针
*********************************************************************************************************
*/
#if OS_Q_FLUSH_EN > 0
INT8U OSQFlush (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
OS_Q *pq;
#if OS_ARG_CHK_EN > 0//允许参数检验
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}//不合理的参数pevent
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//不是事件块类型
#endif
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue storage structure */
//保存结构指针
pq->OSQIn = pq->OSQStart;
pq->OSQOut = pq->OSQStart;//将队列的插入指针IN和取出指针OUT复位
pq->OSQEntries = 0;//初始化入口为零
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* PEND ON A QUEUE FOR A MESSAGE
*
* Description: This function waits for a message to be sent to a queue
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* timeout is an optional timeout period (in clock ticks). If non-zero, your task will
* wait for a message to arrive at the queue up to the amount of time
* specified by this argument. If you specify 0, however, your task will wait
* forever at the specified queue or, until a message arrives.
*
* err is a pointer to where an error message will be deposited. Possible error
* messages are:
*
* OS_NO_ERR The call was successful and your task received a
* message.
* OS_TIMEOUT A message was not received within the specified timeout
* OS_ERR_EVENT_TYPE You didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
* OS_ERR_PEND_ISR If you called this function from an ISR and the result
* would lead to a suspension.
*
* Returns : != (void *)0 is a pointer to the message received
* == (void *)0 if no message was received or,
* if 'pevent' is a NULL pointer or,
* if you didn't pass a pointer to a queue.
等待消息队列中的消息
描述：等待消息中的队列
参数：pevent：指向事件控制块结合目标队列的指针
timeout：超时时间选项（按时钟节拍来），如果非零，任务将按照此
参数的定时在队列中等待消息到来，如果设置为零，任务将在目标
队列中永远等待，直到消息到来。
err：指向可能的错误消息的指针，可能为：
* OS_NO_ERR 调用成功，任务接收到消息
* OS_TIMEOUT 定时时间内消息没有来
* OS_ERR_EVENT_TYPE 你没有传递指针到队列
* OS_ERR_PEVENT_NULL 如果 'pevent' 是一个空指针
* OS_ERR_PEND_ISR 如果从ISR中调用，结果将出现异常
*********************************************************************************************************
*/
void *OSQPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
void *msg;
OS_Q *pq;
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */
return ((void *)0);//不能在ISR中挂起
}
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return ((void *)0);//不合理的pevent
}
if (pevent->OSEventType != OS_EVENT_TYPE_Q) {/* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return ((void *)0);//不是事件块类型
}
#endif
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point at queue control block */
//取出队列控制块指针
if (pq->OSQEntries > 0) { /* See if any messages in the queue */
//大于零，表示有消息可以用。此时，OSQPend得到事件控制块的.OSQOut域所指
//向的消息，将指向消息的指针复制到msg变量中，并让.OSQOut指针指向
//队列中的下个单元
msg = *pq->OSQOut++; /* Yes, extract oldest message from the queue */
pq->OSQEntries--; /* Update the number of entries in the queue */
// 队列中有效消息减一
if (pq->OSQOut == pq->OSQEnd) { /* Wrap OUT pointer if we are at the end of the queue */
pq->OSQOut = pq->OSQStart;
}//消息队列是一个循环缓冲区，如果超出了队列中最末一个单元，发生
//这种越界时，就要将.OSQOut重新调整到指向队列的起始单元
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
return (msg); /* Return message received *///返回接收到的消息
}
OSTCBCur->OSTCBStat |= OS_STAT_Q; /* Task will have to pend for a message to be posted */
//设置任务的TCB状态标志，以表明等待消息队列消息的任务被挂起
OSTCBCur->OSTCBDly = timeout; /* Load timeout into TCB */
//装载定时器到TCB
OS_EventTaskWait(pevent); /* Suspend task until event or timeout occurs */
//挂起任务直到消息到来或者超时。在用户进程中，调用此函数的任务
//并不知道消息没有到来之前自己被挂起，队列接收到一则消息或者超时
//时，此函数就会调用调度函数恢复运行。
OS_EXIT_CRITICAL();
OS_Sched(); /* Find next highest priority task ready to run */
//挂起后要进行任务调度。
OS_ENTER_CRITICAL();
msg = OSTCBCur->OSTCBMsg;//任务调度后，任务会检查此函数是不是将消息放到了
//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：
* 1) OS_POST_OPT_NONE
* 相当于 OSQPost()
*
* 2) OS_POST_OPT_FRONT
* 相当于 OSQPostFront()
*
* 3) OS_POST_OPT_BROADCAST
* 相当于 OSQPost() 但可以以广播方式发送 to ALL waiting tasks
*
* 4) OS_POST_OPT_FRONT + OS_POST_OPT_BROADCAST 相当于
* OSQPostFront() 可以以广播方式发送
*********************************************************************************************************
*/
#if OS_Q_POST_OPT_EN > 0
INT8U OSQPostOpt (OS_EVENT *pevent, void *msg, INT8U opt)
{
#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);
}//非法pevent
if (msg == (void *)0) { /* Make sure we are not posting a NULL pointer */
return (OS_ERR_POST_NULL_PTR);
}//保证没有送空指针
