OS_MBOX.C
/*
*********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* MESSAGE MAILBOX MANAGEMENT
*
* (c) Copyright 1992-2002, Jean J. Labrosse, Weston, FL
* All Rights Reserved
*
* File : OS_MBOX.C
* By : Jean J. Labrosse
*********************************************************************************************************
*/
#ifndef OS_MASTER_FILE
#include "includes.h"
#endif
#if OS_MBOX_EN > 0
/*
*********************************************************************************************************
* ACCEPT MESSAGE FROM MAILBOX
*
* Description: This function checks the mailbox to see if a message is available. Unlike OSMboxPend(),
* OSMboxAccept() 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 mailbox if one is available. The mailbox is cleared
* so the next time OSMboxAccept() is called, the mailbox will be empty.
* == (void *)0 if the mailbox is empty or,
* if 'pevent' is a NULL pointer or,
* if you didn't pass the proper event pointer.
*********************************************************************************************************
*/
/*
*********************************************************************************************************
无等待地从邮箱中得到一则消息
描述：此函数检查邮箱中是否有消息，不同于OSMboxPend()，如果没有可行消息，
OSMboxAccept() 不会挂起调用此函数的任务
参数；：pevent：是指向事件控制块的指针
返回：!= (void *)0 如果邮箱有消息，它指向邮箱中的一则消息，邮箱被清空，
如果下一次调用，它将是空的。
== (void *)0 如果邮箱为空，或者pevent指向空指针，或者没有传递一个合理事件
指针
*********************************************************************************************************
*/
#if OS_MBOX_ACCEPT_EN > 0
void *OSMboxAccept (OS_EVENT *pevent)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
void *msg;
#if OS_ARG_CHK_EN > 0//允许参数检验
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return ((void *)0);//如果事件无效，返回零
}
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
//检查pevent所指向的事件控制块是不是由OS_EVENT_TYPE_MBOX建立
return ((void *)0);
}
#endif
OS_ENTER_CRITICAL();
msg = pevent->OSEventPtr;//函数得到邮箱的当前内容
pevent->OSEventPtr = (void *)0; /* Clear the mailbox *///清空邮箱
OS_EXIT_CRITICAL();
return (msg); /* Return the message received (or NULL) *///将邮箱中的内容返回，以供调用
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A MESSAGE MAILBOX
*
* Description: This function creates a message mailbox if free event control blocks are available.
*
* Arguments : msg is a pointer to a message that you wish to deposit in the mailbox. If
* you set this value to the NULL pointer (i.e. (void *)0) then the mailbox
* will be considered empty.
*
* Returns : != (OS_EVENT *)0 is a pointer to the event control clock (OS_EVENT) associated with the
* created mailbox
* == (OS_EVENT *)0 if no event control blocks were available
*********************************************************************************************************
*/
/*
*********************************************************************************************************
建立一个邮箱
描述：如果空余事件控制块允许，就建立一个消息邮箱
参数：msg:指向你想存入邮箱的消息指针，如果存入零，我们认为它为空
返回：!= (OS_EVENT *)0：指向所建立邮箱的事件控制块指针
== (OS_EVENT *)0：如果没有可行事件控制块
*********************************************************************************************************
*/
OS_EVENT *OSMboxCreate (void *msg)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
OS_EVENT *pevent;
if (OSIntNesting > 0) { /* See if called from ISR ... */
return ((OS_EVENT *)0); /* ... can't CREATE from an ISR */
}//此函数不能由中断服务程序调用
OS_ENTER_CRITICAL();
pevent = OSEventFreeList; /* Get next free event control block */
//得到一块新的事件控制块
if (OSEventFreeList != (OS_EVENT *)0) { /* See if pool of free ECB pool was empty */
OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
}//如果空余事件控制链表不为空，则进行适当调整，指向下一块空余事件控制块
OS_EXIT_CRITICAL();
if (pevent != (OS_EVENT *)0) {
pevent->OSEventType = OS_EVENT_TYPE_MBOX;//如果ECB可用，则将其设置为邮箱型
pevent->OSEventCnt = 0;//信号量，邮箱中不使用它
pevent->OSEventPtr = msg; /* Deposit message in event control block */
//保存消息在ECB中
OS_EventWaitListInit(pevent);//对事件控制块的等待任务列表进行初始化
}
return (pevent); /* Return pointer to event control block */
//返回事件控制块的指针，对邮箱的操作都通过此指针完成。
}
/*$PAGE*/
/*
*********************************************************************************************************
* DELETE A MAIBOX
*
* Description: This function deletes a mailbox and readies all tasks pending on the mailbox.
