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/* V5.2.0 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the distribution. 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. 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; 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 is included to allow you to distribute a
combined work that includes without being obliged to provide
the source code for any proprietary components. See the licensing section
of for full details.
* *
* Get the FreeRTOS eBook! See *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
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Please ensure to read the configuration and relevant port sections of the
online documentation. - Documentation, latest information, license and
contact details. - A version that is certified for use in safety
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#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 = 0;
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 )++;
void vListRemove( 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 )--;