本篇介紹以下內(nèi)容：

• 簡(jiǎn)單介紹郵箱機(jī)制
• 從郵箱中接收消息void ?*OSMboxAccept (OS_EVENT *pevent
• 建立并初始化一個(gè)郵箱OS_EVENT ?*OSMboxCreate (void *pmsg)
  
• 刪除郵箱OS_EVENT ?*OSMboxDel (OS_EVENT ?*pevent,INT8U ?opt,INT8U ? *perr)
  
• 取消等待消息的任務(wù)OSMboxPendAbort (OS_EVENT ?*pevent,INT8U ?opt,INT8U ?*perr)
  
• 通過(guò)消息郵箱向任務(wù)發(fā)送消息OSMboxPost (OS_EVENT ?*pevent,void ?*pmsg)
  
• 通過(guò)郵箱向(多)任務(wù)發(fā)送消息OSMboxPostOpt (OS_EVENT ?*pevent,void *pmsg,INT8U opt)
  
• ?取得郵箱中的信息OSMboxQuery (OS_EVENT ?*pevent,?OS_MBOX_DATA ?*p_mbox_data)
  

郵箱機(jī)制簡(jiǎn)單介紹一下：

在uc/os-ii中，完成一次兩個(gè)任務(wù)間的消息傳遞，只需要一個(gè)郵箱，并且郵箱中只能存放一個(gè)消息。在消息沒(méi)有取走前，不能在郵箱中存放新的消息。

uc/os-ii中存放和傳遞的是消息內(nèi)容緩沖區(qū)的指針。

在uc/os-ii中，調(diào)度系統(tǒng)不能自動(dòng)通知某個(gè)任務(wù)郵箱中已經(jīng)有消息，需要任務(wù)主動(dòng)去取郵件（調(diào)用函數(shù)OSMboxPend（））。

郵箱操作過(guò)程：uc/os-ii郵箱通信的過(guò)程首先建立一個(gè)數(shù)據(jù)緩沖區(qū)，即創(chuàng)建郵箱。一個(gè)系統(tǒng)中或者一個(gè)任務(wù)可以建立多個(gè)郵箱。不同郵箱通過(guò)郵箱指針來(lái)識(shí)別，該指針在建立郵箱時(shí)產(chǎn)生。郵箱由使用郵箱的任務(wù)函數(shù)建立，也可在系統(tǒng)初始化函數(shù)中建立。郵箱一旦建立，建立后將得到“OS_EVENT”類型的結(jié)構(gòu)指針，任務(wù)函數(shù)通過(guò)該指針可對(duì)郵箱進(jìn)行存取操作。

一個(gè)系統(tǒng)中可以存在多個(gè)郵箱，對(duì)于接收消息的任務(wù)函數(shù)來(lái)說(shuō)，應(yīng)該知道從那個(gè)郵箱中取消息，郵箱的識(shí)別是創(chuàng)建郵箱時(shí)“OSMboxCreate（）”函數(shù)的返回值來(lái)得到的。互相發(fā)送和接收消息的2個(gè)任務(wù)使用同一個(gè)全局變量（“OS_EVENT”類型）來(lái)標(biāo)識(shí)一個(gè)郵箱。

和郵箱相關(guān)的數(shù)據(jù)結(jié)構(gòu)主要是“OS_EVENT”，另外一個(gè)結(jié)構(gòu)“OS_MBOX_DATA”在函數(shù)中作為局部變量使用。在先收后發(fā)的情況下，使用“OS_TCB”的“OSTCBMsg”分量來(lái)存儲(chǔ)消息指針。消息郵箱的數(shù)據(jù)結(jié)構(gòu)為：

typedef struct os_mbox_data {void *OSMsg; /* Pointer to message in mailbox指向郵箱中消息的指針 */OS_PRIO OSEventTbl[OS_EVENT_TBL_SIZE]; /* List of tasks waiting for event to occur消息的等待任務(wù)列表 */OS_PRIO OSEventGrp; /* Group corresponding to tasks waiting for event to occur消息的等待任務(wù)所在的組 */ } OS_MBOX_DATA; typedef struct os_event {INT8U OSEventType;/* Type of event control block (see OS_EVENT_TYPE_xxxx)事件類型 */void *OSEventPtr;/* Pointer to message or queue structure 指向消息或者隊(duì)列結(jié)構(gòu)的指針 */INT16U OSEventCnt;/* Semaphore Count (not used if other EVENT type)*/OS_PRIO OSEventGrp; /* Group corresponding to tasks waiting for event to occur */OS_PRIO OSEventTbl[OS_EVENT_TBL_SIZE]; /* List of tasks waiting for event to occur任務(wù)等待列表*/#if OS_EVENT_NAME_EN > 0uINT8U *OSEventName; #endif } OS_EVENT;

