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/*

	FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org is free software; you can redistribute it and/or modify

	it under the terms of the GNU General Public License as published by

	the Free Software Foundation; either version 2 of the License, or

	(at your option) any later version.

	FreeRTOS.org is distributed in the hope that it will be useful,

	but WITHOUT ANY WARRANTY; without even the implied warranty of

	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License

	along with FreeRTOS.org; if not, write to the Free Software

	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

	A special exception to the GPL can be applied should you wish to distribute

	a combined work that includes FreeRTOS.org, without being obliged to provide

	the source code for any proprietary components.  See the licensing section

	of http://www.FreeRTOS.org for full details of how and when the exception

	can be applied.

	***************************************************************************

	See http://www.FreeRTOS.org for documentation, latest information, license

	and contact details.  Please ensure to read the configuration and relevant

	port sections of the online documentation.

	Also see http://www.SafeRTOS.com for an IEC 61508 compliant version, along

	with development and support options.

	***************************************************************************

*/

/*

Changes from V1.00:

	+ Call to portRESTORE_CONTEXT has been removed.  The first context

	  switch is now performed within sPortStartScheduler().

Changes from V1.01:

	+ More use of 8bit data types.

	+ Function name prefixes changed where the data type returned has changed.

	+ configUSE_TRACE_FACILITY is no longer defined by default.

Changes from V1.2.0

	+ Introduced ucTopReadyPriority.  This tracks the highest priority ready

	  queue that contains a valid TCB and thus makes the context switch

	  slightly faster.

	+ prvAddTaskToReadyQueue() has been made a macro.

Changes from V1.2.6

	+ Added conditional compilation directives.

	+ Extended API.

	+ Rearranged function order.

	+ Creating a task now causes a context switch if the task being created

	  has a higher priority than the calling task - assuming the kernel is

	  running.

	+ vTaskDelete() now only causes a context switch if the calling task is

	  the task being deleted.

Changes from V2.0.0

	+ Allow the type of the tick count to be 16 or 32 bits.

	+ Introduce xPendingReadyList feature to allow the time interrupts have to

	  be disabled to be minimised.

	+ Remove the #if( INCLUDE_vTaskSuspendAll ) statements.  vTaskSuspendAll()

	  is now always included as it is used by the scheduler itself.

Changes from V2.1.0

	+ Bug fix - pxCurrentTCB is now initialised before the call to

	  prvInitializeTaskLists().  Previously pxCurrentTCB could be accessed

	  while null.

Changed from V2.1.1

	+ Change to where lStackSize is declared within sTaskCreate() to prevent

	  compiler warnings with 8051 port.

Changes from V2.2.0

	+ Explicit use of 'signed' qualifier on portCHAR types added.

	+ Changed odd calculation of initial pxTopOfStack value when

	  portSTACK_GROWTH < 0.

	+ Removed pcVersionNumber definition.

Changes from V2.5.3

	+ cTaskResumeAll() modified to ensure it can be called prior to the task

	  lists being initialised.

Changes from V2.5.5

	+ Added API function vTaskDelayUntil().

	+ Added INCLUDE_vTaskDelay conditional compilation.

Changes from V2.6.0

 	+ Updated the vWriteTraceToBuffer macro to always be 4 byte aligned so it

	  can be used on ARM architectures.

	+ tskMAX_TASK_NAME_LEN definition replaced with the port specific

	  configMAX_TASK_NAME_LEN definition.

	+ Removed the call to strcpy when copying across the task name into the

	  TCB.

	+ Added ucTasksDeleted variable to prevent vTaskSuspendAll() being called

	  too often in the idle task.

Changes between V3.0.0 and V2.6.1

	+ When resuming the scheduler a yield is performed if either a tick has

	  been missed, or a task is moved from the pending ready list into a ready

	  list.  Previously a yield was not performed on this second condition.

	+ Introduced the type portBASE_TYPE.  This necessitates several API

	  changes.

