FreeRTOS Real Time Operating System, Modified from Kenji Arai's initial port. See freertos.org for full documentation.
Fork of FreeRTOS_on_mbed_v1 by
semtest.c
00001 /* 00002 FreeRTOS V6.0.3 - Copyright (C) 2010 Real Time Engineers Ltd. 00003 00004 *************************************************************************** 00005 * * 00006 * If you are: * 00007 * * 00008 * + New to FreeRTOS, * 00009 * + Wanting to learn FreeRTOS or multitasking in general quickly * 00010 * + Looking for basic training, * 00011 * + Wanting to improve your FreeRTOS skills and productivity * 00012 * * 00013 * then take a look at the FreeRTOS eBook * 00014 * * 00015 * "Using the FreeRTOS Real Time Kernel - a Practical Guide" * 00016 * http://www.FreeRTOS.org/Documentation * 00017 * * 00018 * A pdf reference manual is also available. Both are usually delivered * 00019 * to your inbox within 20 minutes to two hours when purchased between 8am * 00020 * and 8pm GMT (although please allow up to 24 hours in case of * 00021 * exceptional circumstances). Thank you for your support! * 00022 * * 00023 *************************************************************************** 00024 00025 This file is part of the FreeRTOS distribution. 00026 00027 FreeRTOS is free software; you can redistribute it and/or modify it under 00028 the terms of the GNU General Public License (version 2) as published by the 00029 Free Software Foundation AND MODIFIED BY the FreeRTOS exception. 00030 ***NOTE*** The exception to the GPL is included to allow you to distribute 00031 a combined work that includes FreeRTOS without being obliged to provide the 00032 source code for proprietary components outside of the FreeRTOS kernel. 00033 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT 00034 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 00035 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 00036 more details. You should have received a copy of the GNU General Public 00037 License and the FreeRTOS license exception along with FreeRTOS; if not it 00038 can be viewed here: http://www.freertos.org/a00114.html and also obtained 00039 by writing to Richard Barry, contact details for whom are available on the 00040 FreeRTOS WEB site. 00041 00042 1 tab == 4 spaces! 00043 00044 http://www.FreeRTOS.org - Documentation, latest information, license and 00045 contact details. 00046 00047 http://www.SafeRTOS.com - A version that is certified for use in safety 00048 critical systems. 00049 00050 http://www.OpenRTOS.com - Commercial support, development, porting, 00051 licensing and training services. 00052 */ 00053 00054 /* 00055 * Creates two sets of two tasks. The tasks within a set share a variable, access 00056 * to which is guarded by a semaphore. 00057 * 00058 * Each task starts by attempting to obtain the semaphore. On obtaining a 00059 * semaphore a task checks to ensure that the guarded variable has an expected 00060 * value. It then clears the variable to zero before counting it back up to the 00061 * expected value in increments of 1. After each increment the variable is checked 00062 * to ensure it contains the value to which it was just set. When the starting 00063 * value is again reached the task releases the semaphore giving the other task in 00064 * the set a chance to do exactly the same thing. The starting value is high 00065 * enough to ensure that a tick is likely to occur during the incrementing loop. 00066 * 00067 * An error is flagged if at any time during the process a shared variable is 00068 * found to have a value other than that expected. Such an occurrence would 00069 * suggest an error in the mutual exclusion mechanism by which access to the 00070 * variable is restricted. 00071 * 00072 * The first set of two tasks poll their semaphore. The second set use blocking 00073 * calls. 