77 lines
2.4 KiB
C
77 lines
2.4 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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/*%% $XConsortium: isbsearch.c /main/3 1995/10/23 11:35:44 rswiston $ */
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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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* isbsearch.c
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*
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* Description:
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* Binary search function.
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* If differs from bsearch(3) in that if an exact match is not found,
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* the next lower key is returned. If key is lower than any key in table,
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* NULL value is returned.
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*
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*/
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char *_isbsearch (char *key, char *table, int nelems, int keylen, int (*cmpf) (const void *, const void *))
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{
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int len,l1,result; /* current length of array to search */
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char *p,*low;
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if (nelems <= 0) return (char *) 0;
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/* Check if key is lower than any key in the table. */
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result = (*cmpf) (key,table);
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if (result < 0 ) return (char *) 0; /* Key is lower */
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else if (result == 0) return table; /* Exact match */
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for (low = table,len = nelems; len > 0;) {
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l1 = len >> 1;
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p = low + keylen * l1;
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if ((result = (*cmpf) (key,p)) == 0) /* Exact match found */
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return p;
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if (result > 0 ) { /* Key is in higher half */
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len -= l1 + 1;
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low = p + keylen;
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}
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else { /* Key is in lower half */
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len = l1 ;
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}
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}
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/* No matching key found, return next lower key */
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return (result>0)?p:(p-keylen);
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}
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