git.sur5r.net Git - freertos/blob - Source/croutine.c

   1 /*\r
   2         FreeRTOS.org V5.0.0 - Copyright (C) 2003-2008 Richard Barry.\r
   3 \r
   4         This file is part of the FreeRTOS.org distribution.\r
   5 \r
   6         FreeRTOS.org is free software; you can redistribute it and/or modify\r
   7         it under the terms of the GNU General Public License as published by\r
   8         the Free Software Foundation; either version 2 of the License, or\r
   9         (at your option) any later version.\r
  10 \r
  11         FreeRTOS.org is distributed in the hope that it will be useful,\r
  12         but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  13         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  14         GNU General Public License for more details.\r
  15 \r
  16         You should have received a copy of the GNU General Public License\r
  17         along with FreeRTOS.org; if not, write to the Free Software\r
  18         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA\r
  19 \r
  20         A special exception to the GPL can be applied should you wish to distribute\r
  21         a combined work that includes FreeRTOS.org, without being obliged to provide\r
  22         the source code for any proprietary components.  See the licensing section\r
  23         of http://www.FreeRTOS.org for full details of how and when the exception\r
  24         can be applied.\r
  25 \r
  26     ***************************************************************************\r
  27     ***************************************************************************\r
  28     *                                                                         *\r
  29     * SAVE TIME AND MONEY!  We can port FreeRTOS.org to your own hardware,    *\r
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  31     * See http://www.OpenRTOS.com for details of the services we provide to   *\r
  32     * expedite your project.                                                  *\r
  33     *                                                                         *\r
  34     ***************************************************************************\r
  35     ***************************************************************************\r
  36 \r
  37         Please ensure to read the configuration and relevant port sections of the\r
  38         online documentation.\r
  39 \r
  40         http://www.FreeRTOS.org - Documentation, latest information, license and \r
  41         contact details.\r
  42 \r
  43         http://www.SafeRTOS.com - A version that is certified for use in safety \r
  44         critical systems.\r
  45 \r
  46         http://www.OpenRTOS.com - Commercial support, development, porting, \r
  47         licensing and training services.\r
  48 */\r
  49 \r
  50 #include "FreeRTOS.h"\r
  51 #include "task.h"\r
  52 #include "croutine.h"\r
  53 \r
  54 /* Lists for ready and blocked co-routines. --------------------*/\r
  55 static xList pxReadyCoRoutineLists[ configMAX_CO_ROUTINE_PRIORITIES ];  /*< Prioritised ready co-routines. */\r
  56 static xList xDelayedCoRoutineList1;                                                                    /*< Delayed co-routines. */\r
  57 static xList xDelayedCoRoutineList2;                                                                    /*< Delayed co-routines (two lists are used - one for delays that have overflowed the current tick count. */\r
  58 static xList * pxDelayedCoRoutineList;                                                                  /*< Points to the delayed co-routine list currently being used. */\r
  59 static xList * pxOverflowDelayedCoRoutineList;                                                  /*< Points to the delayed co-routine list currently being used to hold co-routines that have overflowed the current tick count. */\r
  60 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. */\r
  61 \r
  62 /* Other file private variables. --------------------------------*/\r
  63 corCRCB * pxCurrentCoRoutine = NULL;\r
  64 static unsigned portBASE_TYPE uxTopCoRoutineReadyPriority = 0;\r
  65 static portTickType xCoRoutineTickCount = 0;\r
  66 \r
  67 /* The initial state of the co-routine when it is created. */\r
  68 #define corINITIAL_STATE        ( 0 )\r
  69 \r
  70 /*\r
  71  * Place the co-routine represented by pxCRCB into the appropriate ready queue\r
  72  * for the priority.  It is inserted at the end of the list.\r
  73  *\r
  74  * This macro accesses the co-routine ready lists and therefore must not be\r
  75  * used from within an ISR.\r
  76  */\r
  77 #define prvAddCoRoutineToReadyQueue( pxCRCB )                                                                                                                                           \\r
  78 {                                                                                                                                                                                                                                       \\r
  79         if( pxCRCB->uxPriority > uxTopCoRoutineReadyPriority )                                                                                                                  \\r
