2 FreeRTOS.org V4.5.0 - Copyright (C) 2003-2007 Richard Barry.
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4 This file is part of the FreeRTOS.org distribution.
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6 FreeRTOS.org is free software; you can redistribute it and/or modify
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7 it under the terms of the GNU General Public License as published by
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8 the Free Software Foundation; either version 2 of the License, or
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9 (at your option) any later version.
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11 FreeRTOS.org is distributed in the hope that it will be useful,
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12 but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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14 GNU General Public License for more details.
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16 You should have received a copy of the GNU General Public License
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17 along with FreeRTOS.org; if not, write to the Free Software
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18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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20 A special exception to the GPL can be applied should you wish to distribute
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21 a combined work that includes FreeRTOS.org, without being obliged to provide
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22 the source code for any proprietary components. See the licensing section
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23 of http://www.FreeRTOS.org for full details of how and when the exception
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26 ***************************************************************************
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27 See http://www.FreeRTOS.org for documentation, latest information, license
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28 and contact details. Please ensure to read the configuration and relevant
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29 port sections of the online documentation.
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31 Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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32 with commercial development and support options.
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33 ***************************************************************************
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39 typedef void * xQueueHandle;
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41 /* For internal use only. */
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42 #define queueSEND_TO_BACK ( 0 )
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43 #define queueSEND_TO_FRONT ( 1 )
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49 xQueueHandle xQueueCreate(
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50 unsigned portBASE_TYPE uxQueueLength,
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51 unsigned portBASE_TYPE uxItemSize
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55 * Creates a new queue instance. This allocates the storage required by the
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56 * new queue and returns a handle for the queue.
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58 * @param uxQueueLength The maximum number of items that the queue can contain.
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60 * @param uxItemSize The number of bytes each item in the queue will require.
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61 * Items are queued by copy, not by reference, so this is the number of bytes
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62 * that will be copied for each posted item. Each item on the queue must be
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65 * @return If the queue is successfully create then a handle to the newly
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66 * created queue is returned. If the queue cannot be created then 0 is
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73 portCHAR ucMessageID;
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74 portCHAR ucData[ 20 ];
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77 void vATask( void *pvParameters )
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79 xQueueHandle xQueue1, xQueue2;
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81 // Create a queue capable of containing 10 unsigned long values.
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82 xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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85 // Queue was not created and must not be used.
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88 // Create a queue capable of containing 10 pointers to AMessage structures.
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89 // These should be passed by pointer as they contain a lot of data.
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90 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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93 // Queue was not created and must not be used.
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96 // ... Rest of task code.
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99 * \defgroup xQueueCreate xQueueCreate
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100 * \ingroup QueueManagement
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102 xQueueHandle xQueueCreate( unsigned portBASE_TYPE uxQueueLength, unsigned portBASE_TYPE uxItemSize );
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107 portBASE_TYPE xQueueSendToToFront(
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108 xQueueHandle xQueue,
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109 const void * pvItemToQueue,
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110 portTickType xTicksToWait
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114 * This is a macro that calls xQueueGenericSend().
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116 * Post an item to the front of a queue. The item is queued by copy, not by
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117 * reference. This function must not be called from an interrupt service
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118 * routine. See xQueueSendFromISR () for an alternative which may be used
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121 * @param xQueue The handle to the queue on which the item is to be posted.
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123 * @param pvItemToQueue A pointer to the item that is to be placed on the
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124 * queue. The size of the items the queue will hold was defined when the
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125 * queue was created, so this many bytes will be copied from pvItemToQueue
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126 * into the queue storage area.
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128 * @param xTicksToWait The maximum amount of time the task should block
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129 * waiting for space to become available on the queue, should it already
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130 * be full. The call will return immediately if this is set to 0. The
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131 * time is defined in tick periods so the constant portTICK_RATE_MS
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132 * should be used to convert to real time if this is required.
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134 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
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140 portCHAR ucMessageID;
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141 portCHAR ucData[ 20 ];
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144 unsigned portLONG ulVar = 10UL;
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146 void vATask( void *pvParameters )
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148 xQueueHandle xQueue1, xQueue2;
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149 struct AMessage *pxMessage;
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151 // Create a queue capable of containing 10 unsigned long values.
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152 xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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154 // Create a queue capable of containing 10 pointers to AMessage structures.
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155 // These should be passed by pointer as they contain a lot of data.
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156 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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162 // Send an unsigned long. Wait for 10 ticks for space to become
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163 // available if necessary.
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164 if( xQueueSendToFront( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
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166 // Failed to post the message, even after 10 ticks.