	+ Removed the sUsingPreemption variable.  The constant defined in

	  portmacro.h is now used directly.

	+ The idle task can now include an optional hook function - and no longer

	  completes its time slice if other tasks with equal priority to it are

	  ready to run.

	+ See the FreeRTOS.org documentation for more information on V2.x.x to

	  V3.x.x modifications.

Changes from V3.1.1

	+ Modified vTaskPrioritySet() and vTaskResume() to allow these functions to

	  be called while the scheduler is suspended.

	+ Corrected the task ordering within event lists.

Changes from V3.2.0

	+ Added function xTaskGetCurrentTaskHandle().

Changes from V3.2.4

	+ Changed the volatile declarations on some variables to reflect the 

	  changes to the list definitions.

	+ Changed the order of the TCB definition so there is commonality between

	  the task control block and a co-routine control block.

	+ Allow the scheduler to be started even if no tasks other than the idle

	  task has been created.  This allows co-routines to run even when no tasks

	  have been created.

	+ The need for a context switch is now signalled if a task woken by an 

	  event has a priority greater or equal to the currently running task.

	  Previously this was only greater than.

Changes from V4.0.0

	+ Added the xMissedYield handling.

Changes from V4.0.1

	+ The function vTaskList() now suspends the scheduler rather than disabling

	  interrupts during the creation of the task list.  

	+ Allow a task to delete itself by passing in its own handle.  Previously 

	  this could only be done by passing in NULL.

	+ The tick hook function is now called only within a tick isr.  Previously

	  it was also called when the tick function was called during the scheduler

	  unlocking process.

Changes from V4.0.3

	+ Extra checks have been placed in vTaskPrioritySet() to avoid unnecessary

	  yields.

Changed from V4.0.4

	+ Bug fix:  The 'value' of the event list item is updated when the priority

	  of a task is changed.  Previously only the priority of the TCB itself was

	  changed.

	+ When resuming a task a check is first made to see if the task is actually

	  suspended.

	+ vTaskPrioritySet() and vTaskResume() no longer use the event list item.

	  This has not been necessary since V4.0.1 when the xMissedYield handling

	  was added.

	+ Implement xTaskResumeFromISR().

Changes from V4.0.5

	+ Added utility functions and xOverflowCount variable to facilitate the

	  queue.c changes.

Changes from V4.1.2

	+ Tasks that block on events with a timeout of portMAX_DELAY are now

	  blocked indefinitely if configINCLUDE_vTaskSuspend is defined. 

	  Previously portMAX_DELAY was just the longest block time possible.

Changes from V4.1.3

	+ Very small change made to xTaskCheckForTimeout() as a result of the 

	SafeRTOS testing.  This corrects the case where the function can return an

	invalid value - but only in an extremely unlikely scenario.

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "FreeRTOS.h"

#include "task.h"

/*

 * Macro to define the amount of stack available to the idle task.

 */

#define tskIDLE_STACK_SIZE	configMINIMAL_STACK_SIZE

/*

 * Default a definitions for backwards compatibility with old

 * portmacro.h files.

 */

#ifndef configMAX_TASK_NAME_LEN

#define configMAX_TASK_NAME_LEN 16

#endif

#ifndef INCLUDE_xTaskGetCurrentTaskHandle

#define INCLUDE_xTaskGetCurrentTaskHandle 0

#endif

#ifndef configIDLE_SHOULD_YIELD

#define configIDLE_SHOULD_YIELD		1

#endif

#if configMAX_TASK_NAME_LEN < 1

#undef configMAX_TASK_NAME_LEN

#define configMAX_TASK_NAME_LEN 1

#endif

#ifndef INCLUDE_xTaskResumeFromISR

#define INCLUDE_xTaskResumeFromISR 1

#endif

/*

 * Task control block.  A task control block (TCB) is allocated to each task,

 * and stores the context of the task.

