emos_mbox.c

emos是一个新的类似于ucos的内核

/****************************************************************************
 *
 * (c) Copyright 2001,2008, EMB system, All Rights Reserved.
 * THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF EMB SYSTEM, INC.
 * The copyright notice above does not evidence any actual or intended
 * publication of such source code. 
 *
 *  Subsystem:    EMOS 
 *  File:         emos_mbox.c
 *  Author:       zenf zhao
 *  Description:  embedded software system MBOX managenent
 *
 ****************************************************************************/
#include "emos_inc.h"
#include "emos_cfg.h"
#include "emos_core.h"

#if EMOS_MBOX_EN
/*********************************************************************************************************
* 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    : != (void *)0  is a pointer to the event control clock (EMOS_EVENT) associated with the
*                            created mailbox
*              == (void *)0  if no event control blocks were available
**********************************************************************************************************/
EMOS_EVENT_T* emosMboxCreate (void *msg)
{
    EMOS_EVENT_T* pevent;

    if(msg == NULL) return NULL;
    
    EMOS_ENTER_CRITICAL();
    pevent = gEmosEventFreeList; /* Get next free event control block */
    if (gEmosEventFreeList != (EMOS_EVENT_T*)0) 
    {  
    	/* See if pool of free ECB pool was empty*/
        gEmosEventFreeList = (EMOS_EVENT_T*)gEmosEventFreeList->osEventPtr;
    }
    EMOS_EXIT_CRITICAL();
    
    if (pevent != (EMOS_EVENT_T*)0)
    {
        pevent->osEventType = EMOS_EVENT_TYPE_MBOX;
        pevent->osEventPtr  = msg; /* Deposit message in event control block */
        emosEventWaitListInit(pevent);
    }

    /* Return pointer to event control block, notes one event ID only can contain
      one MBox message*/
    return (pevent);  
}


/*********************************************************************************************************
* ACCEPT MESSAGE FROM MAILBOX
* Description: This function checks the mailbox to see if a message is available.  Unlike emosMboxPend(),
*              emosMboxAccept() 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 emosMboxAccept() is called, the mailbox will be empty.
*              == (void *)0  if the mailbox is empty or if you didn't pass the proper event pointer.
**********************************************************************************************************/
void *emosMboxAccept (EMOS_EVENT_T *pevent)
{
    void  *msg;
    if(NULL == pevent)  return NULL;
    
    EMOS_ENTER_CRITICAL();
    if (pevent->osEventType != EMOS_EVENT_TYPE_MBOX)
    {  
    	/* Validate event block type*/
        EMOS_EXIT_CRITICAL();
        return ((void *)0);
    }
    
    msg = pevent->osEventPtr; 
    if (msg != (void *)0) 
    {  
    	/* See if there is already a message*/
        pevent->osEventPtr = (void *)0; /* Clear the mailbox*/
    }
    EMOS_EXIT_CRITICAL();
    return (msg);  /* Return the message received (or NULL*/
}


/*********************************************************************************************************
* 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:
*                            EMOS_NO_ERR         The call was successful and your task received a message.
*                            EMOS_TIMEOUT        A message was not received within the specified timeout
*                            EMOS_ERR_EVENT_TYPE Invalid event type
*                            EMOS_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 you didn't pass the proper pointer to the
*                            event control block.
**********************************************************************************************************/
void *emosMboxPend (EMOS_EVENT_T* pevent, uint16 timeout, uint8 *err)
{
    void  *msg;
    
    EMOS_ENTER_CRITICAL();
    if (pevent->osEventType != EMOS_EVENT_TYPE_MBOX)
    {  
    	/* Validate event block type */
        EMOS_EXIT_CRITICAL();
        *err = EMOS_ERR_EVENT_TYPE;
        return ((void *)0);
    }

    /*check, whether a msg has pended on the pevent, one pevent only contains
      max one msg, this is the condition for MBox*/
    msg = pevent->osEventPtr;
    if (msg != (void *)0) 
    {  
    	/* See if there is already a message,
    	   Clear the mailbox and return no error*/
        pevent->osEventPtr = (void *)0;
        EMOS_EXIT_CRITICAL();
        *err = EMOS_NO_ERR;
    } 
    else if (gEmosIntNesting > 0) 
    {  
    	/* See if called from ISR*/
        EMOS_EXIT_CRITICAL();    /*can't PEND from an ISR*/
        *err = EMOS_ERR_PEND_ISR;
    } 
    else 
    {
    	/* Message not available now, task will pend on mbox to wait*/
        gEmosTCBCur->osTCBStat |= EMOS_STAT_MBOX;      
        gEmosTCBCur->osTCBDly   = timeout;  /*Load timeout in TCB*/
        
