1 /* $OpenBSD: lstDeQueue.c,v 1.3 1996/11/30 21:09:12 millert 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. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the University of 22 * California, Berkeley and its contributors. 23 * 4. Neither the name of the University nor the names of its contributors 24 * may be used to endorse or promote products derived from this software 25 * without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 37 * SUCH DAMAGE. 38 */ 39 40 #ifndef lint 41 #if 0 42 static char sccsid[] = "@(#)lstDeQueue.c 8.1 (Berkeley) 6/6/93"; 43 #else 44 static char rcsid[] = "$OpenBSD: lstDeQueue.c,v 1.3 1996/11/30 21:09:12 millert Exp $"; 45 #endif 46 #endif /* not lint */ 47 48 /*- 49 * LstDeQueue.c -- 50 * Remove the node and return its datum from the head of the list 51 */ 52 53 #include "lstInt.h" 54 55 /*- 56 *----------------------------------------------------------------------- 57 * Lst_DeQueue -- 58 * Remove and return the datum at the head of the given list. 59 * 60 * Results: 61 * The datum in the node at the head or (ick) NIL if the list 62 * is empty. 63 * 64 * Side Effects: 65 * The head node is removed from the list. 66 * 67 *----------------------------------------------------------------------- 68 */ 69 ClientData 70 Lst_DeQueue (l) 71 Lst l; 72 { 73 ClientData rd; 74 register ListNode tln; 75 76 tln = (ListNode) Lst_First (l); 77 if (tln == NilListNode) { 78 return ((ClientData) NIL); 79 } 80 81 rd = tln->datum; 82 if (Lst_Remove (l, (LstNode)tln) == FAILURE) { 83 return ((ClientData) NIL); 84 } else { 85 return (rd); 86 } 87 } 88 89