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