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172 // Send a pointer to a struct AMessage object. Don't block if the
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173 // queue is already full.
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174 pxMessage = & xMessage;
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175 xQueueSendToFront( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
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178 // ... Rest of task code.
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181 * \defgroup xQueueSend xQueueSend
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182 * \ingroup QueueManagement
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184 #define xQueueSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_FRONT )
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189 portBASE_TYPE xQueueSendToBack(
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190 xQueueHandle xQueue,
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191 const void * pvItemToQueue,
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192 portTickType xTicksToWait
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196 * This is a macro that calls xQueueGenericSend().
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198 * Post an item to the back of a queue. The item is queued by copy, not by
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199 * reference. This function must not be called from an interrupt service
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200 * routine. See xQueueSendFromISR () for an alternative which may be used
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203 * @param xQueue The handle to the queue on which the item is to be posted.
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205 * @param pvItemToQueue A pointer to the item that is to be placed on the
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206 * queue. The size of the items the queue will hold was defined when the
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207 * queue was created, so this many bytes will be copied from pvItemToQueue
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208 * into the queue storage area.
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210 * @param xTicksToWait The maximum amount of time the task should block
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211 * waiting for space to become available on the queue, should it already
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212 * be full. The call will return immediately if this is set to 0. The
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213 * time is defined in tick periods so the constant portTICK_RATE_MS
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214 * should be used to convert to real time if this is required.
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216 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
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222 portCHAR ucMessageID;
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223 portCHAR ucData[ 20 ];
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226 unsigned portLONG ulVar = 10UL;
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228 void vATask( void *pvParameters )
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230 xQueueHandle xQueue1, xQueue2;
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231 struct AMessage *pxMessage;
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233 // Create a queue capable of containing 10 unsigned long values.
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234 xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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236 // Create a queue capable of containing 10 pointers to AMessage structures.
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237 // These should be passed by pointer as they contain a lot of data.
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238 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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244 // Send an unsigned long. Wait for 10 ticks for space to become
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245 // available if necessary.
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246 if( xQueueSendToBack( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
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248 // Failed to post the message, even after 10 ticks.
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254 // Send a pointer to a struct AMessage object. Don't block if the
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255 // queue is already full.
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256 pxMessage = & xMessage;
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257 xQueueSendToBack( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
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260 // ... Rest of task code.
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263 * \defgroup xQueueSend xQueueSend
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264 * \ingroup QueueManagement
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266 #define xQueueSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_BACK )
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271 portBASE_TYPE xQueueSend(
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272 xQueueHandle xQueue,
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273 const void * pvItemToQueue,
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274 portTickType xTicksToWait
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278 * This is a macro that calls xQueueGenericSend(). It is included for
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279 * backward compatibility with versions of FreeRTOS.org that did not
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280 * include the xQueueSendToFront() and xQueueSendToBack() macros. It is
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281 * equivalent to xQueueSendToBack().
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283 * Post an item on a queue. The item is queued by copy, not by reference.
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284 * This function must not be called from an interrupt service routine.
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285 * See xQueueSendFromISR () for an alternative which may be used in an ISR.
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287 * @param xQueue The handle to the queue on which the item is to be posted.
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289 * @param pvItemToQueue A pointer to the item that is to be placed on the
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290 * queue. The size of the items the queue will hold was defined when the
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291 * queue was created, so this many bytes will be copied from pvItemToQueue
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292 * into the queue storage area.
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294 * @param xTicksToWait The maximum amount of time the task should block
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295 * waiting for space to become available on the queue, should it already
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296 * be full. The call will return immediately if this is set to 0. The
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297 * time is defined in tick periods so the constant portTICK_RATE_MS
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298 * should be used to convert to real time if this is required.
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300 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
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306 portCHAR ucMessageID;
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307 portCHAR ucData[ 20 ];
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310 unsigned portLONG ulVar = 10UL;
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312 void vATask( void *pvParameters )
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314 xQueueHandle xQueue1, xQueue2;
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315 struct AMessage *pxMessage;
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317 // Create a queue capable of containing 10 unsigned long values.
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318 xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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320 // Create a queue capable of containing 10 pointers to AMessage structures.
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321 // These should be passed by pointer as they contain a lot of data.
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322 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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328 // Send an unsigned long. Wait for 10 ticks for space to become
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329 // available if necessary.
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330 if( xQueueSend( xQueue1, ( void * ) &ulVar, ( portTickType ) 10 ) != pdPASS )
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332 // Failed to post the message, even after 10 ticks.
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338 // Send a pointer to a struct AMessage object. Don't block if the
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339 // queue is already full.
