FreeRTOS/Common/Minimal/AltBlckQ.c

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  52 */
  53
  54 /*
  55  * This is a version of BlockQ.c that uses the alternative (Alt) API.
  56  *
  57  * Creates six tasks that operate on three queues as follows:
  58  *
  59  * The first two tasks send and receive an incrementing number to/from a queue.
  60  * One task acts as a producer and the other as the consumer.  The consumer is a
  61  * higher priority than the producer and is set to block on queue reads.  The queue
  62  * only has space for one item - as soon as the producer posts a message on the
  63  * queue the consumer will unblock, pre-empt the producer, and remove the item.
  64  *
  65  * The second two tasks work the other way around.  Again the queue used only has
  66  * enough space for one item.  This time the consumer has a lower priority than the
  67  * producer.  The producer will try to post on the queue blocking when the queue is
  68  * full.  When the consumer wakes it will remove the item from the queue, causing
  69  * the producer to unblock, pre-empt the consumer, and immediately re-fill the
  70  * queue.
  71  *
  72  * The last two tasks use the same queue producer and consumer functions.  This time the queue has
  73  * enough space for lots of items and the tasks operate at the same priority.  The
  74  * producer will execute, placing items into the queue.  The consumer will start
  75  * executing when either the queue becomes full (causing the producer to block) or
  76  * a context switch occurs (tasks of the same priority will time slice).
  77  *
  78  */
  79
  80
  81 #include <stdlib.h>
  82
  83 /* Scheduler include files. */
  84 #include "FreeRTOS.h"
  85 #include "task.h"
  86 #include "queue.h"
  87
  88 /* Demo program include files. */
  89 #include "AltBlckQ.h"
  90
  91 #define blckqSTACK_SIZE         configMINIMAL_STACK_SIZE
  92 #define blckqNUM_TASK_SETS      ( 3 )
  93
  94 /* Structure used to pass parameters to the blocking queue tasks. */
  95 typedef struct BLOCKING_QUEUE_PARAMETERS
  96 {
  97         xQueueHandle xQueue;                                    /*< The queue to be used by the task. */
  98         portTickType xBlockTime;                                /*< The block time to use on queue reads/writes. */
  99         volatile portSHORT *psCheckVariable;    /*< Incremented on each successful cycle to check the task is still running. */
 100 } xBlockingQueueParameters;
 101
 102 /* Task function that creates an incrementing number and posts it on a queue. */
 103 static portTASK_FUNCTION_PROTO( vBlockingQueueProducer, pvParameters );
 104
 105 /* Task function that removes the incrementing number from a queue and checks that
 106 it is the expected number. */
 107 static portTASK_FUNCTION_PROTO( vBlockingQueueConsumer, pvParameters );
 108
 109 /* Variables which are incremented each time an item is removed from a queue, and
 110 found to be the expected value.
 111 These are used to check that the tasks are still running. */
 112 static volatile portSHORT sBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
 113
 114 /* Variable which are incremented each time an item is posted on a queue.   These
 115 are used to check that the tasks are still running. */
 116 static volatile portSHORT sBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
 117
 118 /*-----------------------------------------------------------*/
 119
 120 void vStartAltBlockingQueueTasks( unsigned portBASE_TYPE uxPriority )
 121 {
 122 xBlockingQueueParameters *pxQueueParameters1, *pxQueueParameters2;
 123 xBlockingQueueParameters *pxQueueParameters3, *pxQueueParameters4;
 124 xBlockingQueueParameters *pxQueueParameters5, *pxQueueParameters6;
 125 const unsigned portBASE_TYPE uxQueueSize1 = 1, uxQueueSize5 = 5;
 126 const portTickType xBlockTime = ( portTickType ) 1000 / portTICK_RATE_MS;
 127 const portTickType xDontBlock = ( portTickType ) 0;
 128
 129         /* Create the first two tasks as described at the top of the file. */
 130
 131         /* First create the structure used to pass parameters to the consumer tasks. */
 132         pxQueueParameters1 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 133
 134         /* Create the queue used by the first two tasks to pass the incrementing number.