00074 * 00075 */ 00076 00077 00078 #include <stdlib.h> 00079 00080 /* Scheduler include files. */ 00081 #include "FreeRTOS.h" 00082 #include "task.h" 00083 #include "semphr.h" 00084 00085 00086 /* Demo app include files. */ 00087 #include "semtest.h" 00088 00089 /* The value to which the shared variables are counted. */ 00090 #define semtstBLOCKING_EXPECTED_VALUE ( ( unsigned long ) 0xfff ) 00091 #define semtstNON_BLOCKING_EXPECTED_VALUE ( ( unsigned long ) 0xff ) 00092 00093 #define semtstSTACK_SIZE configMINIMAL_STACK_SIZE 00094 00095 #define semtstNUM_TASKS ( 4 ) 00096 00097 #define semtstDELAY_FACTOR ( ( portTickType ) 10 ) 00098 00099 /* The task function as described at the top of the file. */ 00100 static portTASK_FUNCTION_PROTO( prvSemaphoreTest, pvParameters ); 00101 00102 /* Structure used to pass parameters to each task. */ 00103 typedef struct SEMAPHORE_PARAMETERS 00104 { 00105 xSemaphoreHandle xSemaphore; 00106 volatile unsigned long *pulSharedVariable; 00107 portTickType xBlockTime; 00108 } xSemaphoreParameters; 00109 00110 /* Variables used to check that all the tasks are still running without errors. */ 00111 static volatile short sCheckVariables[ semtstNUM_TASKS ] = { 0 }; 00112 static volatile short sNextCheckVariable = 0; 00113 00114 /*-----------------------------------------------------------*/ 00115 00116 void vStartSemaphoreTasks( unsigned portBASE_TYPE uxPriority ) 00117 { 00118 xSemaphoreParameters *pxFirstSemaphoreParameters, *pxSecondSemaphoreParameters; 00119 const portTickType xBlockTime = ( portTickType ) 100; 00120 00121 /* Create the structure used to pass parameters to the first two tasks. */ 00122 pxFirstSemaphoreParameters = ( xSemaphoreParameters * ) pvPortMalloc( sizeof( xSemaphoreParameters ) ); 00123 00124 if( pxFirstSemaphoreParameters != NULL ) 00125 { 00126 /* Create the semaphore used by the first two tasks. */ 00127 vSemaphoreCreateBinary( pxFirstSemaphoreParameters->xSemaphore ); 00128 00129 if( pxFirstSemaphoreParameters->xSemaphore != NULL ) 00130 { 00131 /* Create the variable which is to be shared by the first two tasks. */ 00132 pxFirstSemaphoreParameters->pulSharedVariable = ( unsigned long * ) pvPortMalloc( sizeof( unsigned long ) ); 00133 00134 /* Initialise the share variable to the value the tasks expect. */ 00135 *( pxFirstSemaphoreParameters->pulSharedVariable ) = semtstNON_BLOCKING_EXPECTED_VALUE; 00136 00137 /* The first two tasks do not block on semaphore calls. */ 00138 pxFirstSemaphoreParameters->xBlockTime = ( portTickType ) 0; 00139 00140 /* Spawn the first two tasks. As they poll they operate at the idle priority. */ 00141 xTaskCreate( prvSemaphoreTest, ( signed char * ) "PolSEM1", semtstSTACK_SIZE, ( void * ) pxFirstSemaphoreParameters, tskIDLE_PRIORITY, ( xTaskHandle * ) NULL ); 00142 xTaskCreate( prvSemaphoreTest, ( signed char * ) "PolSEM2", semtstSTACK_SIZE, ( void * ) pxFirstSemaphoreParameters, tskIDLE_PRIORITY, ( xTaskHandle * ) NULL ); 00143 } 00144 } 00145 00146 /* Do exactly the same to create the second set of tasks, only this time 00147 provide a block time for the semaphore calls. */ 00148 pxSecondSemaphoreParameters = ( xSemaphoreParameters * ) pvPortMalloc( sizeof( xSemaphoreParameters ) ); 00149 if( pxSecondSemaphoreParameters != NULL ) 00150 { 00151 vSemaphoreCreateBinary( pxSecondSemaphoreParameters->xSemaphore ); 00152 00153 if( pxSecondSemaphoreParameters->xSemaphore != NULL ) 00154 { 00155 pxSecondSemaphoreParameters->pulSharedVariable = ( unsigned long * ) pvPortMalloc( sizeof( unsigned long ) ); 00156 *( pxSecondSemaphoreParameters->pulSharedVariable ) = semtstBLOCKING_EXPECTED_VALUE; 00157 pxSecondSemaphoreParameters->xBlockTime = xBlockTime / portTICK_RATE_MS; 00158 00159 xTaskCreate( prvSemaphoreTest, ( signed char * ) "BlkSEM1", semtstSTACK_SIZE, ( void * ) pxSecondSemaphoreParameters, uxPriority, ( xTaskHandle * ) NULL ); 00160 xTaskCreate( prvSemaphoreTest, ( signed char * ) "BlkSEM2", semtstSTACK_SIZE, ( void * ) pxSecondSemaphoreParameters, uxPriority, ( xTaskHandle * ) NULL ); 00161 } 00162 } 00163 00164 /* vQueueAddToRegistry() adds the semaphore to the registry, if one is 00165 in use. The registry is provided as a means for kernel aware 00166 debuggers to locate semaphores and has no purpose if a kernel aware debugger 00167 is not being used. The call to vQueueAddToRegistry() will be removed 00168 by the