1 /* $OpenPackages$ */ 2 /* $OpenBSD: lstDeQueue.c,v 1.13 2001/05/29 12:53:45 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. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 */ 40 41 /*- 42 * LstDeQueue.c -- 43 * Remove the node and return its datum from the head of the list 44 */ 45 46 #include "lstInt.h" 47 #include <stdlib.h> 48 49 /*- 50 *----------------------------------------------------------------------- 51 * Lst_DeQueue -- 52 * Remove and return the datum at the head of the given list. 53 * 54 * Results: 55 * The datum in the node at the head or NULL if the list is empty. 56 * 57 * Side Effects: 58 * The head node is removed from the list. 59 *----------------------------------------------------------------------- 60 */ 61 void * 62 Lst_DeQueue(l) 63 Lst l; 64 { 65 void *rd; 66 LstNode tln; 67 68 tln = l->firstPtr; 69 if (tln == NULL) 70 return NULL; 71 72 rd = tln->datum; 73 l->firstPtr = tln->nextPtr; 74 if (l->firstPtr) 75 l->firstPtr->prevPtr = NULL; 76 else 77 l->lastPtr = NULL; 78 free(tln); 79 return rd; 80 } 81 82