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[/] [openrisc/] [trunk/] [rtos/] [freertos-6.1.1/] [Source/] [list.c] - Blame information for rev 593

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1 572 jeremybenn
/*
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    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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    ***************************************************************************
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    *                                                                         *
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    * If you are:                                                             *
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    *                                                                         *
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    *    + New to FreeRTOS,                                                   *
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    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
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    *    + Looking for basic training,                                        *
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    *    + Wanting to improve your FreeRTOS skills and productivity           *
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    *                                                                         *
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    * then take a look at the FreeRTOS books - available as PDF or paperback  *
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    *                                                                         *
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    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
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    *                  http://www.FreeRTOS.org/Documentation                  *
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    *                                                                         *
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    * A pdf reference manual is also available.  Both are usually delivered   *
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    * to your inbox within 20 minutes to two hours when purchased between 8am *
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    * and 8pm GMT (although please allow up to 24 hours in case of            *
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    * exceptional circumstances).  Thank you for your support!                *
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    *                                                                         *
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    ***************************************************************************
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    This file is part of the FreeRTOS distribution.
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    FreeRTOS is free software; you can redistribute it and/or modify it under
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    the terms of the GNU General Public License (version 2) as published by the
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    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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    ***NOTE*** The exception to the GPL is included to allow you to distribute
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    a combined work that includes FreeRTOS without being obliged to provide the
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    source code for proprietary components outside of the FreeRTOS kernel.
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    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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    more details. You should have received a copy of the GNU General Public
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    License and the FreeRTOS license exception along with FreeRTOS; if not it
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    can be viewed here: http://www.freertos.org/a00114.html and also obtained
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    by writing to Richard Barry, contact details for whom are available on the
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    FreeRTOS WEB site.
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    1 tab == 4 spaces!
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    http://www.FreeRTOS.org - Documentation, latest information, license and
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    contact details.
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    http://www.SafeRTOS.com - A version that is certified for use in safety
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    critical systems.
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    http://www.OpenRTOS.com - Commercial support, development, porting,
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    licensing and training services.
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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 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 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 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 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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                /* *** NOTE ***********************************************************
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                If you find your application is crashing here then likely causes are:
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                        1) Stack overflow -
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                           see http://www.freertos.org/Stacks-and-stack-overflow-checking.html
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                        2) Incorrect interrupt priority assignment, especially on Cortex M3
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                           parts where numerically high priority values denote low actual
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                           interrupt priories, which can seem counter intuitive.  See
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                           configMAX_SYSCALL_INTERRUPT_PRIORITY on http://www.freertos.org/a00110.html
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                        3) Calling an API function from within a critical section or when
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                           the scheduler is suspended.
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                        4) Using a queue or semaphore before it has been initialised or
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                           before the scheduler has been started (are interrupts firing
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                           before vTaskStartScheduler() has been called?).
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                See http://www.freertos.org/FAQHelp.html for more tips.
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                **********************************************************************/
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                for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; 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 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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