Hello
This code is source file of list. generally List means the number of items. I want to understand what is use of this program ? why do we need this source file ?
This code is source file of list. generally List means the number of items. I want to understand what is use of this program ? why do we need this source file ?
Code:
#include <stdlib.h>
#include "FreeRTOS.h"
#include "list.h"
void vListInitialise( xList * const 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 ); /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
/* 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 ); /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
pxList->xListEnd.pxPrevious = ( xListItem * ) &( pxList->xListEnd );/*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
pxList->uxNumberOfItems = ( unsigned portBASE_TYPE ) 0U;
}
/*-----------------------------------------------------------*/
void vListInitialiseItem( xListItem * const pxItem )
{
/* Make sure the list item is not recorded as being on a list. */
pxItem->pvContainer = NULL;
}
/*-----------------------------------------------------------*/
void vListInsertEnd( xList * const pxList, xListItem * const pxNewListItem )
{
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. */
pxIndex = pxList->pxIndex;
pxNewListItem->pxNext = pxIndex;
pxNewListItem->pxPrevious = pxIndex->pxPrevious;
pxIndex->pxPrevious->pxNext = pxNewListItem;
pxIndex->pxPrevious = pxNewListItem;
/* Remember which list the item is in. */
pxNewListItem->pvContainer = ( void * ) pxList;
( pxList->uxNumberOfItems )++;
}
/*-----------------------------------------------------------*/
void vListInsert( xList * const pxList, xListItem * const pxNewListItem )
{
xListItem *pxIterator;
portTickType xValueOfInsertion;
/* Insert the new list item into the list, sorted in ulListItem order. */
xValueOfInsertion = pxNewListItem->xItemValue;
if( xValueOfInsertion == portMAX_DELAY )
{
pxIterator = pxList->xListEnd.pxPrevious;
}
else
{
for( pxIterator = ( xListItem * ) &( pxList->xListEnd ); pxIterator->pxNext->xItemValue <= xValueOfInsertion; pxIterator = pxIterator->pxNext ) /*lint !e826 !e740 The mini list structure is used as the list end to save RAM. This is checked and valid. */
{
/* There is nothing to do here, we are just iterating to the
wanted insertion position. */
}
}
pxNewListItem->pxNext = pxIterator->pxNext;
pxNewListItem->pxNext->pxPrevious = pxNewListItem;
pxNewListItem->pxPrevious = pxIterator;
pxIterator->pxNext = pxNewListItem;
/* Remember which list the item is in. This allows fast removal of the
item later. */
pxNewListItem->pvContainer = ( void * ) pxList;
( pxList->uxNumberOfItems )++;
}
/*-----------------------------------------------------------*/
unsigned portBASE_TYPE uxListRemove( xListItem * const 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 )--;
return pxList->uxNumberOfItems;
}