FreeRTOS/Common/Full/print.c

   1 /*
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
   3
   4     ***************************************************************************
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  14     *                                                                         *
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  17     *                                                                         *
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  24
  25     This file is part of the FreeRTOS distribution.
  26
  27     FreeRTOS is free software; you can redistribute it and/or modify it under
  28     the terms of the GNU General Public License (version 2) as published by the
  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
  30     ***NOTE*** The exception to the GPL is included to allow you to distribute
  31     a combined work that includes FreeRTOS without being obliged to provide the
  32     source code for proprietary components outside of the FreeRTOS kernel.
  33     FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
  34     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  35     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  36     more details. You should have received a copy of the GNU General Public
  37     License and the FreeRTOS license exception along with FreeRTOS; if not it
  38     can be viewed here: http://www.freertos.org/a00114.html and also obtained
  39     by writing to Richard Barry, contact details for whom are available on the
  40     FreeRTOS WEB site.
  41
  42     1 tab == 4 spaces!
  43
  44     http://www.FreeRTOS.org - Documentation, latest information, license and
  45     contact details.
  46
  47     http://www.SafeRTOS.com - A version that is certified for use in safety
  48     critical systems.
  49
  50     http://www.OpenRTOS.com - Commercial support, development, porting,
  51     licensing and training services.
  52 */
  53
  54 /**
  55  * Manages a queue of strings that are waiting to be displayed.  This is used to
  56  * ensure mutual exclusion of console output.
  57  *
  58  * A task wishing to display a message will call vPrintDisplayMessage (), with a
  59  * pointer to the string as the parameter. The pointer is posted onto the
  60  * xPrintQueue queue.
  61  *
  62  * The task spawned in main. c blocks on xPrintQueue.  When a message becomes
  63  * available it calls pcPrintGetNextMessage () to obtain a pointer to the next
  64  * string, then uses the functions defined in the portable layer FileIO. c to
  65  * display the message.
  66  *
  67  * <b>NOTE:</b>
  68  * Using console IO can disrupt real time performance - depending on the port.
  69  * Standard C IO routines are not designed for real time applications.  While
  70  * standard IO is useful for demonstration and debugging an alternative method
  71  * should be used if you actually require console IO as part of your application.
  72  *
  73  * \page PrintC print.c
  74  * \ingroup DemoFiles
  75  * <HR>
  76  */
  77
  78 /*
  79 Changes from V2.0.0
  80
  81         + Delay periods are now specified using variables and constants of
  82           portTickType rather than unsigned long.
  83 */
  84
  85 #include <stdlib.h>
  86
  87 /* Scheduler include files. */
  88 #include "FreeRTOS.h"
  89 #include "queue.h"
  90
  91 /* Demo program include files. */
  92 #include "print.h"
  93
  94 static xQueueHandle xPrintQueue;
  95
  96 /*-----------------------------------------------------------*/
  97
  98 void vPrintInitialise( void )
  99 {
 100 const unsigned portBASE_TYPE uxQueueSize = 20;
 101
 102         /* Create the queue on which errors will be reported. */
 103         xPrintQueue = xQueueCreate( uxQueueSize, ( unsigned portBASE_TYPE ) sizeof( char * ) );
 104 }
 105 /*-----------------------------------------------------------*/
 106
 107 void vPrintDisplayMessage( const char * const * ppcMessageToSend )
 108 {
 109         #ifdef USE_STDIO
 110                 xQueueSend( xPrintQueue, ( void * ) ppcMessageToSend, ( portTickType ) 0 );
 111         #else
 112         /* Stop warnings. */
 113                 ( void ) ppcMessageToSend;
 114         #endif
 115 }
 116 /*-----------------------------------------------------------*/
 117
 118 const char *pcPrintGetNextMessage( portTickType xPrintRate )
 119 {
 120 char *pcMessage;
 121
 122         if( xQueueReceive( xPrintQueue, &pcMessage, xPrintRate ) == pdPASS )
 123         {
 124                 return pcMessage;
 125         }
 126         else
 127         {
 128                 return NULL;
 129         }
 130 }
 131
 132