1 /* $OpenPackages$ */
2 /* $OpenBSD: lstDeQueue.c,v 1.15 2004/04/07 13:11:36 espie Exp $ */
3 /* $NetBSD: lstDeQueue.c,v 1.5 1996/11/06 17:59:36 christos Exp $ */
4
5 /*
6 * Copyright (c) 1988, 1989, 1990, 1993
7 * The Regents of the University of California. All rights reserved.
8 *
9 * This code is derived from software contributed to Berkeley by
10 * Adam de Boor.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. 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 * LstDeQueue.c --
39 * Remove the node and return its datum from the head of the list
40 */
41
42 #include "lstInt.h"
43 #include <stdlib.h>
44
45 /*-
46 *-----------------------------------------------------------------------
47 * Lst_DeQueue --
48 * Remove and return the datum at the head of the given list.
49 *
50 * Results:
51 * The datum in the node at the head or NULL if the list is empty.
52 *
53 * Side Effects:
54 * The head node is removed from the list.
55 *-----------------------------------------------------------------------
56 */
57 void *
Lst_DeQueue(Lst l)58 Lst_DeQueue(Lst l)
59 {
60 void *rd;
61 LstNode tln;
62
63 tln = l->firstPtr;
64 if (tln == NULL)
65 return NULL;
66
67 rd = tln->datum;
68 l->firstPtr = tln->nextPtr;
69 if (l->firstPtr)
70 l->firstPtr->prevPtr = NULL;
71 else
72 l->lastPtr = NULL;
73 free(tln);
74 return rd;
75 }
76
77