  80         {                                                                                                                                                                                                                               \\r
  81                 uxTopCoRoutineReadyPriority = pxCRCB->uxPriority;                                                                                                                       \\r
  82         }                                                                                                                                                                                                                               \\r
  83         vListInsertEnd( ( xList * ) &( pxReadyCoRoutineLists[ pxCRCB->uxPriority ] ), &( pxCRCB->xGenericListItem ) );  \\r
  84 }       \r
  85 \r
  86 /*\r
  87  * Utility to ready all the lists used by the scheduler.  This is called\r
  88  * automatically upon the creation of the first co-routine.\r
  89  */\r
  90 static void prvInitialiseCoRoutineLists( void );\r
  91 \r
  92 /*\r
  93  * Co-routines that are readied by an interrupt cannot be placed directly into\r
  94  * the ready lists (there is no mutual exclusion).  Instead they are placed in\r
  95  * in the pending ready list in order that they can later be moved to the ready\r
  96  * list by the co-routine scheduler.\r
  97  */\r
  98 static inline void prvCheckPendingReadyList( void );\r
  99 \r
 100 /*\r
 101  * Macro that looks at the list of co-routines that are currently delayed to\r
 102  * see if any require waking.\r
 103  *\r
 104  * Co-routines are stored in the queue in the order of their wake time -\r
 105  * meaning once one co-routine has been found whose timer has not expired\r
 106  * we need not look any further down the list.\r
 107  */\r
 108 static inline void prvCheckDelayedList( void );\r
 109 \r
 110 /*-----------------------------------------------------------*/\r
 111 \r
 112 signed portBASE_TYPE xCoRoutineCreate( crCOROUTINE_CODE pxCoRoutineCode, unsigned portBASE_TYPE uxPriority, unsigned portBASE_TYPE uxIndex )\r
 113 {\r
 114 signed portBASE_TYPE xReturn;\r
 115 corCRCB *pxCoRoutine;\r
 116 \r
 117         /* Allocate the memory that will store the co-routine control block. */\r
 118         pxCoRoutine = ( corCRCB * ) pvPortMalloc( sizeof( corCRCB ) );\r
 119         if( pxCoRoutine )\r
 120         {\r
 121                 /* If pxCurrentCoRoutine is NULL then this is the first co-routine to\r
 122                 be created and the co-routine data structures need initialising. */\r
 123                 if( pxCurrentCoRoutine == NULL )\r
 124                 {\r
 125                         pxCurrentCoRoutine = pxCoRoutine;\r
 126                         prvInitialiseCoRoutineLists();\r
 127                 }\r
 128 \r
 129                 /* Check the priority is within limits. */\r
 130                 if( uxPriority >= configMAX_CO_ROUTINE_PRIORITIES )\r
 131                 {\r
 132                         uxPriority = configMAX_CO_ROUTINE_PRIORITIES - 1;\r
 133                 }\r
 134 \r
 135                 /* Fill out the co-routine control block from the function parameters. */\r
 136                 pxCoRoutine->uxState = corINITIAL_STATE;\r
 137                 pxCoRoutine->uxPriority = uxPriority;\r
 138                 pxCoRoutine->uxIndex = uxIndex;\r
 139                 pxCoRoutine->pxCoRoutineFunction = pxCoRoutineCode;\r
 140 \r
 141                 /* Initialise all the other co-routine control block parameters. */\r
 142                 vListInitialiseItem( &( pxCoRoutine->xGenericListItem ) );\r
 143                 vListInitialiseItem( &( pxCoRoutine->xEventListItem ) );\r
 144 \r
 145                 /* Set the co-routine control block as a link back from the xListItem.\r
 146                 This is so we can get back to the containing CRCB from a generic item\r
 147                 in a list. */\r
 148                 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xGenericListItem ), pxCoRoutine );\r
 149                 listSET_LIST_ITEM_OWNER( &( pxCoRoutine->xEventListItem ), pxCoRoutine );\r
 150         \r
 151                 /* Event lists are always in priority order. */\r
 152                 listSET_LIST_ITEM_VALUE( &( pxCoRoutine->xEventListItem ), configMAX_PRIORITIES - ( portTickType ) uxPriority );\r
 153                 \r
 154                 /* Now the co-routine has been initialised it can be added to the ready\r
 155                 list at the correct priority. */\r
 156                 prvAddCoRoutineToReadyQueue( pxCoRoutine );\r
 157 \r
 158                 xReturn = pdPASS;\r
 159         }\r
 160         else\r
 161         {               \r
 162                 xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;\r
 163         }\r
 164         \r
 165         return xReturn; \r
 166 }\r
 167 /*-----------------------------------------------------------*/\r
 168 \r
 169 void vCoRoutineAddToDelayedList( portTickType xTicksToDelay, xList *pxEventList )\r
 170 {\r
 171 portTickType xTimeToWake;\r
