Demo/Common/Full/print.c

/*
    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************
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    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
    ***NOTE*** The exception to the GPL is included to allow you to distribute
    a combined work that includes FreeRTOS without being obliged to provide the
    source code for proprietary components outside of the FreeRTOS kernel.
    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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    License and the FreeRTOS license exception along with FreeRTOS; if not it 
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    by writing to Richard Barry, contact details for whom are available on the
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*/

/**
 * Manages a queue of strings that are waiting to be displayed.  This is used to 
 * ensure mutual exclusion of console output.
 *
 * A task wishing to display a message will call vPrintDisplayMessage (), with a 
 * pointer to the string as the parameter. The pointer is posted onto the 
 * xPrintQueue queue.
 *
 * The task spawned in main. c blocks on xPrintQueue.  When a message becomes 
 * available it calls pcPrintGetNextMessage () to obtain a pointer to the next 
 * string, then uses the functions defined in the portable layer FileIO. c to 
 * display the message.
 *
 * <b>NOTE:</b>
 * Using console IO can disrupt real time performance - depending on the port.  
 * Standard C IO routines are not designed for real time applications.  While 
 * standard IO is useful for demonstration and debugging an alternative method 
 * should be used if you actually require console IO as part of your application.
 *
 * \page PrintC print.c
 * \ingroup DemoFiles
 * <HR>
 */

/*
Changes from V2.0.0

	+ Delay periods are now specified using variables and constants of
	  portTickType rather than unsigned long.
*/

#include <stdlib.h>

/* Scheduler include files. */
#include "FreeRTOS.h"
#include "queue.h"

/* Demo program include files. */
#include "print.h"

static xQueueHandle xPrintQueue;

/*-----------------------------------------------------------*/

void vPrintInitialise( void )
{
const unsigned portBASE_TYPE uxQueueSize = 20;

	/* Create the queue on which errors will be reported. */
	xPrintQueue = xQueueCreate( uxQueueSize, ( unsigned portBASE_TYPE ) sizeof( char * ) );
}
/*-----------------------------------------------------------*/

void vPrintDisplayMessage( const char * const * ppcMessageToSend )
{
	#ifdef USE_STDIO
		xQueueSend( xPrintQueue, ( void * ) ppcMessageToSend, ( portTickType ) 0 );
	#else
    	/* Stop warnings. */
		( void ) ppcMessageToSend;
	#endif
}
/*-----------------------------------------------------------*/

const char *pcPrintGetNextMessage( portTickType xPrintRate )
{
char *pcMessage;

	if( xQueueReceive( xPrintQueue, &pcMessage, xPrintRate ) == pdPASS )
	{
		return pcMessage;
	}
	else
	{
		return NULL;
	}
}