2 FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 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 ***************************************************************************
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29 * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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31 * This is a concise, step by step, 'hands on' guide that describes both *
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32 * general multitasking concepts and FreeRTOS specifics. It presents and *
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33 * explains numerous examples that are written using the FreeRTOS API. *
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34 * Full source code for all the examples is provided in an accompanying *
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37 ***************************************************************************
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38 ***************************************************************************
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40 Please ensure to read the configuration and relevant port sections of the
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41 online documentation.
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43 http://www.FreeRTOS.org - Documentation, latest information, license and
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46 http://www.SafeRTOS.com - A version that is certified for use in safety
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49 http://www.OpenRTOS.com - Commercial support, development, porting,
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50 licensing and training services.
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53 #ifndef INC_FREERTOS_H
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54 #error "#include FreeRTOS.h" must appear in source files before "#include croutine.h"
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60 #ifndef CO_ROUTINE_H
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61 #define CO_ROUTINE_H
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69 /* Used to hide the implementation of the co-routine control block. The
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70 control block structure however has to be included in the header due to
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71 the macro implementation of the co-routine functionality. */
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72 typedef void * xCoRoutineHandle;
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74 /* Defines the prototype to which co-routine functions must conform. */
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75 typedef void (*crCOROUTINE_CODE)( xCoRoutineHandle, unsigned portBASE_TYPE );
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77 typedef struct corCoRoutineControlBlock
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79 crCOROUTINE_CODE pxCoRoutineFunction;
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80 xListItem xGenericListItem; /*< List item used to place the CRCB in ready and blocked queues. */
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81 xListItem xEventListItem; /*< List item used to place the CRCB in event lists. */
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82 unsigned portBASE_TYPE uxPriority; /*< The priority of the co-routine in relation to other co-routines. */
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83 unsigned portBASE_TYPE uxIndex; /*< Used to distinguish between co-routines when multiple co-routines use the same co-routine function. */
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84 unsigned portSHORT uxState; /*< Used internally by the co-routine implementation. */
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85 } corCRCB; /* Co-routine control block. Note must be identical in size down to uxPriority with tskTCB. */
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90 portBASE_TYPE xCoRoutineCreate(
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91 crCOROUTINE_CODE pxCoRoutineCode,
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92 unsigned portBASE_TYPE uxPriority,
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93 unsigned portBASE_TYPE uxIndex
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96 * Create a new co-routine and add it to the list of co-routines that are
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99 * @param pxCoRoutineCode Pointer to the co-routine function. Co-routine
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100 * functions require special syntax - see the co-routine section of the WEB
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101 * documentation for more information.
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103 * @param uxPriority The priority with respect to other co-routines at which
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104 * the co-routine will run.
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106 * @param uxIndex Used to distinguish between different co-routines that
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107 * execute the same function. See the example below and the co-routine section
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108 * of the WEB documentation for further information.
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110 * @return pdPASS if the co-routine was successfully created and added to a ready
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111 * list, otherwise an error code defined with ProjDefs.h.
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115 // Co-routine to be created.
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116 void vFlashCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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118 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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119 // This may not be necessary for const variables.
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120 static const char cLedToFlash[ 2 ] = { 5, 6 };
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121 static const portTickType xTimeToDelay[ 2 ] = { 200, 400 };
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123 // Must start every co-routine with a call to crSTART();
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124 crSTART( xHandle );
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128 // This co-routine just delays for a fixed period, then toggles
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129 // an LED. Two co-routines are created using this function, so
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130 // the uxIndex parameter is used to tell the co-routine which
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131 // LED to flash and how long to delay. This assumes xQueue has
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132 // already been created.
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133 vParTestToggleLED( cLedToFlash[ uxIndex ] );
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134 crDELAY( xHandle, uxFlashRates[ uxIndex ] );
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137 // Must end every co-routine with a call to crEND();
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141 // Function that creates two co-routines.
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142 void vOtherFunction( void )
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144 unsigned char ucParameterToPass;
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145 xTaskHandle xHandle;
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147 // Create two co-routines at priority 0. The first is given index 0
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148 // so (from the code above) toggles LED 5 every 200 ticks. The second
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149 // is given index 1 so toggles LED 6 every 400 ticks.
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150 for( uxIndex = 0; uxIndex < 2; uxIndex++ )
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152 xCoRoutineCreate( vFlashCoRoutine, 0, uxIndex );
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156 * \defgroup xCoRoutineCreate xCoRoutineCreate
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159 signed portBASE_TYPE xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, unsigned portBASE_TYPE uxPriority, unsigned portBASE_TYPE uxIndex );
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165 void vCoRoutineSchedule( void );</pre>
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167 * Run a co-routine.