*
* Arguments : pevent is a pointer to the event control block associated with the desired
* mailbox.
*
* opt determines delete options as follows:
* opt == OS_DEL_NO_PEND Delete the mailbox ONLY if no task pending
* opt == OS_DEL_ALWAYS Deletes the mailbox 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 mailbox was deleted
* OS_ERR_DEL_ISR If you attempted to delete the mailbox from an ISR
* OS_ERR_INVALID_OPT An invalid option was specified
* OS_ERR_TASK_WAITING One or more tasks were waiting on the mailbox
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a mailbox
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer.
*
* Returns : pevent upon error
* (OS_EVENT *)0 if the mailbox was successfully deleted.
*
* Note(s) : 1) This function must be used with care. Tasks that would normally expect the presence of
* the mailbox MUST check the return code of OSMboxPend().
* 2) OSMboxAccept() callers will not know that the intended mailbox has been deleted!
* 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 mailbox.
* 4) Because ALL tasks pending on the mailbox will be readied, you MUST be careful in
* applications where the mailbox is used for mutual exclusion because the resource(s)
* will no longer be guarded by the mailbox.
删除一个邮箱
描述：此任务删除一个邮箱，准备好邮箱中挂起的所有任务
参数：pevent：指向想要邮箱的ECB的指针
opt：确定删除选项如下：
opt == OS_DEL_NO_PEND：如果没有任务挂起就删除邮箱
opt == OS_DEL_ALWAYS：即使任务等待也删除邮箱，这种情况下，所有挂起的任务将就绪
err：包含以下值的错误代码指针：
OS_NO_ERR：调用成功，删除邮箱
OS_ERR_DEL_ISR ：如果从ISR中删除邮箱
* OS_ERR_INVALID_OPT ：指定了不合理选项
* OS_ERR_TASK_WAITING ：一个或者几个任务在邮箱中等待
* OS_ERR_EVENT_TYPE ：没有传递指针给邮箱
* OS_ERR_PEVENT_NULL :pevent是空指针，即邮箱的ECB为空。
返回：pevent：操作错误
(OS_EVENT *)0：邮箱成功删除
备注：1、此函数必须小心使用，任务希望在场的邮箱检查OSMboxPend()的返回代码
2、OSMboxAccept()调用将不知道想要的邮箱已经被删除
3、这个函数将潜在地关中断一长段时间，关中断时间与在邮箱中等待的任务
数成正比
4、因为所有在邮箱中挂起的任务将就绪，你必须在邮箱相互排斥情况下小心使用
因为资源不再被邮箱保护
*********************************************************************************************************
*/
#if OS_MBOX_DEL_EN > 0
OS_EVENT *OSMboxDel (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;//typedef unsigned char BOOLEAN
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_DEL_ISR; /* ... can't DELETE from an ISR */
return (pevent);//如果在中断中调用，不能删除
}
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return (pevent);//如果pevent不合理
}
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return (pevent);//如果事件不是邮箱模式
}
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any tasks waiting on mailbox */
//看邮箱中有没有任务在等待
tasks_waiting = TRUE; /* Yes */
} else {
tasks_waiting = FALSE; /* No */
}
switch (opt) {
case OS_DEL_NO_PEND: /* Delete mailbox only if no task waiting */
//没有任务等待的情况下才删除邮箱
if (tasks_waiting == FALSE) {//如果没有任务等待
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;//将事件标志为没有用的
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
//将ECB返回给空闲列表
OSEventFreeList = pevent; /* Get next free event control block */
//它指向新的空闲列表
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;//成功删除
return ((OS_EVENT *)0); /* Mailbox has been deleted */
} else {
OS_EXIT_CRITICAL();
*err = OS_ERR_TASK_WAITING;//如果有任务在等待
return (pevent);
}
case OS_DEL_ALWAYS: /* Always delete the mailbox */
while (pevent->OSEventGrp != 0x00) { /* Ready ALL tasks waiting for mailbox */
OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MBOX);
}//所以等待该信号的任务都进入就绪态，每个任务都以为自己得到了
//NULL指针，每个任务必须检查返回的指针，看是不是非NULL，另外，
//当每个任务都进入就绪态，中断是关的，也延长了中断响应时间。
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
OSEventFreeList = pevent; /* Get next free event control block */
//同上面一样，将ECB返回给空闲列表，并指向新的表头
OS_EXIT_CRITICAL();
if (tasks_waiting == TRUE) { /* Reschedule only if task(s) were waiting */
//只有有任务等待的时候才需要任务调度
OS_Sched(); /* Find highest priority task ready to run */
}
*err = OS_NO_ERR;
return ((OS_EVENT *)0); /* Mailbox has been deleted */
default:
OS_EXIT_CRITICAL();
*err = OS_ERR_INVALID_OPT;//如果有其它不合理的选项。
return (pevent);
}
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* PEND ON MAILBOX FOR A MESSAGE
*
* Description: This function waits for a message to be sent to a mailbox
*
* Arguments : pevent is a pointer to the event control block associated with the desired mailbox
*
* timeout is an optional timeout period (in clock ticks). If non-zero, your task will
* wait for a message to arrive at the mailbox up to the amount of time
* specified by this argument. If you specify 0, however, your task will wait
* forever at the specified mailbox 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 Invalid event type
* 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
*
* 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 the proper pointer to the event control block.
等待邮箱中的消息
描述：等待将要送到邮箱中的消息
参数：pevent：指向目标邮箱ECB的指针
timeout：超时阶段的选项，如果非零，事件将在邮箱中等待消息的到来
直到这个值的时间到；如果是零，消息将永远等待，直到消息到来。
err：指向将要传递的错误消息指针。可能如下：
OS_NO_ERR 操作成功，任务得到消息
* OS_TIMEOUT 规定时间内没有收到消息
* OS_ERR_EVENT_TYPE 非法事件类型
* OS_ERR_PEND_ISR 如果在中断中调用，结果将中止
* OS_ERR_PEVENT_NULL 如果pevent 是空指针
*********************************************************************************************************
*/
void *OSMboxPend (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;
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */
return ((void *)0);
}//中断服务子程序不能等待。
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return ((void *)0);//目标邮箱ECB指针为零，不合理
}
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
//事件类型不是邮箱类型
*err = OS_ERR_EVENT_TYPE;
return ((void *)0);
}
#endif
OS_ENTER_CRITICAL();
msg = pevent->OSEventPtr;
if (msg != (void *)0) { /* See if there is already a message */
//如果邮箱中有消息，则从中取出消息，返回给调用函数，并将NULL存入邮箱，
//同时返回无错代码给它的调用函数，这个返回结果表示，已由另一个任务或者中断
//服务子程序将信息发送到邮箱中。如果为空的话，调用此函数的任务将进入睡眠状态
//等待另一个任务（可中断服务程序）通过邮箱发送消息，OSMboxPend（）允许定义一个
//最长等待时间作为它的参数，防止任务无期限等待
pevent->OSEventPtr = (void *)0; /* Clear the mailbox */
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
return (msg); /* Return the message received (or NULL) */
//返回得到的消息
}
OSTCBCur->OSTCBStat |= OS_STAT_MBOX; /* Message not available, task will pend */
//消息无效，挂起任务，进入睡眠，等待其它邮箱消息唤醒
OSTCBCur->OSTCBDly = timeout; /* Load timeout in TCB */
//等待时间也放入任务控制块中，该址在OSTimeTick()中被逐次减一
OS_EventTaskWait(pevent); /* Suspend task until event or timeout occurs */
//真正将任务进入睡眠，
OS_EXIT_CRITICAL();
OS_Sched(); /* Find next highest priority task ready to run */
//任务调度，下一个优先级的任务运行。
OS_ENTER_CRITICAL();
msg = OSTCBCur->OSTCBMsg;//取出消息
if (msg != (void *)0) { /* See if we were given the message */
OSTCBCur->OSTCBMsg = (void *)0; /* Yes, clear message received */