OS_EVENT結(jié)構(gòu)中的OSEventType用來(lái)表示事件類型，包括：

郵箱事件：OS_EVENT_TYPE_MBOX;

消息列表事件：OS_EVENT_TYPE_Q;

信號(hào)量事件：OS_EVENT_TYPE_SEM;

對(duì)于郵箱通信，我們只需要OS_EVENT中的”O(jiān)SEventTb1“和”O(jiān)SEventGrp“還有”O(jiān)SEventPtr“就可以了。

7.郵箱的容量：在郵箱創(chuàng)建時(shí)，系統(tǒng)并不分配郵箱的大小，郵箱的存儲(chǔ)空間實(shí)際上是發(fā)信任務(wù)定義的。消息傳遞過(guò)程中，只傳遞所發(fā)消息的指針，函數(shù)OSMboxPost（）將消息指針傳遞給“OS_EVENT”中的“OSEventPtr”。

8.注意一點(diǎn)：對(duì)于使用消息的任務(wù)函數(shù)來(lái)說(shuō)，由于是指針傳遞，使用局部變量來(lái)儲(chǔ)存發(fā)送消息，消息可能會(huì)在被收到前消失，所以，最好用全局變量來(lái)存儲(chǔ)發(fā)送消息。

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以上關(guān)于郵箱機(jī)制的介紹很清楚了，下面是uc/os-ii中os_mbox.c的部分代碼（代碼只做簡(jiǎn)單的語(yǔ)句注釋，不贅述其他）。

從郵箱中接收消息void ?*OSMboxAccept (OS_EVENT *pevent)：（部分代碼）

#if OS_MBOX_EN > 0u /* ********************************************************************************************************* * ACCEPT MESSAGE FROM MAILBOX * 從郵箱中接收消息 * 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. *描述：該功能檢查郵箱看是否有可以獲得的消息。與OSMboxPend（）不同的是，如果消息不可獲得，OSMboxAccept（）下任務(wù)不會(huì)被掛起。 * Arguments : pevent is a pointer to the event control block *參數(shù)： --pevent：指向事件控制塊的指針 * 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.返回值：!= (void *)0：如果有消息可以獲得，返回該消息。郵箱被清除，當(dāng)下一次調(diào)用OSMboxAccept（）時(shí)，郵箱狀態(tài)為空 ********************************************************************************************************* */ #if OS_MBOX_ACCEPT_EN > 0u void *OSMboxAccept (OS_EVENT *pevent) {void *pmsg;/*指向消息的指針*/ OS_ENTER_CRITICAL();/*進(jìn)入中斷*/pmsg = pevent->OSEventPtr;pevent->OSEventPtr = (void *)0;/*清空郵箱*/OS_EXIT_CRITICAL();/*退出中斷*/return (pmsg); /* 返回收到的消息或null*/

建立并初始化一個(gè)郵箱OS_EVENT ?*OSMboxCreate (void *pmsg)：（部分代碼）

/*$PAGE*/ /* ********************************************************************************************************* * CREATE A MESSAGE MAILBOX * 建立并初始化一個(gè)郵箱 * Description: This function creates a message mailbox if free event control blocks are available. *描述：如果有空閑的事件控制塊，創(chuàng)建一個(gè)郵箱。 * Arguments : pmsg 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. *參數(shù)： --pmsg：指向你將要存儲(chǔ)在郵箱的消息的指針。如果該指針為空，默認(rèn)郵箱為空。 * 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 返回值：!= (OS_EVENT *)0：指向與創(chuàng)建的郵箱關(guān)聯(lián)的事件控制塊的指針。== (OS_EVENT *)0：沒(méi)有可用的事件控制塊。 ********************************************************************************************************* */OS_EVENT *OSMboxCreate (void *pmsg) {OS_EVENT *pevent; OS_ENTER_CRITICAL();/*進(jìn)入中斷*/pevent = OSEventFreeList;/*得到空閑的事件控制塊 */if (OSEventFreeList != (OS_EVENT *)0) /*如果有空閑的事件控制塊*/{ OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;/*更新空閑列表*/}OS_EXIT_CRITICAL();/*退出中斷*/if (pevent != (OS_EVENT *)0)/*如果得到了空閑的事件控制塊*/{pevent->OSEventType = OS_EVENT_TYPE_MBOX;/*將OS_EVENT結(jié)構(gòu)中的事件類型設(shè)置為郵箱事件*/pevent->OSEventCnt = 0u;pevent->OSEventPtr = pmsg; /*將消息存儲(chǔ)在事件控制塊中 */#if OS_EVENT_NAME_EN > 0upevent->OSEventName = (INT8U *)(void *)"?";#endifOS_EventWaitListInit(pevent);/*初始化事件等待列表*/}return (pevent);/* 返回指向事件控制塊的指針*/

