1 /* $OpenPackages$ */ 2 /* $OpenBSD: lstDeQueue.c,v 1.18 2007/09/16 09:46:14 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 * 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