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/*

        FreeRTOS.org V4.2.0 - 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.

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

*/

/*

Changes from V1.2.0

        + Removed the volatile modifier from the function parameters.  This was

          only ever included to prevent compiler warnings.  Now warnings are

          removed by casting parameters where the calls are made.

        + prvListGetOwnerOfNextEntry() and prvListGetOwnerOfHeadEntry() have been

          removed from the c file and added as macros to the h file.

        + uxNumberOfItems has been added to the list structure.  This removes the

          need for a pointer comparison when checking if a list is empty, and so

          is slightly faster.

        + Removed the NULL check in vListRemove().  This makes the call faster but

          necessitates any application code utilising the list implementation to

          ensure NULL pointers are not passed.

Changes from V2.0.0

        + Double linked the lists to allow faster removal item removal.

Changes from V2.6.1

        + Make use of the new portBASE_TYPE definition where ever appropriate.

Changes from V3.0.0

        + API changes as described on the FreeRTOS.org WEB site.

Changes from V3.2.4

        + Removed the pxHead member of the xList structure.  This always pointed

          to the same place so has been removed to free a few bytes of RAM.

        + Introduced the xMiniListItem structure that does not include the

          xListItem members that are not required by the xListEnd member of a list.

          Again this was done to reduce RAM usage.

        + Changed the volatile definitions of some structure members to clean up

          the code where the list structures are used.

Changes from V4.0.4

        + Optimised vListInsert() in the case when the wake time is the maximum

          tick count value.

*/

#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;

        }

        else

        {

                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 )--;

}

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