刪除郵箱OS_EVENT ?*OSMboxDel (OS_EVENT ?*pevent,INT8U opt,INT8U ?*perr)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * DELETE A MAIBOX * 刪除郵箱 * Description: This function deletes a mailbox and readies all tasks pending on the mailbox. *描述：該函數(shù)是刪除郵箱并將所有在該郵箱掛起的任務(wù)設(shè)置為就緒態(tài) * Arguments : pevent is a pointer to the event control block associated with the desired mailbox. *參數(shù)： --pevent：指向郵箱消息對(duì)應(yīng)的事件控制塊的指針 * 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. * --opt：刪除方式選擇：opt == OS_DEL_NO_PEND：當(dāng)沒(méi)有任務(wù)掛起時(shí)才能刪除；opt == OS_DEL_ALWAYS：即使有任務(wù)等待也將郵箱刪除。這種情況下，所有等待的任務(wù)都轉(zhuǎn)為就緒態(tài)。 * perr is a pointer to an error code that can contain one of the following values: * OS_ERR_NONE 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. * --perr：指向錯(cuò)誤碼的指針：OS_ERR_NONE：成功調(diào)用，郵箱被刪除；OS_ERR_DEL_ISR：從中斷服務(wù)子程序中刪除郵箱；OS_ERR_INVALID_OPT：無(wú)效的選擇方式；OS_ERR_TASK_WAITING：一個(gè)或多個(gè)任務(wù)正在等待；OS_ERR_EVENT_TYPE：沒(méi)有指向郵箱的指針；OS_ERR_PEVENT_NULL：pevent為空指針。 * Returns : pevent upon error * (OS_EVENT *)0 if the mailbox was successfully deleted. *返回值：如果成功刪除，返回值為空。如果沒(méi)有成功，返回pevent。 * 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.注釋：1）該功能需要小心使用。等待郵箱消息的任務(wù)必須先檢查OSMboxPend（）函數(shù)的返回值。2）調(diào)用OSMboxAccept（）的任務(wù)無(wú)法知道要郵箱是否已經(jīng)被刪除。3）該函數(shù)調(diào)用會(huì)中斷很長(zhǎng)時(shí)間，時(shí)間與等待郵箱的任務(wù)的數(shù)量相關(guān)。4）因?yàn)樗袙炱鸬娜蝿?wù)都會(huì)被轉(zhuǎn)為就緒態(tài)，所以如果郵箱中的消息是互斥型信號(hào)量就需要特別注意了，因?yàn)榇藭r(shí)資源是開放的。 ********************************************************************************************************* */#if OS_MBOX_DEL_EN > 0u OS_EVENT *OSMboxDel (OS_EVENT *pevent,INT8U opt,INT8U *perr) {BOOLEAN tasks_waiting;/*檢測(cè)是否有正在等待的任務(wù)*/OS_EVENT *pevent_return;/*返回指針*/#if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u;#endif#ifdef OS_SAFETY_CRITICALif (perr == (INT8U *)0) {OS_SAFETY_CRITICAL_EXCEPTION();}#endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { *perr = OS_ERR_PEVENT_NULL;return (pevent);}#endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { *perr = OS_ERR_EVENT_TYPE;return (pevent);}if (OSIntNesting > 0u) { *perr = OS_ERR_DEL_ISR; return (pevent);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*/if (pevent->OSEventGrp != 0u)/*檢測(cè)是否有任務(wù)正在等待*/{ tasks_waiting = OS_TRUE; /*有任務(wù)等待，將等待標(biāo)志設(shè)置為true*/} else{tasks_waiting = OS_FALSE; /* 沒(méi)有任務(wù)等待，將等待標(biāo)志設(shè)置為false*/}switch (opt) /*選擇刪除方式并進(jìn)行相應(yīng)操作*/{case OS_DEL_NO_PEND: /* 無(wú)掛起才刪除*/if (tasks_waiting == OS_FALSE) /*沒(méi)有任務(wù)等待*/{#if OS_EVENT_NAME_EN > 0upevent->OSEventName = (INT8U *)(void *)"?";/*名字設(shè)為未命名*/#endifpevent->OSEventType = OS_EVENT_TYPE_UNUSED;/*事件類型設(shè)置為未使用類型*/pevent->OSEventPtr = OSEventFreeList; /*將事件控制塊返還給空閑列表*/pevent->OSEventCnt = 0u;OSEventFreeList = pevent;/*更新空閑列表 */OS_EXIT_CRITICAL();/*退出中斷*/*perr = OS_ERR_NONE;pevent_return = (OS_EVENT *)0; /*返回值設(shè)為空，郵箱已經(jīng)被刪除*/}else/*有任務(wù)正在等待*/{OS_EXIT_CRITICAL();/*退出中斷*/*perr = OS_ERR_TASK_WAITING;/*設(shè)置錯(cuò)誤類型*/pevent_return = pevent;/*將事件控制塊指針?lè)祷?/}break;case OS_DEL_ALWAYS: /* 無(wú)論怎樣都刪除郵箱*/while (pevent->OSEventGrp != 0u) { (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MBOX, OS_STAT_PEND_OK);/*將所有的任務(wù)都設(shè)置為就緒態(tài)*/}#if OS_EVENT_NAME_EN > 0upevent->OSEventName = (INT8U *)(void *)"?";#endifpevent->OSEventType = OS_EVENT_TYPE_UNUSED;/*事件類型設(shè)置為未使用類型*/pevent->OSEventPtr = OSEventFreeList;/* 將事件控制塊返回給空閑列表 */pevent->OSEventCnt = 0u;OSEventFreeList = pevent;/* 更新空閑列表 */OS_EXIT_CRITICAL();/*退出中斷*/if (tasks_waiting == OS_TRUE) /*有任務(wù)正在等待*/{ OS_Sched(); /* 找到就緒任務(wù)中優(yōu)先級(jí)最高的任務(wù)進(jìn)行調(diào)度*/}*perr = OS_ERR_NONE;pevent_return = (OS_EVENT *)0;/*郵箱被刪除，返回空指針*/break;default:/*兩種刪除情況都不是*/OS_EXIT_CRITICAL();/*退出中斷*/*perr = OS_ERR_INVALID_OPT;/*設(shè)置錯(cuò)誤類型*/pevent_return = pevent;/*將事件控制塊指針?lè)祷?/break;}return (pevent_return); } #endif

