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list.c revision 1.8 
      1 /*	$NetBSD: list.c,v 1.8 2014/03/22 22:09:14 dholland 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. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 /*
     36  * Copyright (c) 1987 by Ed James, UC Berkeley.  All rights reserved.
     37  *
     38  * Copy permission is hereby granted provided that this notice is
     39  * retained on all partial or complete copies.
     40  *
     41  * For more info on this and all of my stuff, mail edjames (at) berkeley.edu.
     42  */
     43 
     44 #include <sys/cdefs.h>
     45 #ifndef lint
     46 #if 0
     47 static char sccsid[] = "@(#)list.c	8.1 (Berkeley) 5/31/93";
     48 #else
     49 __RCSID("$NetBSD: list.c,v 1.8 2014/03/22 22:09:14 dholland Exp $");
     50 #endif
     51 #endif /* not lint */
     52 
     53 #include "include.h"
     54 
     55 PLANE *
     56 newplane(void)
     57 {
     58 	return calloc(1, sizeof (PLANE));
     59 }
     60 
     61 void
     62 append(LIST *l, PLANE *p)
     63 {
     64 	PLANE 	*q = NULL, *r = NULL;
     65 
     66 	if (l->head == NULL) {
     67 		p->next = p->prev = NULL;
     68 		l->head = l->tail = p;
     69 	} else {
     70 		q = l -> head;
     71 
     72 		while (q != NULL && q->plane_no < p->plane_no) {
     73 			r = q;
     74 			q = q -> next;
     75 		}
     76 
     77 		if (q) {
     78 			if (r) {
     79 				p->prev = r;
     80 				r->next = p;
     81 				p->next = q;
     82 				q->prev = p;
     83 			} else {
     84 				p->next = q;
     85 				p->prev = NULL;
     86 				q->prev = p;
     87 				l->head = p;
     88 			}
     89 		} else {
     90 			l->tail->next = p;
     91 			p->next = NULL;
     92 			p->prev = l->tail;
     93 			l->tail = p;
     94 		}
     95 	}
     96 }
     97 
     98 void
     99 delete(LIST *l, PLANE *p)
    100 {
    101 	if (l->head == NULL)
    102 		loser(p, "deleted a non-existent plane! Get help!");
    103 
    104 	if (l->head == p && l->tail == p)
    105 		l->head = l->tail = NULL;
    106 	else if (l->head == p) {
    107 		l->head = p->next;
    108 		l->head->prev = NULL;
    109 	} else if (l->tail == p) {
    110 		l->tail = p->prev;
    111 		l->tail->next = NULL;
    112 	} else {
    113 		p->prev->next = p->next;
    114 		p->next->prev = p->prev;
    115 	}
    116 }
    117