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