pre-processor if configQUEUE_REGISTRY_SIZE is not defined or is 00169 defined to be less than 1. */ 00170 vQueueAddToRegistry( ( xQueueHandle ) pxFirstSemaphoreParameters->xSemaphore, ( signed char * ) "Counting_Sem_1" ); 00171 vQueueAddToRegistry( ( xQueueHandle ) pxSecondSemaphoreParameters->xSemaphore, ( signed char * ) "Counting_Sem_2" ); 00172 } 00173 /*-----------------------------------------------------------*/ 00174 00175 static portTASK_FUNCTION( prvSemaphoreTest, pvParameters ) 00176 { 00177 xSemaphoreParameters *pxParameters; 00178 volatile unsigned long *pulSharedVariable, ulExpectedValue; 00179 unsigned long ulCounter; 00180 short sError = pdFALSE, sCheckVariableToUse; 00181 00182 /* See which check variable to use. sNextCheckVariable is not semaphore 00183 protected! */ 00184 portENTER_CRITICAL(); 00185 sCheckVariableToUse = sNextCheckVariable; 00186 sNextCheckVariable++; 00187 portEXIT_CRITICAL(); 00188 00189 /* A structure is passed in as the parameter. This contains the shared 00190 variable being guarded. */ 00191 pxParameters = ( xSemaphoreParameters * ) pvParameters; 00192 pulSharedVariable = pxParameters->pulSharedVariable; 00193 00194 /* If we are blocking we use a much higher count to ensure loads of context 00195 switches occur during the count. */ 00196 if( pxParameters->xBlockTime > ( portTickType ) 0 ) 00197 { 00198 ulExpectedValue = semtstBLOCKING_EXPECTED_VALUE; 00199 } 00200 else 00201 { 00202 ulExpectedValue = semtstNON_BLOCKING_EXPECTED_VALUE; 00203 } 00204 00205 for( ;; ) 00206 { 00207 /* Try to obtain the semaphore. */ 00208 if( xSemaphoreTake( pxParameters->xSemaphore, pxParameters->xBlockTime ) == pdPASS ) 00209 { 00210 /* We have the semaphore and so expect any other tasks using the 00211 shared variable to have left it in the state we expect to find 00212 it. */ 00213 if( *pulSharedVariable != ulExpectedValue ) 00214 { 00215 sError = pdTRUE; 00216 } 00217 00218 /* Clear the variable, then count it back up to the expected value 00219 before releasing the semaphore. Would expect a context switch or 00220 two during this time. */ 00221 for( ulCounter = ( unsigned long ) 0; ulCounter <= ulExpectedValue; ulCounter++ ) 00222 { 00223 *pulSharedVariable = ulCounter; 00224 if( *pulSharedVariable != ulCounter ) 00225 { 00226 sError = pdTRUE; 00227 } 00228 } 00229 00230 /* Release the semaphore, and if no errors have occurred increment the check 00231 variable. */ 00232 if( xSemaphoreGive( pxParameters->xSemaphore ) == pdFALSE ) 00233 { 00234 sError = pdTRUE; 00235 } 00236 00237 if( sError == pdFALSE ) 00238 { 00239 if( sCheckVariableToUse < semtstNUM_TASKS ) 00240 { 00241 ( sCheckVariables[ sCheckVariableToUse ] )++; 00242 } 00243 } 00244 00245 /* If we have a block time then we are running at a priority higher 00246 than the idle priority. This task takes a long time to complete 00247 a cycle (deliberately so to test the guarding) so will be starving 00248 out lower priority tasks. Block for some time to allow give lower 00249 priority tasks some processor time. */ 00250 vTaskDelay( pxParameters->xBlockTime * semtstDELAY_FACTOR ); 00251 } 00252 else 00253 { 00254 if( pxParameters->xBlockTime == ( portTickType ) 0 ) 00255 { 00256 /* We have not got the semaphore yet, so no point using the 00257 processor. We are not blocking when attempting to obtain the 00258 semaphore. */ 00259 taskYIELD(); 00260 } 00261 } 00262 } 00263 } 00264 /*-----------------------------------------------------------*/ 00265 00266 /* This is called to check that all the created tasks are still running. */ 00267 portBASE_TYPE xAreSemaphoreTasksStillRunning( void ) 00268 { 00269 static short sLastCheckVariables[ semtstNUM_TASKS ] = { 0 }; 00270 portBASE_TYPE xTask, xReturn = pdTRUE; 00271 00272 for( xTask = 0; xTask < semtstNUM_TASKS; xTask++ ) 00273 { 00274 if( sLastCheckVariables[ xTask ] == sCheckVariables[ xTask ] ) 00275 { 00276 xReturn = pdFALSE; 00277 } 00278 00279 sLastCheckVariables[ xTask ] = sCheckVariables[ xTask ]; 00280 } 00281 00282 return xReturn; 00283 } 00284 00285
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