begriffs open source - cmsis-freertos/blob - Demo/Common/Minimal/QueueOverwrite.c

1 /*

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67 1 tab == 4 spaces!

68 */

69

70 /*

71 * Basic task to demonstrate the xQueueOverwrite() function. See the comments

72 * in the function itself.

73 */

74

75 /* Scheduler include files. */

76 #include "FreeRTOS.h"

77 #include "task.h"

78 #include "queue.h"

79

80 /* Demo program include files. */

81 #include "QueueOverwrite.h"

82

83 /* A block time of 0 just means "don't block". */

84 #define qoDONT_BLOCK 0

85

86 /* Number of times to overwrite the value in the queue. */

87 #define qoLOOPS 5

88

89 /* The task that uses the queue. */

90 static void prvQueueOverwriteTask( void *pvParameters );

91

92 /* Variable that is incremented on each loop of prvQueueOverwriteTask() provided

93 prvQueueOverwriteTask() has not found any errors. */

94 static uint32_t ulLoopCounter = 0;

95

96 /* Set to pdFALSE if an error is discovered by the

97 vQueueOverwritePeriodicISRDemo() function. */

98 static BaseType_t xISRTestStatus = pdPASS;

99

100 /* The queue that is accessed from the ISR. The queue accessed by the task is

101 created inside the task itself. */

102 static QueueHandle_t xISRQueue = NULL;

103

104 /*-----------------------------------------------------------*/

105

106 void vStartQueueOverwriteTask( UBaseType_t uxPriority )

107 {

108 const UBaseType_t uxQueueLength = 1;

109

110 /* Create the queue used by the ISR. xQueueOverwriteFromISR() should only

111 be used on queues that have a length of 1. */

112 xISRQueue = xQueueCreate( uxQueueLength, ( UBaseType_t ) sizeof( uint32_t ) );

113

114 /* Create the test task. The queue used by the test task is created inside

115 the task itself. */

116 xTaskCreate( prvQueueOverwriteTask, "QOver", configMINIMAL_STACK_SIZE, NULL, uxPriority, ( TaskHandle_t * ) NULL );

117 }

118 /*-----------------------------------------------------------*/

119

120 static void prvQueueOverwriteTask( void *pvParameters )

121 {

122 QueueHandle_t xTaskQueue;

123 const UBaseType_t uxQueueLength = 1;

124 uint32_t ulValue, ulStatus = pdPASS, x;

125

126 /* The parameter is not used. */

127 ( void ) pvParameters;

128

129 /* Create the queue. xQueueOverwrite() should only be used on queues that

130 have a length of 1. */

131 xTaskQueue = xQueueCreate( uxQueueLength, ( UBaseType_t ) sizeof( uint32_t ) );

132 configASSERT( xTaskQueue );

133

134 for( ;; )

135 {

136 /* The queue is empty. Writing to the queue then reading from the queue

137 should return the item written. */

138 ulValue = 10;

139 xQueueOverwrite( xTaskQueue, &ulValue );

140

141 ulValue = 0;

142 xQueueReceive( xTaskQueue, &ulValue, qoDONT_BLOCK );

143

144 if( ulValue != 10 )

145 {

146 ulStatus = pdFAIL;

147 }

148

149 /* Now try writing to the queue several times. Each time the value

150 in the queue should get overwritten. */

151 for( x = 0; x < qoLOOPS; x++ )

152 {

153 /* Write to the queue. */

154 xQueueOverwrite( xTaskQueue, &x );

155

156 /* Check the value in the queue is that written, even though the

157 queue was not necessarily empty. */

158 xQueuePeek( xTaskQueue, &ulValue, qoDONT_BLOCK );

159 if( ulValue != x )

160 {

161 ulStatus = pdFAIL;

162 }

163

164 /* There should always be one item in the queue. */

165 if( uxQueueMessagesWaiting( xTaskQueue ) != uxQueueLength )

166 {

167 ulStatus = pdFAIL;

168 }

169 }

170

171 /* Empty the queue again. */

172 xQueueReceive( xTaskQueue, &ulValue, qoDONT_BLOCK );

173

174 if( uxQueueMessagesWaiting( xTaskQueue ) != 0 )

175 {

176 ulStatus = pdFAIL;

177 }

178

179 if( ulStatus != pdFAIL )

180 {

181 /* Increment a counter to show this task is still running without

182 error. */

183 ulLoopCounter++;

184 }

185

186 #if( configUSE_PREEMPTION == 0 )

187 taskYIELD();

188 #endif

189 }

190 }

191 /*-----------------------------------------------------------*/

192

193 BaseType_t xIsQueueOverwriteTaskStillRunning( void )

194 {

195 BaseType_t xReturn;

196

197 if( xISRTestStatus != pdPASS )

198 {

199 xReturn = pdFAIL;

200 }

201 else if( ulLoopCounter > 0 )

202 {

203 xReturn = pdPASS;

204 }

205 else

206 {

207 /* The task has either stalled of discovered an error. */

208 xReturn = pdFAIL;

209 }

210

211 ulLoopCounter = 0;

212

213 return xReturn;

214 }

215 /*-----------------------------------------------------------*/

216

217 void vQueueOverwritePeriodicISRDemo( void )

218 {

219 static uint32_t ulCallCount = 0;

220 const uint32_t ulTx1 = 10UL, ulTx2 = 20UL, ulNumberOfSwitchCases = 3UL;

221 uint32_t ulRx;

222

223 /* This function should be called from an interrupt, such as the tick hook

224 function vApplicationTickHook(). */

225

226 configASSERT( xISRQueue );

227

228 switch( ulCallCount )

229 {

230 case 0:

231 /* The queue is empty. Write ulTx1 to the queue. In this demo the

232 last parameter is not used because there are no tasks blocked on

233 this queue. */

234 xQueueOverwriteFromISR( xISRQueue, &ulTx1, NULL );

235

236 /* Peek the queue to check it holds the expected value. */

237 xQueuePeekFromISR( xISRQueue, &ulRx );

238 if( ulRx != ulTx1 )

239 {

240 xISRTestStatus = pdFAIL;

241 }

242 break;

243

244 case 1:

245 /* The queue already holds ulTx1. Overwrite the value in the queue

246 with ulTx2. */

247 xQueueOverwriteFromISR( xISRQueue, &ulTx2, NULL );

248 break;

249

250 case 2:

251 /* Read from the queue to empty the queue again. The value read

252 should be ulTx2. */

253 xQueueReceiveFromISR( xISRQueue, &ulRx, NULL );

254

255 if( ulRx != ulTx2 )

256 {

257 xISRTestStatus = pdFAIL;

258 }

259 break;

260 }

261

262 /* Run the next case in the switch statement above next time this function

263 is called. */

264 ulCallCount++;

265

266 if( ulCallCount >= ulNumberOfSwitchCases )

267 {

268 /* Go back to the start. */

269 ulCallCount = 0;

270 }

271 }

272