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/*
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FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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with commercial development and support options.
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***************************************************************************
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*/
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/*
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Changes from V1.2.0
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+ Removed the volatile modifier from the function parameters. This was
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only ever included to prevent compiler warnings. Now warnings are
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removed by casting parameters where the calls are made.
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+ prvListGetOwnerOfNextEntry() and prvListGetOwnerOfHeadEntry() have been
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removed from the c file and added as macros to the h file.
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+ uxNumberOfItems has been added to the list structure. This removes the
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need for a pointer comparison when checking if a list is empty, and so
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is slightly faster.
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+ Removed the NULL check in vListRemove(). This makes the call faster but
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necessitates any application code utilising the list implementation to
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ensure NULL pointers are not passed.
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Changes from V2.0.0
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+ Double linked the lists to allow faster removal item removal.
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Changes from V2.6.1
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+ Make use of the new portBASE_TYPE definition where ever appropriate.
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Changes from V3.0.0
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+ API changes as described on the FreeRTOS.org WEB site.
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Changes from V3.2.4
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+ Removed the pxHead member of the xList structure. This always pointed
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to the same place so has been removed to free a few bytes of RAM.
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+ Introduced the xMiniListItem structure that does not include the
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xListItem members that are not required by the xListEnd member of a list.
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Again this was done to reduce RAM usage.
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+ Changed the volatile definitions of some structure members to clean up
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the code where the list structures are used.
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Changes from V4.0.4
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+ Optimised vListInsert() in the case when the wake time is the maximum
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tick count value.
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*/
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#include <stdlib.h>
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#include "FreeRTOS.h"
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#include "list.h"
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/*-----------------------------------------------------------
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* PUBLIC LIST API documented in list.h
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*----------------------------------------------------------*/
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void
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vListInitialise (xList * pxList)
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{
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/* The list structure contains a list item which is used to mark the
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end of the list. To initialise the list the list end is inserted
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as the only list entry. */
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pxList->pxIndex = (xListItem *) & (pxList->xListEnd);
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/* The list end value is the highest possible value in the list to
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ensure it remains at the end of the list. */
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pxList->xListEnd.xItemValue = portMAX_DELAY;
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/* The list end next and previous pointers point to itself so we know
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when the list is empty. */
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pxList->xListEnd.pxNext = (xListItem *) & (pxList->xListEnd);
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pxList->xListEnd.pxPrevious = (xListItem *) & (pxList->xListEnd);
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pxList->uxNumberOfItems = 0;
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}
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/*-----------------------------------------------------------*/
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void
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vListInitialiseItem (xListItem * pxItem)
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{
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/* Make sure the list item is not recorded as being on a list. */
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pxItem->pvContainer = NULL;
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}
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/*-----------------------------------------------------------*/
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void
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vListInsertEnd (xList * pxList, xListItem * pxNewListItem)
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{
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volatile xListItem *pxIndex;
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/* Insert a new list item into pxList, but rather than sort the list,
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makes the new list item the last item to be removed by a call to
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pvListGetOwnerOfNextEntry. This means it has to be the item pointed to by
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the pxIndex member. */
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pxIndex = pxList->pxIndex;
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pxNewListItem->pxNext = pxIndex->pxNext;
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pxNewListItem->pxPrevious = pxList->pxIndex;
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pxIndex->pxNext->pxPrevious = (volatile xListItem *) pxNewListItem;
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pxIndex->pxNext = (volatile xListItem *) pxNewListItem;
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pxList->pxIndex = (volatile xListItem *) pxNewListItem;
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/* Remember which list the item is in. */
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pxNewListItem->pvContainer = (void *) pxList;
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(pxList->uxNumberOfItems)++;
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}
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/*-----------------------------------------------------------*/
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void
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vListInsert (xList * pxList, xListItem * pxNewListItem)
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{
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volatile xListItem *pxIterator;
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portTickType xValueOfInsertion;
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/* Insert the new list item into the list, sorted in ulListItem order. */
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xValueOfInsertion = pxNewListItem->xItemValue;
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/* If the list already contains a list item with the same item value then
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the new list item should be placed after it. This ensures that TCB's which
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are stored in ready lists (all of which have the same ulListItem value)
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get an equal share of the CPU. However, if the xItemValue is the same as
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the back marker the iteration loop below will not end. This means we need
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to guard against this by checking the value first and modifying the
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algorithm slightly if necessary. */
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if (xValueOfInsertion == portMAX_DELAY)
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{
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pxIterator = pxList->xListEnd.pxPrevious;
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}
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else
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{
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for (pxIterator = (xListItem *) & (pxList->xListEnd);
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pxIterator->pxNext->xItemValue <= xValueOfInsertion;
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pxIterator = pxIterator->pxNext)
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{
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/* There is nothing to do here, we are just iterating to the
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wanted insertion position. */
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}
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}
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pxNewListItem->pxNext = pxIterator->pxNext;
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pxNewListItem->pxNext->pxPrevious = (volatile xListItem *) pxNewListItem;
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pxNewListItem->pxPrevious = pxIterator;
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pxIterator->pxNext = (volatile xListItem *) pxNewListItem;
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/* Remember which list the item is in. This allows fast removal of the
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item later. */
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pxNewListItem->pvContainer = (void *) pxList;
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(pxList->uxNumberOfItems)++;
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}
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/*-----------------------------------------------------------*/
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void
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vListRemove (xListItem * pxItemToRemove)
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{
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xList *pxList;
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pxItemToRemove->pxNext->pxPrevious = pxItemToRemove->pxPrevious;
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pxItemToRemove->pxPrevious->pxNext = pxItemToRemove->pxNext;
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/* The list item knows which list it is in. Obtain the list from the list
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item. */
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pxList = (xList *) pxItemToRemove->pvContainer;
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/* Make sure the index is left pointing to a valid item. */
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if (pxList->pxIndex == pxItemToRemove)
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{
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pxList->pxIndex = pxItemToRemove->pxPrevious;
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}
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pxItemToRemove->pvContainer = NULL;
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(pxList->uxNumberOfItems)--;
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}
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/*-----------------------------------------------------------*/
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