 135         Pass a pointer to the queue in the parameter structure. */
 136         pxQueueParameters1->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
 137
 138         /* The consumer is created first so gets a block time as described above. */
 139         pxQueueParameters1->xBlockTime = xBlockTime;
 140
 141         /* Pass in the variable that this task is going to increment so we can check it
 142         is still running. */
 143         pxQueueParameters1->psCheckVariable = &( sBlockingConsumerCount[ 0 ] );
 144
 145         /* Create the structure used to pass parameters to the producer task. */
 146         pxQueueParameters2 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 147
 148         /* Pass the queue to this task also, using the parameter structure. */
 149         pxQueueParameters2->xQueue = pxQueueParameters1->xQueue;
 150
 151         /* The producer is not going to block - as soon as it posts the consumer will
 152         wake and remove the item so the producer should always have room to post. */
 153         pxQueueParameters2->xBlockTime = xDontBlock;
 154
 155         /* Pass in the variable that this task is going to increment so we can check
 156         it is still running. */
 157         pxQueueParameters2->psCheckVariable = &( sBlockingProducerCount[ 0 ] );
 158
 159
 160         /* Note the producer has a lower priority than the consumer when the tasks are
 161         spawned. */
 162         xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QConsB1", blckqSTACK_SIZE, ( void * ) pxQueueParameters1, uxPriority, NULL );
 163         xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QProdB2", blckqSTACK_SIZE, ( void * ) pxQueueParameters2, tskIDLE_PRIORITY, NULL );
 164
 165
 166
 167         /* Create the second two tasks as described at the top of the file.   This uses
 168         the same mechanism but reverses the task priorities. */
 169
 170         pxQueueParameters3 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 171         pxQueueParameters3->xQueue = xQueueCreate( uxQueueSize1, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
 172         pxQueueParameters3->xBlockTime = xDontBlock;
 173         pxQueueParameters3->psCheckVariable = &( sBlockingProducerCount[ 1 ] );
 174
 175         pxQueueParameters4 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 176         pxQueueParameters4->xQueue = pxQueueParameters3->xQueue;
 177         pxQueueParameters4->xBlockTime = xBlockTime;
 178         pxQueueParameters4->psCheckVariable = &( sBlockingConsumerCount[ 1 ] );
 179
 180         xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QProdB3", blckqSTACK_SIZE, ( void * ) pxQueueParameters3, tskIDLE_PRIORITY, NULL );
 181         xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QConsB4", blckqSTACK_SIZE, ( void * ) pxQueueParameters4, uxPriority, NULL );
 182
 183
 184
 185         /* Create the last two tasks as described above.  The mechanism is again just
 186         the same.  This time both parameter structures are given a block time. */
 187         pxQueueParameters5 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 188         pxQueueParameters5->xQueue = xQueueCreate( uxQueueSize5, ( unsigned portBASE_TYPE ) sizeof( unsigned portSHORT ) );
 189         pxQueueParameters5->xBlockTime = xBlockTime;
 190         pxQueueParameters5->psCheckVariable = &( sBlockingProducerCount[ 2 ] );
 191
 192         pxQueueParameters6 = ( xBlockingQueueParameters * ) pvPortMalloc( sizeof( xBlockingQueueParameters ) );
 193         pxQueueParameters6->xQueue = pxQueueParameters5->xQueue;
 194         pxQueueParameters6->xBlockTime = xBlockTime;
 195         pxQueueParameters6->psCheckVariable = &( sBlockingConsumerCount[ 2 ] );
 196
 197         xTaskCreate( vBlockingQueueProducer, ( signed portCHAR * ) "QProdB5", blckqSTACK_SIZE, ( void * ) pxQueueParameters5, tskIDLE_PRIORITY, NULL );
 198         xTaskCreate( vBlockingQueueConsumer, ( signed portCHAR * ) "QConsB6", blckqSTACK_SIZE, ( void * ) pxQueueParameters6, tskIDLE_PRIORITY, NULL );
 199 }
 200 /*-----------------------------------------------------------*/
 201
 202 static portTASK_FUNCTION( vBlockingQueueProducer, pvParameters )
 203 {
 204 unsigned portSHORT usValue = 0;
 205 xBlockingQueueParameters *pxQueueParameters;
 206 portSHORT sErrorEverOccurred = pdFALSE;
 207
 208         #ifdef USE_STDIO
 209         void vPrintDisplayMessage( const portCHAR * const * ppcMessageToSend );
 210
 211                 const portCHAR * const pcTaskStartMsg = "Alt blocking queue producer task started.\r\n";
 212
 213                 /* Queue a message for printing to say the task has started. */
 214                 vPrintDisplayMessage( &pcTaskStartMsg );