等待消息進(jìn)入郵箱void ?*OSMboxPend (OS_EVENT ?*pevent,INT32U ?timeout,INT8U ?*perr)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * PEND ON MAILBOX FOR A MESSAGE * 等待消息進(jìn)入郵箱 * Description: This function waits for a message to be sent to a mailbox *描述：該功能用來(lái)等地啊消息進(jìn)入郵箱。 * Arguments : pevent is a pointer to the event control block associated with the desired mailbox *參數(shù)： --pevent：指向事件控制塊的指針 * 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. * --timeout：時(shí)間片。如果不為0，任務(wù)將等待消息到來(lái)，直到時(shí)間到達(dá)設(shè)定的值。如果設(shè)置為0，任務(wù)將無(wú)限等待，直到有消息到來(lái)。 * perr is a pointer to where an error message will be deposited. Possible error * messages are: * OS_ERR_NONE The call was successful and your task received a * message. * OS_ERR_TIMEOUT A message was not received within the specified 'timeout'. * OS_ERR_PEND_ABORT The wait on the mailbox was aborted. * 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 * OS_ERR_PEND_LOCKED If you called this function when the scheduler is locked * --perr：指向錯(cuò)誤碼的指針：OS_ERR_NONE：成功調(diào)用，任務(wù)收到消息；OS_ERR_TIMEOUT：在規(guī)定時(shí)間內(nèi)沒(méi)有收到消息（超時(shí)錯(cuò)）；OS_ERR_PEND_ABORT：取消了正在等待的任務(wù)；OS_ERR_EVENT_TYPE：無(wú)效的事件類型；OS_ERR_PEND_ISR：從中斷服務(wù)子程序中調(diào)用該函數(shù)；OS_ERR_PEVENT_NULL：pevent為空指針；OS_ERR_PEND_LOCKED：調(diào)度器上鎖時(shí)進(jìn)行調(diào)用。 * 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.返回值：!= (void *)0：指向收到的消息的指針；== (void *)0：沒(méi)有收到消息或者pevnet為空指針或者沒(méi)有指向事件控制塊的指針時(shí)返回空。 ********************************************************************************************************* */ /*$PAGE*/ void *OSMboxPend (OS_EVENT *pevent,INT32U timeout,INT8U *perr) {void *pmsg;/*指向消息的指針*/ #if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u; #endif#ifdef OS_SAFETY_CRITICALif (perr == (INT8U *)0) {OS_SAFETY_CRITICAL_EXCEPTION();} #endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { *perr = OS_ERR_PEVENT_NULL;return ((void *)0);} #endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { *perr = OS_ERR_EVENT_TYPE;return ((void *)0);}if (OSIntNesting > 0u) { *perr = OS_ERR_PEND_ISR; return ((void *)0);}if (OSLockNesting > 0u) { *perr = OS_ERR_PEND_LOCKED; return ((void *)0);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*/pmsg = pevent->OSEventPtr;/*指向消息*/if (pmsg != (void *)0)/*如果有消息存在*/{ pevent->OSEventPtr = (void *)0; /* 清除郵箱 */OS_EXIT_CRITICAL();/*退出中斷*/*perr = OS_ERR_NONE;return (pmsg); /*返回消息*/}/*如果沒(méi)有消息*/OSTCBCur->OSTCBStat |= OS_STAT_MBOX; /*將任務(wù)掛起*/OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK;OSTCBCur->OSTCBDly = timeout;/*最長(zhǎng)等待時(shí)間＝timeout，遞減式*/OS_EventTaskWait(pevent); /* 將任務(wù)掛起，直到有消息到來(lái)或者時(shí)間到*/OS_EXIT_CRITICAL();/*退出中斷*/OS_Sched(); /*選擇優(yōu)先級(jí)高的任務(wù)進(jìn)行調(diào)度*/OS_ENTER_CRITICAL();/*進(jìn)入中斷*/switch (OSTCBCur->OSTCBStatPend) /*檢查掛起狀態(tài)原因，是超時(shí)還是任務(wù)被取消*/{ case OS_STAT_PEND_OK:/*無(wú)超時(shí)，也沒(méi)被取消，正常的等待消息*/pmsg = OSTCBCur->OSTCBMsg;/*返回消息*/*perr = OS_ERR_NONE;break;case OS_STAT_PEND_ABORT:/*被取消*/pmsg = (void *)0;/*返回空*/*perr = OS_ERR_PEND_ABORT; break;case OS_STAT_PEND_TO:/*超時(shí)*/default:/*其他情況*/OS_EventTaskRemove(OSTCBCur, pevent);/*將任務(wù)移除*/pmsg = (void *)0;/*返回空*/*perr = OS_ERR_TIMEOUT;break;}OSTCBCur->OSTCBStat = OS_STAT_RDY; /* 將當(dāng)前任務(wù)狀態(tài)設(shè)置為就緒態(tài)*/OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK; /*清除掛起狀態(tài)*/OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0; /*清除事件指針*/#if (OS_EVENT_MULTI_EN > 0u)OSTCBCur->OSTCBEventMultiPtr = (OS_EVENT **)0;#endifOSTCBCur->OSTCBMsg = (void *)0;/*清除收到的消息*/OS_EXIT_CRITICAL();/*退出中斷*/return (pmsg);/*返回收到的消息*/ }