 */

typedef struct tskTaskControlBlock

{

  volatile portSTACK_TYPE *pxTopOfStack;	/*< Points to the location of the last item placed on the tasks stack.  THIS MUST BE THE FIRST MEMBER OF THE STRUCT. */

  xListItem xGenericListItem;	/*< List item used to place the TCB in ready and blocked queues. */

  xListItem xEventListItem;	/*< List item used to place the TCB in event lists. */

  unsigned portBASE_TYPE uxPriority;	/*< The priority of the task where 0 is the lowest priority. */

  portSTACK_TYPE *pxStack;	/*< Points to the start of the stack. */

  unsigned portBASE_TYPE uxTCBNumber;	/*< This is used for tracing the scheduler and making debugging easier only. */

  signed portCHAR pcTaskName[configMAX_TASK_NAME_LEN];	/*< Descriptive name given to the task when created.  Facilitates debugging only. */

  unsigned portSHORT usStackDepth;	/*< Total depth of the stack (when empty).  This is defined as the number of variables the stack can hold, not the number of bytes. */

} tskTCB;

/*lint -e956 */

tskTCB *volatile pxCurrentTCB = NULL;

/* Lists for ready and blocked tasks. --------------------*/

static xList pxReadyTasksLists[configMAX_PRIORITIES];	/*< Prioritised ready tasks. */

static xList xDelayedTaskList1;	/*< Delayed tasks. */

static xList xDelayedTaskList2;	/*< Delayed tasks (two lists are used - one for delays that have overflowed the current tick count. */

static xList *volatile pxDelayedTaskList;	/*< Points to the delayed task list currently being used. */

static xList *volatile pxOverflowDelayedTaskList;	/*< Points to the delayed task list currently being used to hold tasks that have overflowed the current tick count. */

static xList xPendingReadyList;	/*< Tasks that have been readied while the scheduler was suspended.  They will be moved to the ready queue when the scheduler is resumed. */

#if ( INCLUDE_vTaskDelete == 1 )

static volatile xList xTasksWaitingTermination;	/*< Tasks that have been deleted - but the their memory not yet freed. */

static volatile unsigned portBASE_TYPE uxTasksDeleted =

  (unsigned portBASE_TYPE) 0;

#endif

#if ( INCLUDE_vTaskSuspend == 1 )

static xList xSuspendedTaskList;	/*< Tasks that are currently suspended. */

#endif

/* File private variables. --------------------------------*/

static volatile unsigned portBASE_TYPE uxCurrentNumberOfTasks =

  (unsigned portBASE_TYPE) 0;

static volatile portTickType xTickCount = (portTickType) 0;

static unsigned portBASE_TYPE uxTopUsedPriority = tskIDLE_PRIORITY;

static volatile unsigned portBASE_TYPE uxTopReadyPriority = tskIDLE_PRIORITY;

static volatile signed portBASE_TYPE xSchedulerRunning = pdFALSE;

static volatile unsigned portBASE_TYPE uxSchedulerSuspended =

  (unsigned portBASE_TYPE) pdFALSE;

static volatile unsigned portBASE_TYPE uxMissedTicks =

  (unsigned portBASE_TYPE) 0;

static volatile portBASE_TYPE xMissedYield = (portBASE_TYPE) pdFALSE;

static volatile portBASE_TYPE xNumOfOverflows = (portBASE_TYPE) 0;

/* Debugging and trace facilities private variables and macros. ------------*/

/*

 * The value used to fill the stack of a task when the task is created.  This

 * is used purely for checking the high water mark for tasks.

 */

#define tskSTACK_FILL_BYTE	( 0xa5 )

/*

 * Macros used by vListTask to indicate which state a task is in.

 */

#define tskBLOCKED_CHAR		( ( signed portCHAR ) 'B' )

#define tskREADY_CHAR		( ( signed portCHAR ) 'R' )

#define tskDELETED_CHAR		( ( signed portCHAR ) 'D' )

#define tskSUSPENDED_CHAR	( ( signed portCHAR ) 'S' )

/*

 * Macros and private variables used by the trace facility.