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340 pxMessage = & xMessage;
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341 xQueueSend( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0 );
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344 // ... Rest of task code.
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347 * \defgroup xQueueSend xQueueSend
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348 * \ingroup QueueManagement
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350 #define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( xQueue, pvItemToQueue, xTicksToWait, queueSEND_TO_BACK )
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356 portBASE_TYPE xQueueGenericSend(
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357 xQueueHandle xQueue,
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358 const void * pvItemToQueue,
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359 portTickType xTicksToWait
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360 portBASE_TYPE xCopyPosition
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364 * It is preferred that the macros xQueueSend(), xQueueSendToFront() and
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365 * xQueueSendToBack() are used in place of calling this function directly.
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367 * Post an item on a queue. The item is queued by copy, not by reference.
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368 * This function must not be called from an interrupt service routine.
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369 * See xQueueSendFromISR () for an alternative which may be used in an ISR.
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371 * @param xQueue The handle to the queue on which the item is to be posted.
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373 * @param pvItemToQueue A pointer to the item that is to be placed on the
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374 * queue. The size of the items the queue will hold was defined when the
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375 * queue was created, so this many bytes will be copied from pvItemToQueue
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376 * into the queue storage area.
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378 * @param xTicksToWait The maximum amount of time the task should block
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379 * waiting for space to become available on the queue, should it already
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380 * be full. The call will return immediately if this is set to 0. The
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381 * time is defined in tick periods so the constant portTICK_RATE_MS
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382 * should be used to convert to real time if this is required.
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384 * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
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385 * item at the back of the queue, or queueSEND_TO_FRONT to place the item
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386 * at the front of the queue (for high priority messages).
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388 * @return pdTRUE if the item was successfully posted, otherwise errQUEUE_FULL.
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394 portCHAR ucMessageID;
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395 portCHAR ucData[ 20 ];
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398 unsigned portLONG ulVar = 10UL;
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400 void vATask( void *pvParameters )
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402 xQueueHandle xQueue1, xQueue2;
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403 struct AMessage *pxMessage;
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405 // Create a queue capable of containing 10 unsigned long values.
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406 xQueue1 = xQueueCreate( 10, sizeof( unsigned portLONG ) );
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408 // Create a queue capable of containing 10 pointers to AMessage structures.
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409 // These should be passed by pointer as they contain a lot of data.
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410 xQueue2 = xQueueCreate( 10, sizeof( struct AMessage * ) );
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416 // Send an unsigned long. Wait for 10 ticks for space to become
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417 // available if necessary.
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418 if( xQueueGenericSend( xQueue1, ( void * ) &ulVar, ( portTickType ) 10, queueSEND_TO_BACK ) != pdPASS )
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420 // Failed to post the message, even after 10 ticks.
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426 // Send a pointer to a struct AMessage object. Don't block if the
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427 // queue is already full.
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428 pxMessage = & xMessage;
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429 xQueueGenericSend( xQueue2, ( void * ) &pxMessage, ( portTickType ) 0, queueSEND_TO_BACK );
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432 // ... Rest of task code.
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435 * \defgroup xQueueSend xQueueSend
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436 * \ingroup QueueManagement
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438 signed portBASE_TYPE xQueueGenericSend( xQueueHandle xQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portTickType xCopyPosition );
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443 portBASE_TYPE xQueuePeek(
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444 xQueueHandle xQueue,
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446 portTickType xTicksToWait
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449 * This is a macro that calls the xQueueGenericReceive() function.
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451 * Receive an item from a queue without removing the item from the queue.
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452 * The item is received by copy so a buffer of adequate size must be
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453 * provided. The number of bytes copied into the buffer was defined when
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454 * the queue was created.
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456 * Successfully received items remain on the queue so will be returned again
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457 * by the next call, or a call to xQueueReceive().
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459 * This macro must not be used in an interrupt service routine.
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461 * @param pxQueue The handle to the queue from which the item is to be
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464 * @param pvBuffer Pointer to the buffer into which the received item will
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467 * @param xTicksToWait The maximum amount of time the task should block
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468 * waiting for an item to receive should the queue be empty at the time
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469 * of the call. The time is defined in tick periods so the constant
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470 * portTICK_RATE_MS should be used to convert to real time if this is required.
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472 * @return pdTRUE if an item was successfully received from the queue,
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473 * otherwise pdFALSE.
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479 portCHAR ucMessageID;
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480 portCHAR ucData[ 20 ];
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483 xQueueHandle xQueue;
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485 // Task to create a queue and post a value.
