FreeRTOS/Common/Full/BlockQ.c

   1 /*
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
   3
   4     ***************************************************************************
   5     *                                                                         *
   6     * If you are:                                                             *
   7     *                                                                         *
   8     *    + New to FreeRTOS,                                                   *
   9     *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
  10     *    + Looking for basic training,                                        *
  11     *    + Wanting to improve your FreeRTOS skills and productivity           *
  12     *                                                                         *
  13     * then take a look at the FreeRTOS eBook                                  *
  14     *                                                                         *
  15     *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
  16     *                  http://www.FreeRTOS.org/Documentation                  *
  17     *                                                                         *
  18     * A pdf reference manual is also available.  Both are usually delivered   *
  19     * to your inbox within 20 minutes to two hours when purchased between 8am *
  20     * and 8pm GMT (although please allow up to 24 hours in case of            *
  21     * exceptional circumstances).  Thank you for your support!                *
  22     *                                                                         *
  23     ***************************************************************************
  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  * Creates six tasks that operate on three queues as follows:
  56  *
  57  * The first two tasks send and receive an incrementing number to/from a queue.
  58  * One task acts as a producer and the other as the consumer.  The consumer is a
  59  * higher priority than the producer and is set to block on queue reads.  The queue
  60  * only has space for one item - as soon as the producer posts a message on the
  61  * queue the consumer will unblock, pre-empt the producer, and remove the item.
  62  *
  63  * The second two tasks work the other way around.  Again the queue used only has
  64  * enough space for one item.  This time the consumer has a lower priority than the
  65  * producer.  The producer will try to post on the queue blocking when the queue is
  66  * full.  When the consumer wakes it will remove the item from the queue, causing
  67  * the producer to unblock, pre-empt the consumer, and immediately re-fill the
  68  * queue.
  69  *
  70  * The last two tasks use the same queue producer and consumer functions.  This time the queue has
  71  * enough space for lots of items and the tasks operate at the same priority.  The
  72  * producer will execute, placing items into the queue.  The consumer will start
  73  * executing when either the queue becomes full (causing the producer to block) or
  74  * a context switch occurs (tasks of the same priority will time slice).
  75  *
  76  * \page BlockQC blockQ.c
  77  * \ingroup DemoFiles
  78  * <HR>
  79  */
  80
  81 /*
  82 Changes from V1.00:
  83
  84         + Reversed the priority and block times of the second two demo tasks so
  85           they operate as per the description above.
  86
  87 Changes from V2.0.0
  88
  89         + Delay periods are now specified using variables and constants of
  90           portTickType rather than unsigned long.
  91
  92 Changes from V4.0.2
  93
  94         + The second set of tasks were created the wrong way around.  This has been
  95           corrected.
  96 */
  97
  98
  99 #include <stdlib.h>
 100
 101 /* Scheduler include files. */
 102 #include "FreeRTOS.h"
 103 #include "task.h"
 104 #include "queue.h"
 105
 106 /* Demo program include files. */
 107 #include "BlockQ.h"
 108 #include "print.h"
 109
 110 #define blckqSTACK_SIZE         ( ( unsigned short ) configMINIMAL_STACK_SIZE )
 111 #define blckqNUM_TASK_SETS      ( 3 )
 112
 113 /* Structure used to pass parameters to the blocking queue tasks. */
 114 typedef struct BLOCKING_QUEUE_PARAMETERS
 115 {
 116         xQueueHandle xQueue;                                    /*< The queue to be used by the task. */
 117         portTickType xBlockTime;                        /*< The block time to use on queue reads/writes. */
 118         volatile short *psCheckVariable;        /*< Incremented on each successful cycle to check the task is still running. */
 119 } xBlockingQueueParameters;
 120
 121 /* Task function that creates an incrementing number and posts it on a queue. */
 122 static void vBlockingQueueProducer( void *pvParameters );
 123
 124 /* Task function that removes the incrementing number from a queue and checks that
 125 it is the expected number. */
 126 static void vBlockingQueueConsumer( void *pvParameters );
 127
 128 /* Variables which are incremented each time an item is removed from a queue, and
 129 found to be the expected value.
