os_mbox.c

lpc2368-keil环境下的ucos的移植例程

/*
*********************************************************************************************************
*   											 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 "..\APP\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.
*********************************************************************************************************
*/

#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
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'						 */
		return ((void *) 0);
	}
	if (pevent->OSEventType != OS_EVENT_TYPE_MBOX)
	{
		/* Validate event block type				 */
		return ((void *) 0);
	}
#endif
	OS_ENTER_CRITICAL();
	msg = pevent->OSEventPtr;
	pevent->OSEventPtr = (void *) 0;					   /* Clear the mailbox 						*/
	OS_EXIT_CRITICAL();
	return (msg);   									  /* Return the message received (or NULL)     */
}
#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
*********************************************************************************************************
*/

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                       */
	}
	OS_ENTER_CRITICAL();
	pevent = OSEventFreeList;   				 /* Get next free event control block   			   */
	if (OSEventFreeList != (OS_EVENT *) 0)
	{
		/* See if pool of free ECB pool was empty   		  */
		OSEventFreeList = (OS_EVENT *) OSEventFreeList->OSEventPtr;
	}
	OS_EXIT_CRITICAL();
	if (pevent != (OS_EVENT *) 0)
	{
		pevent->OSEventType = OS_EVENT_TYPE_MBOX;
		pevent->OSEventCnt = 0;
		pevent->OSEventPtr = msg;   			/* Deposit message in event control block   		  */
		OS_EventWaitListInit(pevent);
	}
	return (pevent);							 /* Return pointer to event control block   		   */
}
/*$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.
*********************************************************************************************************
*/

#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;


	if (OSIntNesting > 0)
	{
		/* See if called from ISR ...   			*/
		*err = OS_ERR_DEL_ISR;  						   /* ... can't DELETE from an ISR             */
		return (pevent);
	}
#if OS_ARG_CHK_EN > 0
	if (pevent == (OS_EVENT *) 0)
	{
		/* Validate 'pevent'						*/
		*err = OS_ERR_PEVENT_NULL;
		return (pevent);
	}
	if (pevent->OSEventType != OS_EVENT_TYPE_MBOX)
	{
		/* Validate event block type				*/
		*err = OS_ERR_EVENT_TYPE;
		return (pevent);
	}
#endif
	OS_ENTER_CRITICAL();
	if (pevent->OSEventGrp != 0x00)
	{
		/* See if any tasks waiting on mailbox  	*/
		tasks_waiting = TRUE;   						   /* Yes   								   */
	}
	else
	{
		tasks_waiting = FALSE;  						   /* No									   */
	}
	switch (opt)
	{
		case OS_DEL_NO_PEND:
			/* Delete mailbox only if no task waiting   */
			if (tasks_waiting == FALSE)
			{
				pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
				pevent->OSEventPtr = OSEventFreeList;    /* Return Event Control Block to free list  */
				OSEventFreeList = pevent;   		  /* Get next free event control block  	  */
				OS_EXIT_CRITICAL();
				*err = OS_NO_ERR;
				return ((OS_EVENT *) 0);				   /* Mailbox has been deleted  			   */
			}
			else
			{
				OS_EXIT_CRITICAL();
				*err = OS_ERR_TASK_WAITING;
				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);
			}
			pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
			pevent->OSEventPtr = OSEventFreeList;   	 /* Return Event Control Block to free list  */
			OSEventFreeList = pevent;   			  /* Get next free event control block  	  */
			OS_EXIT_CRITICAL();
			if (tasks_waiting == TRUE)
			{
				/* Reschedule only if task(s) were waiting  */
				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;
			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.
*********************************************************************************************************
*/

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);
	}
#if OS_ARG_CHK_EN > 0
	if (pevent == (OS_EVENT *) 0)