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//不是事件块类型
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any task pending on queue */
//如果有任务在队列中挂起
if ((opt & OS_POST_OPT_BROADCAST) != 0x00) { /* Do we need to post msg to ALL waiting tasks ? */
//向所有任务发送？
while (pevent->OSEventGrp != 0x00) { /* Yes, Post to ALL tasks waiting on queue */
OS_EventTaskRdy(pevent, msg, OS_STAT_Q);
}//是的。如果将opt参数中的OS_POST_OPT_BROADCAST位置为1，则所有正在等待消息
//的任务都能接收到这则消息，并且被OS_EventTaskRdy从等待列表中删除。
} else {//不要向所有的等待任务发消息
OS_EventTaskRdy(pevent, msg, OS_STAT_Q); /* No, Post to HPT waiting on queue */
//那就只发优先级最高的。
}
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
//要任务调度
return (OS_NO_ERR);
}
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue control block */
//指向队列控制块
if (pq->OSQEntries >= pq->OSQSize) { /* Make sure queue is not full */
OS_EXIT_CRITICAL();//如果满了，返回错误代码
return (OS_Q_FULL);
}
if ((opt & OS_POST_OPT_FRONT) != 0x00) { /* Do we post to the FRONT of the queue? */
//FIFO还是LIFO，如果是LIFO
if (pq->OSQOut == pq->OSQStart) { /* Yes, Post as LIFO, Wrap OUT pointer if we ... */
pq->OSQOut = pq->OSQEnd; /* ... are at the 1st queue entry */
}//如果是后进先出，则相当于OSQPostFront 。如果我人在队列第一个，则调整
pq->OSQOut--;
*pq->OSQOut = msg; /* Insert message into queue */
//插入消息
} else { /* No, Post as FIFO */
//如果是FIFO
*pq->OSQIn++ = msg; /* Insert message into queue */
if (pq->OSQIn == pq->OSQEnd) { /* Wrap IN ptr if we are at end of queue */
pq->OSQIn = pq->OSQStart;//如果在最末尾，则调整
}
}
pq->OSQEntries++; /* Update the nbr of entries in the queue */
//更新消息条数
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* QUERY A MESSAGE QUEUE
*
* Description: This function obtains information about a message queue.
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* pdata is a pointer to a structure that will contain information about the message
* queue.
*
* Returns : OS_NO_ERR The call was successful and the message was sent
* OS_ERR_EVENT_TYPE If you are attempting to obtain data from a non queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
获取消息队列状态
描述：获取消息队列的信息
参数：pevent：指向事件控制块结合目标队列的指针
pdata：指向消息队列包含信息的结构指针
返回：OS_NO_ERR 调用成功，消息成功发送
* OS_ERR_EVENT_TYPE 你想获取非队列的信息
* OS_ERR_PEVENT_NULL 如果 'pevent' 是一个NULL指针
*********************************************************************************************************
*/
#if OS_Q_QUERY_EN > 0
INT8U OSQQuery (OS_EVENT *pevent, OS_Q_DATA *pdata)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
OS_Q *pq;
INT8U *psrc;
INT8U *pdest;
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}//非法pevent
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//保证没有送空指针
#endif
OS_ENTER_CRITICAL();
//复制等待任务列表
pdata->OSEventGrp = pevent->OSEventGrp; /* Copy message queue wait list */
psrc = &pevent->OSEventTbl[0];
pdest = &pdata->OSEventTbl[0];
#if OS_EVENT_TBL_SIZE > 0//从0开始，慢慢复制吧。
*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
pq = (OS_Q *)pevent->OSEventPtr;
if (pq->OSQEntries > 0) {//如果有消息等待，则提取出（并没有删除）队列中最早进入
//队列的消息，并将其复制到OSMsg中，OSQQuery并没有改动.OSQOut的指针。
pdata->OSMsg = *pq->OSQOut; /* Get next message to return if available */
} else {//如果没有任务等待，则返回空指针
pdata->OSMsg = (void *)0;
}
pdata->OSNMsgs = pq->OSQEntries;//队列中消息数
pdata->OSQSize = pq->OSQSize;//队列容易大小
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif /* OS_Q_QUERY_EN */
/*$PAGE*/
/*
*********************************************************************************************************
* QUEUE MODULE INITIALIZATION
*
* Description : This function is called by uC/OS-II to initialize the message queue module. Your
* application MUST NOT call this function.
*
* Arguments : none
*
* Returns : none
*
* Note(s) : This function is INTERNAL to uC/OS-II and your application should not call it.
初始化消息队列
描述：由ucos调用初始化消息队列模型，应用程序不能调用
参数：无
返回：无
备注：由ucos调用初始化消息队列模型，应用程序不能调用
*********************************************************************************************************
*/
void OS_QInit (void)
{
#if OS_MAX_QS == 1//如果只有一个队列
OSQFreeList = &OSQTbl[0]; /* Only ONE queue! */
OSQFreeList->OSQPtr = (OS_Q *)0;//前趋为零指针
#endif
#if OS_MAX_QS >= 2
INT16U i;
OS_Q *pq1;
OS_Q *pq2;
pq1 = &OSQTbl[0];
pq2 = &OSQTbl[1];
for (i = 0; i < (OS_MAX_QS - 1); i++) { /* Init. list of free QUEUE control blocks */
//初始化空闲队列控制块，组成一个单向链表
pq1->OSQPtr = pq2;
pq1++;
pq2++;
}
pq1->OSQPtr = (OS_Q *)0;//后趋附指向NULL指针
OSQFreeList = &OSQTbl[0];//空链表指针指向首地址。
#endif
}
#endif /* OS_Q_EN */
