-/* Need a method of switching to an overflow list. _RB_*/\r
+/* Need to consider the switching of timer lists, and the placement of tasks into\r
+the current and overflow timer lists very carefully. For example, should the\r
+assessment as to which list a timer should be inserted into be relative the the\r
+tick count at the timer, or the tick count when the timer task unblocked, etc. */\r
\r
/*\r
FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.\r
tmrTIMER_CALLBACK pxCallbackFunction; /*<< The function that will be called when the timer expires. */\r
} xTIMER;\r
\r
-/* The definition of messages that can be sent and received on the timer \r
+/* The definition of messages that can be sent and received on the timer\r
queue. */\r
typedef struct tmrTimerQueueMessage\r
{\r
/* The list in which active timers are stored. Timers are referenced in expire\r
time order, with the nearest expiry time at the front of the list. Only the\r
timer service task is allowed to access xActiveTimerList. */\r
-PRIVILEGED_DATA static xList xActiveTimerList;\r
+PRIVILEGED_DATA static xList xActiveTimerList1;\r
+PRIVILEGED_DATA static xList xActiveTimerList2;\r
+PRIVILEGED_DATA static xList *pxCurrentTimerList;\r
+PRIVILEGED_DATA static xList *pxOverflowTimerList;\r
\r
/* A queue that is used to send commands to the timer service task. */\r
PRIVILEGED_DATA static xQueueHandle xTimerQueue = NULL;\r
\r
/*-----------------------------------------------------------*/\r
\r
-/* \r
+/*\r
* Initialise the infrustructure used by the timer service task if it has not\r
* been initialised already.\r
*/\r
\r
/*\r
* The timer service task (daemon). Timer functionality is controlled by this\r
- * task. Other tasks communicate with the timer service task using the \r
+ * task. Other tasks communicate with the timer service task using the\r
* xTimerQueue queue.\r
*/\r
static void prvTimerTask( void *pvParameters ) PRIVILEGED_FUNCTION;\r
\r
-/* \r
- * The following functions handle the commands that are sent to the timer\r
- * service task via the xTimerQueue queue.\r
- */\r
-static void prvTimerStart( xTIMER *pxTimer ) PRIVILEGED_FUNCTION;\r
-\r
/*\r
* Called by the timer service task to interpret and process a command it\r
- * received on the timer queue. \r
+ * received on the timer queue.\r
*/\r
static void prvProcessReceivedCommands( void ) PRIVILEGED_FUNCTION;\r
\r
+/*\r
+ * Insert the timer into either xActiveTimerList1, or xActiveTimerList2, \r
+ * depending on if the expire time causes a timer counter overflow. \r
+ */\r
+static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime );\r
+\r
/*-----------------------------------------------------------*/\r
\r
portBASE_TYPE xTimerCreateTimerTask( void )\r
{\r
portBASE_TYPE xReturn = pdFAIL;\r
\r
- /* This function is called when the scheduler is started if \r
+ /* This function is called when the scheduler is started if\r
configUSE_TIMERS is set to 1. Check that the infrustructure used by the\r
timer service task has been created/initialised. If timers have already\r
been created then the initialisation will already have been performed. */\r
\r
if( xTimerQueue != NULL )\r
{\r
- xReturn = xTaskCreate( prvTimerTask, ( const signed char * ) "Timers", configTIMER_TASK_STACK_DEPTH, NULL, configTIMER_TASK_PRIORITY, NULL );\r
