xref: /illumos-gate/usr/src/lib/libc/port/gen/tfind.c (revision ddb365bfc9e868ad24ccdcb0dc91af18b10df082)
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 (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 /*	Copyright (c) 1988 AT&T	*/
28 /*	  All Rights Reserved  	*/
29 
30 /*
31  * Tree search algorithm, generalized from Knuth (6.2.2) Algorithm T.
32  *
33  * The NODE * arguments are declared in the lint files as char *,
34  * because the definition of NODE isn't available to the user.
35  */
36 
37 #pragma weak _tfind = tfind
38 
39 #include "lint.h"
40 #include <mtlib.h>
41 #include <sys/types.h>
42 #include <search.h>
43 #include <thread.h>
44 #include <synch.h>
45 
46 typedef struct node { void *key; struct node *llink, *rlink; } NODE;
47 
48 
49 /*	tfind - find a node, or return 0	*/
50 /*
51  * ky is Key to be located
52  * rtp is the Address of the root of the tree
53  * compar is the Comparison function
54  */
55 void *
56 tfind(const void *ky, void *const *rtp,
57     int (*compar)(const void *, const void *))
58 {
59 	void *key = (char *)ky;
60 	NODE **rootp = (NODE **)rtp;
61 	if (rootp == NULL)
62 		return (NULL);
63 	while (*rootp != NULL) {			/* T1: */
64 		int r = (*compar)(key, (*rootp)->key);	/* T2: */
65 		if (r == 0)
66 			return ((void *)*rootp);	/* Key found */
67 		rootp = (r < 0) ?
68 		    &(*rootp)->llink :		/* T3: Take left branch */
69 		    &(*rootp)->rlink;		/* T4: Take right branch */
70 	}
71 	return (NULL);
72 }
73