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list.c revision 1.6 
      1 /*	$NetBSD: list.c,v 1.6 2003/08/07 09:36:54 agc 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 1.6 2003/08/07 09:36:54 agc Exp $");
     50 #endif
     51 #endif /* not lint */
     52 
     53 #include "include.h"
     54 
     55 PLANE	*
     56 newplane()
     57 {
     58 	return ((PLANE *) calloc(1, sizeof (PLANE)));
     59 }
     60 
     61 void
     62 append(l, p)
     63 	LIST	*l;
     64 	PLANE	*p;
     65 {
     66 	PLANE 	*q = NULL, *r = NULL;
     67 
     68 	if (l->head == NULL) {
     69 		p->next = p->prev = NULL;
     70 		l->head = l->tail = p;
     71 	} else {
     72 		q = l -> head;
     73 
     74 		while (q != NULL && q->plane_no < p->plane_no) {
     75 			r = q;
     76 			q = q -> next;
     77 		}
     78 
     79 		if (q) {
     80 			if (r) {
     81 				p->prev = r;
     82 				r->next = p;
     83 				p->next = q;
     84 				q->prev = p;
     85 			} else {
     86 				p->next = q;
     87 				p->prev = NULL;
     88 				q->prev = p;
     89 				l->head = p;
     90 			}
     91 		} else {
     92 			l->tail->next = p;
     93 			p->next = NULL;
     94 			p->prev = l->tail;
     95 			l->tail = p;
     96 		}
     97 	}
     98 }
     99 
    100 void
    101 delete(l, p)
    102 	LIST	*l;
    103 	PLANE	*p;
    104 {
    105 	if (l->head == NULL)
    106 		loser(p, "deleted a non-existent plane! Get help!");
    107 
    108 	if (l->head == p && l->tail == p)
    109 		l->head = l->tail = NULL;
    110 	else if (l->head == p) {
    111 		l->head = p->next;
    112 		l->head->prev = NULL;
    113 	} else if (l->tail == p) {
    114 		l->tail = p->prev;
    115 		l->tail->next = NULL;
    116 	} else {
    117 		p->prev->next = p->next;
    118 		p->next->prev = p->prev;
    119 	}
    120 }
    121