2 FreeRTOS V8.2.2 - Copyright (C) 2015 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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13 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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71 * The first test creates three tasks - two counter tasks (one continuous count
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72 * and one limited count) and one controller. A "count" variable is shared
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73 * between all three tasks. The two counter tasks should never be in a "ready"
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74 * state at the same time. The controller task runs at the same priority as
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75 * the continuous count task, and at a lower priority than the limited count
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78 * One counter task loops indefinitely, incrementing the shared count variable
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79 * on each iteration. To ensure it has exclusive access to the variable it
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80 * raises it's priority above that of the controller task before each
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81 * increment, lowering it again to it's original priority before starting the
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84 * The other counter task increments the shared count variable on each
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85 * iteration of it's loop until the count has reached a limit of 0xff - at
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86 * which point it suspends itself. It will not start a new loop until the
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87 * controller task has made it "ready" again by calling vTaskResume ().
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88 * This second counter task operates at a higher priority than controller
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89 * task so does not need to worry about mutual exclusion of the counter
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92 * The controller task is in two sections. The first section controls and
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93 * monitors the continuous count task. When this section is operational the
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94 * limited count task is suspended. Likewise, the second section controls
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95 * and monitors the limited count task. When this section is operational the
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96 * continuous count task is suspended.
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98 * In the first section the controller task first takes a copy of the shared
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99 * count variable. To ensure mutual exclusion on the count variable it
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100 * suspends the continuous count task, resuming it again when the copy has been
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101 * taken. The controller task then sleeps for a fixed period - during which
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102 * the continuous count task will execute and increment the shared variable.
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103 * When the controller task wakes it checks that the continuous count task
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104 * has executed by comparing the copy of the shared variable with its current
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105 * value. This time, to ensure mutual exclusion, the scheduler itself is
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106 * suspended with a call to vTaskSuspendAll (). This is for demonstration
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107 * purposes only and is not a recommended technique due to its inefficiency.
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109 * After a fixed number of iterations the controller task suspends the
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110 * continuous count task, and moves on to its second section.
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112 * At the start of the second section the shared variable is cleared to zero.
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113 * The limited count task is then woken from it's suspension by a call to
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114 * vTaskResume (). As this counter task operates at a higher priority than
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115 * the controller task the controller task should not run again until the
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116 * shared variable has been counted up to the limited value causing the counter
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117 * task to suspend itself. The next line after vTaskResume () is therefore
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118 * a check on the shared variable to ensure everything is as expected.
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121 * The second test consists of a couple of very simple tasks that post onto a
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122 * queue while the scheduler is suspended. This test was added to test parts
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123 * of the scheduler not exercised by the first test.
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126 * The final set of two tasks implements a third test. This simply raises the
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127 * priority of a task while the scheduler is suspended. Again this test was
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128 * added to exercise parts of the code not covered by the first test.
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130 * \page Priorities dynamic.c
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131 * \ingroup DemoFiles
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136 Changes from V2.0.0
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138 + Delay periods are now specified using variables and constants of
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139 TickType_t rather than unsigned long.
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140 + Added a second, simple test that uses the functions
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141 vQueueReceiveWhenSuspendedTask() and vQueueSendWhenSuspendedTask().
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143 Changes from V3.1.1
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145 + Added a third simple test that uses the vTaskPrioritySet() function
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146 while the scheduler is suspended.
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147 + Modified the controller task slightly to test the calling of
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148 vTaskResumeAll() while the scheduler is suspended.
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151 #include <stdlib.h>
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153 /* Scheduler include files. */
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154 #include "FreeRTOS.h"
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156 #include "semphr.h"
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158 /* Demo app include files. */
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159 #include "dynamic.h"
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162 /* Function that implements the "limited count" task as described above. */
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163 static void vLimitedIncrementTask( void * pvParameters );
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165 /* Function that implements the "continuous count" task as described above. */
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166 static void vContinuousIncrementTask( void * pvParameters );
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168 /* Function that implements the controller task as described above. */
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169 static void vCounterControlTask( void * pvParameters );
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171 /* The simple test functions that check sending and receiving while the
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172 scheduler is suspended. */
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173 static void vQueueReceiveWhenSuspendedTask( void *pvParameters );
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174 static void vQueueSendWhenSuspendedTask( void *pvParameters );
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176 /* The simple test functions that check raising and lowering of task priorities
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177 while the scheduler is suspended. */
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178 static void prvChangePriorityWhenSuspendedTask( void *pvParameters );
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179 static void prvChangePriorityHelperTask( void *pvParameters );
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182 /* Demo task specific constants. */
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183 #define priSTACK_SIZE ( ( unsigned short ) configMINIMAL_STACK_SIZE )
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184 #define priSLEEP_TIME ( ( TickType_t ) 50 )
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185 #define priLOOPS ( 5 )
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186 #define priMAX_COUNT ( ( unsigned long ) 0xff )
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187 #define priNO_BLOCK ( ( TickType_t ) 0 )
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188 #define priSUSPENDED_QUEUE_LENGTH ( 1 )
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190 /*-----------------------------------------------------------*/
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192 /* Handles to the two counter tasks. These could be passed in as parameters
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193 to the controller task to prevent them having to be file scope. */
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194 static TaskHandle_t xContinuousIncrementHandle, xLimitedIncrementHandle, xChangePriorityWhenSuspendedHandle;
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196 /* The shared counter variable. This is passed in as a parameter to the two
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197 counter variables for demonstration purposes. */
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198 static unsigned long ulCounter;
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200 /* Variable used in a similar way by the test that checks the raising and
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201 lowering of task priorities while the scheduler is suspended. */
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202 static unsigned long ulPrioritySetCounter;
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204 /* Variables used to check that the tasks are still operating without error.
