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list.c revision 1.4 
      1 /*	$NetBSD: list.c,v 1.4 1997/10/10 02:07:23 lukem Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Ed James.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Copyright (c) 1987 by Ed James, UC Berkeley.  All rights reserved.
     41  *
     42  * Copy permission is hereby granted provided that this notice is
     43  * retained on all partial or complete copies.
     44  *
     45  * For more info on this and all of my stuff, mail edjames (at) berkeley.edu.
     46  */
     47 
     48 #include <sys/cdefs.h>
     49 #ifndef lint
     50 #if 0
     51 static char sccsid[] = "@(#)list.c	8.1 (Berkeley) 5/31/93";
     52 #else
     53 __RCSID("$NetBSD: list.c,v 1.4 1997/10/10 02:07:23 lukem Exp $");
     54 #endif
     55 #endif /* not lint */
     56 
     57 #include "include.h"
     58 
     59 PLANE	*
     60 newplane()
     61 {
     62 	return ((PLANE *) calloc(1, sizeof (PLANE)));
     63 }
     64 
     65 void
     66 append(l, p)
     67 	LIST	*l;
     68 	PLANE	*p;
     69 {
     70 	PLANE 	*q = NULL, *r = NULL;
     71 
     72 	if (l->head == NULL) {
     73 		p->next = p->prev = NULL;
     74 		l->head = l->tail = p;
     75 	} else {
     76 		q = l -> head;
     77 
     78 		while (q != NULL && q->plane_no < p->plane_no) {
     79 			r = q;
     80 			q = q -> next;
     81 		}
     82 
     83 		if (q) {
     84 			if (r) {
     85 				p->prev = r;
     86 				r->next = p;
     87 				p->next = q;
     88 				q->prev = p;
     89 			} else {
     90 				p->next = q;
     91 				p->prev = NULL;
     92 				q->prev = p;
     93 				l->head = p;
     94 			}
     95 		} else {
     96 			l->tail->next = p;
     97 			p->next = NULL;
     98 			p->prev = l->tail;
     99 			l->tail = p;
    100 		}
    101 	}
    102 }
    103 
    104 void
    105 delete(l, p)
    106 	LIST	*l;
    107 	PLANE	*p;
    108 {
    109 	if (l->head == NULL)
    110 		loser(p, "deleted a non-existant plane! Get help!");
    111 
    112 	if (l->head == p && l->tail == p)
    113 		l->head = l->tail = NULL;
    114 	else if (l->head == p) {
    115 		l->head = p->next;
    116 		l->head->prev = NULL;
    117 	} else if (l->tail == p) {
    118 		l->tail = p->prev;
    119 		l->tail->next = NULL;
    120 	} else {
    121 		p->prev->next = p->next;
    122 		p->next->prev = p->prev;
    123 	}
    124 }
    125