FreeRTOS/Source/croutine.c

   1 /*
   2     FreeRTOS V6.0.5 - Copyright (C) 2010 Real Time Engineers Ltd.
   3
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  24
  25     This file is part of the FreeRTOS distribution.
  26
  27     FreeRTOS is free software; you can redistribute it and/or modify it under
  28     the terms of the GNU General Public License (version 2) as published by the
  29     Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
  30     ***NOTE*** The exception to the GPL is included to allow you to distribute
  31     a combined work that includes FreeRTOS without being obliged to provide the
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  35     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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  44     http://www.FreeRTOS.org - Documentation, latest information, license and
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  52 */
  53
  54 #include "FreeRTOS.h"
  55 #include "task.h"
  56 #include "croutine.h"
  57
  58 /*
  59  * Some kernel aware debuggers require data to be viewed to be global, rather
  60  * than file scope.
  61  */
  62 #ifdef portREMOVE_STATIC_QUALIFIER
  63         #define static
  64 #endif
  65
  66
  67 /* Lists for ready and blocked co-routines. --------------------*/
  68 static xList pxReadyCoRoutineLists[ configMAX_CO_ROUTINE_PRIORITIES ];  /*< Prioritised ready co-routines. */
  69 static xList xDelayedCoRoutineList1;                                                                    /*< Delayed co-routines. */
  70 static xList xDelayedCoRoutineList2;                                                                    /*< Delayed co-routines (two lists are used - one for delays that have overflowed the current tick count. */
  71 static xList * pxDelayedCoRoutineList;                                                                  /*< Points to the delayed co-routine list currently being used. */
  72 static xList * pxOverflowDelayedCoRoutineList;                                                  /*< Points to the delayed co-routine list currently being used to hold co-routines that have overflowed the current tick count. */
  73 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. */
  74
  75 /* Other file private variables. --------------------------------*/
  76 corCRCB * pxCurrentCoRoutine = NULL;
  77 static unsigned portBASE_TYPE uxTopCoRoutineReadyPriority = 0;
  78 static portTickType xCoRoutineTickCount = 0, xLastTickCount = 0, xPassedTicks = 0;
  79
  80 /* The initial state of the co-routine when it is created. */
  81 #define corINITIAL_STATE        ( 0 )
  82
  83 /*
  84  * Place the co-routine represented by pxCRCB into the appropriate ready queue
  85  * for the priority.  It is inserted at the end of the list.
  86  *
  87  * This macro accesses the co-routine ready lists and therefore must not be
  88  * used from within an ISR.
  89  */
  90 #define prvAddCoRoutineToReadyQueue( pxCRCB )                                                                                                                                           \
  91 {                                                                                                                                                                                                                                       \
  92         if( pxCRCB->uxPriority > uxTopCoRoutineReadyPriority )                                                                                                                  \
  93         {                                                                                                                                                                                                                               \
  94                 uxTopCoRoutineReadyPriority = pxCRCB->uxPriority;                                                                                                                       \
  95         }                                                                                                                                                                                                                               \
  96         vListInsertEnd( ( xList * ) &( pxReadyCoRoutineLists[ pxCRCB->uxPriority ] ), &( pxCRCB->xGenericListItem ) );  \
  97 }
  98
  99 /*
 100  * Utility to ready all the lists used by the scheduler.  This is called
 101  * automatically upon the creation of the first co-routine.
 102  */
 103 static void prvInitialiseCoRoutineLists( void );
 104
 105 /*
 106  * Co-routines that are readied by an interrupt cannot be placed directly into
 107  * the ready lists (there is no mutual exclusion).  Instead they are placed in
 108  * in the pending ready list in order that they can later be moved to the ready
 109  * list by the co-routine scheduler.
 110  */
 111 static void prvCheckPendingReadyList( void );
 112
 113 /*
 114  * Macro that looks at the list of co-routines that are currently delayed to
 115  * see if any require waking.
 116  *
 117  * Co-routines are stored in the queue in the order of their wake time -
 118  * meaning once one co-routine has been found whose timer has not expired
 119  * we need not look any further down the list.