取消等待消息的任務(wù)OSMboxPendAbort (OS_EVENT ?*pevent,INT8U ? opt,INT8U ?*perr)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * ABORT WAITING ON A MESSAGE MAILBOX * 取消等待消息的任務(wù) * Description: This function aborts & readies any tasks currently waiting on a mailbox. This function * should be used to fault-abort the wait on the mailbox, rather than to normally signal * the mailbox via OSMboxPost() or OSMboxPostOpt(). *描述：該函數(shù)將正在等待郵箱消息的任務(wù)取消。該函數(shù)不需要通過(guò)OSMboxPost()或者OSMboxPostOpt()函數(shù)來(lái)通知郵箱進(jìn)行刪除， 是默認(rèn)取消。 * Arguments : pevent is a pointer to the event control block associated with the desired mailbox. *參數(shù)：--pevent：指向事件控制塊的指針。 * opt determines the type of ABORT performed: * OS_PEND_OPT_NONE ABORT wait for a single task (HPT) waiting on the * mailbox * OS_PEND_OPT_BROADCAST ABORT wait for ALL tasks that are waiting on the * mailbox * --opt：取消方式：OS_PEND_OPT_NONE：取消一個(gè)；OS_PEND_OPT_BROADCAST：全部取消； * perr is a pointer to where an error message will be deposited. Possible error * messages are: * OS_ERR_NONE No tasks were waiting on the mailbox. * OS_ERR_PEND_ABORT At least one task waiting on the mailbox was readied * and informed of the aborted wait; check return value * for the number of tasks whose wait on the mailbox * was aborted. * OS_ERR_EVENT_TYPE If you didn't pass a pointer to a mailbox. * OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer. * --perr：錯(cuò)誤碼指針：OS_ERR_NONE：沒(méi)有任務(wù)在等待；OS_ERR_PEND_ABORT：至少一個(gè)被通知取消等待的任務(wù)是就緒態(tài)。OS_ERR_EVENT_TYPE：沒(méi)有指向郵箱的指針；OS_ERR_PEVENT_NULL：pevent為空指針。 * Returns : == 0 if no tasks were waiting on the mailbox, or upon error. * > 0 if one or more tasks waiting on the mailbox are now readied and informed.返回值： == 0：沒(méi)有任務(wù)在等待，返回空；> 0：一個(gè)或者多個(gè)正在等待郵箱并且已經(jīng)被通知取消的任務(wù)是就緒態(tài)。 ********************************************************************************************************* */#if OS_MBOX_PEND_ABORT_EN > 0u INT8U OSMboxPendAbort (OS_EVENT *pevent,INT8U opt,INT8U *perr) {INT8U nbr_tasks;#if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u;#endif#ifdef OS_SAFETY_CRITICALif (perr == (INT8U *)0) {OS_SAFETY_CRITICAL_EXCEPTION();}#endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { *perr = OS_ERR_PEVENT_NULL;return (0u);}#endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { *perr = OS_ERR_EVENT_TYPE;return (0u);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*/if (pevent->OSEventGrp != 0u) /*有任務(wù)正在等待郵箱*/{ nbr_tasks = 0u;switch (opt)/*選擇取消的方式并進(jìn)行相關(guān)操作*/{case OS_PEND_OPT_BROADCAST:/*所有任務(wù)都清除*/while (pevent->OSEventGrp != 0u){ (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MBOX, OS_STAT_PEND_ABORT);/*所有任務(wù)設(shè)為就緒態(tài)*/nbr_tasks++;}break;case OS_PEND_OPT_NONE:/*只清除一個(gè)*/default: /*其他情況 */(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MBOX, OS_STAT_PEND_ABORT);/*將最高優(yōu)先級(jí)的任務(wù)設(shè)為就緒態(tài)*/nbr_tasks++;break;}OS_EXIT_CRITICAL();/*退出中斷*/OS_Sched(); /*對(duì)最高優(yōu)先級(jí)任務(wù)進(jìn)行任務(wù)調(diào)度*/*perr = OS_ERR_PEND_ABORT;return (nbr_tasks);}OS_EXIT_CRITICAL();/*退出中斷*/*perr = OS_ERR_NONE;return (0u);/*沒(méi)有任務(wù)等待返回空 */ } #endif