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486 void vATask( void *pvParameters )
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488 struct AMessage *pxMessage;
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490 // Create a queue capable of containing 10 pointers to AMessage structures.
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491 // These should be passed by pointer as they contain a lot of data.
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492 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
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495 // Failed to create the queue.
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500 // Send a pointer to a struct AMessage object. Don't block if the
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501 // queue is already full.
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502 pxMessage = & xMessage;
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503 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
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505 // ... Rest of task code.
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508 // Task to peek the data from the queue.
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509 void vADifferentTask( void *pvParameters )
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511 struct AMessage *pxRxedMessage;
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515 // Peek a message on the created queue. Block for 10 ticks if a
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516 // message is not immediately available.
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517 if( xQueuePeek( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
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519 // pcRxedMessage now points to the struct AMessage variable posted
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520 // by vATask, but the item still remains on the queue.
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524 // ... Rest of task code.
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527 * \defgroup xQueueReceive xQueueReceive
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528 * \ingroup QueueManagement
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530 #define xQueuePeek( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( xQueue, pvBuffer, xTicksToWait, pdTRUE )
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535 portBASE_TYPE xQueueReceive(
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536 xQueueHandle xQueue,
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538 portTickType xTicksToWait
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541 * This is a macro that calls the xQueueGenericReceive() function.
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543 * Receive an item from a queue. The item is received by copy so a buffer of
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544 * adequate size must be provided. The number of bytes copied into the buffer
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545 * was defined when the queue was created.
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547 * Successfully received items are removed from the queue.
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549 * This function must not be used in an interrupt service routine. See
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550 * xQueueReceiveFromISR for an alternative that can.
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552 * @param pxQueue The handle to the queue from which the item is to be
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555 * @param pvBuffer Pointer to the buffer into which the received item will
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558 * @param xTicksToWait The maximum amount of time the task should block
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559 * waiting for an item to receive should the queue be empty at the time
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560 * of the call. The time is defined in tick periods so the constant
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561 * portTICK_RATE_MS should be used to convert to real time if this is required.
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563 * @return pdTRUE if an item was successfully received from the queue,
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564 * otherwise pdFALSE.
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570 portCHAR ucMessageID;
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571 portCHAR ucData[ 20 ];
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574 xQueueHandle xQueue;
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576 // Task to create a queue and post a value.
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577 void vATask( void *pvParameters )
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579 struct AMessage *pxMessage;
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581 // Create a queue capable of containing 10 pointers to AMessage structures.
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582 // These should be passed by pointer as they contain a lot of data.
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583 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
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586 // Failed to create the queue.
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591 // Send a pointer to a struct AMessage object. Don't block if the
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592 // queue is already full.
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593 pxMessage = & xMessage;
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594 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
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596 // ... Rest of task code.
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599 // Task to receive from the queue.
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600 void vADifferentTask( void *pvParameters )
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602 struct AMessage *pxRxedMessage;
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606 // Receive a message on the created queue. Block for 10 ticks if a
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607 // message is not immediately available.
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608 if( xQueueReceive( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
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610 // pcRxedMessage now points to the struct AMessage variable posted
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615 // ... Rest of task code.
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618 * \defgroup xQueueReceive xQueueReceive
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619 * \ingroup QueueManagement
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621 #define xQueueReceive( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( xQueue, pvBuffer, xTicksToWait, pdFALSE )
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627 portBASE_TYPE xQueueGenericReceive(
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628 xQueueHandle xQueue,
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630 portTickType xTicksToWait
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631 portBASE_TYPE xJustPeek
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634 * It is preferred that the macro xQueueReceive() be used rather than calling
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635 * this function directly.
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637 * Receive an item from a queue. The item is received by copy so a buffer of
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638 * adequate size must be provided. The number of bytes copied into the buffer
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639 * was defined when the queue was created.
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641 * This function must not be used in an interrupt service routine. See
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642 * xQueueReceiveFromISR for an alternative that can.
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644 * @param pxQueue The handle to the queue from which the item is to be
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647 * @param pvBuffer Pointer to the buffer into which the received item will
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650 * @param xTicksToWait The maximum amount of time the task should block
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651 * waiting for an item to receive should the queue be empty at the time
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652 * of the call. The time is defined in tick periods so the constant
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653 * portTICK_RATE_MS should be used to convert to real time if this is required.
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655 * @param xJustPeek When set to true, the item received from the queue is not
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656 * actually removed from the queue - meaning a subsequent call to
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657 * xQueueReceive() will return the same item. When set to false, the item
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658 * being received from the queue is also removed from the queue.