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205 Each complete iteration of the controller task increments this variable
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206 provided no errors have been found. The variable maintaining the same value
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207 is therefore indication of an error. */
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208 static unsigned short usCheckVariable = ( unsigned short ) 0;
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209 static portBASE_TYPE xSuspendedQueueSendError = pdFALSE;
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210 static portBASE_TYPE xSuspendedQueueReceiveError = pdFALSE;
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211 static portBASE_TYPE xPriorityRaiseWhenSuspendedError = pdFALSE;
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213 /* Queue used by the second test. */
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214 QueueHandle_t xSuspendedTestQueue;
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216 /*-----------------------------------------------------------*/
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218 * Start the seven tasks as described at the top of the file.
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219 * Note that the limited count task is given a higher priority.
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221 void vStartDynamicPriorityTasks( void )
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223 xSuspendedTestQueue = xQueueCreate( priSUSPENDED_QUEUE_LENGTH, sizeof( unsigned long ) );
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224 xTaskCreate( vContinuousIncrementTask, "CONT_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY, &xContinuousIncrementHandle );
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225 xTaskCreate( vLimitedIncrementTask, "LIM_INC", priSTACK_SIZE, ( void * ) &ulCounter, tskIDLE_PRIORITY + 1, &xLimitedIncrementHandle );
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226 xTaskCreate( vCounterControlTask, "C_CTRL", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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227 xTaskCreate( vQueueSendWhenSuspendedTask, "SUSP_SEND", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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228 xTaskCreate( vQueueReceiveWhenSuspendedTask, "SUSP_RECV", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );
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229 xTaskCreate( prvChangePriorityWhenSuspendedTask, "1st_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY + 1, NULL );
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230 xTaskCreate( prvChangePriorityHelperTask, "2nd_P_CHANGE", priSTACK_SIZE, NULL, tskIDLE_PRIORITY, &xChangePriorityWhenSuspendedHandle );
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232 /*-----------------------------------------------------------*/
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235 * Just loops around incrementing the shared variable until the limit has been
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236 * reached. Once the limit has been reached it suspends itself.
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238 static void vLimitedIncrementTask( void * pvParameters )
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240 unsigned long *pulCounter;
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242 /* Take a pointer to the shared variable from the parameters passed into
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244 pulCounter = ( unsigned long * ) pvParameters;
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246 /* This will run before the control task, so the first thing it does is
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247 suspend - the control task will resume it when ready. */
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248 vTaskSuspend( NULL );
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252 /* Just count up to a value then suspend. */
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253 ( *pulCounter )++;
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255 if( *pulCounter >= priMAX_COUNT )
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257 vTaskSuspend( NULL );
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261 /*-----------------------------------------------------------*/
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264 * Just keep counting the shared variable up. The control task will suspend
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265 * this task when it wants.
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267 static void vContinuousIncrementTask( void * pvParameters )
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269 unsigned long *pulCounter;
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270 unsigned portBASE_TYPE uxOurPriority;
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272 /* Take a pointer to the shared variable from the parameters passed into
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274 pulCounter = ( unsigned long * ) pvParameters;
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276 /* Query our priority so we can raise it when exclusive access to the
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277 shared variable is required. */
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278 uxOurPriority = uxTaskPriorityGet( NULL );
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282 /* Raise our priority above the controller task to ensure a context
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283 switch does not occur while we are accessing this variable. */
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284 vTaskPrioritySet( NULL, uxOurPriority + 1 );
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285 ( *pulCounter )++;
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286 vTaskPrioritySet( NULL, uxOurPriority );
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288 #if configUSE_PREEMPTION == 0
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293 /*-----------------------------------------------------------*/
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296 * Controller task as described above.