+ xReturn = xTaskCreate( prvTimerTask, ( const signed char * ) "Timer Service", configTIMER_TASK_STACK_DEPTH, NULL, configTIMER_TASK_PRIORITY, NULL );\r
}\r
\r
return xReturn;\r
the timer with the nearest expiry time will expire. If there are no\r
active timers then just set the next expire time to the maximum possible\r
time to ensure this task does not run unnecessarily. */\r
- if( listLIST_IS_EMPTY( &xActiveTimerList ) == pdFALSE )\r
+ if( listLIST_IS_EMPTY( pxCurrentTimerList ) == pdFALSE )\r
{\r
- xNextExpireTime = listGET_ITEM_VALUE_OF_HEAD_ENTRY( &xActiveTimerList );\r
+ xNextExpireTime = listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxCurrentTimerList );\r
}\r
else\r
{\r
if( xNextExpireTime <= xTaskGetTickCount() )\r
{\r
/* Remove the timer from the list of active timers. */\r
- pxTimer = listGET_OWNER_OF_HEAD_ENTRY( &xActiveTimerList );\r
+ pxTimer = listGET_OWNER_OF_HEAD_ENTRY( pxCurrentTimerList );\r
vListRemove( &( pxTimer->xTimerListItem ) );\r
\r
/* If the timer is an autoreload timer then calculate the next\r
expiry time and re-insert the timer in the list of active timers. */\r
if( pxTimer->uxAutoReload == pdTRUE )\r
{\r
- listSET_LIST_ITEM_VALUE( &( pxTimer->xTimerListItem ), ( xNextExpireTime + pxTimer->xTimerPeriodInTicks ) );\r
- vListInsert( &xActiveTimerList, &( pxTimer->xTimerListItem ) );\r
+ prvInsertTimerInActiveList( pxTimer, ( xNextExpireTime + pxTimer->xTimerPeriodInTicks ) ); \r
}\r
\r
/* Call the timer callback. */\r
xTimeNow = xTaskGetTickCount();\r
if( xTimeNow < xNextExpireTime )\r
{\r
- /* This is a simple fast function - a yield will not be \r
+ /* This is a simple fast function - a yield will not be\r
performed until after this critical section exits. */\r
vQueueWaitForMessageRestricted( xTimerQueue, ( xNextExpireTime - xTimeNow ) );\r
}\r
}\r
taskEXIT_CRITICAL();\r
\r
- /* Yield to wait for either a command to arrive, or the block time \r
- to expire. If a command arrived between the critical section being \r
+ /* Yield to wait for either a command to arrive, or the block time\r
+ to expire. If a command arrived between the critical section being\r
exited and this yeild then the yield will just return to the same\r
task. */\r
portYIELD_WITHIN_API();\r
}\r
/*-----------------------------------------------------------*/\r
\r
+static void prvInsertTimerInActiveList( xTIMER *pxTimer, portTickType xNextExpiryTime )\r
+{\r
+ listSET_LIST_ITEM_VALUE( &( pxTimer->xTimerListItem ), xNextExpiryTime );\r
+ listSET_LIST_ITEM_OWNER( &( pxTimer->xTimerListItem ), pxTimer );\r
+ \r
+ if( xNextExpiryTime < xTaskGetTickCount() )\r
+ {\r
+ vListInsert( pxOverflowTimerList, &( pxTimer->xTimerListItem ) );\r
+ }\r
+ else\r
+ {\r
+ vListInsert( pxCurrentTimerList, &( pxTimer->xTimerListItem ) );\r
+ }\r
+}\r
+/*-----------------------------------------------------------*/\r
+\r
static void prvProcessReceivedCommands( void )\r
{\r
xTIMER_MESSAGE xMessage;\r
-portTickType xTimeToExpire;\r
xTIMER *pxTimer;\r
+xList *pxTemp;\r
\r
while( xQueueReceive( xTimerQueue, &xMessage, tmrNO_DELAY ) != pdFAIL )\r
{\r
pxTimer = xMessage.pxTimer;\r
\r
- /* Is the timer already in the list of active timers? */\r