通過(guò)消息郵箱向任務(wù)發(fā)送消息OSMboxPost (OS_EVENT ?*pevent,void ?*pmsg)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * POST MESSAGE TO A MAILBOX * 通過(guò)消息郵箱向任務(wù)發(fā)送消息 * Description: This function sends a message to a mailbox *描述：該功能是將消息發(fā)送給郵箱。 * Arguments : pevent is a pointer to the event control block associated with the desired mailbox *參數(shù)： --pevent：指向事件控制塊的指針。 * pmsg is a pointer to the message to send. You MUST NOT send a NULL pointer. * --pmsg：指向要發(fā)送的消息的指針，不可以為空 * Returns : OS_ERR_NONE The call was successful and the message was sent * OS_ERR_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 *返回值：OS_ERR_NONE：成功調(diào)用，消息被發(fā)出。OS_ERR_MBOX_FULL：郵箱已經(jīng)包含了消息，一次只能給郵箱放一個(gè)消息。在郵箱消息沒(méi)有發(fā)送出去前不能再往里面放消息了。OS_ERR_EVENT_TYPE：不是給郵箱發(fā)消息；OS_ERR_PEVENT_NULL：pevent為空指針OS_ERR_POST_NULL_PTR：發(fā)送的是個(gè)空消息（空指針） * Note(s) : 1) HPT means Highest Priority Task 注釋：1）HPT表示最高優(yōu)先級(jí)任務(wù)。 ********************************************************************************************************* */#if OS_MBOX_POST_EN > 0u INT8U OSMboxPost (OS_EVENT *pevent,void *pmsg) {#if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u;#endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { return (OS_ERR_PEVENT_NULL);}if (pmsg == (void *)0) { return (OS_ERR_POST_NULL_PTR);}#endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { return (OS_ERR_EVENT_TYPE);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*/if (pevent->OSEventGrp != 0u) /*如果有任務(wù)正在等郵箱*/{ (void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_MBOX, OS_STAT_PEND_OK);/*將所有任務(wù)設(shè)置為就緒態(tài)*/OS_EXIT_CRITICAL();/*退出中斷*/OS_Sched(); /*找到最高優(yōu)先級(jí)任務(wù)進(jìn)行調(diào)度*/return (OS_ERR_NONE);}if (pevent->OSEventPtr != (void *)0) /*郵箱不為空，里面已經(jīng)有消息存在*/{ OS_EXIT_CRITICAL();/*退出中斷*/return (OS_ERR_MBOX_FULL);}pevent->OSEventPtr = pmsg;/* 將消息放在郵箱中 */OS_EXIT_CRITICAL();/*退出中斷*/return (OS_ERR_NONE); } #endif