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169 * vCoRoutineSchedule() executes the highest priority co-routine that is able
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170 * to run. The co-routine will execute until it either blocks, yields or is
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171 * preempted by a task. Co-routines execute cooperatively so one
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172 * co-routine cannot be preempted by another, but can be preempted by a task.
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174 * If an application comprises of both tasks and co-routines then
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175 * vCoRoutineSchedule should be called from the idle task (in an idle task
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180 // This idle task hook will schedule a co-routine each time it is called.
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181 // The rest of the idle task will execute between co-routine calls.
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182 void vApplicationIdleHook( void )
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184 vCoRoutineSchedule();
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187 // Alternatively, if you do not require any other part of the idle task to
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188 // execute, the idle task hook can call vCoRoutineScheduler() within an
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190 void vApplicationIdleHook( void )
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194 vCoRoutineSchedule();
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198 * \defgroup vCoRoutineSchedule vCoRoutineSchedule
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201 void vCoRoutineSchedule( void );
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206 crSTART( xCoRoutineHandle xHandle );</pre>
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208 * This macro MUST always be called at the start of a co-routine function.
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212 // Co-routine to be created.
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213 void vACoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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215 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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216 static portLONG ulAVariable;
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218 // Must start every co-routine with a call to crSTART();
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219 crSTART( xHandle );
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223 // Co-routine functionality goes here.
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226 // Must end every co-routine with a call to crEND();
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229 * \defgroup crSTART crSTART
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232 #define crSTART( pxCRCB ) switch( ( ( corCRCB * )pxCRCB )->uxState ) { case 0:
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239 * This macro MUST always be called at the end of a co-routine function.
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243 // Co-routine to be created.
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244 void vACoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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246 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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247 static portLONG ulAVariable;
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249 // Must start every co-routine with a call to crSTART();
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250 crSTART( xHandle );
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254 // Co-routine functionality goes here.
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257 // Must end every co-routine with a call to crEND();
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260 * \defgroup crSTART crSTART
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266 * These macros are intended for internal use by the co-routine implementation
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267 * only. The macros should not be used directly by application writers.
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269 #define crSET_STATE0( xHandle ) ( ( corCRCB * )xHandle)->uxState = (__LINE__ * 2); return; case (__LINE__ * 2):
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270 #define crSET_STATE1( xHandle ) ( ( corCRCB * )xHandle)->uxState = ((__LINE__ * 2)+1); return; case ((__LINE__ * 2)+1):
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275 crDELAY( xCoRoutineHandle xHandle, portTickType xTicksToDelay );</pre>
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277 * Delay a co-routine for a fixed period of time.
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279 * crDELAY can only be called from the co-routine function itself - not
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280 * from within a function called by the co-routine function. This is because
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281 * co-routines do not maintain their own stack.
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283 * @param xHandle The handle of the co-routine to delay. This is the xHandle
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284 * parameter of the co-routine function.
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286 * @param xTickToDelay The number of ticks that the co-routine should delay
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287 * for. The actual amount of time this equates to is defined by
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288 * configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant portTICK_RATE_MS
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289 * can be used to convert ticks to milliseconds.
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293 // Co-routine to be created.
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294 void vACoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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296 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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297 // This may not be necessary for const variables.
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298 // We are to delay for 200ms.
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299 static const xTickType xDelayTime = 200 / portTICK_RATE_MS;
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301 // Must start every co-routine with a call to crSTART();
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302 crSTART( xHandle );
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306 // Delay for 200ms.
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307 crDELAY( xHandle, xDelayTime );
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309 // Do something here.
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312 // Must end every co-routine with a call to crEND();
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315 * \defgroup crDELAY crDELAY
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318 #define crDELAY( xHandle, xTicksToDelay ) \
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319 if( xTicksToDelay > 0 ) \
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321 vCoRoutineAddToDelayedList( xTicksToDelay, NULL ); \
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323 crSET_STATE0( xHandle );
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328 xCoRoutineHandle xHandle,
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329 xQueueHandle pxQueue,
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330 void *pvItemToQueue,
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331 portTickType xTicksToWait,
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332 portBASE_TYPE *pxResult
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335 * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
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336 * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
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338 * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
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339 * xQueueSend() and xQueueReceive() can only be used from tasks.
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341 * crQUEUE_SEND can only be called from the co-routine function itself - not
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342 * from within a function called by the co-routine function. This is because
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343 * co-routines do not maintain their own stack.