OSTCBCur->OSTCBStat = OS_STAT_RDY;
OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0; /* No longer waiting for event */
OS_EXIT_CRITICAL();
//是否真正接收到消息，如果是，进入就绪态，不再等待事件，
*err = OS_NO_ERR;
return (msg); /* Return the message received */
//将收到的消息返回
}
OS_EventTO(pevent); /* Timed out, Make task ready */
//如果超时，让任务就绪
OS_EXIT_CRITICAL();
*err = OS_TIMEOUT; /* Indicate that a timeout occured */
return ((void *)0); /* Return a NULL message */
//返回空指针
}
/*$PAGE*/
/*
*********************************************************************************************************
* POST MESSAGE TO A MAILBOX
*
* Description: This function sends a message to a mailbox
*
* Arguments : pevent is a pointer to the event control block associated with the desired mailbox
*
* 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_MBOX_FULL If the mailbox already contains a message. You can can only send one
* message at a time and thus, the message MUST be consumed before you
* are allowed to send another one.
* OS_ERR_EVENT_TYPE If you are attempting to post to a non mailbox.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
* OS_ERR_POST_NULL_PTR If you are attempting to post a NULL pointer
向邮箱发送一则消息
描述：向邮箱发送一则消息
参数：pevent：指向目标邮箱的ECB的指针
msg:将要发送的消息指针，不能发送空指针
返回：OS_NO_ERR：消息发送成功
OS_MBOX_FULL ：如果邮箱中已经有消息了，一次只能发送一条消息，
在你允许发送另一条前，消息必须用掉
OS_ERR_EVENT_TYPE：如果你要发送到的不是邮箱
OS_ERR_PEVENT_NULL：如果目标ECB是空指针
OS_ERR_POST_NULL_PTR：如果你想发空指针
*********************************************************************************************************
*/
#if OS_MBOX_POST_EN > 0
INT8U OSMboxPost (OS_EVENT *pevent, void *msg)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}//合理的目标ECB
if (msg == (void *)0) { /* Make sure we are not posting a NULL pointer */
return (OS_ERR_POST_NULL_PTR);
}//发送的不是空指针
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any task pending on mailbox */
//是不是有任务在等待该邮箱中的消息，如果OSEventGrp非零，则表明有任务
OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX); /* Ready highest priority task waiting on event */
//将最高优先级的任务从等待列表中删除
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
//任务调度，检查该任务是否系统中就绪任务优先级最高，如果是，任务切换，
//该任务得以执行，如果不是，则OS_Sched（）返回，OSMboxPost的调用函数继续。
return (OS_NO_ERR);
}
if (pevent->OSEventPtr != (void *)0) { /* Make sure mailbox doesn't already have a msg */
OS_EXIT_CRITICAL();
return (OS_MBOX_FULL);//如果邮箱中有消息，表明邮箱满了
}
pevent->OSEventPtr = msg; /* Place message in mailbox */
//将消息放到邮箱中
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* POST MESSAGE TO A MAILBOX
*
* Description: This function sends a message to a mailbox
*
* Arguments : pevent is a pointer to the event control block associated with the desired mailbox
*
* 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 OSMboxPost())
* OS_POST_OPT_BROADCAST POST to ALL tasks that are waiting on the mailbox
*
* Returns : OS_NO_ERR The call was successful and the message was sent
* OS_MBOX_FULL If the mailbox already contains a message. You can can only send one
* message at a time and thus, the message MUST be consumed before you
* are allowed to send another one.
* OS_ERR_EVENT_TYPE If you are attempting to post to a non mailbox.
* 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 mailbox.
