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 * 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