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345 * See the co-routine section of the WEB documentation for information on
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346 * passing data between tasks and co-routines and between ISR's and
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349 * @param xHandle The handle of the calling co-routine. This is the xHandle
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350 * parameter of the co-routine function.
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352 * @param pxQueue The handle of the queue on which the data will be posted.
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353 * The handle is obtained as the return value when the queue is created using
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354 * the xQueueCreate() API function.
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356 * @param pvItemToQueue A pointer to the data being posted onto the queue.
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357 * The number of bytes of each queued item is specified when the queue is
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358 * created. This number of bytes is copied from pvItemToQueue into the queue
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361 * @param xTickToDelay The number of ticks that the co-routine should block
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362 * to wait for space to become available on the queue, should space not be
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363 * available immediately. The actual amount of time this equates to is defined
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364 * by configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant
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365 * portTICK_RATE_MS can be used to convert ticks to milliseconds (see example
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368 * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
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369 * data was successfully posted onto the queue, otherwise it will be set to an
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370 * error defined within ProjDefs.h.
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374 // Co-routine function that blocks for a fixed period then posts a number onto
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376 static void prvCoRoutineFlashTask( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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378 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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379 static portBASE_TYPE xNumberToPost = 0;
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380 static portBASE_TYPE xResult;
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382 // Co-routines must begin with a call to crSTART().
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383 crSTART( xHandle );
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387 // This assumes the queue has already been created.
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388 crQUEUE_SEND( xHandle, xCoRoutineQueue, &xNumberToPost, NO_DELAY, &xResult );
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390 if( xResult != pdPASS )
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392 // The message was not posted!
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395 // Increment the number to be posted onto the queue.
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398 // Delay for 100 ticks.
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399 crDELAY( xHandle, 100 );
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402 // Co-routines must end with a call to crEND().
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405 * \defgroup crQUEUE_SEND crQUEUE_SEND
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408 #define crQUEUE_SEND( xHandle, pxQueue, pvItemToQueue, xTicksToWait, pxResult ) \
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410 *pxResult = xQueueCRSend( pxQueue, pvItemToQueue, xTicksToWait ); \
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411 if( *pxResult == errQUEUE_BLOCKED ) \
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413 crSET_STATE0( xHandle ); \
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414 *pxResult = xQueueCRSend( pxQueue, pvItemToQueue, 0 ); \
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416 if( *pxResult == errQUEUE_YIELD ) \
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418 crSET_STATE1( xHandle ); \
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419 *pxResult = pdPASS; \
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427 xCoRoutineHandle xHandle,
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428 xQueueHandle pxQueue,
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430 portTickType xTicksToWait,
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431 portBASE_TYPE *pxResult
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434 * The macro's crQUEUE_SEND() and crQUEUE_RECEIVE() are the co-routine
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435 * equivalent to the xQueueSend() and xQueueReceive() functions used by tasks.
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437 * crQUEUE_SEND and crQUEUE_RECEIVE can only be used from a co-routine whereas
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438 * xQueueSend() and xQueueReceive() can only be used from tasks.
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440 * crQUEUE_RECEIVE can only be called from the co-routine function itself - not
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441 * from within a function called by the co-routine function. This is because
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442 * co-routines do not maintain their own stack.
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444 * See the co-routine section of the WEB documentation for information on
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445 * passing data between tasks and co-routines and between ISR's and
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448 * @param xHandle The handle of the calling co-routine. This is the xHandle
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449 * parameter of the co-routine function.
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451 * @param pxQueue The handle of the queue from which the data will be received.
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452 * The handle is obtained as the return value when the queue is created using
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453 * the xQueueCreate() API function.
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455 * @param pvBuffer The buffer into which the received item is to be copied.
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456 * The number of bytes of each queued item is specified when the queue is
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457 * created. This number of bytes is copied into pvBuffer.
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459 * @param xTickToDelay The number of ticks that the co-routine should block
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460 * to wait for data to become available from the queue, should data not be
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461 * available immediately. The actual amount of time this equates to is defined
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462 * by configTICK_RATE_HZ (set in FreeRTOSConfig.h). The constant
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463 * portTICK_RATE_MS can be used to convert ticks to milliseconds (see the
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464 * crQUEUE_SEND example).
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466 * @param pxResult The variable pointed to by pxResult will be set to pdPASS if
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467 * data was successfully retrieved from the queue, otherwise it will be set to
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468 * an error code as defined within ProjDefs.h.
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472 // A co-routine receives the number of an LED to flash from a queue. It
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473 // blocks on the queue until the number is received.
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474 static void prvCoRoutineFlashWorkTask( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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476 // Variables in co-routines must be declared static if they must maintain value across a blocking call.