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660 * @return pdTRUE if an item was successfully received from the queue,
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661 * otherwise pdFALSE.
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667 portCHAR ucMessageID;
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668 portCHAR ucData[ 20 ];
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671 xQueueHandle xQueue;
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673 // Task to create a queue and post a value.
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674 void vATask( void *pvParameters )
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676 struct AMessage *pxMessage;
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678 // Create a queue capable of containing 10 pointers to AMessage structures.
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679 // These should be passed by pointer as they contain a lot of data.
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680 xQueue = xQueueCreate( 10, sizeof( struct AMessage * ) );
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683 // Failed to create the queue.
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688 // Send a pointer to a struct AMessage object. Don't block if the
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689 // queue is already full.
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690 pxMessage = & xMessage;
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691 xQueueSend( xQueue, ( void * ) &pxMessage, ( portTickType ) 0 );
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693 // ... Rest of task code.
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696 // Task to receive from the queue.
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697 void vADifferentTask( void *pvParameters )
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699 struct AMessage *pxRxedMessage;
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703 // Receive a message on the created queue. Block for 10 ticks if a
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704 // message is not immediately available.
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705 if( xQueueGenericReceive( xQueue, &( pxRxedMessage ), ( portTickType ) 10 ) )
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707 // pcRxedMessage now points to the struct AMessage variable posted
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712 // ... Rest of task code.
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715 * \defgroup xQueueReceive xQueueReceive
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716 * \ingroup QueueManagement
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718 signed portBASE_TYPE xQueueGenericReceive( xQueueHandle xQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeek );
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722 * <pre>unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle xQueue );</pre>
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724 * Return the number of messages stored in a queue.
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726 * @param xQueue A handle to the queue being queried.
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728 * @return The number of messages available in the queue.
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730 * \page uxQueueMessagesWaiting uxQueueMessagesWaiting
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731 * \ingroup QueueManagement
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733 unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle xQueue );
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737 * <pre>void vQueueDelete( xQueueHandle xQueue );</pre>
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739 * Delete a queue - freeing all the memory allocated for storing of items
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740 * placed on the queue.
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742 * @param xQueue A handle to the queue to be deleted.
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744 * \page vQueueDelete vQueueDelete
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745 * \ingroup QueueManagement
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747 void vQueueDelete( xQueueHandle xQueue );
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752 portBASE_TYPE xQueueSendToFrontFromISR(
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753 xQueueHandle pxQueue,
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754 const void *pvItemToQueue,
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755 portBASE_TYPE xTaskPreviouslyWoken
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759 * This is a macro that calls xQueueGenericSendFromISR().
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761 * Post an item to the front of a queue. It is safe to use this macro from
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762 * within an interrupt service routine.
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764 * Items are queued by copy not reference so it is preferable to only
\r
765 * queue small items, especially when called from an ISR. In most cases
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766 * it would be preferable to store a pointer to the item being queued.
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768 * @param xQueue The handle to the queue on which the item is to be posted.
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770 * @param pvItemToQueue A pointer to the item that is to be placed on the
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771 * queue. The size of the items the queue will hold was defined when the
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772 * queue was created, so this many bytes will be copied from pvItemToQueue
\r
773 * into the queue storage area.
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775 * @param cTaskPreviouslyWoken This is included so an ISR can post onto
\r
776 * the same queue multiple times from a single interrupt. The first call
\r
777 * should always pass in pdFALSE. Subsequent calls should pass in
\r
778 * the value returned from the previous call. See the file serial .c in the
\r
779 * PC port for a good example of this mechanism.
\r
781 * @return pdTRUE if a task was woken by posting onto the queue. This is
\r
782 * used by the ISR to determine if a context switch may be required following
\r
785 * Example usage for buffered IO (where the ISR can obtain more than one value
\r
788 void vBufferISR( void )
\r
791 portBASE_TYPE xTaskWokenByPost;
\r
793 // We have not woken a task at the start of the ISR.
\r
794 cTaskWokenByPost = pdFALSE;
\r
796 // Loop until the buffer is empty.
\r
799 // Obtain a byte from the buffer.
\r
800 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
\r
802 // Post the byte. The first time round the loop cTaskWokenByPost
\r
803 // will be pdFALSE. If the queue send causes a task to wake we do
\r
804 // not want the task to run until we have finished the ISR, so
\r
805 // xQueueSendFromISR does not cause a context switch. Also we
\r
806 // don't want subsequent posts to wake any other tasks, so we store
\r
807 // the return value back into cTaskWokenByPost so xQueueSendFromISR
\r
808 // knows not to wake any task the next iteration of the loop.
