usr/src/lib/libc/port/gen/lsearch.c
author stevel@tonic-gate
Tue, 14 Jun 2005 00:00:00 -0700
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OpenSolaris Launch
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/*
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 * CDDL HEADER START
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 *
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 * The contents of this file are subject to the terms of the
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 * Common Development and Distribution License, Version 1.0 only
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 * (the "License").  You may not use this file except in compliance
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 * with the License.
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 *
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 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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 * or http://www.opensolaris.org/os/licensing.
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 * See the License for the specific language governing permissions
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 * and limitations under the License.
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 *
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 * When distributing Covered Code, include this CDDL HEADER in each
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 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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 * If applicable, add the following below this CDDL HEADER, with the
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 * fields enclosed by brackets "[]" replaced with your own identifying
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 * information: Portions Copyright [yyyy] [name of copyright owner]
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 *
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 * CDDL HEADER END
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 */
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/*
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 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
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 * Use is subject to license terms.
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 */
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#pragma ident	"%Z%%M%	%I%	%E% SMI"
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/*	Copyright (c) 1988 AT&T	*/
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/*	  All Rights Reserved  	*/
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/*
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 * Linear search algorithm, generalized from Knuth (6.1) Algorithm Q.
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 *
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 * This version no longer has anything to do with Knuth's Algorithm Q,
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 * which first copies the new element into the table, then looks for it.
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 * The assumption there was that the cost of checking for the end of the
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 * table before each comparison outweighed the cost of the comparison, which
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 * isn't true when an arbitrary comparison function must be called and when the
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 * copy itself takes a significant number of cycles.
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 * Actually, it has now reverted to Algorithm S, which is "simpler."
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 */
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#pragma weak lsearch = _lsearch
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#include "synonyms.h"
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#include <mtlib.h>
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#include <sys/types.h>
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#include <stddef.h>
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#include <string.h>
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#include <thread.h>
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#include <synch.h>
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void *
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lsearch(const void *ky, void *bs, size_t *nelp, size_t width,
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	int (*compar)(const void *, const void *))
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{
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	char *key = (char *)ky;
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	char *base = (char *)bs;
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	char *next = base + *nelp * width;	/* End of table */
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	void *res;
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	for (; base < next; base += width)
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		if ((*compar)(key, base) == 0)
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			return (base);	/* Key found */
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	++*nelp;			/* Not found, add to table */
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	res = memcpy(base, key, width);	/* base now == next */
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	return (res);
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}