2 FreeRTOS.org V4.0.3 - Copyright (C) 2003-2006 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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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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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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30 ***************************************************************************
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33 #include "FreeRTOS.h"
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35 #include "croutine.h"
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37 /* Lists for ready and blocked co-routines. --------------------*/
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38 static xList pxReadyCoRoutineLists[ configMAX_CO_ROUTINE_PRIORITIES ]; /*< Prioritised ready co-routines. */
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39 static xList xDelayedCoRoutineList1; /*< Delayed co-routines. */
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40 static xList xDelayedCoRoutineList2; /*< Delayed co-routines (two lists are used - one for delays that have overflowed the current tick count. */
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41 static xList * pxDelayedCoRoutineList; /*< Points to the delayed co-routine list currently being used. */
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42 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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43 static xList xPendingReadyList; /*< 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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45 /* Other file private variables. --------------------------------*/
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46 corCRCB * pxCurrentCoRoutine = NULL;
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47 static unsigned portBASE_TYPE uxTopCoRoutineReadyPriority = 0;
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48 static portTickType xCoRoutineTickCount = 0;
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50 /* The initial state of the co-routine when it is created. */
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51 #define corINITIAL_STATE ( 0 )
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54 * Place the co-routine represented by pxCRCB into the appropriate ready queue
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55 * for the priority. It is inserted at the end of the list.
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57 * This macro accesses the co-routine ready lists and therefore must not be
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58 * used from within an ISR.
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60 #define prvAddCoRoutineToReadyQueue( pxCRCB ) \
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62 if( pxCRCB->uxPriority > uxTopCoRoutineReadyPriority ) \
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64 uxTopCoRoutineReadyPriority = pxCRCB->uxPriority; \
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66 vListInsertEnd( ( xList * ) &( pxReadyCoRoutineLists[ pxCRCB->uxPriority ] ), &( pxCRCB->xGenericListItem ) ); \
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70 * Utility to ready all the lists used by the scheduler. This is called
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71 * automatically upon the creation of the first co-routine.
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73 static void prvInitialiseCoRoutineLists( void );
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76 * Co-routines that are readied by an interrupt cannot be placed directly into
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77 * the ready lists (there is no mutual exclusion). Instead they are placed in
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78 * in the pending ready list in order that they can later be moved to the ready
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79 * list by the co-routine scheduler.
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81 static inline void prvCheckPendingReadyList( void );
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84 * Macro that looks at the list of co-routines that are currently delayed to
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85 * see if any require waking.
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87 * Co-routines are stored in the queue in the order of their wake time -
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88 * meaning once one co-routine has been found whose timer has not expired
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89 * we need not look any further down the list.
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91 static inline void prvCheckDelayedList( void );
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93 /*-----------------------------------------------------------*/
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95 portBASE_TYPE xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, unsigned portBASE_TYPE uxPriority, unsigned portBASE_TYPE uxIndex )
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97 portBASE_TYPE xReturn;
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98 corCRCB *pxCoRoutine;
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100 /* Allocate the memory that will store the co-routine control block. */
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101 pxCoRoutine = ( corCRCB * ) pvPortMalloc( sizeof( corCRCB ) );
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104 /* If pxCurrentCoRoutine is NULL then this is the first co-routine to
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105 be created and the co-routine data structures need initialising. */
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106 if( pxCurrentCoRoutine == NULL )
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108 pxCurrentCoRoutine = pxCoRoutine;
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109 prvInitialiseCoRoutineLists();
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112 /* Check the priority is within limits. */
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113 if( uxPriority >= configMAX_CO_ROUTINE_PRIORITIES )
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115 uxPriority = configMAX_CO_ROUTINE_PRIORITIES - 1;
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118 /* Fill out the co-routine control block from the function parameters. */
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119 pxCoRoutine->uxState = corINITIAL_STATE;
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120 pxCoRoutine->uxPriority = uxPriority;
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121 pxCoRoutine->uxIndex = uxIndex;
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122 pxCoRoutine->pxCoRoutineFunction = pxCoRoutineCode;
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124 /* Initialise all the other co-routine control block parameters. */
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125 vListInitialiseItem( &( pxCoRoutine->xGenericListItem ) );
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126 vListInitialiseItem( &( pxCoRoutine->xEventListItem ) );
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128 /* Set the co-routine control block as a link back from the xListItem.
