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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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 #include "FreeRTOS.h"
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55 #include "croutine.h"
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58 * Some kernel aware debuggers require data to be viewed to be global, rather
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61 #ifdef portREMOVE_STATIC_QUALIFIER
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66 /* Lists for ready and blocked co-routines. --------------------*/
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67 static xList pxReadyCoRoutineLists[ configMAX_CO_ROUTINE_PRIORITIES ]; /*< Prioritised ready co-routines. */
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68 static xList xDelayedCoRoutineList1; /*< Delayed co-routines. */
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69 static xList xDelayedCoRoutineList2; /*< Delayed co-routines (two lists are used - one for delays that have overflowed the current tick count. */
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70 static xList * pxDelayedCoRoutineList; /*< Points to the delayed co-routine list currently being used. */
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71 static xList * pxOverflowDelayedCoRoutineList; /*< Points to the delayed co-routine list currently being used to hold co-routines that have overflowed the current tick count. */
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72 static xList xPendingReadyCoRoutineList; /*< Holds co-routines that have been readied by an external event. They cannot be added directly to the ready lists as the ready lists cannot be accessed by interrupts. */
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74 /* Other file private variables. --------------------------------*/
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75 corCRCB * pxCurrentCoRoutine = NULL;
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76 static unsigned portBASE_TYPE uxTopCoRoutineReadyPriority = 0;
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77 static portTickType xCoRoutineTickCount = 0, xLastTickCount = 0, xPassedTicks = 0;
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79 /* The initial state of the co-routine when it is created. */
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80 #define corINITIAL_STATE ( 0 )
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83 * Place the co-routine represented by pxCRCB into the appropriate ready queue
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84 * for the priority. It is inserted at the end of the list.
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86 * This macro accesses the co-routine ready lists and therefore must not be
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87 * used from within an ISR.
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89 #define prvAddCoRoutineToReadyQueue( pxCRCB ) \
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91 if( pxCRCB->uxPriority > uxTopCoRoutineReadyPriority ) \
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93 uxTopCoRoutineReadyPriority = pxCRCB->uxPriority; \
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95 vListInsertEnd( ( xList * ) &( pxReadyCoRoutineLists[ pxCRCB->uxPriority ] ), &( pxCRCB->xGenericListItem ) ); \
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99 * Utility to ready all the lists used by the scheduler. This is called
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100 * automatically upon the creation of the first co-routine.
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102 static void prvInitialiseCoRoutineLists( void );
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105 * Co-routines that are readied by an interrupt cannot be placed directly into
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106 * the ready lists (there is no mutual exclusion). Instead they are placed in
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107 * in the pending ready list in order that they can later be moved to the ready
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108 * list by the co-routine scheduler.
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110 static void prvCheckPendingReadyList( void );
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113 * Macro that looks at the list of co-routines that are currently delayed to
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114 * see if any require waking.
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116 * Co-routines are stored in the queue in the order of their wake time -
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117 * meaning once one co-routine has been found whose timer has not expired
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118 * we need not look any further down the list.
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120 static void prvCheckDelayedList( void );
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122 /*-----------------------------------------------------------*/
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124 signed portBASE_TYPE xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, unsigned portBASE_TYPE uxPriority, unsigned portBASE_TYPE uxIndex )
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126 signed portBASE_TYPE xReturn;
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127 corCRCB *pxCoRoutine;
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129 /* Allocate the memory that will store the co-routine control block. */
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130 pxCoRoutine = ( corCRCB * ) pvPortMalloc( sizeof( corCRCB ) );
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133 /* If pxCurrentCoRoutine is NULL then this is the first co-routine to
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134 be created and the co-routine data structures need initialising. */
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135 if( pxCurrentCoRoutine == NULL )
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137 pxCurrentCoRoutine = pxCoRoutine;
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138 prvInitialiseCoRoutineLists();
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141 /* Check the priority is within limits. */
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142 if( uxPriority >= configMAX_CO_ROUTINE_PRIORITIES )
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144 uxPriority = configMAX_CO_ROUTINE_PRIORITIES - 1;
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147 /* Fill out the co-routine control block from the function parameters. */
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148 pxCoRoutine->uxState = corINITIAL_STATE;
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149 pxCoRoutine->uxPriority = uxPriority;
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150 pxCoRoutine->uxIndex = uxIndex;
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151 pxCoRoutine->pxCoRoutineFunction = pxCoRoutineCode;
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153 /* Initialise all the other co-routine control block parameters. */
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154 vListInitialiseItem( &( pxCoRoutine->xGenericListItem ) );
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155 vListInitialiseItem( &( pxCoRoutine->xEventListItem ) );
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157 /* Set the co-routine control block as a link back from the xListItem.