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298 static void vCounterControlTask( void * pvParameters )
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300 unsigned long ulLastCounter;
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302 short sError = pdFALSE;
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303 const char * const pcTaskStartMsg = "Priority manipulation tasks started.\r\n";
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304 const char * const pcTaskFailMsg = "Priority manipulation Task Failed\r\n";
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306 /* Just to stop warning messages. */
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307 ( void ) pvParameters;
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309 /* Queue a message for printing to say the task has started. */
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310 vPrintDisplayMessage( &pcTaskStartMsg );
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314 /* Start with the counter at zero. */
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315 ulCounter = ( unsigned long ) 0;
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317 /* First section : */
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319 /* Check the continuous count task is running. */
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320 for( sLoops = 0; sLoops < priLOOPS; sLoops++ )
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322 /* Suspend the continuous count task so we can take a mirror of the
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323 shared variable without risk of corruption. */
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324 vTaskSuspend( xContinuousIncrementHandle );
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325 ulLastCounter = ulCounter;
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326 vTaskResume( xContinuousIncrementHandle );
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328 /* Now delay to ensure the other task has processor time. */
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329 vTaskDelay( priSLEEP_TIME );
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331 /* Check the shared variable again. This time to ensure mutual
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332 exclusion the whole scheduler will be locked. This is just for
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336 if( ulLastCounter == ulCounter )
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338 /* The shared variable has not changed. There is a problem
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339 with the continuous count task so flag an error. */
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342 vPrintDisplayMessage( &pcTaskFailMsg );
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350 /* Second section: */
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352 /* Suspend the continuous counter task so it stops accessing the shared variable. */
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353 vTaskSuspend( xContinuousIncrementHandle );
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355 /* Reset the variable. */
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356 ulCounter = ( unsigned long ) 0;
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358 /* Resume the limited count task which has a higher priority than us.
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359 We should therefore not return from this call until the limited count
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360 task has suspended itself with a known value in the counter variable.
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361 The scheduler suspension is not necessary but is included for test
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364 vTaskResume( xLimitedIncrementHandle );
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367 /* Does the counter variable have the expected value? */
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368 if( ulCounter != priMAX_COUNT )
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371 vPrintDisplayMessage( &pcTaskFailMsg );
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374 if( sError == pdFALSE )
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376 /* If no errors have occurred then increment the check variable. */
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377 portENTER_CRITICAL();
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379 portEXIT_CRITICAL();
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382 #if configUSE_PREEMPTION == 0
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386 /* Resume the continuous count task and do it all again. */
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387 vTaskResume( xContinuousIncrementHandle );
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390 /*-----------------------------------------------------------*/
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392 static void vQueueSendWhenSuspendedTask( void *pvParameters )
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394 static unsigned long ulValueToSend = ( unsigned long ) 0;
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395 const char * const pcTaskStartMsg = "Queue send while suspended task started.\r\n";
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396 const char * const pcTaskFailMsg = "Queue send while suspended failed.\r\n";
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398 /* Just to stop warning messages. */
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399 ( void ) pvParameters;
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401 /* Queue a message for printing to say the task has started. */
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402 vPrintDisplayMessage( &pcTaskStartMsg );
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408 /* We must not block while the scheduler is suspended! */
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409 if( xQueueSend( xSuspendedTestQueue, ( void * ) &ulValueToSend, priNO_BLOCK ) != pdTRUE )
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411 if( xSuspendedQueueSendError == pdFALSE )
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414 vPrintDisplayMessage( &pcTaskFailMsg );
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418 xSuspendedQueueSendError = pdTRUE;
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423 vTaskDelay( priSLEEP_TIME );
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428 /*-----------------------------------------------------------*/
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430 static void vQueueReceiveWhenSuspendedTask( void *pvParameters )
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432 static unsigned long ulExpectedValue = ( unsigned long ) 0, ulReceivedValue;
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433 const char * const pcTaskStartMsg = "Queue receive while suspended task started.\r\n";
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434 const char * const pcTaskFailMsg = "Queue receive while suspended failed.\r\n";
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435 portBASE_TYPE xGotValue;
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437 /* Just to stop warning messages. */
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438 ( void ) pvParameters;
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440 /* Queue a message for printing to say the task has started. */
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441 vPrintDisplayMessage( &pcTaskStartMsg );
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447 /* Suspending the scheduler here is fairly pointless and
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448 undesirable for a normal application. It is done here purely
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449 to test the scheduler. The inner xTaskResumeAll() should
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450 never return pdTRUE as the scheduler is still locked by the