 215         #endif
 216
 217         pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
 218
 219         for( ;; )
 220         {
 221                 if( xQueueAltSendToBack( pxQueueParameters->xQueue, ( void * ) &usValue, pxQueueParameters->xBlockTime ) != pdPASS )
 222                 {
 223                         sErrorEverOccurred = pdTRUE;
 224                 }
 225                 else
 226                 {
 227                         /* We have successfully posted a message, so increment the variable
 228                         used to check we are still running. */
 229                         if( sErrorEverOccurred == pdFALSE )
 230                         {
 231                                 ( *pxQueueParameters->psCheckVariable )++;
 232                         }
 233
 234                         /* Increment the variable we are going to post next time round.  The
 235                         consumer will expect the numbers to     follow in numerical order. */
 236                         ++usValue;
 237                 }
 238         }
 239 }
 240 /*-----------------------------------------------------------*/
 241
 242 static portTASK_FUNCTION( vBlockingQueueConsumer, pvParameters )
 243 {
 244 unsigned portSHORT usData, usExpectedValue = 0;
 245 xBlockingQueueParameters *pxQueueParameters;
 246 portSHORT sErrorEverOccurred = pdFALSE;
 247
 248         #ifdef USE_STDIO
 249         void vPrintDisplayMessage( const portCHAR * const * ppcMessageToSend );
 250
 251                 const portCHAR * const pcTaskStartMsg = "Alt blocking queue consumer task started.\r\n";
 252
 253                 /* Queue a message for printing to say the task has started. */
 254                 vPrintDisplayMessage( &pcTaskStartMsg );
 255         #endif
 256
 257         pxQueueParameters = ( xBlockingQueueParameters * ) pvParameters;
 258
 259         for( ;; )
 260         {
 261                 if( xQueueAltReceive( pxQueueParameters->xQueue, &usData, pxQueueParameters->xBlockTime ) == pdPASS )
 262                 {
 263                         if( usData != usExpectedValue )
 264                         {
 265                                 /* Catch-up. */
 266                                 usExpectedValue = usData;
 267
 268                                 sErrorEverOccurred = pdTRUE;
 269                         }
 270                         else
 271                         {
 272                                 /* We have successfully received a message, so increment the
 273                                 variable used to check we are still running. */
 274                                 if( sErrorEverOccurred == pdFALSE )
 275                                 {
 276                                         ( *pxQueueParameters->psCheckVariable )++;
 277                                 }
 278
 279                                 /* Increment the value we expect to remove from the queue next time
 280                                 round. */
 281                                 ++usExpectedValue;
 282                         }
 283                 }
 284         }
 285 }
 286 /*-----------------------------------------------------------*/
 287
 288 /* This is called to check that all the created tasks are still running. */
 289 portBASE_TYPE xAreAltBlockingQueuesStillRunning( void )
 290 {
 291 static portSHORT sLastBlockingConsumerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
 292 static portSHORT sLastBlockingProducerCount[ blckqNUM_TASK_SETS ] = { ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0, ( unsigned portSHORT ) 0 };
 293 portBASE_TYPE xReturn = pdPASS, xTasks;
 294
 295         /* Not too worried about mutual exclusion on these variables as they are 16
 296         bits and we are only reading them. We also only care to see if they have
 297         changed or not.
 298
 299         Loop through each check variable to and return pdFALSE if any are found not
 300         to have changed since the last call. */
 301
 302         for( xTasks = 0; xTasks < blckqNUM_TASK_SETS; xTasks++ )
 303         {
 304                 if( sBlockingConsumerCount[ xTasks ] == sLastBlockingConsumerCount[ xTasks ]  )
 305                 {
 306                         xReturn = pdFALSE;
 307                 }
 308                 sLastBlockingConsumerCount[ xTasks ] = sBlockingConsumerCount[ xTasks ];
 309
 310
 311                 if( sBlockingProducerCount[ xTasks ] == sLastBlockingProducerCount[ xTasks ]  )
 312                 {
 313                         xReturn = pdFALSE;
 314                 }
 315                 sLastBlockingProducerCount[ xTasks ] = sBlockingProducerCount[ xTasks ];
 316         }
 317
 318         return xReturn;
 319 }
 320