os_mbox.c

ucosii 实例

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                       MESSAGE MAILBOX MANAGEMENT
*
*                              (c) Copyright 1992-2009, Micrium, Weston, FL
*                                           All Rights Reserved
*
* File    : OS_MBOX.C
* By      : Jean J. Labrosse
* Version : V2.91
*
* LICENSING TERMS:
* ---------------
*   uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research.
* If you plan on using  uC/OS-II  in a commercial product you need to contact Micri祄 to properly license
* its use in your product. We provide ALL the source code for your convenience and to help you experience
* uC/OS-II.   The fact that the  source is provided does  NOT  mean that you can use it without  paying a
* licensing fee.
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#endif

#if OS_MBOX_EN > 0u
/*
*********************************************************************************************************
*                                     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.
*********************************************************************************************************
*/

#if OS_MBOX_ACCEPT_EN > 0u
void  *OSMboxAccept (OS_EVENT *pevent)
{
    void      *pmsg;
#if OS_CRITICAL_METHOD == 3u                              /* Allocate storage for CPU status register  */
    OS_CPU_SR  cpu_sr = 0u;
#endif



#if OS_ARG_CHK_EN > 0u
    if (pevent == (OS_EVENT *)0) {                        /*事件控制块指针是否有效    */
        return ((void *)0);
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {      /* 事件控制块类型是否有效 */
        return ((void *)0);
    }
    OS_ENTER_CRITICAL();
    pmsg               = pevent->OSEventPtr;
    pevent->OSEventPtr = (void *)0;                       /* 清邮箱   */
    OS_EXIT_CRITICAL();
    return (pmsg);                                        /* 返回获得的消息（或空指针）  */
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
*                                        CREATE A MESSAGE MAILBOX
*
* Description: This function creates a message mailbox if free event control blocks are available.
*
* 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.
*
* 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
*********************************************************************************************************
*/

OS_EVENT  *OSMboxCreate (void *pmsg)
{
    OS_EVENT  *pevent;
#if OS_CRITICAL_METHOD == 3u                     /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr = 0u;
#endif



#ifdef OS_SAFETY_CRITICAL_IEC61508
    if (OSSafetyCriticalStartFlag == OS_TRUE) {
        OS_SAFETY_CRITICAL_EXCEPTION();
    }
#endif

    if (OSIntNesting > 0u) {                     /* 查看是否在中断服务程序ISR中调用本函数*/
        return ((OS_EVENT *)0);                  /* 不允许在中断服务程序ISR中调用本函数*/
    }
    OS_ENTER_CRITICAL();
    pevent = OSEventFreeList;                    /* 取得空闲的事件控制块ECB*/
    if (OSEventFreeList != (OS_EVENT *)0) {      /* 是否没有可用的事件控制块ECB? */
        OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
    }
    OS_EXIT_CRITICAL();
    if (pevent != (OS_EVENT *)0) {
        pevent->OSEventType    = OS_EVENT_TYPE_MBOX;
        pevent->OSEventCnt     = 0u;
        pevent->OSEventPtr     = pmsg;           /* 在ECB中存储消息地址*/
#if OS_EVENT_NAME_EN > 0u
        pevent->OSEventName    = (INT8U *)(void *)"?";
#endif
        OS_EventWaitListInit(pevent);
    }
    return (pevent);                             /* 返回事件控制块地址*/
}
/*$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.
*
*              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.
*
* 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.
*********************************************************************************************************
*/

#if OS_MBOX_DEL_EN > 0u
OS_EVENT  *OSMboxDel (OS_EVENT  *pevent,
                      INT8U      opt,
                      INT8U     *perr)
{
    BOOLEAN    tasks_waiting;
    OS_EVENT  *pevent_return;
#if OS_CRITICAL_METHOD == 3u                               /* Allocate storage for CPU status register */
    OS_CPU_SR  cpu_sr = 0u;
#endif



#ifdef OS_SAFETY_CRITICAL
    if (perr == (INT8U *)0) {
        OS_SAFETY_CRITICAL_EXCEPTION();
    }
#endif

#if OS_ARG_CHK_EN > 0u
    if (pevent == (OS_EVENT *)0) {                         /*事件控制块指针是否有效   */
        *perr = OS_ERR_PEVENT_NULL;
        return (pevent);
    }
#endif
    if (pevent->OSEventType != OS_EVENT_TYPE_MBOX) {       /* 事件控制块类型是否有效*/
        *perr = OS_ERR_EVENT_TYPE;
        return (pevent);
    }
    if (OSIntNesting > 0u) {                               /* 查看是否在中断服务程序ISR中调用本函数               */
        *perr = OS_ERR_DEL_ISR;                            /* ... can't DELETE from an ISR             */
        return (pevent);
    }
    OS_ENTER_CRITICAL();
    if (pevent->OSEventGrp != 0u) {                        /* See if any tasks waiting on mailbox      */
        tasks_waiting = OS_TRUE;                           /* Yes                                      */
    } else {
        tasks_waiting = OS_FALSE;                          /* No                                       */
    }
    switch (opt) {
        case OS_DEL_NO_PEND:                               /* Delete mailbox only if no task waiting   */
             if (tasks_waiting == OS_FALSE) {
#if OS_EVENT_NAME_EN > 0u
                 pevent->OSEventName = (INT8U *)(void *)"?";
#endif
                 pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
                 pevent->OSEventPtr  = OSEventFreeList;    /* Return Event Control Block to free list  */
                 pevent->OSEventCnt  = 0u;
                 OSEventFreeList     = pevent;             /* 取得空闲的事件控制块ECB      */
                 OS_EXIT_CRITICAL();
                 *perr               = OS_ERR_NONE;
                 pevent_return       = (OS_EVENT *)0;      /* Mailbox has been deleted                 */
             } else {
                 OS_EXIT_CRITICAL();
                 *perr               = OS_ERR_TASK_WAITING;
                 pevent_return       = pevent;
             }