 */

#if ( configUSE_TRACE_FACILITY == 1 )

#define tskSIZE_OF_EACH_TRACE_LINE			( ( unsigned portLONG ) ( sizeof( unsigned portLONG ) + sizeof( unsigned portLONG ) ) )

static volatile signed portCHAR *volatile pcTraceBuffer;

static signed portCHAR *pcTraceBufferStart;

static signed portCHAR *pcTraceBufferEnd;

static signed portBASE_TYPE xTracing = pdFALSE;

#endif

/*

 * Macro that writes a trace of scheduler activity to a buffer.  This trace

 * shows which task is running when and is very useful as a debugging tool.

 * As this macro is called each context switch it is a good idea to undefine

 * it if not using the facility.

 */

#if ( configUSE_TRACE_FACILITY == 1 )

#define vWriteTraceToBuffer()																	\

	{																								\

		if( xTracing )																				\

		{																							\

			static unsigned portBASE_TYPE uxPreviousTask = 255;										\

																									\

			if( uxPreviousTask != pxCurrentTCB->uxTCBNumber )										\

			{																						\

				if( ( pcTraceBuffer + tskSIZE_OF_EACH_TRACE_LINE ) < pcTraceBufferEnd )				\

				{																					\

					uxPreviousTask = pxCurrentTCB->uxTCBNumber;										\

					*( unsigned portLONG * ) pcTraceBuffer = ( unsigned portLONG ) xTickCount;		\

					pcTraceBuffer += sizeof( unsigned portLONG );									\

					*( unsigned portLONG * ) pcTraceBuffer = ( unsigned portLONG ) uxPreviousTask;	\

					pcTraceBuffer += sizeof( unsigned portLONG );									\

				}																					\

				else																				\

				{																					\

					xTracing = pdFALSE;																\

				}																					\

			}																						\

		}																							\

	}

#else

#define vWriteTraceToBuffer()

#endif

/*

 * Place the task represented by pxTCB into the appropriate ready queue for

 * the task.  It is inserted at the end of the list.  One quirk of this is

 * that if the task being inserted is at the same priority as the currently

 * executing task, then it will only be rescheduled after the currently

 * executing task has been rescheduled.

 */

#define prvAddTaskToReadyQueue( pxTCB )																			\

{																												\

	if( pxTCB->uxPriority > uxTopReadyPriority )																\

	{																											\

		uxTopReadyPriority = pxTCB->uxPriority;																	\

	}																											\

	vListInsertEnd( ( xList * ) &( pxReadyTasksLists[ pxTCB->uxPriority ] ), &( pxTCB->xGenericListItem ) );	\

}

/*

 * Macro that looks at the list of tasks that are currently delayed to see if

 * any require waking.

 *

 * Tasks are stored in the queue in the order of their wake time - meaning

 * once one tasks has been found whose timer has not expired we need not look

 * any further down the list.

 */

#define prvCheckDelayedTasks()																						\

{																													\

register tskTCB *pxTCB;																								\

																													\

	while( ( pxTCB = ( tskTCB * ) listGET_OWNER_OF_HEAD_ENTRY( pxDelayedTaskList ) ) != NULL )						\

	{																												\

		if( xTickCount < listGET_LIST_ITEM_VALUE( &( pxTCB->xGenericListItem ) ) )									\

		{																											\

			break;																									\

		}																											\

		vListRemove( &( pxTCB->xGenericListItem ) );																\

		/* Is the task waiting on an event also? */																	\

		if( pxTCB->xEventListItem.pvContainer )																		\

		{																											\

			vListRemove( &( pxTCB->xEventListItem ) );																\

		}																											\

		prvAddTaskToReadyQueue( pxTCB );														\

	}																												\

}

/*

 * Several functions take an xTaskHandle parameter that can optionally be NULL,

 * where NULL is used to indicate that the handle of the currently executing

 * task should be used in place of the parameter.  This macro simply checks to

 * see if the parameter is NULL and returns a pointer to the appropriate TCB.

