source/ubiqx/ubi_sLinkList.c

   1 /* ========================================================================== **
   2  *                              ubi_sLinkList.c
   3  *
   4  *  Copyright (C) 1997 by Christopher R. Hertel
   5  *
   6  *  Email: crh@ubiqx.mn.org
   7  * -------------------------------------------------------------------------- **
   8  *  This module implements a really simple singly-linked list.
   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  * Revision 0.2  1997/10/21 03:35:18  crh
  28  * Added parameter <After> in function Insert().  Made necessary changes
  29  * to macro AddHead() and added macro AddHere().
  30  *
  31  * Revision 0.1  1997/10/16 02:53:45  crh
  32  * Initial Revision.
  33  *
  34  * ========================================================================== **
  35  */
  36
  37 #include "ubi_sLinkList.h"
  38
  39 /* ========================================================================== **
  40  * Functions...
  41  */
  42
  43 ubi_slListPtr ubi_slInitList( ubi_slListPtr ListPtr )
  44   /* ------------------------------------------------------------------------ **
  45    * Initialize a singly-linked list header.
  46    *
  47    *  Input:  ListPtr - A pointer to the list structure that is to be
  48    *                    initialized for use.
  49    *
  50    *  Output: A pointer to the initialized list header (i.e., same as
  51    *          <ListPtr>).
  52    *
  53    * ------------------------------------------------------------------------ **
  54    */
  55   {
  56   ListPtr->Head  = NULL;
  57   ListPtr->count = 0;
  58   return( ListPtr );
  59   } /* ubi_slInitList */
  60
  61 ubi_slNodePtr ubi_slInsert( ubi_slListPtr ListPtr,
  62                             ubi_slNodePtr New,
  63                             ubi_slNodePtr After )
  64   /* ------------------------------------------------------------------------ **
  65    * Insert a new node at the head of the list.
  66    *
  67    *  Input:  ListPtr - A pointer to the list into which the node is to
  68    *                    be inserted.
  69    *          New     - Pointer to the node that is to be added to the list.
  70    *          After   - Pointer to a list in a node after which the new node
  71    *                    will be inserted.  If NULL, then the new node will
  72    *                    be added at the head of the list.
  73    *
  74    *  Output: A pointer to the node that was inserted into the list (i.e.,
  75    *          the same as <New>).
  76    *
  77    * ------------------------------------------------------------------------ **
  78    */
  79   {
  80   ubi_slNodePtr *PredPtr;
  81
  82   PredPtr = ( NULL == After ) ? &(ListPtr->Head) : &(After->Next);
  83   New->Next = *PredPtr;
  84   *PredPtr  = New;
  85   ++(ListPtr->count);
  86   return( New );
  87   } /* ubi_slInsert */
  88
  89 ubi_slNodePtr ubi_slRemove( ubi_slListPtr ListPtr )
  90   /* ------------------------------------------------------------------------ **
  91    * Remove a node from the head of the list.
  92    *
  93    *  Input:  ListPtr - A pointer to the list from which the node is to be
  94    *                    removed.
  95    *
  96    *  Output: A pointer to the node that was removed.
  97    *
  98    * ------------------------------------------------------------------------ **
  99    */
 100   {
 101   ubi_slNodePtr Old = ListPtr->Head;
 102
 103   if( NULL != Old )
 104     {
 105     ListPtr->Head = Old->Next;
 106     --(ListPtr->count);
 107     }
 108   return( Old );
 109   } /* ubi_slRemove */
 110
 111
 112 /* ================================ The End ================================= */