lsearch.c (2312B)
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 /* from OpenSolaris "lsearch.c 1.15 05/06/08 SMI" */ 28 29 /* 30 * Portions Copyright (c) 2005 Gunnar Ritter, Freiburg i. Br., Germany 31 * 32 * Sccsid @(#)lsearch.c 1.4 (gritter) 11/26/05 33 */ 34 35 /* Copyright (c) 1988 AT&T */ 36 /* All Rights Reserved */ 37 38 39 /* 40 * Linear search algorithm, generalized from Knuth (6.1) Algorithm Q. 41 * 42 * This version no longer has anything to do with Knuth's Algorithm Q, 43 * which first copies the new element into the table, then looks for it. 44 * The assumption there was that the cost of checking for the end of the 45 * table before each comparison outweighed the cost of the comparison, which 46 * isn't true when an arbitrary comparison function must be called and when the 47 * copy itself takes a significant number of cycles. 48 * Actually, it has now reverted to Algorithm S, which is "simpler." 49 */ 50 51 #include <sys/types.h> 52 #include <stddef.h> 53 #include <string.h> 54 #include "search.h" 55 56 void * 57 xlsearch(const void *ky, void *bs, unsigned *nelp, unsigned width, 58 int (*compar)(const void *, const void *)) 59 { 60 char *key = (char *)ky; 61 char *base = (char *)bs; 62 char *next = base + *nelp * width; /* End of table */ 63 void *res; 64 65 for (; base < next; base += width) 66 if ((*compar)(key, base) == 0) 67 return (base); /* Key found */ 68 ++*nelp; /* Not found, add to table */ 69 res = memcpy(base, key, width); /* base now == next */ 70 return (res); 71 }