1236769Sobrien/* $NetBSD: lstNext.c,v 1.12 2008/12/13 15:19:29 dsl Exp $ */ 2236769Sobrien 3236769Sobrien/* 4236769Sobrien * Copyright (c) 1988, 1989, 1990, 1993 5236769Sobrien * The Regents of the University of California. All rights reserved. 6236769Sobrien * 7236769Sobrien * This code is derived from software contributed to Berkeley by 8236769Sobrien * Adam de Boor. 9236769Sobrien * 10236769Sobrien * Redistribution and use in source and binary forms, with or without 11236769Sobrien * modification, are permitted provided that the following conditions 12236769Sobrien * are met: 13236769Sobrien * 1. Redistributions of source code must retain the above copyright 14236769Sobrien * notice, this list of conditions and the following disclaimer. 15236769Sobrien * 2. Redistributions in binary form must reproduce the above copyright 16236769Sobrien * notice, this list of conditions and the following disclaimer in the 17236769Sobrien * documentation and/or other materials provided with the distribution. 18236769Sobrien * 3. Neither the name of the University nor the names of its contributors 19236769Sobrien * may be used to endorse or promote products derived from this software 20236769Sobrien * without specific prior written permission. 21236769Sobrien * 22236769Sobrien * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23236769Sobrien * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24236769Sobrien * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25236769Sobrien * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26236769Sobrien * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27236769Sobrien * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28236769Sobrien * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29236769Sobrien * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30236769Sobrien * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31236769Sobrien * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32236769Sobrien * SUCH DAMAGE. 33236769Sobrien */ 34236769Sobrien 35236769Sobrien#ifndef MAKE_NATIVE 36236769Sobrienstatic char rcsid[] = "$NetBSD: lstNext.c,v 1.12 2008/12/13 15:19:29 dsl Exp $"; 37236769Sobrien#else 38236769Sobrien#include <sys/cdefs.h> 39236769Sobrien#ifndef lint 40236769Sobrien#if 0 41236769Sobrienstatic char sccsid[] = "@(#)lstNext.c 8.1 (Berkeley) 6/6/93"; 42236769Sobrien#else 43236769Sobrien__RCSID("$NetBSD: lstNext.c,v 1.12 2008/12/13 15:19:29 dsl Exp $"); 44236769Sobrien#endif 45236769Sobrien#endif /* not lint */ 46236769Sobrien#endif 47236769Sobrien 48236769Sobrien/*- 49236769Sobrien * LstNext.c -- 50236769Sobrien * Return the next node for a list. 51236769Sobrien * The sequential functions access the list in a slightly different way. 52236769Sobrien * CurPtr points to their idea of the current node in the list and they 53236769Sobrien * access the list based on it. Because the list is circular, Lst_Next 54236769Sobrien * and Lst_Prev will go around the list forever. Lst_IsAtEnd must be 55236769Sobrien * used to determine when to stop. 56236769Sobrien */ 57236769Sobrien 58236769Sobrien#include "lstInt.h" 59236769Sobrien 60236769Sobrien/*- 61236769Sobrien *----------------------------------------------------------------------- 62236769Sobrien * Lst_Next -- 63236769Sobrien * Return the next node for the given list. 64236769Sobrien * 65236769Sobrien * Results: 66236769Sobrien * The next node or NULL if the list has yet to be opened. Also 67236769Sobrien * if the list is non-circular and the end has been reached, NULL 68236769Sobrien * is returned. 69236769Sobrien * 70236769Sobrien * Side Effects: 71236769Sobrien * the curPtr field is updated. 72236769Sobrien * 73236769Sobrien *----------------------------------------------------------------------- 74236769Sobrien */ 75236769SobrienLstNode 76236769SobrienLst_Next(Lst l) 77236769Sobrien{ 78236769Sobrien ListNode tln; 79236769Sobrien List list = l; 80236769Sobrien 81236769Sobrien if ((LstValid (l) == FALSE) || 82236769Sobrien (list->isOpen == FALSE)) { 83236769Sobrien return NULL; 84236769Sobrien } 85236769Sobrien 86236769Sobrien list->prevPtr = list->curPtr; 87236769Sobrien 88236769Sobrien if (list->curPtr == NULL) { 89236769Sobrien if (list->atEnd == Unknown) { 90236769Sobrien /* 91236769Sobrien * If we're just starting out, atEnd will be Unknown. 92236769Sobrien * Then we want to start this thing off in the right 93236769Sobrien * direction -- at the start with atEnd being Middle. 94236769Sobrien */ 95236769Sobrien list->curPtr = tln = list->firstPtr; 96236769Sobrien list->atEnd = Middle; 97236769Sobrien } else { 98236769Sobrien tln = NULL; 99236769Sobrien list->atEnd = Tail; 100236769Sobrien } 101236769Sobrien } else { 102236769Sobrien tln = list->curPtr->nextPtr; 103236769Sobrien list->curPtr = tln; 104236769Sobrien 105236769Sobrien if (tln == list->firstPtr || tln == NULL) { 106236769Sobrien /* 107236769Sobrien * If back at the front, then we've hit the end... 108236769Sobrien */ 109236769Sobrien list->atEnd = Tail; 110236769Sobrien } else { 111236769Sobrien /* 112236769Sobrien * Reset to Middle if gone past first. 113236769Sobrien */ 114236769Sobrien list->atEnd = Middle; 115236769Sobrien } 116236769Sobrien } 117236769Sobrien 118236769Sobrien return (tln); 119236769Sobrien} 120236769Sobrien 121