- if( listIS_CONTAINED_WITHIN( NULL, &( pxTimer->xTimerListItem ) ) == pdFALSE )\r
+ /* Is the timer already in the list of active timers? When the command\r
+ is trmCOMMAND_PROCESS_TIMER_OVERFLOW, the timer will be NULL as the\r
+ command is to the task rather than to an individual timer. */\r
+ if( pxTimer != NULL )\r
{\r
- /* The timer is in the list, remove it. */\r
- vListRemove( &( pxTimer->xTimerListItem ) );\r
+ if( listIS_CONTAINED_WITHIN( NULL, &( pxTimer->xTimerListItem ) ) == pdFALSE )\r
+ {\r
+ /* The timer is in the list, remove it. */\r
+ vListRemove( &( pxTimer->xTimerListItem ) );\r
+ }\r
}\r
\r
switch( xMessage.xMessageID )\r
{\r
case tmrCOMMAND_START : \r
/* Start or restart a timer. */\r
- xTimeToExpire = xTaskGetTickCount() + pxTimer->xTimerPeriodInTicks;\r
- listSET_LIST_ITEM_VALUE( &( pxTimer->xTimerListItem ), xTimeToExpire );\r
- listSET_LIST_ITEM_OWNER( &( pxTimer->xTimerListItem ), pxTimer );\r
- vListInsert( &xActiveTimerList, &( pxTimer->xTimerListItem ) );\r
+ prvInsertTimerInActiveList( pxTimer, xTaskGetTickCount() + pxTimer->xTimerPeriodInTicks );\r
break;\r
\r
case tmrCOMMAND_STOP : \r
\r
case tmrCOMMAND_CHANGE_PERIOD :\r
pxTimer->xTimerPeriodInTicks = xMessage.xMessageValue;\r
- xTimeToExpire = xTaskGetTickCount() + pxTimer->xTimerPeriodInTicks;\r
- listSET_LIST_ITEM_VALUE( &( pxTimer->xTimerListItem ), xTimeToExpire );\r
- listSET_LIST_ITEM_OWNER( &( pxTimer->xTimerListItem ), pxTimer );\r
- vListInsert( &xActiveTimerList, &( pxTimer->xTimerListItem ) );\r
+ prvInsertTimerInActiveList( pxTimer, ( xTaskGetTickCount() + pxTimer->xTimerPeriodInTicks ) );\r
break;\r
\r
case tmrCOMMAND_DELETE :\r
just free up the memory. */\r
vPortFree( pxTimer );\r
break;\r
+ \r
+ case trmCOMMAND_PROCESS_TIMER_OVERFLOW :\r
+ /* The tick count has overflowed. The timer lists must be\r
+ switched. */\r
+ pxTemp = pxCurrentTimerList;\r
+ pxCurrentTimerList = pxOverflowTimerList;\r
+ pxOverflowTimerList = pxTemp;\r
+ break;\r
\r
default : \r
/* Don't expect to get here. */\r
static void prvCheckForValidListAndQueue( void )\r
{\r
/* Check that the list from which active timers are referenced, and the\r
- queue used to communicate with the timer service, have been \r
+ queue used to communicate with the timer service, have been\r
initialised. */\r
taskENTER_CRITICAL();\r
{\r
if( xTimerQueue == NULL )\r
{\r
- vListInitialise( &xActiveTimerList );\r
+ vListInitialise( &xActiveTimerList1 );\r
+ vListInitialise( &xActiveTimerList2 );\r
+ pxCurrentTimerList = &xActiveTimerList1;\r
+ pxOverflowTimerList = &xActiveTimerList2;\r
xTimerQueue = xQueueCreate( configTIMER_QUEUE_LENGTH, sizeof( xTIMER_MESSAGE ) );\r
}\r
}\r
/* Is the timer in the list of active timers? */\r
taskENTER_CRITICAL();\r
{\r
- xTimerIsInActiveList = listIS_CONTAINED_WITHIN( &xActiveTimerList, &( pxTimer->xTimerListItem ) );\r
+ /* Checking to see if it is in the NULL list in effect checks to see if\r
+ it is referenced from either the current or the overflow timer lists in\r
+ one go, but the logic has to be reversed, hence the '!'. */\r
+ xTimerIsInActiveList = !( listIS_CONTAINED_WITHIN( NULL, &( pxTimer->xTimerListItem ) ) );\r
}\r
taskEXIT_CRITICAL();\r
\r
projects / freertos / blobdiff