109 lines
3.6 KiB
C
109 lines
3.6 KiB
C
/*
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* CDE - Common Desktop Environment
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*
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* Copyright (c) 1993-2012, The Open Group. All rights reserved.
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*
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* These libraries and programs are free software; you can
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* redistribute them and/or modify them under the terms of the GNU
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* Lesser General Public License as published by the Free Software
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* Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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* These libraries and programs are distributed in the hope that
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* they will be useful, but WITHOUT ANY WARRANTY; without even the
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* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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* PURPOSE. See the GNU Lesser General Public License for more
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* details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with these libraries and programs; if not, write
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* to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
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* Floor, Boston, MA 02110-1301 USA
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*/
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/*%% (c) Copyright 1993, 1994 Hewlett-Packard Company */
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/*%% (c) Copyright 1993, 1994 International Business Machines Corp. */
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/*%% (c) Copyright 1993, 1994 Sun Microsystems, Inc. */
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/*%% (c) Copyright 1993, 1994 Novell, Inc. */
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/*%% $TOG: isdlink.c /main/4 1999/09/29 15:03:15 mgreess $ */
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/*
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* Copyright (c) 1988 by Sun Microsystems, Inc.
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*/
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/*
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* isdlink.c
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*
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* Description:
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* Double link list functions
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*/
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#include "isam_impl.h"
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/* _isdln_base_insert () - Insert element into list (at the front) -----------*/
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void _isdln_base_insert (char *base, struct dlink *l,
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struct dlink *e)
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{
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e->dln_forward = l->dln_forward;
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l->dln_forward = (char *)e - base;
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e->dln_backward = (char *)l - base;
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((struct dlink *)(base + e->dln_forward))->dln_backward = (char *)e - base;
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}
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/* _isdln_base_append () - Append element to list (at the end) -------------*/
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void _isdln_base_append (char *base, struct dlink *l,
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struct dlink *e)
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{
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e->dln_backward = l->dln_backward;
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l->dln_backward = (char *)e - base;
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e->dln_forward = (char *)l - base;
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((struct dlink *)(base + e->dln_backward))->dln_forward = (char *)e - base;
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}
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/* _isdln_base_remove () - Remove element from list -------------------------*/
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void _isdln_base_remove (char *base, struct dlink *e)
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{
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((struct dlink *)(base + e->dln_backward))->dln_forward = e->dln_forward;
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((struct dlink *)(base + e->dln_forward))->dln_backward = e->dln_backward;
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}
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/* _isdln_base_first () - Return first element of the list -------------------*/
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struct dlink * _isdln_base_first(char *base, struct dlink *l)
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{
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struct dlink *val = (struct dlink *)(base + l->dln_forward);
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if (val == NULL) {
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if (NULL == (struct dlink *)(base + l->dln_forward) &&
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NULL == (struct dlink *)(base + l->dln_backward))
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_isdln_base_makeempty(base, l);
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val = l;
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}
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return(val);
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}
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/* _isdln_base_next () - Return next element in the list --------------------*/
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struct dlink * _isdln_base_next(char *base, struct dlink *l)
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{
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return (((struct dlink *)(base + l->dln_forward)));
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}
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/* _isdln_base_prev () - Return previous element in the list ----------------*/
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struct dlink * _isdln_base_prev(char *base, struct dlink *l)
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{
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return (((struct dlink *)(base + l->dln_backward)));
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}
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/* _isdln_base_makeempty () - Make head of empty list -----------------------*/
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void _isdln_base_makeempty(char *base, struct dlink *l)
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{
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l->dln_forward = l->dln_backward = (char *)l - base;
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}
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/* _isdln_base_isempty () - Test if list is empty---------------------------*/
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int _isdln_base_isempty(char *base, struct dlink *l)
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{
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return (l->dln_forward == (char *)l - base &&
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l->dln_backward == (char *)l - base);
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}
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