games/atc/list.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * This code is derived from software contributed to Berkeley by
   6  * Ed James.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)list.c   8.1 (Berkeley) 5/31/93
  37  * $FreeBSD: src/games/atc/list.c,v 1.4 1999/11/30 03:48:20 billf Exp $
  38  * $DragonFly: src/games/atc/list.c,v 1.4 2007/05/17 08:19:00 swildner Exp $
  39  */
  40
  41 /*
  42  * Copyright (c) 1987 by Ed James, UC Berkeley.  All rights reserved.
  43  *
  44  * Copy permission is hereby granted provided that this notice is
  45  * retained on all partial or complete copies.
  46  *
  47  * For more info on this and all of my stuff, mail edjames@berkeley.edu.
  48  */
  49
  50 #include "include.h"
  51
  52
  53 PLANE   *
  54 newplane(void)
  55 {
  56         return ((PLANE *) calloc(1, sizeof (PLANE)));
  57 }
  58
  59 void
  60 append(LIST *l, PLANE *p)
  61 {
  62         PLANE   *q = NULL, *r = NULL;
  63
  64         if (l->head == NULL) {
  65                 p->next = p->prev = NULL;
  66                 l->head = l->tail = p;
  67         } else {
  68                 q = l -> head;
  69
  70                 while (q != NULL && q->plane_no < p->plane_no) {
  71                         r = q;
  72                         q = q -> next;
  73                 }
  74
  75                 if (q) {
  76                         if (r) {
  77                                 p->prev = r;
  78                                 r->next = p;
  79                                 p->next = q;
  80                                 q->prev = p;
  81                         } else {
  82                                 p->next = q;
  83                                 p->prev = NULL;
  84                                 q->prev = p;
  85                                 l->head = p;
  86                         }
  87                 } else {
  88                         l->tail->next = p;
  89                         p->next = NULL;
  90                         p->prev = l->tail;
  91                         l->tail = p;
  92                 }
  93         }
  94 }
  95
  96 void
  97 delete(LIST *l, PLANE *p)
  98 {
  99         if (l->head == NULL)
 100                 loser(p, "deleted a non-existent plane! Get help!");
 101
 102         if (l->head == p && l->tail == p)
 103                 l->head = l->tail = NULL;
 104         else if (l->head == p) {
 105                 l->head = p->next;
 106                 l->head->prev = NULL;
 107         } else if (l->tail == p) {
 108                 l->tail = p->prev;
 109                 l->tail->next = NULL;
 110         } else {
 111                 p->prev->next = p->next;
 112                 p->next->prev = p->prev;
 113         }
 114 }