xref: /titanic_52/usr/src/lib/libbc/libc/gen/common/lsearch.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*      Copyright (c) 1984 AT&T */
/*        All Rights Reserved   */

#pragma ident	"%Z%%M%	%I%	%E% SMI"  /* from S5R2 1.8 */

/*LINTLIBRARY*/
/*
 * Linear search algorithm, generalized from Knuth (6.1) Algorithm Q.
 *
 * This version no longer has anything to do with Knuth's Algorithm Q,
 * which first copies the new element into the table, then looks for it.
 * The assumption there was that the cost of checking for the end of the
 * table before each comparison outweighed the cost of the comparison, which
 * isn't true when an arbitrary comparison function must be called and when the
 * copy itself takes a significant number of cycles.
 * Actually, it has now reverted to Algorithm S, which is "simpler."
 */

typedef char *POINTER;
extern POINTER memcpy();

POINTER
lsearch(key, base, nelp, width, compar)
register POINTER key;		/* Key to be located */
register POINTER base;		/* Beginning of table */
unsigned *nelp;			/* Pointer to current table size */
register unsigned width;	/* Width of an element (bytes) */
int (*compar)();		/* Comparison function */
{
	register POINTER next = base + *nelp * width;	/* End of table */

	for ( ; base < next; base += width)
		if ((*compar)(key, base) == 0)
			return (base);	/* Key found */
	++*nelp;			/* Not found, add to table */
	return (memcpy(base, key, (int)width));	/* base now == next */
}