\r
809 xTaskWokenByPost = xQueueSendToFrontFromISR( xRxQueue, &cIn, cTaskWokenByPost );
\r
811 } while( portINPUT_BYTE( BUFFER_COUNT ) );
\r
813 // Now the buffer is empty we can switch context if necessary.
\r
814 if( cTaskWokenByPost )
\r
821 * \defgroup xQueueSendFromISR xQueueSendFromISR
\r
822 * \ingroup QueueManagement
\r
824 #define xQueueSendToFrontFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken, queueSEND_TO_FRONT )
\r
830 portBASE_TYPE xQueueSendToBackFromISR(
\r
831 xQueueHandle pxQueue,
\r
832 const void *pvItemToQueue,
\r
833 portBASE_TYPE xTaskPreviouslyWoken
\r
837 * This is a macro that calls xQueueGenericSendFromISR().
\r
839 * Post an item to the back of a queue. It is safe to use this macro from
\r
840 * within an interrupt service routine.
\r
842 * Items are queued by copy not reference so it is preferable to only
\r
843 * queue small items, especially when called from an ISR. In most cases
\r
844 * it would be preferable to store a pointer to the item being queued.
\r
846 * @param xQueue The handle to the queue on which the item is to be posted.
\r
848 * @param pvItemToQueue A pointer to the item that is to be placed on the
\r
849 * queue. The size of the items the queue will hold was defined when the
\r
850 * queue was created, so this many bytes will be copied from pvItemToQueue
\r
851 * into the queue storage area.
\r
853 * @param cTaskPreviouslyWoken This is included so an ISR can post onto
\r
854 * the same queue multiple times from a single interrupt. The first call
\r
855 * should always pass in pdFALSE. Subsequent calls should pass in
\r
856 * the value returned from the previous call. See the file serial .c in the
\r
857 * PC port for a good example of this mechanism.
\r
859 * @return pdTRUE if a task was woken by posting onto the queue. This is
\r
860 * used by the ISR to determine if a context switch may be required following
\r
863 * Example usage for buffered IO (where the ISR can obtain more than one value
\r
866 void vBufferISR( void )
\r
869 portBASE_TYPE xTaskWokenByPost;
\r
871 // We have not woken a task at the start of the ISR.
\r
872 cTaskWokenByPost = pdFALSE;
\r
874 // Loop until the buffer is empty.
\r
877 // Obtain a byte from the buffer.
\r
878 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
\r
880 // Post the byte. The first time round the loop cTaskWokenByPost
\r
881 // will be pdFALSE. If the queue send causes a task to wake we do
\r
882 // not want the task to run until we have finished the ISR, so
\r
883 // xQueueSendFromISR does not cause a context switch. Also we
\r
884 // don't want subsequent posts to wake any other tasks, so we store
\r
885 // the return value back into cTaskWokenByPost so xQueueSendFromISR
\r
886 // knows not to wake any task the next iteration of the loop.
\r
887 xTaskWokenByPost = xQueueSendToBackFromISR( xRxQueue, &cIn, cTaskWokenByPost );
\r
889 } while( portINPUT_BYTE( BUFFER_COUNT ) );
\r
891 // Now the buffer is empty we can switch context if necessary.
\r
892 if( cTaskWokenByPost )
\r
899 * \defgroup xQueueSendFromISR xQueueSendFromISR
\r
900 * \ingroup QueueManagement
\r
902 #define xQueueSendToBackFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken, queueSEND_TO_BACK )
\r
908 portBASE_TYPE xQueueSendFromISR(
\r
909 xQueueHandle pxQueue,
\r
910 const void *pvItemToQueue,
\r
911 portBASE_TYPE xTaskPreviouslyWoken
\r
915 * This is a macro that calls xQueueGenericSendFromISR(). It is included
\r
916 * for backward compatibility with versions of FreeRTOS.org that did not
\r
917 * include the xQueueSendToBackFromISR() and xQueueSendToFrontFromISR()
\r
920 * Post an item to the back of a queue. It is safe to use this function from
\r
921 * within an interrupt service routine.
\r
923 * Items are queued by copy not reference so it is preferable to only
\r
924 * queue small items, especially when called from an ISR. In most cases
\r
925 * it would be preferable to store a pointer to the item being queued.
\r
927 * @param xQueue The handle to the queue on which the item is to be posted.
\r
929 * @param pvItemToQueue A pointer to the item that is to be placed on the
\r
930 * queue. The size of the items the queue will hold was defined when the
\r
931 * queue was created, so this many bytes will be copied from pvItemToQueue
\r
932 * into the queue storage area.