功能更强的向邮箱中发送一则消息
描述：发送一个消息到邮箱
参数：pevent：指向目标邮箱的ECB的指针
msg:将要发送的消息指针，不能发送空指针
opt：决定如下发送模式：
OS_POST_OPT_NONE ：发给单片等待任务，这个和OSMboxPost()等同。
OS_POST_OPT_BROADCAST：向在邮箱中等待的所有任务发送。
返回： OS_NO_ERR：消息发送成功
OS_MBOX_FULL ：如果邮箱中已经有消息了，一次只能发送一条消息，
在你允许发送另一条前，消息必须用掉
OS_ERR_EVENT_TYPE：如果你要发送到的不是邮箱
OS_ERR_PEVENT_NULL：如果目标ECB是空指针
OS_ERR_POST_NULL_PTR：如果你想发空指针
*********************************************************************************************************
*/
#if OS_MBOX_POST_OPT_EN > 0
INT8U OSMboxPostOpt (OS_EVENT *pevent, void *msg, INT8U opt)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}
if (msg == (void *)0) { /* Make sure we are not posting a NULL pointer */
return (OS_ERR_POST_NULL_PTR);
}//保证传递的不是空指针
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//保证是邮箱类型
#endif
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00) { /* See if any task pending on mailbox */
//是否有任务在邮箱中挂起
if ((opt & OS_POST_OPT_BROADCAST) != 0x00) { /* Do we need to post msg to ALL waiting tasks ? */
//是不是向所有任务发消息？
while (pevent->OSEventGrp != 0x00) { /* Yes, Post to ALL tasks waiting on mailbox */
//如果是，向所有等待任务发，将所有任务从等待列表中删除
OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX);
}
} else {
OS_EventTaskRdy(pevent, msg, OS_STAT_MBOX); /* No, Post to HPT waiting on mbox */
//如果没有广播，则只有最高优先级进入就绪态，准备运行，
//OS_EventTaskRdy函数只将最高优先级任务从等待列表中删除
}
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
//任务调度
return (OS_NO_ERR);
}
if (pevent->OSEventPtr != (void *)0) { /* Make sure mailbox doesn't already have a msg */
OS_EXIT_CRITICAL();
return (OS_MBOX_FULL);//如果邮箱中有邮件，返回已经满了。
}
pevent->OSEventPtr = msg; /* Place message in mailbox */
//保存邮箱中的消息
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* QUERY A MESSAGE MAILBOX
*
* Description: This function obtains information about a message mailbox.
*
* Arguments : pevent is a pointer to the event control block associated with the desired mailbox
*
* pdata is a pointer to a structure that will contain information about the message
* mailbox.
*
* 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 mailbox.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
查询一个邮箱的状态
描述：包含消息邮箱的信息
参数：pevent：指向目标邮箱ECB的指针
pdata：包含消息邮箱信息的结构指针
返回：OS_NO_ERR 调用成功，消息发送成功
* OS_ERR_EVENT_TYPE 你想从非邮箱中得到数据
* OS_ERR_PEVENT_NULL 如果pevent是NULL
*********************************************************************************************************
*/
#if OS_MBOX_QUERY_EN > 0
INT8U OSMboxQuery (OS_EVENT *pevent, OS_MBOX_DATA *pdata)
{
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr;
#endif
INT8U *psrc;
INT8U *pdest;
#if OS_ARG_CHK_EN > 0
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}//不合理的pevent
if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}//如果不是邮箱类型
#endif
OS_ENTER_CRITICAL();
pdata->OSEventGrp = pevent->OSEventGrp; /* Copy message mailbox wait list */
//拷贝消息邮箱等待列表
psrc = &pevent->OSEventTbl[0];
pdest = &pdata->OSEventTbl[0];//邮箱中等待事件发生链表
//复制等待任务列表，，之所以使用条件编译产生的内嵌代码，不用循环语句，
//是因为这样代码运行速度更快
#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
pdata->OSMsg = pevent->OSEventPtr; /* Get message from mailbox */
//从邮箱中获得消息
OS_EXIT_CRITICAL();
return (OS_NO_ERR);
}
#endif /* OS_MBOX_QUERY_EN */
#endif /* OS_MBOX_EN */