 */

#define prvGetTCBFromHandle( pxHandle ) ( ( pxHandle == NULL ) ? ( tskTCB * ) pxCurrentTCB : ( tskTCB * ) pxHandle )

/* File private functions. --------------------------------*/

/*

 * Utility to ready a TCB for a given task.  Mainly just copies the parameters

 * into the TCB structure.

 */

static void prvInitialiseTCBVariables (tskTCB * pxTCB,

				       unsigned portSHORT usStackDepth,

				       const signed portCHAR * const pcName,

				       unsigned portBASE_TYPE uxPriority);

/*

 * Utility to ready all the lists used by the scheduler.  This is called

 * automatically upon the creation of the first task.

 */

static void prvInitialiseTaskLists (void);

/*

 * The idle task, which as all tasks is implemented as a never ending loop.

 * The idle task is automatically created and added to the ready lists upon

 * creation of the first user task.

 *

 * The portTASK_FUNCTION_PROTO() macro is used to allow port/compiler specific

 * language extensions.  The equivalent prototype for this function is:

 *

 * void prvIdleTask( void *pvParameters );

 *

 */

static portTASK_FUNCTION_PROTO (prvIdleTask, pvParameters);

/*

 * Utility to free all memory allocated by the scheduler to hold a TCB,

 * including the stack pointed to by the TCB.

 *

 * This does not free memory allocated by the task itself (i.e. memory

 * allocated by calls to pvPortMalloc from within the tasks application code).

 */

#if ( ( INCLUDE_vTaskDelete == 1 ) || ( INCLUDE_vTaskCleanUpResources == 1 ) )

static void prvDeleteTCB (tskTCB * pxTCB);

#endif

/*

 * Used only by the idle task.  This checks to see if anything has been placed

 * in the list of tasks waiting to be deleted.  If so the task is cleaned up

 * and its TCB deleted.

 */

static void prvCheckTasksWaitingTermination (void);

/*

 * Allocates memory from the heap for a TCB and associated stack.  Checks the

 * allocation was successful.

 */

static tskTCB *prvAllocateTCBAndStack (unsigned portSHORT usStackDepth);

/*

 * Called from vTaskList.  vListTasks details all the tasks currently under

 * control of the scheduler.  The tasks may be in one of a number of lists.

 * prvListTaskWithinSingleList accepts a list and details the tasks from

 * within just that list.

 *

 * THIS FUNCTION IS INTENDED FOR DEBUGGING ONLY, AND SHOULD NOT BE CALLED FROM

 * NORMAL APPLICATION CODE.

 */

#if ( configUSE_TRACE_FACILITY == 1 )

static void prvListTaskWithinSingleList (signed portCHAR * pcWriteBuffer,

					 xList * pxList,

					 signed portCHAR cStatus);

#endif

/*

 * When a task is created, the stack of the task is filled with a known value.

 * This function determines the 'high water mark' of the task stack by

 * determining how much of the stack remains at the original preset value.

 */

#if ( configUSE_TRACE_FACILITY == 1 )

unsigned portSHORT usTaskCheckFreeStackSpace (const unsigned portCHAR *

					      pucStackByte);

#endif

/*lint +e956 */

/*-----------------------------------------------------------

 * TASK CREATION API documented in task.h

 *----------------------------------------------------------*/

signed portBASE_TYPE

xTaskCreate (pdTASK_CODE pvTaskCode, const signed portCHAR * const pcName,

	     unsigned portSHORT usStackDepth, void *pvParameters,

	     unsigned portBASE_TYPE uxPriority, xTaskHandle * pxCreatedTask)

{

  signed portBASE_TYPE xReturn;

  tskTCB *pxNewTCB;

  static unsigned portBASE_TYPE uxTaskNumber = 0;	/*lint !e956 Static is deliberate - this is guarded before use. */

  /* Allocate the memory required by the TCB and stack for the new task.