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129 This is so we can get back to the containing CRCB from a generic item
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131 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xGenericListItem ), pxCoRoutine );
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132 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xEventListItem ), pxCoRoutine );
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134 /* Event lists are always in priority order. */
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135 listSET_LIST_ITEM_VALUE( &( pxCoRoutine->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxPriority );
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137 /* Now the co-routine has been initialised it can be added to the ready
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138 list at the correct priority. */
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139 prvAddCoRoutineToReadyQueue( pxCoRoutine );
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145 xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
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150 /*-----------------------------------------------------------*/
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152 void vCoRoutineAddToDelayedList( portTickType xTicksToDelay, xList *pxEventList )
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154 portTickType xTimeToWake;
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156 /* Calculate the time to wake - this may overflow but this is
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158 xTimeToWake = xCoRoutineTickCount + xTicksToDelay;
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160 /* We must remove ourselves from the ready list before adding
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161 ourselves to the blocked list as the same list item is used for
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163 vListRemove( ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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165 /* The list item will be inserted in wake time order. */
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166 listSET_LIST_ITEM_VALUE( &( pxCurrentCoRoutine->xGenericListItem ), xTimeToWake );
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168 if( xTimeToWake < xCoRoutineTickCount )
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170 /* Wake time has overflowed. Place this item in the
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172 vListInsert( ( xList * ) pxOverflowDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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176 /* The wake time has not overflowed, so we can use the
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177 current block list. */
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178 vListInsert( ( xList * ) pxDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
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183 /* Also add the co-routine to an event list. If this is done then the
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184 function must be called with interrupts disabled. */
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185 vListInsert( pxEventList, &( pxCurrentCoRoutine->xEventListItem ) );
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188 /*-----------------------------------------------------------*/
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190 static inline void prvCheckPendingReadyList( void )
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192 /* Are there any co-routines waiting to get moved to the ready list? These
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193 are co-routines that have been readied by an ISR. The ISR cannot access
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194 the ready lists itself. */
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195 while( !listLIST_IS_EMPTY( &xPendingReadyList ) )
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197 corCRCB *pxUnblockedCRCB;
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199 /* The pending ready list can be accessed by an ISR. */
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200 portDISABLE_INTERRUPTS();
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202 pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( (&xPendingReadyList) );
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203 vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
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205 portENABLE_INTERRUPTS();
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207 vListRemove( &( pxUnblockedCRCB->xGenericListItem ) );
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208 prvAddCoRoutineToReadyQueue( pxUnblockedCRCB );
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211 /*-----------------------------------------------------------*/
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213 static inline void prvCheckDelayedList( void )
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215 static portTickType xLastTickCount, xPassedTicks;
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218 xPassedTicks = xTaskGetTickCount() - xLastTickCount;
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219 while( xPassedTicks )
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221 xCoRoutineTickCount++;
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224 /* If the tick count has overflowed we need to swap the ready lists. */
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225 if( xCoRoutineTickCount == 0 )
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229 /* Tick count has overflowed so we need to swap the delay lists. If there are
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230 any items in pxDelayedCoRoutineList here then there is an error! */
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231 pxTemp = pxDelayedCoRoutineList;
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232 pxDelayedCoRoutineList = pxOverflowDelayedCoRoutineList;
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233 pxOverflowDelayedCoRoutineList = pxTemp;
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236 /* See if this tick has made a timeout expire. */
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237 while( ( pxCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedCoRoutineList ) ) != NULL )
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239 if( xCoRoutineTickCount < listGET_LIST_ITEM_VALUE( &( pxCRCB->xGenericListItem ) ) )
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241 /* Timeout not yet expired. */
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245 portDISABLE_INTERRUPTS();
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247 /* The event could have occurred just before this critical
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248 section. If this is the case then the generic list item will
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249 have been moved to the pending ready list and the following
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250 line is still valid. Also the pvContainer parameter will have
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251 been set to NULL so the following lines are also valid. */
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252 vListRemove( &( pxCRCB->xGenericListItem ) );
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254 /* Is the co-routine waiting on an event also? */
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255 if( pxCRCB->xEventListItem.pvContainer )
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257 vListRemove( &( pxCRCB->xEventListItem ) );
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260 portENABLE_INTERRUPTS();
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262 prvAddCoRoutineToReadyQueue( pxCRCB );
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266 xLastTickCount = xCoRoutineTickCount;
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268 /*-----------------------------------------------------------*/
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270 void vCoRoutineSchedule( void )
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272 /* See if any co-routines readied by events need moving to the ready lists. */
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273 prvCheckPendingReadyList();
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275 /* See if any delayed co-routines have timed out. */
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276 prvCheckDelayedList();
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278 /* Find the highest priority queue that contains ready co-routines. */
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279 while( listLIST_IS_EMPTY( &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) ) )
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281 if( uxTopCoRoutineReadyPriority == 0 )
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283 /* No more co-routines to check. */
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286 --uxTopCoRoutineReadyPriority;
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289 /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the co-routines
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290 of the same priority get an equal share of the processor time. */
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291 listGET_OWNER_OF_NEXT_ENTRY( pxCurrentCoRoutine, &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) );
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293 /* Call the co-routine. */
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294 ( pxCurrentCoRoutine->pxCoRoutineFunction )( pxCurrentCoRoutine, pxCurrentCoRoutine->uxIndex );
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298 /*-----------------------------------------------------------*/
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300 static void prvInitialiseCoRoutineLists( void )
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302 unsigned portBASE_TYPE uxPriority;
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304 for( uxPriority = 0; uxPriority < configMAX_CO_ROUTINE_PRIORITIES; uxPriority++ )
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306 vListInitialise( ( xList * ) &( pxReadyCoRoutineLists[ uxPriority ] ) );
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309 vListInitialise( ( xList * ) &xDelayedCoRoutineList1 );
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310 vListInitialise( ( xList * ) &xDelayedCoRoutineList2 );
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311 vListInitialise( ( xList * ) &xPendingReadyList );
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313 /* Start with pxDelayedCoRoutineList using list1 and the
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314 pxOverflowDelayedCoRoutineList using list2. */
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315 pxDelayedCoRoutineList = &xDelayedCoRoutineList1;
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316 pxOverflowDelayedCoRoutineList = &xDelayedCoRoutineList2;
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318 /*-----------------------------------------------------------*/
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320 portBASE_TYPE xCoRoutineRemoveFromEventList( const xList *pxEventList )
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322 corCRCB *pxUnblockedCRCB;
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323 portBASE_TYPE xReturn;
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325 /* This function is called from within an interrupt. It can only access
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326 event lists and the pending ready list. */
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327 pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );
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328 vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
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329 vListInsertEnd( ( xList * ) &( xPendingReadyList ), &( pxUnblockedCRCB->xEventListItem ) );
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331 if( pxUnblockedCRCB->uxPriority >= pxCurrentCoRoutine->uxPriority )
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