 130 These are used to check that the tasks are still running. */
 131 static volatile short sBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( short ) 0, ( short ) 0, ( short ) 0 };
 132
 133 /* Variable which are incremented each time an item is posted on a queue.   These
 134 are used to check that the tasks are still running. */
 135 static volatile short sBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( short ) 0, ( short ) 0, ( short ) 0 };
 136
 137 /*-----------------------------------------------------------*/
 138
 139 void vStartBlockingQueueTasks( unsigned portBASE_TYPE uxPriority )
 140 {
 141 xBlockingQueueParameters *pxQueueParameters1, *pxQueueParameters2;
 142 xBlockingQueueParameters *pxQueueParameters3, *pxQueueParameters4;
 143 xBlockingQueueParameters *pxQueueParameters5, *pxQueueParameters6;
 144 const unsigned portBASE_TYPE uxQueueSize1 = 1, uxQueueSize5 = 5;
 145 const portTickType xBlockTime = ( portTickType ) 1000 / portTICK_RATE_MS;
 146 const portTickType xDontBlock = ( portTickType ) 0;
 147
 148         /* Create the first two tasks as described at the top of the file. */
 149
 150         /* First create the structure used to pass parameters to the consumer tasks. */
 151         pxQueueParameters1 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 152
 153         /* Create the queue used by the first two tasks to pass the incrementing number.
 154         Pass a pointer to the queue in the parameter structure. */
 155         pxQueueParameters1->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
 156
 157         /* The consumer is created first so gets a block time as described above. */
 158         pxQueueParameters1->xBlockTime = xBlockTime;
 159
 160         /* Pass in the variable that this task is going to increment so we can check it
 161         is still running. */
 162         pxQueueParameters1->psCheckVariable = &( sBlockingConsumerCount[ 0 ] );
 163
 164         /* Create the structure used to pass parameters to the producer task. */
 165         pxQueueParameters2 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 166
 167         /* Pass the queue to this task also, using the parameter structure. */
 168         pxQueueParameters2->xQueue = pxQueueParameters1->xQueue;
 169
 170         /* The producer is not going to block - as soon as it posts the consumer will
 171         wake and remove the item so the producer should always have room to post. */
 172         pxQueueParameters2->xBlockTime = xDontBlock;
 173
 174         /* Pass in the variable that this task is going to increment so we can check
 175         it is still running. */
 176         pxQueueParameters2->psCheckVariable = &( sBlockingProducerCount[ 0 ] );
 177
 178
 179         /* Note the producer has a lower priority than the consumer when the tasks are
 180         spawned. */
 181         xTaskCreate( vBlockingQueueConsumer, "QConsB1", blckqSTACK_SIZE, ( void * ) pxQueueParameters1, uxPriority, NULL );
 182         xTaskCreate( vBlockingQueueProducer, "QProdB2", blckqSTACK_SIZE, ( void * ) pxQueueParameters2, tskIDLE_PRIORITY, NULL );
 183
 184
 185
 186         /* Create the second two tasks as described at the top of the file.   This uses
 187         the same mechanism but reverses the task priorities. */
 188
 189         pxQueueParameters3 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 190         pxQueueParameters3->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
 191         pxQueueParameters3->xBlockTime = xDontBlock;
 192         pxQueueParameters3->psCheckVariable = &( sBlockingProducerCount[ 1 ] );
 193
 194         pxQueueParameters4 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 195         pxQueueParameters4->xQueue = pxQueueParameters3->xQueue;
 196         pxQueueParameters4->xBlockTime = xBlockTime;
 197         pxQueueParameters4->psCheckVariable = &( sBlockingConsumerCount[ 1 ] );
 198
 199         xTaskCreate( vBlockingQueueProducer, "QProdB3", blckqSTACK_SIZE, ( void * ) pxQueueParameters3, tskIDLE_PRIORITY, NULL );
 200         xTaskCreate( vBlockingQueueConsumer, "QConsB4", blckqSTACK_SIZE, ( void * ) pxQueueParameters4, uxPriority, NULL );
 201
 202
 203
 204         /* Create the last two tasks as described above.  The mechanism is again just
 205         the same.  This time both parameter structures are given a block time. */
 206         pxQueueParameters5 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 207         pxQueueParameters5->xQueue = xQueueCreate( uxQueueSize5, ( unsigned portBASE_TYPE ) sizeof( unsigned short ) );
 208         pxQueueParameters5->xBlockTime = xBlockTime;
 209         pxQueueParameters5->psCheckVariable = &( sBlockingProducerCount[ 2 ] );
 210
 211         pxQueueParameters6 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 212         pxQueueParameters6->xQueue = pxQueueParameters5->xQueue;
 213         pxQueueParameters6->xBlockTime = xBlockTime;
 214         pxQueueParameters6->psCheckVariable = &( sBlockingConsumerCount[ 2 ] );
 215
 216         xTaskCreate( vBlockingQueueProducer, "QProdB5", blckqSTACK_SIZE, ( void * ) pxQueueParameters5, tskIDLE_PRIORITY, NULL );
 217         xTaskCreate( vBlockingQueueConsumer, "QConsB6", blckqSTACK_SIZE, ( void * ) pxQueueParameters6, tskIDLE_PRIORITY, NULL );
