xref: /openbsd-src/usr.bin/make/lst.lib/lstDeQueue.c (revision bb4544df9ace63bacb4f113c781faab96bfc1dec)
1*bb4544dfSespie /*	$OpenBSD: lstDeQueue.c,v 1.19 2010/07/19 19:46:44 espie Exp $	*/
2789486c7Smillert /*	$NetBSD: lstDeQueue.c,v 1.5 1996/11/06 17:59:36 christos Exp $	*/
3df930be7Sderaadt 
4df930be7Sderaadt /*
5789486c7Smillert  * Copyright (c) 1988, 1989, 1990, 1993
6789486c7Smillert  *	The Regents of the University of California.  All rights reserved.
7df930be7Sderaadt  *
8df930be7Sderaadt  * This code is derived from software contributed to Berkeley by
9df930be7Sderaadt  * Adam de Boor.
10df930be7Sderaadt  *
11df930be7Sderaadt  * Redistribution and use in source and binary forms, with or without
12df930be7Sderaadt  * modification, are permitted provided that the following conditions
13df930be7Sderaadt  * are met:
14df930be7Sderaadt  * 1. Redistributions of source code must retain the above copyright
15df930be7Sderaadt  *    notice, this list of conditions and the following disclaimer.
16df930be7Sderaadt  * 2. Redistributions in binary form must reproduce the above copyright
17df930be7Sderaadt  *    notice, this list of conditions and the following disclaimer in the
18df930be7Sderaadt  *    documentation and/or other materials provided with the distribution.
19f75387cbSmillert  * 3. Neither the name of the University nor the names of its contributors
20df930be7Sderaadt  *    may be used to endorse or promote products derived from this software
21df930be7Sderaadt  *    without specific prior written permission.
22df930be7Sderaadt  *
23df930be7Sderaadt  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24df930be7Sderaadt  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25df930be7Sderaadt  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26df930be7Sderaadt  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27df930be7Sderaadt  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28df930be7Sderaadt  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29df930be7Sderaadt  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30df930be7Sderaadt  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31df930be7Sderaadt  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32df930be7Sderaadt  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33df930be7Sderaadt  * SUCH DAMAGE.
34df930be7Sderaadt  */
35df930be7Sderaadt 
36df930be7Sderaadt /*-
37df930be7Sderaadt  * LstDeQueue.c --
38df930be7Sderaadt  *	Remove the node and return its datum from the head of the list
39df930be7Sderaadt  */
40df930be7Sderaadt 
41df930be7Sderaadt #include	"lstInt.h"
429d9c3e66Sespie #include 	<stdlib.h>
43761218d5Sespie 
44df930be7Sderaadt /*-
45df930be7Sderaadt  *-----------------------------------------------------------------------
46df930be7Sderaadt  * Lst_DeQueue --
47df930be7Sderaadt  *	Remove and return the datum at the head of the given list.
48df930be7Sderaadt  *
49df930be7Sderaadt  * Results:
5004ed836eSespie  *	The datum in the node at the head or NULL if the list is empty.
51df930be7Sderaadt  *
52df930be7Sderaadt  * Side Effects:
53df930be7Sderaadt  *	The head node is removed from the list.
54df930be7Sderaadt  *-----------------------------------------------------------------------
55df930be7Sderaadt  */
56aa523a8eSespie void *
Lst_DeQueue(Lst l)57ad2b054bSespie Lst_DeQueue(Lst l)
58df930be7Sderaadt {
59aa523a8eSespie 	void *rd;
606cbd4985Sespie 	LstNode tln;
61df930be7Sderaadt 
6204ed836eSespie 	tln = l->firstPtr;
636cbd4985Sespie 	if (tln == NULL)
64ea727097Sespie 		return NULL;
65df930be7Sderaadt 
6618e775c1Sespie 	rd = tln->datum;
6704ed836eSespie 	l->firstPtr = tln->nextPtr;
6804ed836eSespie 	if (l->firstPtr)
6904ed836eSespie 		l->firstPtr->prevPtr = NULL;
7004ed836eSespie 	else
7104ed836eSespie 		l->lastPtr = NULL;
7204ed836eSespie 	free(tln);
736cbd4985Sespie 	return rd;
74df930be7Sderaadt }
75df930be7Sderaadt 
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