\r
934 * @param cTaskPreviouslyWoken This is included so an ISR can post onto
\r
935 * the same queue multiple times from a single interrupt. The first call
\r
936 * should always pass in pdFALSE. Subsequent calls should pass in
\r
937 * the value returned from the previous call. See the file serial .c in the
\r
938 * PC port for a good example of this mechanism.
\r
940 * @return pdTRUE if a task was woken by posting onto the queue. This is
\r
941 * used by the ISR to determine if a context switch may be required following
\r
944 * Example usage for buffered IO (where the ISR can obtain more than one value
\r
947 void vBufferISR( void )
\r
950 portBASE_TYPE xTaskWokenByPost;
\r
952 // We have not woken a task at the start of the ISR.
\r
953 cTaskWokenByPost = pdFALSE;
\r
955 // Loop until the buffer is empty.
\r
958 // Obtain a byte from the buffer.
\r
959 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
\r
961 // Post the byte. The first time round the loop cTaskWokenByPost
\r
962 // will be pdFALSE. If the queue send causes a task to wake we do
\r
963 // not want the task to run until we have finished the ISR, so
\r
964 // xQueueSendFromISR does not cause a context switch. Also we
\r
965 // don't want subsequent posts to wake any other tasks, so we store
\r
966 // the return value back into cTaskWokenByPost so xQueueSendFromISR
\r
967 // knows not to wake any task the next iteration of the loop.
\r
968 xTaskWokenByPost = xQueueSendFromISR( xRxQueue, &cIn, cTaskWokenByPost );
\r
970 } while( portINPUT_BYTE( BUFFER_COUNT ) );
\r
972 // Now the buffer is empty we can switch context if necessary.
\r
973 if( cTaskWokenByPost )
\r
980 * \defgroup xQueueSendFromISR xQueueSendFromISR
\r
981 * \ingroup QueueManagement
\r
983 #define xQueueSendFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken ) xQueueGenericSendFromISR( pxQueue, pvItemToQueue, xTaskPreviouslyWoken, queueSEND_TO_BACK )
\r
988 portBASE_TYPE xQueueGenericSendFromISR(
\r
989 xQueueHandle pxQueue,
\r
990 const void *pvItemToQueue,
\r
991 portBASE_TYPE xTaskPreviouslyWoken
\r
992 portBASE_TYPE xCopyPosition
\r
996 * It is preferred that the macros xQueueSendFromISR(),
\r
997 * xQueueSendToFrontFromISR() and xQueueSendToBackFromISR() be used in place
\r
998 * of calling this function directly.
\r
1000 * Post an item on a queue. It is safe to use this function from within an
\r
1001 * interrupt service routine.
\r
1003 * Items are queued by copy not reference so it is preferable to only
\r
1004 * queue small items, especially when called from an ISR. In most cases
\r
1005 * it would be preferable to store a pointer to the item being queued.
\r
1007 * @param xQueue The handle to the queue on which the item is to be posted.
\r
1009 * @param pvItemToQueue A pointer to the item that is to be placed on the
\r
1010 * queue. The size of the items the queue will hold was defined when the
\r
1011 * queue was created, so this many bytes will be copied from pvItemToQueue
\r
1012 * into the queue storage area.
\r
1014 * @param cTaskPreviouslyWoken This is included so an ISR can post onto
\r
1015 * the same queue multiple times from a single interrupt. The first call
\r
1016 * should always pass in pdFALSE. Subsequent calls should pass in
\r
1017 * the value returned from the previous call. See the file serial .c in the
\r
1018 * PC port for a good example of this mechanism.
\r
1020 * @param xCopyPosition Can take the value queueSEND_TO_BACK to place the
\r
1021 * item at the back of the queue, or queueSEND_TO_FRONT to place the item
\r
1022 * at the front of the queue (for high priority messages).
\r
1024 * @return pdTRUE if a task was woken by posting onto the queue. This is
\r
1025 * used by the ISR to determine if a context switch may be required following
\r
1028 * Example usage for buffered IO (where the ISR can obtain more than one value
\r
1031 void vBufferISR( void )
\r
1034 portBASE_TYPE xTaskWokenByPost;
\r
1036 // We have not woken a task at the start of the ISR.
\r
1037 cTaskWokenByPost = pdFALSE;
\r
1039 // Loop until the buffer is empty.
\r
1042 // Obtain a byte from the buffer.
