1 /* $OpenBSD: lstDeQueue.c,v 1.19 2010/07/19 19:46:44 espie Exp $ */
2 /* $NetBSD: lstDeQueue.c,v 1.5 1996/11/06 17:59:36 christos Exp $ */
3
4 /*
5 * Copyright (c) 1988, 1989, 1990, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Adam de Boor.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /*-
37 * LstDeQueue.c --
38 * Remove the node and return its datum from the head of the list
39 */
40
41 #include "lstInt.h"
42 #include <stdlib.h>
43
44 /*-
45 *-----------------------------------------------------------------------
46 * Lst_DeQueue --
47 * Remove and return the datum at the head of the given list.
48 *
49 * Results:
50 * The datum in the node at the head or NULL if the list is empty.
51 *
52 * Side Effects:
53 * The head node is removed from the list.
54 *-----------------------------------------------------------------------
55 */
56 void *
Lst_DeQueue(Lst l)57 Lst_DeQueue(Lst l)
58 {
59 void *rd;
60 LstNode tln;
61
62 tln = l->firstPtr;
63 if (tln == NULL)
64 return NULL;
65
66 rd = tln->datum;
67 l->firstPtr = tln->nextPtr;
68 if (l->firstPtr)
69 l->firstPtr->prevPtr = NULL;
70 else
71 l->lastPtr = NULL;
72 free(tln);
73 return rd;
74 }
75
76