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/* ========================================================================== **
* ubi_dLinkList.c
*
* Copyright (C) 1997 by Christopher R. Hertel
*
* Email: crh@ubiqx.mn.org
* -------------------------------------------------------------------------- **
* This module implements simple doubly-linked lists.
* -------------------------------------------------------------------------- **
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* -------------------------------------------------------------------------- **
*
* Revision 0.3 1997/10/15 03:05:39 crh
* Added some handy type casting to the macros. Added AddHere and RemThis
* macros.
*
* Revision 0.2 1997/10/08 03:07:21 crh
* Fixed a few forgotten link-ups in Insert(), and fixed the AddHead()
* macro, which was passing the wrong value for <After> to Insert().
*
* Revision 0.1 1997/10/07 04:34:07 crh
* Initial Revision.
*
*
* ========================================================================== **
*/
#include "ubi_dLinkList.h"
/* ========================================================================== **
* Functions...
*/
ubi_dlListPtr ubi_dlInitList( ubi_dlListPtr ListPtr )
/* ------------------------------------------------------------------------ **
* Initialize a doubly-linked list header.
*
* Input: ListPtr - A pointer to the list structure that is to be
* initialized for use.
*
* Output: A pointer to the initialized list header (i.e., same as
* <ListPtr>).
*
* ------------------------------------------------------------------------ **
*/
{
ListPtr->Head = NULL;
ListPtr->Tail = NULL;
ListPtr->count = 0;
return( ListPtr );
} /* ubi_dlInitList */
ubi_dlNodePtr ubi_dlInsert( ubi_dlListPtr ListPtr,
ubi_dlNodePtr New,
ubi_dlNodePtr After )
/* ------------------------------------------------------------------------ **
* Insert a new node into the list.
*
* Input: ListPtr - A pointer to the list into which the node is to
* be inserted.
* New - Pointer to the new node.
* After - NULL, or a pointer to a node that is already in the
* list.
* If NULL, then <New> will be added at the head of the
* list, else it will be added following <After>.
*
* Output: A pointer to the node that was inserted into the list (i.e.,
* the same as <New>).
*
* ------------------------------------------------------------------------ **
*/
{
if( NULL == After )
{
New->Next = ListPtr->Head;
New->Prev = NULL;
if( NULL != ListPtr->Head )
ListPtr->Head->Prev = New;
else
ListPtr->Tail = New;
ListPtr->Head = New;
}
else
{
New->Next = After->Next;
New->Prev = After;
if( NULL != After->Next )
After->Next->Prev = New;
else
ListPtr->Tail = New;
After->Next = New;
}
++(ListPtr->count);
return( New );
} /* ubi_dlInsert */
ubi_dlNodePtr ubi_dlRemove( ubi_dlListPtr ListPtr, ubi_dlNodePtr Old )
/* ------------------------------------------------------------------------ **
* Remove a node from the list.
*
* Input: ListPtr - A pointer to the list from which <Old> is to be
* removed.
* Old - A pointer to the node that is to be removed from the
* list.
*
* Output: A pointer to the node that was removed (i.e., <Old>).
*
* ------------------------------------------------------------------------ **
*/
{
if( NULL != Old )
{
if( Old->Next )
Old->Next->Prev = Old->Prev;
else
ListPtr->Tail = Old->Prev;
if( Old->Prev )
Old->Prev->Next = Old->Next;
else
ListPtr->Head = Old->Next;
--(ListPtr->count);
}
return( Old );
} /* ubi_dlRemove */
/* ================================ The End ================================= */
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