 120  */
 121 static void prvCheckDelayedList( void );
 122
 123 /*-----------------------------------------------------------*/
 124
 125 signed portBASE_TYPE xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, unsigned portBASE_TYPE uxPriority, unsigned portBASE_TYPE uxIndex )
 126 {
 127 signed portBASE_TYPE xReturn;
 128 corCRCB *pxCoRoutine;
 129
 130         /* Allocate the memory that will store the co-routine control block. */
 131         pxCoRoutine = ( corCRCB * ) pvPortMalloc( sizeof( corCRCB ) );
 132         if( pxCoRoutine )
 133         {
 134                 /* If pxCurrentCoRoutine is NULL then this is the first co-routine to
 135                 be created and the co-routine data structures need initialising. */
 136                 if( pxCurrentCoRoutine == NULL )
 137                 {
 138                         pxCurrentCoRoutine = pxCoRoutine;
 139                         prvInitialiseCoRoutineLists();
 140                 }
 141
 142                 /* Check the priority is within limits. */
 143                 if( uxPriority >= configMAX_CO_ROUTINE_PRIORITIES )
 144                 {
 145                         uxPriority = configMAX_CO_ROUTINE_PRIORITIES - 1;
 146                 }
 147
 148                 /* Fill out the co-routine control block from the function parameters. */
 149                 pxCoRoutine->uxState = corINITIAL_STATE;
 150                 pxCoRoutine->uxPriority = uxPriority;
 151                 pxCoRoutine->uxIndex = uxIndex;
 152                 pxCoRoutine->pxCoRoutineFunction = pxCoRoutineCode;
 153
 154                 /* Initialise all the other co-routine control block parameters. */
 155                 vListInitialiseItem( &( pxCoRoutine->xGenericListItem ) );
 156                 vListInitialiseItem( &( pxCoRoutine->xEventListItem ) );
 157
 158                 /* Set the co-routine control block as a link back from the xListItem.
 159                 This is so we can get back to the containing CRCB from a generic item
 160                 in a list. */
 161                 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xGenericListItem ), pxCoRoutine );
 162                 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xEventListItem ), pxCoRoutine );
 163
 164                 /* Event lists are always in priority order. */
 165                 listSET_LIST_ITEM_VALUE( &( pxCoRoutine->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxPriority );
 166
 167                 /* Now the co-routine has been initialised it can be added to the ready
 168                 list at the correct priority. */
 169                 prvAddCoRoutineToReadyQueue( pxCoRoutine );
 170
 171                 xReturn = pdPASS;
 172         }
 173         else
 174         {
 175                 xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;
 176         }
 177
 178         return xReturn;
 179 }
 180 /*-----------------------------------------------------------*/
 181
 182 void vCoRoutineAddToDelayedList( portTickType xTicksToDelay, xList *pxEventList )
 183 {
 184 portTickType xTimeToWake;
 185
 186         /* Calculate the time to wake - this may overflow but this is
 187         not a problem. */
 188         xTimeToWake = xCoRoutineTickCount + xTicksToDelay;
 189
 190         /* We must remove ourselves from the ready list before adding
 191         ourselves to the blocked list as the same list item is used for
 192         both lists. */
 193         vListRemove( ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
 194
 195         /* The list item will be inserted in wake time order. */
 196         listSET_LIST_ITEM_VALUE( &( pxCurrentCoRoutine->xGenericListItem ), xTimeToWake );
 197
 198         if( xTimeToWake < xCoRoutineTickCount )
 199         {
 200                 /* Wake time has overflowed.  Place this item in the
 201                 overflow list. */
 202                 vListInsert( ( xList * ) pxOverflowDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
 203         }
 204         else
 205         {
 206                 /* The wake time has not overflowed, so we can use the
 207                 current block list. */
 208                 vListInsert( ( xList * ) pxDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );
 209         }
 210
 211         if( pxEventList )
 212         {
 213                 /* Also add the co-routine to an event list.  If this is done then the
 214                 function must be called with interrupts disabled. */
 215                 vListInsert( pxEventList, &( pxCurrentCoRoutine->xEventListItem ) );
 216         }
 217 }
 218 /*-----------------------------------------------------------*/
 219
 220 static void prvCheckPendingReadyList( void )
 221 {
 222         /* Are there any co-routines waiting to get moved to the ready list?  These
 223         are co-routines that have been readied by an ISR.  The ISR cannot access
 224         the     ready lists itself. */
 225         while( !listLIST_IS_EMPTY( &xPendingReadyCoRoutineList ) )
 226         {
 227                 corCRCB *pxUnblockedCRCB;
 228
 229                 /* The pending ready list can be accessed by an ISR. */
 230                 portDISABLE_INTERRUPTS();
 231                 {
 232                         pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( (&xPendingReadyCoRoutineList) );
 233                         vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
 234                 }
 235                 portENABLE_INTERRUPTS();
 236
 237                 vListRemove( &( pxUnblockedCRCB->xGenericListItem ) );
 238                 prvAddCoRoutineToReadyQueue( pxUnblockedCRCB );
 239         }
 240 }
 241 /*-----------------------------------------------------------*/
 242