     checking that the allocation was successful. */

  pxNewTCB = prvAllocateTCBAndStack (usStackDepth);

  if (pxNewTCB != NULL)

    {

      portSTACK_TYPE *pxTopOfStack;

      /* Setup the newly allocated TCB with the initial state of the task. */

      prvInitialiseTCBVariables (pxNewTCB, usStackDepth, pcName, uxPriority);

      /* Calculate the top of stack address.  This depends on whether the

         stack grows from high memory to low (as per the 80x86) or visa versa.

         portSTACK_GROWTH is used to make the result positive or negative as

         required by the port. */

#if portSTACK_GROWTH < 0

      {

	pxTopOfStack = pxNewTCB->pxStack + (pxNewTCB->usStackDepth - 1);

      }

#else

      {

	pxTopOfStack = pxNewTCB->pxStack;

      }

#endif

      /* Initialize the TCB stack to look as if the task was already running,

         but had been interrupted by the scheduler.  The return address is set

         to the start of the task function. Once the stack has been initialised

         the  top of stack variable is updated. */

      pxNewTCB->pxTopOfStack =

	pxPortInitialiseStack (pxTopOfStack, pvTaskCode, pvParameters);

      /* We are going to manipulate the task queues to add this task to a

         ready list, so must make sure no interrupts occur. */

      portENTER_CRITICAL ();

      {

	uxCurrentNumberOfTasks++;

	if (uxCurrentNumberOfTasks == (unsigned portBASE_TYPE) 1)

	  {

	    /* As this is the first task it must also be the current task. */

	    pxCurrentTCB = pxNewTCB;

	    /* This is the first task to be created so do the preliminary

	       initialisation required.  We will not recover if this call

	       fails, but we will report the failure. */

	    prvInitialiseTaskLists ();

	  }

	else

	  {

	    /* If the scheduler is not already running, make this task the

	       current task if it is the highest priority task to be created

	       so far. */

	    if (xSchedulerRunning == pdFALSE)

	      {

		if (pxCurrentTCB->uxPriority <= uxPriority)

		  {

		    pxCurrentTCB = pxNewTCB;

		  }

	      }

	  }

	/* Remember the top priority to make context switching faster.  Use

	   the priority in pxNewTCB as this has been capped to a valid value. */

	if (pxNewTCB->uxPriority > uxTopUsedPriority)

	  {

	    uxTopUsedPriority = pxNewTCB->uxPriority;

	  }

	/* Add a counter into the TCB for tracing only. */

	pxNewTCB->uxTCBNumber = uxTaskNumber;

	uxTaskNumber++;

	prvAddTaskToReadyQueue (pxNewTCB);

	xReturn = pdPASS;

      }

      portEXIT_CRITICAL ();

    }

  else

    {

      xReturn = errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY;

    }

  if (xReturn == pdPASS)

    {

      if ((void *) pxCreatedTask != NULL)

	{

	  /* Pass the TCB out - in an anonymous way.  The calling function/

	     task can use this as a handle to delete the task later if

	     required. */

	  *pxCreatedTask = (xTaskHandle) pxNewTCB;

	}

      if (xSchedulerRunning != pdFALSE)

	{

	  /* If the created task is of a higher priority than the current task

	     then it should run now. */

	  if (pxCurrentTCB->uxPriority < uxPriority)

	    {

	      taskYIELD ();

	    }

	}

    }

  return xReturn;

}

/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskDelete == 1 )

void

vTaskDelete (xTaskHandle pxTaskToDelete)

{

  tskTCB *pxTCB;

  taskENTER_CRITICAL ();

  {

    /* Ensure a yield is performed if the current task is being 

       deleted. */

    if (pxTaskToDelete == pxCurrentTCB)

      {

	pxTaskToDelete = NULL;

      }

    /* If null is passed in here then we are deleting ourselves. */

    pxTCB = prvGetTCBFromHandle (pxTaskToDelete);

    /* Remove task from the ready list and place in the     termination list.

