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 /* Copyright (c) 1984 AT&T */
23*0Sstevel@tonic-gate /* All Rights Reserved */
24*0Sstevel@tonic-gate
25*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" /* from S5R2 1.5 */
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate /*LINTLIBRARY*/
28*0Sstevel@tonic-gate /*
29*0Sstevel@tonic-gate * Binary search algorithm, generalized from Knuth (6.2.1) Algorithm B.
30*0Sstevel@tonic-gate *
31*0Sstevel@tonic-gate */
32*0Sstevel@tonic-gate
33*0Sstevel@tonic-gate typedef char *POINTER;
34*0Sstevel@tonic-gate
35*0Sstevel@tonic-gate POINTER
bsearch(key,base,nel,width,compar)36*0Sstevel@tonic-gate bsearch(key, base, nel, width, compar)
37*0Sstevel@tonic-gate POINTER key; /* Key to be located */
38*0Sstevel@tonic-gate POINTER base; /* Beginning of table */
39*0Sstevel@tonic-gate unsigned nel; /* Number of elements in the table */
40*0Sstevel@tonic-gate unsigned width; /* Width of an element (bytes) */
41*0Sstevel@tonic-gate int (*compar)(); /* Comparison function */
42*0Sstevel@tonic-gate {
43*0Sstevel@tonic-gate int two_width = width + width;
44*0Sstevel@tonic-gate POINTER last = base + width * (nel - 1); /* Last element in table */
45*0Sstevel@tonic-gate
46*0Sstevel@tonic-gate while (last >= base) {
47*0Sstevel@tonic-gate
48*0Sstevel@tonic-gate register POINTER p = base + width * ((last - base)/two_width);
49*0Sstevel@tonic-gate register int res = (*compar)(key, p);
50*0Sstevel@tonic-gate
51*0Sstevel@tonic-gate if (res == 0)
52*0Sstevel@tonic-gate return (p); /* Key found */
53*0Sstevel@tonic-gate if (res < 0)
54*0Sstevel@tonic-gate last = p - width;
55*0Sstevel@tonic-gate else
56*0Sstevel@tonic-gate base = p + width;
57*0Sstevel@tonic-gate }
58*0Sstevel@tonic-gate return ((POINTER) 0); /* Key not found */
59*0Sstevel@tonic-gate }
60