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477 static portBASE_TYPE xResult;
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478 static unsigned portBASE_TYPE uxLEDToFlash;
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480 // All co-routines must start with a call to crSTART().
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481 crSTART( xHandle );
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485 // Wait for data to become available on the queue.
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486 crQUEUE_RECEIVE( xHandle, xCoRoutineQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
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488 if( xResult == pdPASS )
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490 // We received the LED to flash - flash it!
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491 vParTestToggleLED( uxLEDToFlash );
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497 * \defgroup crQUEUE_RECEIVE crQUEUE_RECEIVE
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500 #define crQUEUE_RECEIVE( xHandle, pxQueue, pvBuffer, xTicksToWait, pxResult ) \
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502 *pxResult = xQueueCRReceive( pxQueue, pvBuffer, xTicksToWait ); \
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503 if( *pxResult == errQUEUE_BLOCKED ) \
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505 crSET_STATE0( xHandle ); \
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506 *pxResult = xQueueCRReceive( pxQueue, pvBuffer, 0 ); \
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508 if( *pxResult == errQUEUE_YIELD ) \
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510 crSET_STATE1( xHandle ); \
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511 *pxResult = pdPASS; \
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518 crQUEUE_SEND_FROM_ISR(
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519 xQueueHandle pxQueue,
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520 void *pvItemToQueue,
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521 portBASE_TYPE xCoRoutinePreviouslyWoken
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524 * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
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525 * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
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526 * functions used by tasks.
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528 * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
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529 * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
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530 * xQueueReceiveFromISR() can only be used to pass data between a task and and
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533 * crQUEUE_SEND_FROM_ISR can only be called from an ISR to send data to a queue
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534 * that is being used from within a co-routine.
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536 * See the co-routine section of the WEB documentation for information on
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537 * passing data between tasks and co-routines and between ISR's and
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540 * @param xQueue The handle to the queue on which the item is to be posted.
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542 * @param pvItemToQueue A pointer to the item that is to be placed on the
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543 * queue. The size of the items the queue will hold was defined when the
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544 * queue was created, so this many bytes will be copied from pvItemToQueue
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545 * into the queue storage area.
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547 * @param xCoRoutinePreviouslyWoken This is included so an ISR can post onto
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548 * the same queue multiple times from a single interrupt. The first call
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549 * should always pass in pdFALSE. Subsequent calls should pass in
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550 * the value returned from the previous call.
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552 * @return pdTRUE if a co-routine was woken by posting onto the queue. This is
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553 * used by the ISR to determine if a context switch may be required following
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558 // A co-routine that blocks on a queue waiting for characters to be received.
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559 static void vReceivingCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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561 portCHAR cRxedChar;
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562 portBASE_TYPE xResult;
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564 // All co-routines must start with a call to crSTART().
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565 crSTART( xHandle );
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569 // Wait for data to become available on the queue. This assumes the
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570 // queue xCommsRxQueue has already been created!
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571 crQUEUE_RECEIVE( xHandle, xCommsRxQueue, &uxLEDToFlash, portMAX_DELAY, &xResult );
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573 // Was a character received?
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574 if( xResult == pdPASS )
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576 // Process the character here.
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580 // All co-routines must end with a call to crEND().
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584 // An ISR that uses a queue to send characters received on a serial port to
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586 void vUART_ISR( void )
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588 portCHAR cRxedChar;
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589 portBASE_TYPE xCRWokenByPost = pdFALSE;
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591 // We loop around reading characters until there are none left in the UART.
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592 while( UART_RX_REG_NOT_EMPTY() )
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594 // Obtain the character from the UART.
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595 cRxedChar = UART_RX_REG;
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597 // Post the character onto a queue. xCRWokenByPost will be pdFALSE
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598 // the first time around the loop. If the post causes a co-routine
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599 // to be woken (unblocked) then xCRWokenByPost will be set to pdTRUE.
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600 // In this manner we can ensure that if more than one co-routine is
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601 // blocked on the queue only one is woken by this ISR no matter how
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602 // many characters are posted to the queue.
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603 xCRWokenByPost = crQUEUE_SEND_FROM_ISR( xCommsRxQueue, &cRxedChar, xCRWokenByPost );
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606 * \defgroup crQUEUE_SEND_FROM_ISR crQUEUE_SEND_FROM_ISR
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609 #define crQUEUE_SEND_FROM_ISR( pxQueue, pvItemToQueue, xCoRoutinePreviouslyWoken ) xQueueCRSendFromISR( pxQueue, pvItemToQueue, xCoRoutinePreviouslyWoken )
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615 crQUEUE_SEND_FROM_ISR(
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616 xQueueHandle pxQueue,
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618 portBASE_TYPE * pxCoRoutineWoken
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621 * The macro's crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() are the
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622 * co-routine equivalent to the xQueueSendFromISR() and xQueueReceiveFromISR()
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623 * functions used by tasks.