 243 static void prvCheckDelayedList( void )
 244 {
 245 corCRCB *pxCRCB;
 246
 247         xPassedTicks = xTaskGetTickCount() - xLastTickCount;
 248         while( xPassedTicks )
 249         {
 250                 xCoRoutineTickCount++;
 251                 xPassedTicks--;
 252
 253                 /* If the tick count has overflowed we need to swap the ready lists. */
 254                 if( xCoRoutineTickCount == 0 )
 255                 {
 256                         xList * pxTemp;
 257
 258                         /* Tick count has overflowed so we need to swap the delay lists.  If there are
 259                         any items in pxDelayedCoRoutineList here then there is an error! */
 260                         pxTemp = pxDelayedCoRoutineList;
 261                         pxDelayedCoRoutineList = pxOverflowDelayedCoRoutineList;
 262                         pxOverflowDelayedCoRoutineList = pxTemp;
 263                 }
 264
 265                 /* See if this tick has made a timeout expire. */
 266                 while( ( pxCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedCoRoutineList ) ) != NULL )
 267                 {
 268                         if( xCoRoutineTickCount < listGET_LIST_ITEM_VALUE( &( pxCRCB->xGenericListItem ) ) )
 269                         {
 270                                 /* Timeout not yet expired. */
 271                                 break;
 272                         }
 273
 274                         portDISABLE_INTERRUPTS();
 275                         {
 276                                 /* The event could have occurred just before this critical
 277                                 section.  If this is the case then the generic list item will
 278                                 have been moved to the pending ready list and the following
 279                                 line is still valid.  Also the pvContainer parameter will have
 280                                 been set to NULL so the following lines are also valid. */
 281                                 vListRemove( &( pxCRCB->xGenericListItem ) );
 282
 283                                 /* Is the co-routine waiting on an event also? */
 284                                 if( pxCRCB->xEventListItem.pvContainer )
 285                                 {
 286                                         vListRemove( &( pxCRCB->xEventListItem ) );
 287                                 }
 288                         }
 289                         portENABLE_INTERRUPTS();
 290
 291                         prvAddCoRoutineToReadyQueue( pxCRCB );
 292                 }
 293         }
 294
 295         xLastTickCount = xCoRoutineTickCount;
 296 }
 297 /*-----------------------------------------------------------*/
 298
 299 void vCoRoutineSchedule( void )
 300 {
 301         /* See if any co-routines readied by events need moving to the ready lists. */
 302         prvCheckPendingReadyList();
 303
 304         /* See if any delayed co-routines have timed out. */
 305         prvCheckDelayedList();
 306
 307         /* Find the highest priority queue that contains ready co-routines. */
 308         while( listLIST_IS_EMPTY( &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) ) )
 309         {
 310                 if( uxTopCoRoutineReadyPriority == 0 )
 311                 {
 312                         /* No more co-routines to check. */
 313                         return;
 314                 }
 315                 --uxTopCoRoutineReadyPriority;
 316         }
 317
 318         /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the co-routines
 319          of the same priority get an equal share of the processor time. */
 320         listGET_OWNER_OF_NEXT_ENTRY( pxCurrentCoRoutine, &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) );
 321
 322         /* Call the co-routine. */
 323         ( pxCurrentCoRoutine->pxCoRoutineFunction )( pxCurrentCoRoutine, pxCurrentCoRoutine->uxIndex );
 324
 325         return;
 326 }
 327 /*-----------------------------------------------------------*/
 328
 329 static void prvInitialiseCoRoutineLists( void )
 330 {
 331 unsigned portBASE_TYPE uxPriority;
 332
 333         for( uxPriority = 0; uxPriority < configMAX_CO_ROUTINE_PRIORITIES; uxPriority++ )
 334         {
 335                 vListInitialise( ( xList * ) &( pxReadyCoRoutineLists[ uxPriority ] ) );
 336         }
 337
 338         vListInitialise( ( xList * ) &xDelayedCoRoutineList1 );
 339         vListInitialise( ( xList * ) &xDelayedCoRoutineList2 );
 340         vListInitialise( ( xList * ) &xPendingReadyCoRoutineList );
 341
 342         /* Start with pxDelayedCoRoutineList using list1 and the
 343         pxOverflowDelayedCoRoutineList using list2. */
 344         pxDelayedCoRoutineList = &xDelayedCoRoutineList1;
 345         pxOverflowDelayedCoRoutineList = &xDelayedCoRoutineList2;
 346 }
 347 /*-----------------------------------------------------------*/
 348
 349 signed portBASE_TYPE xCoRoutineRemoveFromEventList( const xList *pxEventList )
 350 {
 351 corCRCB *pxUnblockedCRCB;
 352 signed portBASE_TYPE xReturn;
 353
 354         /* This function is called from within an interrupt.  It can only access
 355         event lists and the pending ready list. */
 356         pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );
 357         vListRemove( &( pxUnblockedCRCB->xEventListItem ) );
 358         vListInsertEnd( ( xList * ) &( xPendingReadyCoRoutineList ), &( pxUnblockedCRCB->xEventListItem ) );
 359
 360         if( pxUnblockedCRCB->uxPriority >= pxCurrentCoRoutine->uxPriority )
 361         {
 362                 xReturn = pdTRUE;
 363         }
 364         else
 365         {
 366                 xReturn = pdFALSE;
 367         }
 368
 369         return xReturn;
 370 }
 371