通過(guò)郵箱向(多)任務(wù)發(fā)送消息OSMboxPostOpt (OS_EVENT ?*pevent,void *pmsg,INT8U opt)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * POST MESSAGE TO A MAILBOX * ???????????????? 通過(guò)郵箱向(多)任務(wù)發(fā)送消息 * Description: This function sends a message to a mailbox *描述：該功能是通過(guò)郵箱向多任務(wù)發(fā)送消息。 * Arguments : pevent is a pointer to the event control block associated with the desired mailbox *參數(shù)： --pevent：指向事件控制塊的指針。 * pmsg is a pointer to the message to send. You MUST NOT send a NULL pointer. * --pmsg：指向要發(fā)送的消息的指針，不可以為空。 * 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 * * OS_POST_OPT_NO_SCHED Indicates that the scheduler will NOT be invoked * --opt：發(fā)送類型：OS_POST_OPT_NONE：只給一個(gè)任務(wù)發(fā)送；OS_POST_OPT_BROADCAST：給所有等待消息的任務(wù)都發(fā)送OS_POST_OPT_NO_SCHED：調(diào)度程序不會(huì)被調(diào)用 * Returns : OS_ERR_NONE The call was successful and the message was sent * OS_ERR_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 *返回值：OS_ERR_NONE：調(diào)用成功，消息被發(fā)出OS_ERR_MBOX_FULL：郵箱中已經(jīng)有消息存在，OS_ERR_EVENT_TYPE：發(fā)送對(duì)象不是郵箱。OS_ERR_PEVENT_NULL：pevent為空指針OS_ERR_POST_NULL_PTR：消息為空。 * Note(s) : 1) HPT means Highest Priority Task *注釋：1）HPT是最高優(yōu)先級(jí)任務(wù)的意思 * 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. 警告：如果選擇了給全部等待任務(wù)發(fā)消息，會(huì)中斷很長(zhǎng)時(shí)間。中斷事件與等待的任務(wù)數(shù)量有關(guān)系。 ********************************************************************************************************* */#if OS_MBOX_POST_OPT_EN > 0u INT8U OSMboxPostOpt (OS_EVENT *pevent,void *pmsg,INT8U opt) {#if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u;#endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { return (OS_ERR_PEVENT_NULL);}if (pmsg == (void *)0) { return (OS_ERR_POST_NULL_PTR);}#endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {return (OS_ERR_EVENT_TYPE);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*/if (pevent->OSEventGrp != 0u)/*看是否有任務(wù)正在等待*/{ if ((opt & OS_POST_OPT_BROADCAST) != 0x00u) /*給所有等待任務(wù)發(fā)消息*/{ while (pevent->OSEventGrp != 0u) { (void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_MBOX, OS_STAT_PEND_OK);}} else/*給一個(gè)等待任務(wù)發(fā)消息*/{ (void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_MBOX, OS_STAT_PEND_OK);}OS_EXIT_CRITICAL();/*退出中斷*/if ((opt & OS_POST_OPT_NO_SCHED) == 0u) /*看是否需要喚醒調(diào)度程序*/{ OS_Sched(); /*選擇優(yōu)先級(jí)最高的任務(wù)進(jìn)行調(diào)度*/}return (OS_ERR_NONE);}/*沒(méi)有任務(wù)正在等待*/if (pevent->OSEventPtr != (void *)0)/*郵箱中有消息存在*/{ OS_EXIT_CRITICAL();/*退出中斷*/return (OS_ERR_MBOX_FULL);}pevent->OSEventPtr = pmsg;/*將消息放在郵箱中*/OS_EXIT_CRITICAL();/*退出中斷*/return (OS_ERR_NONE); } #endif