 172 \r
 173         /* Calculate the time to wake - this may overflow but this is\r
 174         not a problem. */\r
 175         xTimeToWake = xCoRoutineTickCount + xTicksToDelay;\r
 176 \r
 177         /* We must remove ourselves from the ready list before adding\r
 178         ourselves to the blocked list as the same list item is used for\r
 179         both lists. */\r
 180         vListRemove( ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );\r
 181 \r
 182         /* The list item will be inserted in wake time order. */\r
 183         listSET_LIST_ITEM_VALUE( &( pxCurrentCoRoutine->xGenericListItem ), xTimeToWake );\r
 184 \r
 185         if( xTimeToWake < xCoRoutineTickCount )\r
 186         {\r
 187                 /* Wake time has overflowed.  Place this item in the\r
 188                 overflow list. */\r
 189                 vListInsert( ( xList * ) pxOverflowDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );\r
 190         }\r
 191         else\r
 192         {\r
 193                 /* The wake time has not overflowed, so we can use the\r
 194                 current block list. */\r
 195                 vListInsert( ( xList * ) pxDelayedCoRoutineList, ( xListItem * ) &( pxCurrentCoRoutine->xGenericListItem ) );\r
 196         }\r
 197 \r
 198         if( pxEventList )\r
 199         {\r
 200                 /* Also add the co-routine to an event list.  If this is done then the\r
 201                 function must be called with interrupts disabled. */\r
 202                 vListInsert( pxEventList, &( pxCurrentCoRoutine->xEventListItem ) );\r
 203         }\r
 204 }\r
 205 /*-----------------------------------------------------------*/\r
 206 \r
 207 static inline void prvCheckPendingReadyList( void )\r
 208 {\r
 209         /* Are there any co-routines waiting to get moved to the ready list?  These\r
 210         are co-routines that have been readied by an ISR.  The ISR cannot access\r
 211         the     ready lists itself. */\r
 212         while( !listLIST_IS_EMPTY( &xPendingReadyList ) )\r
 213         {\r
 214                 corCRCB *pxUnblockedCRCB;\r
 215 \r
 216                 /* The pending ready list can be accessed by an ISR. */\r
 217                 portDISABLE_INTERRUPTS();\r
 218                 {       \r
 219                         pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( (&xPendingReadyList) );                    \r
 220                         vListRemove( &( pxUnblockedCRCB->xEventListItem ) );\r
 221                 }\r
 222                 portENABLE_INTERRUPTS();\r
 223 \r
 224                 vListRemove( &( pxUnblockedCRCB->xGenericListItem ) );\r
 225                 prvAddCoRoutineToReadyQueue( pxUnblockedCRCB ); \r
 226         }\r
 227 }\r
 228 /*-----------------------------------------------------------*/\r
 229 \r
 230 static inline void prvCheckDelayedList( void )\r
 231 {\r
 232 static portTickType xLastTickCount, xPassedTicks;\r
 233 corCRCB *pxCRCB;\r
 234 \r
 235         xPassedTicks = xTaskGetTickCount() - xLastTickCount;\r
 236         while( xPassedTicks )\r
 237         {\r
 238                 xCoRoutineTickCount++;\r
 239                 xPassedTicks--;\r
 240 \r
 241                 /* If the tick count has overflowed we need to swap the ready lists. */\r
 242                 if( xCoRoutineTickCount == 0 )\r
 243                 {\r
 244                         xList * pxTemp;\r
 245 \r
 246                         /* Tick count has overflowed so we need to swap the delay lists.  If there are\r
 247                         any items in pxDelayedCoRoutineList here then there is an error! */\r
 248                         pxTemp = pxDelayedCoRoutineList;\r
 249                         pxDelayedCoRoutineList = pxOverflowDelayedCoRoutineList;\r
 250                         pxOverflowDelayedCoRoutineList = pxTemp;\r
 251                 }\r
 252 \r
 253                 /* See if this tick has made a timeout expire. */\r
 254                 while( ( pxCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedCoRoutineList ) ) != NULL )\r
 255                 {       \r
 256                         if( xCoRoutineTickCount < listGET_LIST_ITEM_VALUE( &( pxCRCB->xGenericListItem ) ) )                            \r
 257                         {                       \r
 258                                 /* Timeout not yet expired. */                                                                                                                                                  \r
 259                                 break;                                                                                                                                                          \r
 260                         }                                                                                                                                                                               \r
 261 \r
 262                         portDISABLE_INTERRUPTS();\r
 263                         {\r
 264                                 /* The event could have occurred just before this critical\r
