list.c

Show hou use semaphores in RTL-ARM

/* 
 ********************************************************************
 * Project:    GNU-Port FreeRTOS Port
 * File:    	list.c
 *
 * System:   	ARM7TDMI-S 32 Bit (LPC2378)
 * Compiler:  	GCC 4.0.3
 *
 * Date:      	2006-11-17
 * Author:    	Grohmann
 *
 * Rights:    	Hitex Development Tools GmbH
 *            	Greschbachstr. 12
 *            	D-76229 Karlsruhe
 ********************************************************************
 * Description:
 *
 * This file is part of the GNU FreeRTOS Port
 * The code is based on the FreeRTOS originated by Richard Barry
 * This is a small implementation preemtive and semaphore task. 
 * The application runs in ARM mode with high optimization level.
 *	
 ********************************************************************
 * History:
 *
 *  Revision 1.0    2006/11/17      Gn
 *     Initial revision 
 ********************************************************************
 * This is a preliminary version.
 *
 * WARRANTY:  HITEX warrants that the media on which the SOFTWARE is 
 * furnished is free from defects in materials and workmanship under 
 * normal use and service for a period of ninety (90) days. HITEX entire
 * liability and your exclusive remedy shall be the replacement of the 
 * SOFTWARE if the media is defective. This Warranty is void if failure
 * of the media resulted from unauthorized modification, accident, abuse,
 * or misapplication.
 *
 * DISCLAIMER:  OTHER THAN THE ABOVE WARRANTY, THE SOFTWARE IS FURNISHED
 * "AS IS" WITHOUT WARRANTY OF ANY KIND. HITEX DISCLAIMS ALL OTHER WARRANTIES,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * NEITHER HITEX NOR ITS AFFILIATES SHALL BE LIABLE FOR ANY DAMAGES ARISING
 * OUT OF THE USE OF OR INABILITY TO USE THE SOFTWARE, INCLUDING DAMAGES FOR
 * LOSS OF PROFITS, BUSINESS INTERRUPTION, OR ANY SPECIAL, INCIDENTAL, INDIRECT
 * OR CONSEQUENTIAL DAMAGES EVEN IF HITEX HAS BEEN ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGES.
 ********************************************************************/

#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 )--;
}
/*-----------------------------------------------------------*/