取得消息郵箱的信息?OSMboxQuery (OS_EVENT *pevent,OS_MBOX_DATA ?*p_mbox_data)：

/*$PAGE*/ /*2018/2/21 ********************************************************************************************************* * QUERY A MESSAGE MAILBOX * 取得消息郵箱的信息 * Description: This function obtains information about a message mailbox. *描述：該函數(shù)是獲得郵箱中的消息 * Arguments : pevent is a pointer to the event control block associated with the desired mailbox *參數(shù)： --pevent：指向事件控制塊的指針 * p_mbox_data is a pointer to a structure that will contain information about the message * mailbox. * --p_mbox_data：指向p_mbox_data結(jié)構(gòu)體的指針。 * Returns : OS_ERR_NONE 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 * OS_ERR_PDATA_NULL If 'p_mbox_data' is a NULL pointer 返回值：OS_ERR_NONE：調(diào)用成功，消息被發(fā)出；OS_ERR_EVENT_TYPE：不是從郵箱中獲得消息；OS_ERR_PEVENT_NULL：pevent為空指針；OS_ERR_PDATA_NULL：p_mbox_data為空指針。 ********************************************************************************************************* */#if OS_MBOX_QUERY_EN > 0u INT8U OSMboxQuery (OS_EVENT *pevent,OS_MBOX_DATA *p_mbox_data) {INT8U i;OS_PRIO *psrc;OS_PRIO *pdest;#if OS_CRITICAL_METHOD == 3u OS_CPU_SR cpu_sr = 0u;#endif#if OS_ARG_CHK_EN > 0uif (pevent == (OS_EVENT *)0) { return (OS_ERR_PEVENT_NULL);}if (p_mbox_data == (OS_MBOX_DATA *)0) { return (OS_ERR_PDATA_NULL);}#endifif (pevent->OSEventType != OS_EVENT_TYPE_MBOX) { return (OS_ERR_EVENT_TYPE);}OS_ENTER_CRITICAL();/*進(jìn)入中斷*//*將事件(郵箱)結(jié)構(gòu)中的等待任務(wù)列表復(fù)制到pdata數(shù)據(jù)結(jié)構(gòu)中*/p_mbox_data->OSEventGrp = pevent->OSEventGrp;/*等待事件的任務(wù)組中的內(nèi)容傳送到狀態(tài)數(shù)據(jù)結(jié)構(gòu)中*/psrc = &pevent->OSEventTbl[0];/*保存pevent->OSEventTbl[0]對(duì)應(yīng)的地址，源*/pdest = &p_mbox_data->OSEventTbl[0];/*保存pdata->OSEventTbl[0]對(duì)應(yīng)的地址，目的*/for (i = 0u; i < OS_EVENT_TBL_SIZE; i++) {*pdest++ = *psrc++;/*地址指針下移一個(gè)類型地址，獲取消息郵箱的值*/}p_mbox_data->OSMsg = pevent->OSEventPtr;/*將郵箱中的當(dāng)前消息從事件數(shù)據(jù)結(jié)構(gòu)復(fù)制到OS_MBOX_DATA數(shù)據(jù)結(jié)構(gòu) */OS_EXIT_CRITICAL();/*退出中斷*/return (OS_ERR_NONE); } #endif /* OS_MBOX_QUERY_EN */ #endif /* OS_MBOX_EN */

文章到這里就結(jié)束了。

uc/os-ii中的os_mbox.c文件全部讀完。重點(diǎn)是了解郵箱機(jī)制，還要清楚相關(guān)的結(jié)構(gòu)體。看郵箱有沒(méi)有消息什么的都是通過(guò)事件控制塊中的OSEventGrp等判斷的。具體看代碼即可。

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