rzkpeekmessage.c

zilog的实时操作系统RZK,可以移植到多种处理器上

/*
* File			:	RZKPeekMessage.c
*
* Description	:	This file contains RZKPeekMessage function which peeks into
*					the queue to read a message.
*
* Copyright 2004 ZiLOG Inc.  ALL RIGHTS RESERVED.
*
* This file contains unpublished confidential and proprietary information
* of ZiLOG, Inc.
* NO PART OF THIS WORK MAY BE DUPLICATED, STORED, PUBLISHED OR DISCLOSED 
* IN ANY FORM WITHOUT THE PRIOR WRITTEN CONSENT OF ZiLOG, INC.
* This is not a license and no use of any kind of this work is authorized
* in the absence of a written license granted by ZiLOG, Inc. in ZiLOG's 
* sole discretion 
*/

#include <string.h>
#include "ZSysgen.h"
#include "ZTypes.h"
#include "ZThread.h"
#include "ZQueue.h" 
#include "ZMessageQ.h"


#define pMessageQueue  ((RZK_MESSAGEQUEUE_t *) hMessageQueue)

extern void* RZKMemcpy(void *, const void *, RZK_LENGTH_t); // IAR port, UINT changed to RZK_LENGTH_t


/*
* Function		:	RZKPeekMessage
*
* Description	:	Peeks into the specified message queue and copies the message 
*					from the queue to the specified location and size.
*					If the queue is empty it returns immediately.
* 
* Inputs		:	hMessageQueue  -  handle to the message queue to peek into.
*					pMessage - pointer to the memory area where message has to be copied. 
*					*uSize - size of the message to be copied and contains value of number of bytes
*					received after API execution	
*
* Outputs		:	RZKERR_SUCCESS - If the message is successfully copied.
*					RZKERR_CB_BUSY- If the message control block is being used by another thread exclusively.
*					RZKERR_INVALID_HANDLE - If the hMessageQueue is invalid.
*					RZKERR_INVALID_ARGUMENTS - If the pMessage parameter is invalid.
*					RZKERR_QUEUE_EMPTY - If the queue is empty.
*
* Dependencies	:	None
*/


RZK_STATUS_t   RZKPeekMessageQueue
						 ( 
							  RZK_MESSAGEQHANDLE_t hMessageQueue,
							  RZK_PTR_t pMessage,
							  COUNT_t *uSize	// IAR changed from UINT to COUNT_t
						 )

{
	/* Local Variable */
	// IAR port
	COUNT_t uSizeActual ;
//	COUNT_t uSizeActual[sizeof(COUNT_t)];

	/* Check for the validity of the arguments */
#ifndef RZK_EFFICIENTQUEUE
#ifdef RZK_DEBUG
		if ( (pMessageQueue==NULL) || ( pMessageQueue -> uState ==  0 ) || 
				( pMessageQueue -> magic_num != MAGIC_NUM_MESSAGEQ))
			return RZKERR_INVALID_HANDLE;
		if ( pMessage == NULL)
			return RZKERR_INVALID_ARGUMENTS;

		if ( uSize == NULL)
			return RZKERR_INVALID_ARGUMENTS;
#endif

#ifndef RZK_PERFORMANCE
		if ( ! ( pMessageQueue->uState & OBJECT_CREATED))
			return RZKERR_CB_BUSY;
#endif
#endif
		if ( pMessageQueue->uMessageSpaceLeft == pMessageQueue->uQueueLength)
			return RZKERR_QUEUE_EMPTY;


		// IAR change... and optimization opportunity here...
		uSizeActual = (COUNT_t) *((COUNT_t *)(pMessageQueue ->pRead)) ;
//		RZKMemcpy (uSizeActual, pMessageQueue ->pRead, sizeof(COUNT_t));	

/* If the requested size of message is less than the actual size of message in the Queue
		return uSize number of bytes else return the uSizeActual number oif bytes*/
		// IAR optimization
		if(*uSize > uSizeActual)
			*uSize = uSizeActual ;

		RZKMemcpy(pMessage,(CADDR_t)pMessageQueue ->pRead+sizeof(COUNT_t) ,*uSize);	
/*
		if(*uSize < *uSizeActual)
		{

			RZKMemcpy(pMessage,(CADDR_t)pMessageQueue ->pRead+sizeof(COUNT_t) ,*uSize);	

		}
		else
		{

			RZKMemcpy(pMessage,(CADDR_t)pMessageQueue ->pRead+sizeof(COUNT_t) ,uSizeActual); // IAR changed

			*uSize = *uSizeActual;
		}
*/
		return RZKERR_SUCCESS;
		/* Note that the next receive will not guarantee the same message */
}  /* end of RZKPeekMessage */