        /*Suspend task on the pevent until event or timeout occurs,
          the task will be deleted from the system active scheduler task array table*/
        emosEventTaskWait(pevent);        
        EMOS_EXIT_CRITICAL();
        
        /*Find next highest priority task ready to run*/
        emosSched(); 

        /*scheduler return, no other higher task or timeout, 
          continue check if mbox available, if there is a msg, set to rdy*/
        EMOS_ENTER_CRITICAL();
        if ((msg = gEmosTCBCur->osTCBMsg) != (void *)0) 
        {  
        	/* See if we were given the message*/
            gEmosTCBCur->osTCBMsg      = (void *)0; /* Yes, clear message received*/
            gEmosTCBCur->osTCBStat     = EMOS_STAT_RDY;
            gEmosTCBCur->osTCBEventPtr = (EMOS_EVENT_T*)0;  /* No longer waiting for even*/
            EMOS_EXIT_CRITICAL();
            *err                    = EMOS_NO_ERR;
        } 
        else if (gEmosTCBCur->osTCBStat & EMOS_STAT_MBOX)
        {  
        	/* If status is not EMOS_STAT_RDY, timed out  */
            emosEventTo(pevent); /* Make task ready*/
            EMOS_EXIT_CRITICAL();
            msg  = (void *)0;      /* Set message contents to NULL*/
            *err = EMOS_TIMEOUT;   /* Indicate that a timeout occured*/
        } 
        else
        {
            msg = pevent->osEventPtr;  /* Message received */
            pevent->osEventPtr      = (void *)0; /* Clear the mailbox */
            gEmosTCBCur->osTCBEventPtr = (EMOS_EVENT_T*)0;
            EMOS_EXIT_CRITICAL();
            *err = EMOS_NO_ERR;
        }
    }
    
    return (msg);  /* Return the message received (or NULL)  */
}


/*********************************************************************************************************
* 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    : EMOS_NO_ERR          The call was successful and the message was sent
*              EMOS_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.
*              EMOS_ERR_EVENT_TYPE  If you are attempting to post to a non mailbox.
**********************************************************************************************************/
uint8 emosMboxPost (EMOS_EVENT_T* pevent, void *msg)
{
    EMOS_ENTER_CRITICAL();
    if (pevent->osEventType != EMOS_EVENT_TYPE_MBOX)
    {  
    	/* Validate event block type  */
        EMOS_EXIT_CRITICAL();
        return (EMOS_ERR_EVENT_TYPE);
    }

    /*if more than one task is pended on this pevent */
    if (pevent->osEventGrp) 
    {  
    	/* See if any task pending on mailbox, cause mulple task may use the
    	same pevent, so Ready the highest priority task waiting on event*/
        emosEventTaskRdy(pevent, msg, EMOS_STAT_MBOX);
        EMOS_EXIT_CRITICAL();
        emosSched(); /* Find highest priority task ready to run */
        return (EMOS_NO_ERR);
    } 
    else
    {
        if (pevent->osEventPtr != (void *)0)
        {   
        	/* Make sure mailbox doesn't already have a msg  */
            EMOS_EXIT_CRITICAL();
            return (EMOS_MBOX_FULL);
        } 
        else
        {
            pevent->osEventPtr = msg;  /* Place message in mailbox */
            EMOS_EXIT_CRITICAL();
            return (EMOS_NO_ERR);
        }
    }
}


/*********************************************************************************************************
* 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    : EMOS_NO_ERR          The call was successful and the message was sent
*              EMOS_ERR_EVENT_TYPE  If you are attempting to obtain data from a non mailbox.
**********************************************************************************************************/
uint8 emosMboxQuery (EMOS_EVENT_T*pevent, EMOS_MBOX_DATA_T *pdata)
{
    uint8  i;
    uint8 *psrc;
    uint8 *pdest;
       
    EMOS_ENTER_CRITICAL();
    if (pevent->osEventType != EMOS_EVENT_TYPE_MBOX) 
    { 
    	/* Validate event block type */
        EMOS_EXIT_CRITICAL();
        return (EMOS_ERR_EVENT_TYPE);
    }
    
    /* Copy message mailbox wait list */
    pdata->osEventGrp = pevent->osEventGrp; 
    psrc              = &pevent->osEventTbl[0];
    pdest             = &pdata->osEventTbl[0];
    for (i = 0; i < EMOS_EVENT_TBL_SIZE; i++) 
    {
        *pdest++ = *psrc++;   
    }
    
    /* Get message from mailbox */
    pdata->osMsg = pevent->osEventPtr; 
    EMOS_EXIT_CRITICAL();
    return (EMOS_NO_ERR);
}
#endif

 /*
 * Please add "$" around "Id" and "Log".
 * $Id$
 * $Log$
 *
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