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158 This is so we can get back to the containing CRCB from a generic item
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160 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xGenericListItem ), pxCoRoutine );
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161 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xEventListItem ), pxCoRoutine );
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163 /* Event lists are always in priority order. */
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164 listSET_LIST_ITEM_VALUE( &( pxCoRoutine->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxPriority );
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166 /* Now the co-routine has been initialised it can be added to the ready
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167 list at the correct priority. */
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168 prvAddCoRoutineToReadyQueue( pxCoRoutine );
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174 xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
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179 /*-----------------------------------------------------------*/
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181 void vCoRoutineAddToDelayedList( portTickType xTicksToDelay, xList *pxEventList )
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183 portTickType xTimeToWake;
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185 /* Calculate the time to wake - this may overflow but this is
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187 xTimeToWake = xCoRoutineTickCount + xTicksToDelay;
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189 /* We must remove ourselves from the ready list before adding
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190 ourselves to the blocked list as the same list item is used for
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192 vListRemove( ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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194 /* The list item will be inserted in wake time order. */
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195 listSET_LIST_ITEM_VALUE( &( pxCurrentCoRoutine->xGenericListItem ), xTimeToWake );
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197 if( xTimeToWake < xCoRoutineTickCount )
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199 /* Wake time has overflowed. Place this item in the
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201 vListInsert( ( xList * ) pxOverflowDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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205 /* The wake time has not overflowed, so we can use the
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206 current block list. */
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207 vListInsert( ( xList * ) pxDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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212 /* Also add the co-routine to an event list. If this is done then the
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213 function must be called with interrupts disabled. */
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214 vListInsert( pxEventList, &( pxCurrentCoRoutine->xEventListItem ) );
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217 /*-----------------------------------------------------------*/
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219 static void prvCheckPendingReadyList( void )
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221 /* Are there any co-routines waiting to get moved to the ready list? These
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222 are co-routines that have been readied by an ISR. The ISR cannot access
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223 the ready lists itself. */
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224 while( !listLIST_IS_EMPTY( &xPendingReadyCoRoutineList ) )
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226 corCRCB *pxUnblockedCRCB;
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228 /* The pending ready list can be accessed by an ISR. */
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229 portDISABLE_INTERRUPTS();
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231 pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( (&xPendingReadyCoRoutineList) );
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232 vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
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234 portENABLE_INTERRUPTS();
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236 vListRemove( &( pxUnblockedCRCB->xGenericListItem ) );
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237 prvAddCoRoutineToReadyQueue( pxUnblockedCRCB );
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240 /*-----------------------------------------------------------*/
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242 static void prvCheckDelayedList( void )
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246 xPassedTicks = xTaskGetTickCount() - xLastTickCount;
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247 while( xPassedTicks )
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249 xCoRoutineTickCount++;
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252 /* If the tick count has overflowed we need to swap the ready lists. */
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253 if( xCoRoutineTickCount == 0 )
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257 /* Tick count has overflowed so we need to swap the delay lists. If there are
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258 any items in pxDelayedCoRoutineList here then there is an error! */
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259 pxTemp = pxDelayedCoRoutineList;
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260 pxDelayedCoRoutineList = pxOverflowDelayedCoRoutineList;
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261 pxOverflowDelayedCoRoutineList = pxTemp;
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264 /* See if this tick has made a timeout expire. */