 218 }
 219 /*-----------------------------------------------------------*/
 220
 221 static void vBlockingQueueProducer( void *pvParameters )
 222 {
 223 unsigned short usValue = 0;
 224 xBlockingQueueParameters *pxQueueParameters;
 225 const char * const pcTaskStartMsg = "Blocking queue producer started.\r\n";
 226 const char * const pcTaskErrorMsg = "Could not post on blocking queue\r\n";
 227 short sErrorEverOccurred = pdFALSE;
 228
 229         pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
 230
 231         /* Queue a message for printing to say the task has started. */
 232         vPrintDisplayMessage( &pcTaskStartMsg );
 233
 234         for( ;; )
 235         {
 236                 if( xQueueSendToBack( pxQueueParameters->xQueue, ( void * ) &usValue, pxQueueParameters->xBlockTime ) != pdPASS )
 237                 {
 238                         vPrintDisplayMessage( &pcTaskErrorMsg );
 239                         sErrorEverOccurred = pdTRUE;
 240                 }
 241                 else
 242                 {
 243                         /* We have successfully posted a message, so increment the variable
 244                         used to check we are still running. */
 245                         if( sErrorEverOccurred == pdFALSE )
 246                         {
 247                                 ( *pxQueueParameters->psCheckVariable )++;
 248                         }
 249
 250                         /* Increment the variable we are going to post next time round.  The
 251                         consumer will expect the numbers to     follow in numerical order. */
 252                         ++usValue;
 253                 }
 254         }
 255 }
 256 /*-----------------------------------------------------------*/
 257
 258 static void vBlockingQueueConsumer( void *pvParameters )
 259 {
 260 unsigned short usData, usExpectedValue = 0;
 261 xBlockingQueueParameters *pxQueueParameters;
 262 const char * const pcTaskStartMsg = "Blocking queue consumer started.\r\n";
 263 const char * const pcTaskErrorMsg = "Incorrect value received on blocking queue.\r\n";
 264 short sErrorEverOccurred = pdFALSE;
 265
 266         /* Queue a message for printing to say the task has started. */
 267         vPrintDisplayMessage( &pcTaskStartMsg );
 268
 269         pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
 270
 271         for( ;; )
 272         {
 273                 if( xQueueReceive( pxQueueParameters->xQueue, &usData, pxQueueParameters->xBlockTime ) == pdPASS )
 274                 {
 275                         if( usData != usExpectedValue )
 276                         {
 277                                 vPrintDisplayMessage( &pcTaskErrorMsg );
 278
 279                                 /* Catch-up. */
 280                                 usExpectedValue = usData;
 281
 282                                 sErrorEverOccurred = pdTRUE;
 283                         }
 284                         else
 285                         {
 286                                 /* We have successfully received a message, so increment the
 287                                 variable used to check we are still running. */
 288                                 if( sErrorEverOccurred == pdFALSE )
 289                                 {
 290                                         ( *pxQueueParameters->psCheckVariable )++;
 291                                 }
 292
 293                                 /* Increment the value we expect to remove from the queue next time
 294                                 round. */
 295                                 ++usExpectedValue;
 296                         }
 297                 }
 298         }
 299 }
 300 /*-----------------------------------------------------------*/
 301
 302 /* This is called to check that all the created tasks are still running. */
 303 portBASE_TYPE xAreBlockingQueuesStillRunning( void )
 304 {
 305 static short sLastBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( short ) 0, ( short ) 0, ( short ) 0 };
 306 static short sLastBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( short ) 0, ( short ) 0, ( short ) 0 };
 307 portBASE_TYPE xReturn = pdPASS, xTasks;
 308
 309         /* Not too worried about mutual exclusion on these variables as they are 16
 310         bits and we are only reading them. We also only care to see if they have
 311         changed or not.
 312
 313         Loop through each check variable and return pdFALSE if any are found not
 314         to have changed since the last call. */
 315
 316         for( xTasks = 0; xTasks < blckqNUM_TASK_SETS; xTasks++ )
 317         {
 318                 if( sBlockingConsumerCount[ xTasks ] == sLastBlockingConsumerCount[ xTasks ]  )
 319                 {
 320                         xReturn = pdFALSE;
 321                 }
 322                 sLastBlockingConsumerCount[ xTasks ] = sBlockingConsumerCount[ xTasks ];
 323
 324
 325                 if( sBlockingProducerCount[ xTasks ] == sLastBlockingProducerCount[ xTasks ]  )
 326                 {
 327                         xReturn = pdFALSE;
 328                 }
 329                 sLastBlockingProducerCount[ xTasks ] = sBlockingProducerCount[ xTasks ];
 330         }
 331
 332         return xReturn;
 333 }
 334