xref: /titanic_41/usr/src/lib/libc/port/gen/lfind.c (revision 986fd29a0dc13f7608ef7f508f6e700bd7bc2720)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 /*	Copyright (c) 1988 AT&T	*/
30 /*	  All Rights Reserved  	*/
31 
32 
33 /*
34  * Linear search algorithm, generalized from Knuth (6.1) Algorithm Q.
35  *
36  * This version no longer has anything to do with Knuth's Algorithm Q,
37  * which first copies the new element into the table, then looks for it.
38  * The assumption there was that the cost of checking for the end of the
39  * table before each comparison outweighed the cost of the comparison, which
40  * isn't true when an arbitrary comparison function must be called and when the
41  * copy itself takes a significant number of cycles.
42  * Actually, it has now reverted to Algorithm S, which is "simpler."
43  */
44 
45 #pragma weak lfind = _lfind
46 
47 #include "synonyms.h"
48 #include <stdlib.h>
49 #include <mtlib.h>
50 #include <sys/types.h>
51 #include <stdio.h>
52 #include <thread.h>
53 #include <synch.h>
54 #include <search.h>
55 
56 void *
57 lfind(const void *ky, const void *bs, size_t *nelp,
58 	size_t width, int (*compar)())
59 {
60 	char *key = (char *)ky;
61 	char *base = (char *)bs;
62 	char *next = base + *nelp * width;	/* End of table */
63 
64 	for (; base < next; base += width)
65 		if ((*compar)(key, base) == 0)
66 			return (base);	/* Key found */
67 	return (NULL);
68 }
69