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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
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* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
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* >>> See for details. <<< *
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* Thank you for using FreeRTOS, and thank you for your support! *
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This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
FreeRTOS 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
and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* *
* *
*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand. - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
#include <stdlib.h>
#include "FreeRTOS.h"
#include "list.h"
* PUBLIC LIST API documented in list.h
void vListInitialise( xList *pxList )
/* The list structure contains a list item which is used to mark the
end of the list. To initialise the list the list end is inserted
as the only list entry. */
pxList->pxIndex = ( xListItem * ) &( pxList->xListEnd );
/* The list end value is the highest possible value in the list to
ensure it remains at the end of the list. */
pxList->xListEnd.xItemValue = portMAX_DELAY;
/* The list end next and previous pointers point to itself so we know
when the list is empty. */
pxList->xListEnd.pxNext = ( xListItem * ) &( pxList->xListEnd );
pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );
pxList->uxNumberOfItems = ( unsigned portBASE_TYPE ) 0U;
void vListInitialiseItem( xListItem *pxItem )
/* Make sure the list item is not recorded as being on a list. */
pxItem->pvContainer = NULL;
void vListInsertEnd( xList *pxList, xListItem *pxNewListItem )
volatile xListItem * pxIndex;
/* Insert a new list item into pxList, but rather than sort the list,
makes the new list item the last item to be removed by a call to
pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
the pxIndex member. */
pxIndex = pxList->pxIndex;
pxNewListItem->pxNext = pxIndex->pxNext;
pxNewListItem->pxPrevious = pxList->pxIndex;
pxIndex->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
pxIndex->pxNext = ( volatile xListItem * ) pxNewListItem;
pxList->pxIndex = ( volatile xListItem * ) pxNewListItem;
/* Remember which list the item is in. */
pxNewListItem->pvContainer = ( void * ) pxList;
( pxList->uxNumberOfItems )++;
void vListInsert( xList *pxList, xListItem *pxNewListItem )
volatile xListItem *pxIterator;
portTickType xValueOfInsertion;
/* Insert the new list item into the list, sorted in ulListItem order. */
xValueOfInsertion = pxNewListItem->xItemValue;
/* If the list already contains a list item with the same item value then
the new list item should be placed after it. This ensures that TCB's which
are stored in ready lists (all of which have the same ulListItem value)
get an equal share of the CPU. However, if the xItemValue is the same as
the back marker the iteration loop below will not end. This means we need
to guard against this by checking the value first and modifying the
algorithm slightly if necessary. */
if( xValueOfInsertion == portMAX_DELAY )
pxIterator = pxList->xListEnd.pxPrevious;
/* *** NOTE ***********************************************************
If you find your application is crashing here then likely causes are:
1) Stack overflow -
2) Incorrect interrupt priority assignment, especially on Cortex-M3
parts where numerically high priority values denote low actual
interrupt priories, which can seem counter intuitive. See
3) Calling an API function from within a critical section or when
the scheduler is suspended.
4) Using a queue or semaphore before it has been initialised or
before the scheduler has been started (are interrupts firing
before vTaskStartScheduler() has been called?).
See for more tips.
for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext )
/* There is nothing to do here, we are just iterating to the
wanted insertion position. */
pxNewListItem->pxNext = pxIterator->pxNext;
pxNewListItem->pxNext->pxPrevious = ( volatile xListItem * ) pxNewListItem;
pxNewListItem->pxPrevious = pxIterator;
pxIterator->pxNext = ( volatile xListItem * ) pxNewListItem;
/* Remember which list the item is in. This allows fast removal of the
item later. */
pxNewListItem->pvContainer = ( void * ) pxList;
( pxList->uxNumberOfItems )++;
unsigned portBASE_TYPE uxListRemove( xListItem *pxItemToRemove )
xList * pxList;
pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
/* The list item knows which list it is in. Obtain the list from the list
item. */
pxList = ( xList * ) pxItemToRemove->pvContainer;
/* Make sure the index is left pointing to a valid item. */
if( pxList->pxIndex == pxItemToRemove )
pxList->pxIndex = pxItemToRemove->pxPrevious;
pxItemToRemove->pvContainer = NULL;
( pxList->uxNumberOfItems )--;
return pxList->uxNumberOfItems;