source3/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 0.11  1999/06/19 16:58:06  crh
  29  * Renamed the ubi_slRemove() function in ubi_sLinkList to
  30  * ubi_slRemoveNext().  I was bothered by the fact that it didn't
  31  * match the functionality of the ubi_dlRemove() function in
  32  * ubi_dLinkList.  The new name is more 'correct'.
  33  *
  34  * Revision 0.10  1998/07/24 07:30:20  crh
  35  * Added the ubi_dlNewList() macro.
  36  *
  37  * Revision 0.9  1998/06/04 21:29:27  crh
  38  * Upper-cased defined constants (eg UBI_BINTREE_H) in some header files.
  39  * This is more "standard", and is what people expect.  Weird, eh?
  40  *
  41  * Revision 0.8  1998/06/03 18:06:03  crh
  42  * Further fiddling with sys_include.h, which has been moved from the .c file
  43  * to the .h file.
  44  *
  45  * Revision 0.7  1998/06/02 01:38:47  crh
  46  * Changed include file name from ubi_null.h to sys_include.h to make it
  47  * more generic.
  48  *
  49  * Revision 0.6  1998/05/20 04:38:05  crh
  50  * The C file now includes ubi_null.h.  See ubi_null.h for more info.
  51  *
  52  * Revision 0.5  1998/03/10 02:55:00  crh
  53  * Simplified the code and added macros for stack & queue manipulations.
  54  *
  55  * Revision 0.4  1998/01/03 01:53:56  crh
  56  * Added ubi_dlCount() macro.
  57  *
  58  * Revision 0.3  1997/10/15 03:05:39  crh
  59  * Added some handy type casting to the macros.  Added AddHere and RemThis
  60  * macros.
  61  *
  62  * Revision 0.2  1997/10/08 03:07:21  crh
  63  * Fixed a few forgotten link-ups in Insert(), and fixed the AddHead()
  64  * macro, which was passing the wrong value for <After> to Insert().
  65  *
  66  * Revision 0.1  1997/10/07 04:34:07  crh
  67  * Initial Revision.
  68  *
  69  * -------------------------------------------------------------------------- **
  70  * This module is similar to the ubi_sLinkList module, but it is neither a
  71  * descendant type nor an easy drop-in replacement for the latter.  One key
  72  * difference is that the ubi_dlRemove() function removes the indicated node,
  73  * while the ubi_slRemoveNext() function (in ubi_sLinkList) removes the node
  74  * *following* the indicated node.
  75  *
  76  * ========================================================================== **
  77  */
  78
  79 #include "ubi_dLinkList.h"  /* Header for *this* module. */
  80
  81 /* ========================================================================== **
  82  * Functions...
  83  */
  84
  85 ubi_dlListPtr ubi_dlInitList( ubi_dlListPtr ListPtr )
  86   /* ------------------------------------------------------------------------ **
  87    * Initialize a doubly-linked list header.
  88    *
  89    *  Input:  ListPtr - A pointer to the list structure that is to be
  90    *                    initialized for use.
  91    *
  92    *  Output: A pointer to the initialized list header (i.e., same as
  93    *          <ListPtr>).
  94    *
  95    * ------------------------------------------------------------------------ **
  96    */
  97   {
  98   ListPtr->Head  = NULL;
  99   ListPtr->Tail  = NULL;
 100   ListPtr->count = 0;
 101   return( ListPtr );
 102   } /* ubi_dlInitList */
 103
 104 ubi_dlNodePtr ubi_dlInsert( ubi_dlListPtr ListPtr,
 105                             ubi_dlNodePtr New,
 106                             ubi_dlNodePtr After )
 107   /* ------------------------------------------------------------------------ **
 108    * Insert a new node into the list.
 109    *
 110    *  Input:  ListPtr - A pointer to the list into which the node is to
 111    *                    be inserted.
 112    *          New     - Pointer to the new node.
 113    *          After   - NULL, or a pointer to a node that is already in the
 114    *                    list.
 115    *                    If NULL, then <New> will be added at the head of the
 116    *                    list, else it will be added following <After>.
 117    *
 118    *  Output: A pointer to the node that was inserted into the list (i.e.,
 119    *          the same as <New>).
 120    *
 121    * ------------------------------------------------------------------------ **
 122    */
 123   {
 124   ubi_dlNodePtr PredNode = After ? After : (ubi_dlNodePtr)ListPtr;
 125
 126   New->Next         = PredNode->Next;
 127   New->Prev         = After;
 128   PredNode->Next    = New;
 129   if( New->Next )
 130     New->Next->Prev = New;
 131   else
 132     ListPtr->Tail   = New;
 133
 134   (ListPtr->count)++;
 135
 136   return( New );
 137   } /* ubi_dlInsert */
 138
 139 ubi_dlNodePtr ubi_dlRemove( ubi_dlListPtr ListPtr, ubi_dlNodePtr Old )
 140   /* ------------------------------------------------------------------------ **
 141    * Remove a node from the list.
 142    *
 143    *  Input:  ListPtr - A pointer to the list from which <Old> is to be
 144    *                    removed.
 145    *          Old     - A pointer to the node that is to be removed from the
 146    *                    list.
 147    *
 148    *  Output: A pointer to the node that was removed (i.e., <Old>).
 149    *
 150    * ------------------------------------------------------------------------ **
 151    */
 152   {
 153   if( Old )
 154     {
 155     if( Old->Next )
 156       Old->Next->Prev = Old->Prev;
 157     else
 158       ListPtr->Tail = Old->Prev;
 159
 160     if( Old->Prev )
 161       Old->Prev->Next = Old->Next;
 162     else
 163       ListPtr->Head = Old->Next;
 164
 165     (ListPtr->count)--;
 166     }
 167
 168   return( Old );
 169   } /* ubi_dlRemove */
 170
 171 /* ================================ The End ================================= */