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625 * crQUEUE_SEND_FROM_ISR() and crQUEUE_RECEIVE_FROM_ISR() can only be used to
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626 * pass data between a co-routine and and ISR, whereas xQueueSendFromISR() and
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627 * xQueueReceiveFromISR() can only be used to pass data between a task and and
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630 * crQUEUE_RECEIVE_FROM_ISR can only be called from an ISR to receive data
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631 * from a queue that is being used from within a co-routine (a co-routine
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632 * posted to the queue).
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634 * See the co-routine section of the WEB documentation for information on
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635 * passing data between tasks and co-routines and between ISR's and
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638 * @param xQueue The handle to the queue on which the item is to be posted.
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640 * @param pvBuffer A pointer to a buffer into which the received item will be
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641 * placed. The size of the items the queue will hold was defined when the
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642 * queue was created, so this many bytes will be copied from the queue into
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645 * @param pxCoRoutineWoken A co-routine may be blocked waiting for space to become
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646 * available on the queue. If crQUEUE_RECEIVE_FROM_ISR causes such a
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647 * co-routine to unblock *pxCoRoutineWoken will get set to pdTRUE, otherwise
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648 * *pxCoRoutineWoken will remain unchanged.
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650 * @return pdTRUE an item was successfully received from the queue, otherwise
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655 // A co-routine that posts a character to a queue then blocks for a fixed
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656 // period. The character is incremented each time.
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657 static void vSendingCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
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659 // cChar holds its value while this co-routine is blocked and must therefore
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660 // be declared static.
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661 static portCHAR cCharToTx = 'a';
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662 portBASE_TYPE xResult;
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664 // All co-routines must start with a call to crSTART().
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665 crSTART( xHandle );
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669 // Send the next character to the queue.
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670 crQUEUE_SEND( xHandle, xCoRoutineQueue, &cCharToTx, NO_DELAY, &xResult );
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672 if( xResult == pdPASS )
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674 // The character was successfully posted to the queue.
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678 // Could not post the character to the queue.
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681 // Enable the UART Tx interrupt to cause an interrupt in this
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682 // hypothetical UART. The interrupt will obtain the character
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683 // from the queue and send it.
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684 ENABLE_RX_INTERRUPT();
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686 // Increment to the next character then block for a fixed period.
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687 // cCharToTx will maintain its value across the delay as it is
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688 // declared static.
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690 if( cCharToTx > 'x' )
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697 // All co-routines must end with a call to crEND().
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701 // An ISR that uses a queue to receive characters to send on a UART.
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702 void vUART_ISR( void )
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704 portCHAR cCharToTx;
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705 portBASE_TYPE xCRWokenByPost = pdFALSE;
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707 while( UART_TX_REG_EMPTY() )
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709 // Are there any characters in the queue waiting to be sent?
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710 // xCRWokenByPost will automatically be set to pdTRUE if a co-routine
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711 // is woken by the post - ensuring that only a single co-routine is
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712 // woken no matter how many times we go around this loop.
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713 if( crQUEUE_RECEIVE_FROM_ISR( pxQueue, &cCharToTx, &xCRWokenByPost ) )
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715 SEND_CHARACTER( cCharToTx );
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719 * \defgroup crQUEUE_RECEIVE_FROM_ISR crQUEUE_RECEIVE_FROM_ISR
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722 #define crQUEUE_RECEIVE_FROM_ISR( pxQueue, pvBuffer, pxCoRoutineWoken ) xQueueCRReceiveFromISR( pxQueue, pvBuffer, pxCoRoutineWoken )
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725 * This function is intended for internal use by the co-routine macros only.
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726 * The macro nature of the co-routine implementation requires that the
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727 * prototype appears here. The function should not be used by application
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730 * Removes the current co-routine from its ready list and places it in the
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731 * appropriate delayed list.
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733 void vCoRoutineAddToDelayedList( portTickType xTicksToDelay, xList *pxEventList );
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736 * This function is intended for internal use by the queue implementation only.
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737 * The function should not be used by application writers.
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739 * Removes the highest priority co-routine from the event list and places it in
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740 * the pending ready list.
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742 signed portBASE_TYPE xCoRoutineRemoveFromEventList( const xList *pxEventList );
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748 #endif /* CO_ROUTINE_H */
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