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list.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1990 The Regents of the University of California.
      3  * 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 
     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 (at) berkeley.edu.
     44  */
     45 
     46 #ifndef lint
     47 static char sccsid[] = "@(#)list.c	5.2 (Berkeley) 4/30/90";
     48 #endif /* not lint */
     49 
     50 #include "include.h"
     51 
     52 PLANE	*
     53 newplane()
     54 {
     55 	return ((PLANE *) calloc(1, sizeof (PLANE)));
     56 }
     57 
     58 append(l, p)
     59 	LIST	*l;
     60 	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 delete(l, p)
     97 	LIST	*l;
     98 	PLANE	*p;
     99 {
    100 	if (l->head == NULL)
    101 		loser(p, "deleted a non-existant plane! Get help!");
    102 
    103 	if (l->head == p && l->tail == p)
    104 		l->head = l->tail = NULL;
    105 	else if (l->head == p) {
    106 		l->head = p->next;
    107 		l->head->prev = NULL;
    108 	} else if (l->tail == p) {
    109 		l->tail = p->prev;
    110 		l->tail->next = NULL;
    111 	} else {
    112 		p->prev->next = p->next;
    113 		p->next->prev = p->prev;
    114 	}
    115 }
    116