\r
1043 cIn = portINPUT_BYTE( RX_REGISTER_ADDRESS );
\r
1045 // Post the byte. The first time round the loop cTaskWokenByPost
\r
1046 // will be pdFALSE. If the queue send causes a task to wake we do
\r
1047 // not want the task to run until we have finished the ISR, so
\r
1048 // xQueueSendFromISR does not cause a context switch. Also we
\r
1049 // don't want subsequent posts to wake any other tasks, so we store
\r
1050 // the return value back into cTaskWokenByPost so xQueueSendFromISR
\r
1051 // knows not to wake any task the next iteration of the loop.
\r
1052 xTaskWokenByPost = xQueueGenericSendFromISR( xRxQueue, &cIn, cTaskWokenByPost, queueSEND_TO_BACK );
\r
1054 } while( portINPUT_BYTE( BUFFER_COUNT ) );
\r
1056 // Now the buffer is empty we can switch context if necessary.
\r
1057 if( cTaskWokenByPost )
\r
1064 * \defgroup xQueueSendFromISR xQueueSendFromISR
\r
1065 * \ingroup QueueManagement
\r
1067 signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken, portBASE_TYPE xCopyPosition );
\r
1072 portBASE_TYPE xQueueReceiveFromISR(
\r
1073 xQueueHandle pxQueue,
\r
1075 portBASE_TYPE *pxTaskWoken
\r
1079 * Receive an item from a queue. It is safe to use this function from within an
\r
1080 * interrupt service routine.
\r
1082 * @param pxQueue The handle to the queue from which the item is to be
\r
1085 * @param pvBuffer Pointer to the buffer into which the received item will
\r
1088 * @param pxTaskWoken A task may be blocked waiting for space to become
\r
1089 * available on the queue. If xQueueReceiveFromISR causes such a task to
\r
1090 * unblock *pxTaskWoken will get set to pdTRUE, otherwise *pxTaskWoken will
\r
1091 * remain unchanged.
\r
1093 * @return pdTRUE if an item was successfully received from the queue,
\r
1094 * otherwise pdFALSE.
\r
1099 xQueueHandle xQueue;
\r
1101 // Function to create a queue and post some values.
\r
1102 void vAFunction( void *pvParameters )
\r
1104 portCHAR cValueToPost;
\r
1105 const portTickType xBlockTime = ( portTickType )0xff;
\r
1107 // Create a queue capable of containing 10 characters.
\r
1108 xQueue = xQueueCreate( 10, sizeof( portCHAR ) );
\r
1111 // Failed to create the queue.
\r
1116 // Post some characters that will be used within an ISR. If the queue
\r
1117 // is full then this task will block for xBlockTime ticks.
\r
1118 cValueToPost = 'a';
\r
1119 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
\r
1120 cValueToPost = 'b';
\r
1121 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
\r
1123 // ... keep posting characters ... this task may block when the queue
\r
1126 cValueToPost = 'c';
\r
1127 xQueueSend( xQueue, ( void * ) &cValueToPost, xBlockTime );
\r
1130 // ISR that outputs all the characters received on the queue.
\r
1131 void vISR_Routine( void )
\r
1133 portBASE_TYPE xTaskWokenByReceive = pdFALSE;
\r
1134 portCHAR cRxedChar;
\r
1136 while( xQueueReceiveFromISR( xQueue, ( void * ) &cRxedChar, &xTaskWokenByReceive) )
\r
1138 // A character was received. Output the character now.
\r
1139 vOutputCharacter( cRxedChar );
\r
1141 // If removing the character from the queue woke the task that was
\r
1142 // posting onto the queue cTaskWokenByReceive will have been set to
\r
1143 // pdTRUE. No matter how many times this loop iterates only one
\r
1144 // task will be woken.
\r
1147 if( cTaskWokenByPost != ( portCHAR ) pdFALSE;
\r
1153 * \defgroup xQueueReceiveFromISR xQueueReceiveFromISR
\r
1154 * \ingroup QueueManagement
\r
1156 signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken );
\r
1160 * The functions defined above are for passing data to and from tasks. The
\r
1161 * functions below are the equivalents for passing data to and from
\r
1164 * These functions are called from the co-routine macro implementation and
\r
1165 * should not be called directly from application code. Instead use the macro
\r
1166 * wrappers defined within croutine.h.
\r
1168 signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken );
\r
1169 signed portBASE_TYPE xQueueCRReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken );
\r
1170 signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait );
\r
1171 signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait );
\r
1174 * For internal use only. Use xSemaphoreCreateMutex() instead of calling
\r
1175 * this function directly.
\r
1177 xQueueHandle xQueueCreateMutex( void );
\r
1179 #endif /* QUEUE_H */
\r