       This will stop the task from be scheduled.  The idle task will check

       the termination list and free up any memory allocated by the

       scheduler for the TCB and stack. */

    vListRemove (&(pxTCB->xGenericListItem));

    /* Is the task waiting on an event also? */

    if (pxTCB->xEventListItem.pvContainer)

      {

	vListRemove (&(pxTCB->xEventListItem));

      }

    vListInsertEnd ((xList *) & xTasksWaitingTermination,

		    &(pxTCB->xGenericListItem));

    /* Increment the ucTasksDeleted variable so the idle task knows

       there is a task that has been deleted and that it should therefore

       check the xTasksWaitingTermination list. */

    ++uxTasksDeleted;

  }

  taskEXIT_CRITICAL ();

  /* Force a reschedule if we have just deleted the current task. */

  if (xSchedulerRunning != pdFALSE)

    {

      if ((void *) pxTaskToDelete == NULL)

	{

	  taskYIELD ();

	}

    }

}

#endif

/*-----------------------------------------------------------

 * TASK CONTROL API documented in task.h

 *----------------------------------------------------------*/

#if ( INCLUDE_vTaskDelayUntil == 1 )

void

vTaskDelayUntil (portTickType * pxPreviousWakeTime,

		 portTickType xTimeIncrement)

{

  portTickType xTimeToWake;

  portBASE_TYPE xAlreadyYielded, xShouldDelay = pdFALSE;

  vTaskSuspendAll ();

  {

    /* Generate the tick time at which the task wants to wake. */

    xTimeToWake = *pxPreviousWakeTime + xTimeIncrement;

    if (xTickCount < *pxPreviousWakeTime)

      {

	/* The tick count has overflowed since this function was

	   lasted called.  In this case the only time we should ever

	   actually delay is if the wake time has also  overflowed,

	   and the wake time is greater than the tick time.  When this

	   is the case it is as if neither time had overflowed. */

	if ((xTimeToWake < *pxPreviousWakeTime) && (xTimeToWake > xTickCount))

	  {

	    xShouldDelay = pdTRUE;

	  }

      }

    else

      {

	/* The tick time has not overflowed.  In this case we will

	   delay if either the wake time has overflowed, and/or the

	   tick time is less than the wake time. */

	if ((xTimeToWake < *pxPreviousWakeTime) || (xTimeToWake > xTickCount))

	  {

	    xShouldDelay = pdTRUE;

	  }

      }

    /* Update the wake time ready for the next call. */

    *pxPreviousWakeTime = xTimeToWake;

    if (xShouldDelay)

      {

	/* We must remove ourselves from the ready list before adding

	   ourselves to the blocked list as the same list item is used for

	   both lists. */

	vListRemove ((xListItem *) & (pxCurrentTCB->xGenericListItem));

	/* The list item will be inserted in wake time order. */

	listSET_LIST_ITEM_VALUE (&(pxCurrentTCB->xGenericListItem),

				 xTimeToWake);

	if (xTimeToWake < xTickCount)

	  {

	    /* Wake time has overflowed.  Place this item in the

	       overflow list. */

	    vListInsert ((xList *) pxOverflowDelayedTaskList,

			 (xListItem *) & (pxCurrentTCB->xGenericListItem));

	  }

	else

	  {

	    /* The wake time has not overflowed, so we can use the

	       current block list. */

	    vListInsert ((xList *) pxDelayedTaskList,

			 (xListItem *) & (pxCurrentTCB->xGenericListItem));

	  }

      }

  }

  xAlreadyYielded = xTaskResumeAll ();

  /* Force a reschedule if xTaskResumeAll has not already done so, we may

     have put ourselves to sleep. */

  if (!xAlreadyYielded)

    {

      taskYIELD ();

    }

}

#endif

/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskDelay == 1 )

void

vTaskDelay (portTickType xTicksToDelay)

{

  portTickType xTimeToWake;

  signed portBASE_TYPE xAlreadyYielded = pdFALSE;

  /* A delay time of zero just forces a reschedule. */

  if (xTicksToDelay > (portTickType) 0)

    {

      vTaskSuspendAll ();

      {

	/* A task that is removed from the event list while the

	   scheduler is suspended will not get placed in the ready

	   list or removed from the blocked list until the scheduler

	   is resumed.