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265 while( ( pxCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedCoRoutineList ) ) != NULL )
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267 if( xCoRoutineTickCount < listGET_LIST_ITEM_VALUE( &( pxCRCB->xGenericListItem ) ) )
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269 /* Timeout not yet expired. */
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273 portDISABLE_INTERRUPTS();
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275 /* The event could have occurred just before this critical
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276 section. If this is the case then the generic list item will
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277 have been moved to the pending ready list and the following
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278 line is still valid. Also the pvContainer parameter will have
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279 been set to NULL so the following lines are also valid. */
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280 vListRemove( &( pxCRCB->xGenericListItem ) );
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282 /* Is the co-routine waiting on an event also? */
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283 if( pxCRCB->xEventListItem.pvContainer )
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285 vListRemove( &( pxCRCB->xEventListItem ) );
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288 portENABLE_INTERRUPTS();
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290 prvAddCoRoutineToReadyQueue( pxCRCB );
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294 xLastTickCount = xCoRoutineTickCount;
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296 /*-----------------------------------------------------------*/
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298 void vCoRoutineSchedule( void )
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300 /* See if any co-routines readied by events need moving to the ready lists. */
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301 prvCheckPendingReadyList();
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303 /* See if any delayed co-routines have timed out. */
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304 prvCheckDelayedList();
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306 /* Find the highest priority queue that contains ready co-routines. */
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307 while( listLIST_IS_EMPTY( &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) ) )
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309 if( uxTopCoRoutineReadyPriority == 0 )
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311 /* No more co-routines to check. */
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314 --uxTopCoRoutineReadyPriority;
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317 /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the co-routines
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318 of the same priority get an equal share of the processor time. */
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319 listGET_OWNER_OF_NEXT_ENTRY( pxCurrentCoRoutine, &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) );
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321 /* Call the co-routine. */
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322 ( pxCurrentCoRoutine->pxCoRoutineFunction )( pxCurrentCoRoutine, pxCurrentCoRoutine->uxIndex );
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326 /*-----------------------------------------------------------*/
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328 static void prvInitialiseCoRoutineLists( void )
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330 unsigned portBASE_TYPE uxPriority;
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332 for( uxPriority = 0; uxPriority < configMAX_CO_ROUTINE_PRIORITIES; uxPriority++ )
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334 vListInitialise( ( xList * ) &( pxReadyCoRoutineLists[ uxPriority ] ) );
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337 vListInitialise( ( xList * ) &xDelayedCoRoutineList1 );
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338 vListInitialise( ( xList * ) &xDelayedCoRoutineList2 );
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339 vListInitialise( ( xList * ) &xPendingReadyCoRoutineList );
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341 /* Start with pxDelayedCoRoutineList using list1 and the
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342 pxOverflowDelayedCoRoutineList using list2. */
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343 pxDelayedCoRoutineList = &xDelayedCoRoutineList1;
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344 pxOverflowDelayedCoRoutineList = &xDelayedCoRoutineList2;
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346 /*-----------------------------------------------------------*/
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348 signed portBASE_TYPE xCoRoutineRemoveFromEventList( const xList *pxEventList )
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350 corCRCB *pxUnblockedCRCB;
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351 signed portBASE_TYPE xReturn;
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353 /* This function is called from within an interrupt. It can only access
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354 event lists and the pending ready list. */
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355 pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );
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356 vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
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357 vListInsertEnd( ( xList * ) &( xPendingReadyCoRoutineList ), &( pxUnblockedCRCB->xEventListItem ) );
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359 if( pxUnblockedCRCB->uxPriority >= pxCurrentCoRoutine->uxPriority )
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