 265                                 section.  If this is the case then the generic list item will\r
 266                                 have been moved to the pending ready list and the following\r
 267                                 line is still valid.  Also the pvContainer parameter will have\r
 268                                 been set to NULL so the following lines are also valid. */\r
 269                                 vListRemove( &( pxCRCB->xGenericListItem ) );                                                                                   \r
 270 \r
 271                                 /* Is the co-routine waiting on an event also? */                                                                                               \r
 272                                 if( pxCRCB->xEventListItem.pvContainer )                                                                                                        \r
 273                                 {                                                                                                                       \r
 274                                         vListRemove( &( pxCRCB->xEventListItem ) );                                                                                     \r
 275                                 }\r
 276                         }\r
 277                         portENABLE_INTERRUPTS();\r
 278 \r
 279                         prvAddCoRoutineToReadyQueue( pxCRCB );                                                                                                  \r
 280                 }                                                                                                                                                                                                       \r
 281         }\r
 282 \r
 283         xLastTickCount = xCoRoutineTickCount;\r
 284 }\r
 285 /*-----------------------------------------------------------*/\r
 286 \r
 287 void vCoRoutineSchedule( void )\r
 288 {\r
 289         /* See if any co-routines readied by events need moving to the ready lists. */\r
 290         prvCheckPendingReadyList();\r
 291 \r
 292         /* See if any delayed co-routines have timed out. */\r
 293         prvCheckDelayedList();\r
 294 \r
 295         /* Find the highest priority queue that contains ready co-routines. */\r
 296         while( listLIST_IS_EMPTY( &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) ) )\r
 297         {\r
 298                 if( uxTopCoRoutineReadyPriority == 0 )\r
 299                 {\r
 300                         /* No more co-routines to check. */\r
 301                         return;\r
 302                 }\r
 303                 --uxTopCoRoutineReadyPriority;\r
 304         }\r
 305 \r
 306         /* listGET_OWNER_OF_NEXT_ENTRY walks through the list, so the co-routines\r
 307          of the same priority get an equal share of the processor time. */\r
 308         listGET_OWNER_OF_NEXT_ENTRY( pxCurrentCoRoutine, &( pxReadyCoRoutineLists[ uxTopCoRoutineReadyPriority ] ) );\r
 309 \r
 310         /* Call the co-routine. */\r
 311         ( pxCurrentCoRoutine->pxCoRoutineFunction )( pxCurrentCoRoutine, pxCurrentCoRoutine->uxIndex );\r
 312 \r
 313         return;\r
 314 }\r
 315 /*-----------------------------------------------------------*/\r
 316 \r
 317 static void prvInitialiseCoRoutineLists( void )\r
 318 {\r
 319 unsigned portBASE_TYPE uxPriority;\r
 320 \r
 321         for( uxPriority = 0; uxPriority < configMAX_CO_ROUTINE_PRIORITIES; uxPriority++ )\r
 322         {\r
 323                 vListInitialise( ( xList * ) &( pxReadyCoRoutineLists[ uxPriority ] ) );\r
 324         }\r
 325 \r
 326         vListInitialise( ( xList * ) &xDelayedCoRoutineList1 );\r
 327         vListInitialise( ( xList * ) &xDelayedCoRoutineList2 );\r
 328         vListInitialise( ( xList * ) &xPendingReadyList );\r
 329 \r
 330         /* Start with pxDelayedCoRoutineList using list1 and the\r
 331         pxOverflowDelayedCoRoutineList using list2. */\r
 332         pxDelayedCoRoutineList = &xDelayedCoRoutineList1;\r
 333         pxOverflowDelayedCoRoutineList = &xDelayedCoRoutineList2;\r
 334 }\r
 335 /*-----------------------------------------------------------*/\r
 336 \r
 337 signed portBASE_TYPE xCoRoutineRemoveFromEventList( const xList *pxEventList )\r
 338 {\r
 339 corCRCB *pxUnblockedCRCB;\r
 340 signed portBASE_TYPE xReturn;\r
 341 \r
 342         /* This function is called from within an interrupt.  It can only access\r
 343         event lists and the pending ready list. */\r
 344         pxUnblockedCRCB = ( corCRCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxEventList );\r
 345         vListRemove( &( pxUnblockedCRCB->xEventListItem ) );\r
 346         vListInsertEnd( ( xList * ) &( xPendingReadyList ), &( pxUnblockedCRCB->xEventListItem ) );\r
 347 \r
 348         if( pxUnblockedCRCB->uxPriority >= pxCurrentCoRoutine->uxPriority )\r
 349         {\r
 350                 xReturn = pdTRUE;\r
 351         }\r
 352         else\r
 353         {\r
 354                 xReturn = pdFALSE;\r
 355         }\r
 356 \r
 357         return xReturn;\r
 358 }\r
 359 \r