	   This task cannot be in an event list as it is the currently

	   executing task. */

	/* Calculate the time to wake - this may overflow but this is

	   not a problem. */

	xTimeToWake = xTickCount + xTicksToDelay;

	/* We must remove ourselves from the ready list before adding

	   ourselves to the blocked list as the same list item is used for

	   both lists. */

	vListRemove ((xListItem *) & (pxCurrentTCB->xGenericListItem));

	/* The list item will be inserted in wake time order. */

	listSET_LIST_ITEM_VALUE (&(pxCurrentTCB->xGenericListItem),

				 xTimeToWake);

	if (xTimeToWake < xTickCount)

	  {

	    /* Wake time has overflowed.  Place this item in the

	       overflow list. */

	    vListInsert ((xList *) pxOverflowDelayedTaskList,

			 (xListItem *) & (pxCurrentTCB->xGenericListItem));

	  }

	else

	  {

	    /* The wake time has not overflowed, so we can use the

	       current block list. */

	    vListInsert ((xList *) pxDelayedTaskList,

			 (xListItem *) & (pxCurrentTCB->xGenericListItem));

	  }

      }

      xAlreadyYielded = xTaskResumeAll ();

    }

  /* Force a reschedule if xTaskResumeAll has not already done so, we may

     have put ourselves to sleep. */

  if (!xAlreadyYielded)

    {

      taskYIELD ();

    }

}

#endif

/*-----------------------------------------------------------*/

#if ( INCLUDE_uxTaskPriorityGet == 1 )

unsigned portBASE_TYPE

uxTaskPriorityGet (xTaskHandle pxTask)

{

  tskTCB *pxTCB;

  unsigned portBASE_TYPE uxReturn;

  taskENTER_CRITICAL ();

  {

    /* If null is passed in here then we are changing the

       priority of the calling function. */

    pxTCB = prvGetTCBFromHandle (pxTask);

    uxReturn = pxTCB->uxPriority;

  }

  taskEXIT_CRITICAL ();

  return uxReturn;

}

#endif

/*-----------------------------------------------------------*/

#if ( INCLUDE_vTaskPrioritySet == 1 )

void

vTaskPrioritySet (xTaskHandle pxTask, unsigned portBASE_TYPE uxNewPriority)

{

  tskTCB *pxTCB;

  unsigned portBASE_TYPE uxCurrentPriority, xYieldRequired = pdFALSE;

  /* Ensure the new priority is valid. */

  if (uxNewPriority >= configMAX_PRIORITIES)

    {

      uxNewPriority = configMAX_PRIORITIES - 1;

    }

  taskENTER_CRITICAL ();

  {

    /* If null is passed in here then we are changing the

       priority of the calling function. */

    pxTCB = prvGetTCBFromHandle (pxTask);

    uxCurrentPriority = pxTCB->uxPriority;

    if (uxCurrentPriority != uxNewPriority)

      {

	/* The priority change may have readied a task of higher

	   priority than the calling task. */

	if (uxNewPriority > pxCurrentTCB->uxPriority)

	  {

	    if (pxTask != NULL)

	      {

		/* The priority of another task is being raised.  If we

		   were raising the priority of the currently running task

		   there would be no need to switch as it must have already

		   been the highest priority task. */

		xYieldRequired = pdTRUE;

	      }

	  }

	else if (pxTask == NULL)

	  {

	    /* Setting our own priority down means there may now be another

	       task of higher priority that is ready to execute. */

	    xYieldRequired = pdTRUE;

	  }

	pxTCB->uxPriority = uxNewPriority;

	listSET_LIST_ITEM_VALUE (&(pxTCB->xEventListItem),