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456 xGotValue = xQueueReceive( xSuspendedTestQueue, ( void * ) &ulReceivedValue, priNO_BLOCK );
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458 if( xTaskResumeAll() )
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460 xSuspendedQueueReceiveError = pdTRUE;
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465 #if configUSE_PREEMPTION == 0
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469 } while( xGotValue == pdFALSE );
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471 if( ulReceivedValue != ulExpectedValue )
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473 if( xSuspendedQueueReceiveError == pdFALSE )
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475 vPrintDisplayMessage( &pcTaskFailMsg );
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477 xSuspendedQueueReceiveError = pdTRUE;
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483 /*-----------------------------------------------------------*/
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485 static void prvChangePriorityWhenSuspendedTask( void *pvParameters )
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487 const char * const pcTaskStartMsg = "Priority change when suspended task started.\r\n";
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488 const char * const pcTaskFailMsg = "Priority change when suspended task failed.\r\n";
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490 /* Just to stop warning messages. */
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491 ( void ) pvParameters;
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493 /* Queue a message for printing to say the task has started. */
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494 vPrintDisplayMessage( &pcTaskStartMsg );
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498 /* Start with the counter at 0 so we know what the counter should be
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499 when we check it next. */
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500 ulPrioritySetCounter = ( unsigned long ) 0;
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502 /* Resume the helper task. At this time it has a priority lower than
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503 ours so no context switch should occur. */
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504 vTaskResume( xChangePriorityWhenSuspendedHandle );
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506 /* Check to ensure the task just resumed has not executed. */
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507 portENTER_CRITICAL();
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509 if( ulPrioritySetCounter != ( unsigned long ) 0 )
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511 xPriorityRaiseWhenSuspendedError = pdTRUE;
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512 vPrintDisplayMessage( &pcTaskFailMsg );
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515 portEXIT_CRITICAL();
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517 /* Now try raising the priority while the scheduler is suspended. */
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520 vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, ( configMAX_PRIORITIES - 1 ) );
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522 /* Again, even though the helper task has a priority greater than
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523 ours, it should not have executed yet because the scheduler is
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525 portENTER_CRITICAL();
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527 if( ulPrioritySetCounter != ( unsigned long ) 0 )
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529 xPriorityRaiseWhenSuspendedError = pdTRUE;
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530 vPrintDisplayMessage( &pcTaskFailMsg );
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533 portEXIT_CRITICAL();
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537 /* Now the scheduler has been resumed the helper task should
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538 immediately preempt us and execute. When it executes it will increment
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539 the ulPrioritySetCounter exactly once before suspending itself.
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541 We should now always find the counter set to 1. */
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542 portENTER_CRITICAL();
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544 if( ulPrioritySetCounter != ( unsigned long ) 1 )
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546 xPriorityRaiseWhenSuspendedError = pdTRUE;
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547 vPrintDisplayMessage( &pcTaskFailMsg );
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550 portEXIT_CRITICAL();
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552 /* Delay until we try this again. */
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553 vTaskDelay( priSLEEP_TIME * 2 );
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555 /* Set the priority of the helper task back ready for the next
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556 execution of this task. */
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558 vTaskPrioritySet( xChangePriorityWhenSuspendedHandle, tskIDLE_PRIORITY );
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562 /*-----------------------------------------------------------*/
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564 static void prvChangePriorityHelperTask( void *pvParameters )
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566 /* Just to stop warning messages. */
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567 ( void ) pvParameters;
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571 /* This is the helper task for prvChangePriorityWhenSuspendedTask().
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572 It has it's priority raised and lowered. When it runs it simply
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573 increments the counter then suspends itself again. This allows
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574 prvChangePriorityWhenSuspendedTask() to know how many times it has
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576 ulPrioritySetCounter++;
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577 vTaskSuspend( NULL );
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580 /*-----------------------------------------------------------*/
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582 /* Called to check that all the created tasks are still running without error. */
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583 portBASE_TYPE xAreDynamicPriorityTasksStillRunning( void )
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585 /* Keep a history of the check variables so we know if it has been incremented
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586 since the last call. */
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587 static unsigned short usLastTaskCheck = ( unsigned short ) 0;
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588 portBASE_TYPE xReturn = pdTRUE;
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590 /* Check the tasks are still running by ensuring the check variable
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591 is still incrementing. */
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593 if( usCheckVariable == usLastTaskCheck )
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595 /* The check has not incremented so an error exists. */
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599 if( xSuspendedQueueSendError == pdTRUE )
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604 if( xSuspendedQueueReceiveError == pdTRUE )
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609 if( xPriorityRaiseWhenSuspendedError == pdTRUE )
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614 usLastTaskCheck = usCheckVariable;
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projects / freertos / blob