source/ubiqx/ubi_dLinkList.c

   1 /* ========================================================================== **
   2  *                              ubi_dLinkList.c
   3  *
   4  *  Copyright (C) 1997, 1998 by Christopher R. Hertel
   5  *
   6  *  Email: crh@ubiqx.mn.org
   7  * -------------------------------------------------------------------------- **
   8  *  This module implements simple doubly-linked lists.
   9  * -------------------------------------------------------------------------- **
  10  *
  11  *  This library is free software; you can redistribute it and/or
  12  *  modify it under the terms of the GNU Library General Public
  13  *  License as published by the Free Software Foundation; either
  14  *  version 2 of the License, or (at your option) any later version.
  15  *
  16  *  This library is distributed in the hope that it will be useful,
  17  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  *  Library General Public License for more details.
  20  *
  21  *  You should have received a copy of the GNU Library General Public
  22  *  License along with this library; if not, write to the Free
  23  *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24  *
  25  * -------------------------------------------------------------------------- **
  26  *
  27  * Log: ubi_dLinkList.c,v
  28  * Revision 0.10  1998/07/24 07:30:20  crh
  29  * Added the ubi_dlNewList() macro.
  30  *
  31  * Revision 0.9  1998/06/04 21:29:27  crh
  32  * Upper-cased defined constants (eg UBI_BINTREE_H) in some header files.
  33  * This is more "standard", and is what people expect.  Weird, eh?
  34  *
  35  * Revision 0.8  1998/06/03 18:06:03  crh
  36  * Further fiddling with sys_include.h, which has been moved from the .c file
  37  * to the .h file.
  38  *
  39  * Revision 0.7  1998/06/02 01:38:47  crh
  40  * Changed include file name from ubi_null.h to sys_include.h to make it
  41  * more generic.
  42  *
  43  * Revision 0.6  1998/05/20 04:38:05  crh
  44  * The C file now includes ubi_null.h.  See ubi_null.h for more info.
  45  *
  46  * Revision 0.5  1998/03/10 02:55:00  crh
  47  * Simplified the code and added macros for stack & queue manipulations.
  48  *
  49  * Revision 0.4  1998/01/03 01:53:56  crh
  50  * Added ubi_dlCount() macro.
  51  *
  52  * Revision 0.3  1997/10/15 03:05:39  crh
  53  * Added some handy type casting to the macros.  Added AddHere and RemThis
  54  * macros.
  55  *
  56  * Revision 0.2  1997/10/08 03:07:21  crh
  57  * Fixed a few forgotten link-ups in Insert(), and fixed the AddHead()
  58  * macro, which was passing the wrong value for <After> to Insert().
  59  *
  60  * Revision 0.1  1997/10/07 04:34:07  crh
  61  * Initial Revision.
  62  *
  63  * -------------------------------------------------------------------------- **
  64  * This module is similar to the ubi_sLinkList module, but it is neither a
  65  * descendant type nor an easy drop-in replacement for the latter.  One key
  66  * difference is that the ubi_dlRemove() function removes the indicated node,
  67  * while the ubi_slRemove() function (in ubi_sLinkList) removes the node
  68  * *following* the indicated node.
  69  *
  70  * ========================================================================== **
  71  */
  72
  73 #include "ubi_dLinkList.h"  /* Header for *this* module. */
  74
  75 /* ========================================================================== **
  76  * Functions...
  77  */
  78
  79 ubi_dlListPtr ubi_dlInitList( ubi_dlListPtr ListPtr )
  80   /* ------------------------------------------------------------------------ **
  81    * Initialize a doubly-linked list header.
  82    *
  83    *  Input:  ListPtr - A pointer to the list structure that is to be
  84    *                    initialized for use.
  85    *
  86    *  Output: A pointer to the initialized list header (i.e., same as
  87    *          <ListPtr>).
  88    *
  89    * ------------------------------------------------------------------------ **
  90    */
  91   {
  92   ListPtr->Head  = NULL;
  93   ListPtr->Tail  = NULL;
  94   ListPtr->count = 0;
  95   return( ListPtr );
  96   } /* ubi_dlInitList */
  97
  98 ubi_dlNodePtr ubi_dlInsert( ubi_dlListPtr ListPtr,
  99                             ubi_dlNodePtr New,
 100                             ubi_dlNodePtr After )
 101   /* ------------------------------------------------------------------------ **
 102    * Insert a new node into the list.
 103    *
 104    *  Input:  ListPtr - A pointer to the list into which the node is to
 105    *                    be inserted.
 106    *          New     - Pointer to the new node.
 107    *          After   - NULL, or a pointer to a node that is already in the
 108    *                    list.
 109    *                    If NULL, then <New> will be added at the head of the
 110    *                    list, else it will be added following <After>.
 111    *
 112    *  Output: A pointer to the node that was inserted into the list (i.e.,
 113    *          the same as <New>).
 114    *
 115    * ------------------------------------------------------------------------ **
 116    */
 117   {
 118   ubi_dlNodePtr PredNode = After ? After : (ubi_dlNodePtr)ListPtr;
 119
 120   New->Next         = PredNode->Next;
 121   New->Prev         = After;
 122   PredNode->Next    = New;
 123   if( New->Next )
 124     New->Next->Prev = New;
 125   else
 126     ListPtr->Tail   = New;
 127
 128   (ListPtr->count)++;
 129
 130   return( New );
 131   } /* ubi_dlInsert */
 132
 133 ubi_dlNodePtr ubi_dlRemove( ubi_dlListPtr ListPtr, ubi_dlNodePtr Old )
 134   /* ------------------------------------------------------------------------ **
 135    * Remove a node from the list.
 136    *
 137    *  Input:  ListPtr - A pointer to the list from which <Old> is to be
 138    *                    removed.
 139    *          Old     - A pointer to the node that is to be removed from the
 140    *                    list.
 141    *
 142    *  Output: A pointer to the node that was removed (i.e., <Old>).
 143    *
 144    * ------------------------------------------------------------------------ **
 145    */
 146   {
 147   if( Old )
 148     {
 149     if( Old->Next )
 150       Old->Next->Prev = Old->Prev;
 151     else
 152       ListPtr->Tail = Old->Prev;
 153
 154     if( Old->Prev )
 155       Old->Prev->Next = Old->Next;
 156     else
 157       ListPtr->Head = Old->Next;
 158
 159     (ListPtr->count)--;
 160     }
 161
 162   return( Old );
 163   } /* ubi_dlRemove */
 164
 165 /* ================================ The End ================================= */