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/* $OpenBSD: lstNext.c,v 1.4 1998/12/05 00:06:32 espie Exp $ */
/* $NetBSD: lstNext.c,v 1.5 1996/11/06 17:59:49 christos Exp $ */
/*
* Copyright (c) 1988, 1989, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Adam de Boor.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)lstNext.c 8.1 (Berkeley) 6/6/93";
#else
static char rcsid[] = "$OpenBSD: lstNext.c,v 1.4 1998/12/05 00:06:32 espie Exp $";
#endif
#endif /* not lint */
/*-
* LstNext.c --
* Return the next node for a list.
* The sequential functions access the list in a slightly different way.
* CurPtr points to their idea of the current node in the list and they
* access the list based on it. Because the list is circular, Lst_Next
* and Lst_Prev will go around the list forever. Lst_IsAtEnd must be
* used to determine when to stop.
*/
#include "lstInt.h"
/*-
*-----------------------------------------------------------------------
* Lst_Next --
* Return the next node for the given list.
*
* Results:
* The next node or NILLNODE if the list has yet to be opened. Also
* if the list is non-circular and the end has been reached, NILLNODE
* is returned.
*
* Side Effects:
* the curPtr field is updated.
*
*-----------------------------------------------------------------------
*/
LstNode
Lst_Next (l)
Lst l;
{
register ListNode tln;
register List list = (List)l;
if ((LstValid (l) == FALSE) ||
(list->isOpen == FALSE)) {
return (NILLNODE);
}
list->prevPtr = list->curPtr;
if (list->curPtr == NilListNode) {
if (list->atEnd == Unknown) {
/*
* If we're just starting out, atEnd will be Unknown.
* Then we want to start this thing off in the right
* direction -- at the start with atEnd being Middle.
*/
list->curPtr = tln = list->firstPtr;
list->atEnd = Middle;
} else {
tln = NilListNode;
list->atEnd = Tail;
}
} else {
tln = list->curPtr->nextPtr;
list->curPtr = tln;
if (tln == list->firstPtr || tln == NilListNode) {
/*
* If back at the front, then we've hit the end...
*/
list->atEnd = Tail;
} else {
/*
* Reset to Middle if gone past first.
*/
list->atEnd = Middle;
}
}
return ((LstNode)tln);
}
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