/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/


/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved. The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/*
 * Copyright (c) 1983, 1984 1985, 1986, 1987, 1988, Sun Microsystems, Inc.
 * All Rights Reserved.
 */

/*	from OpenSolaris "shell.c	1.3	05/06/02 SMI" 	*/

/*
 * Portions Copyright (c) 2005 Gunnar Ritter, Freiburg i. Br., Germany
 *
 * Sccsid @(#)shell.c	1.4 (gritter) 12/25/06
 */

/*
 * SORTS UP.
 * IF THERE ARE NO EXCHANGES (IEX=0) ON A SWEEP
 * THE COMPARISON GAP (IGAP) IS HALVED FOR THE NEXT SWEEP
 */

#include "refer..c"

void
shell (int n, int (*comp)(int, int), int (*exch)(int, int))
{
	int igap, iplusg, iex, i, imax;
	igap=n;
	while (igap > 1)
	{
		igap /= 2;
		imax = n-igap;
		do
		    {
			iex=0;
			for(i=0; i<imax; i++)
			{
				iplusg = i + igap;
				if ((*comp) (i, iplusg) ) continue;
				(*exch) (i, iplusg);
				iex=1;
			}
		} 
		while (iex>0);
	}
}
