xref: /onnv-gate/usr/src/lib/libc/port/gen/lfind.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate /*	Copyright (c) 1988 AT&T	*/
30*0Sstevel@tonic-gate /*	  All Rights Reserved  	*/
31*0Sstevel@tonic-gate 
32*0Sstevel@tonic-gate 
33*0Sstevel@tonic-gate /*
34*0Sstevel@tonic-gate  * Linear search algorithm, generalized from Knuth (6.1) Algorithm Q.
35*0Sstevel@tonic-gate  *
36*0Sstevel@tonic-gate  * This version no longer has anything to do with Knuth's Algorithm Q,
37*0Sstevel@tonic-gate  * which first copies the new element into the table, then looks for it.
38*0Sstevel@tonic-gate  * The assumption there was that the cost of checking for the end of the
39*0Sstevel@tonic-gate  * table before each comparison outweighed the cost of the comparison, which
40*0Sstevel@tonic-gate  * isn't true when an arbitrary comparison function must be called and when the
41*0Sstevel@tonic-gate  * copy itself takes a significant number of cycles.
42*0Sstevel@tonic-gate  * Actually, it has now reverted to Algorithm S, which is "simpler."
43*0Sstevel@tonic-gate  */
44*0Sstevel@tonic-gate 
45*0Sstevel@tonic-gate #pragma weak lfind = _lfind
46*0Sstevel@tonic-gate 
47*0Sstevel@tonic-gate #include "synonyms.h"
48*0Sstevel@tonic-gate #include <stdlib.h>
49*0Sstevel@tonic-gate #include <mtlib.h>
50*0Sstevel@tonic-gate #include <sys/types.h>
51*0Sstevel@tonic-gate #include <stdio.h>
52*0Sstevel@tonic-gate #include <thread.h>
53*0Sstevel@tonic-gate #include <synch.h>
54*0Sstevel@tonic-gate #include <search.h>
55*0Sstevel@tonic-gate 
56*0Sstevel@tonic-gate void *
57*0Sstevel@tonic-gate lfind(const void *ky, const void *bs, size_t *nelp,
58*0Sstevel@tonic-gate 	size_t width, int (*compar)())
59*0Sstevel@tonic-gate {
60*0Sstevel@tonic-gate 	char *key = (char *)ky;
61*0Sstevel@tonic-gate 	char *base = (char *)bs;
62*0Sstevel@tonic-gate 	char *next = base + *nelp * width;	/* End of table */
63*0Sstevel@tonic-gate 
64*0Sstevel@tonic-gate 	for (; base < next; base += width)
65*0Sstevel@tonic-gate 		if ((*compar)(key, base) == 0)
66*0Sstevel@tonic-gate 			return (base);	/* Key found */
67*0Sstevel@tonic-gate 	return (NULL);
68*0Sstevel@tonic-gate }
69