xref: /titanic_52/usr/src/cmd/refer/shell.c (revision 11a8fa6cb17403e630122ac19b39a323c6e64142)
1*11a8fa6cSceastha /*
2*11a8fa6cSceastha  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
3*11a8fa6cSceastha  * Use is subject to license terms.
4*11a8fa6cSceastha  */
5*11a8fa6cSceastha 
67c478bd9Sstevel@tonic-gate /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
77c478bd9Sstevel@tonic-gate /*	  All Rights Reserved  	*/
87c478bd9Sstevel@tonic-gate 
97c478bd9Sstevel@tonic-gate /*
107c478bd9Sstevel@tonic-gate  * Copyright (c) 1980 Regents of the University of California.
117c478bd9Sstevel@tonic-gate  * All rights reserved. The Berkeley software License Agreement
127c478bd9Sstevel@tonic-gate  * specifies the terms and conditions for redistribution.
137c478bd9Sstevel@tonic-gate  */
147c478bd9Sstevel@tonic-gate 
157c478bd9Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
167c478bd9Sstevel@tonic-gate 
177c478bd9Sstevel@tonic-gate /*
187c478bd9Sstevel@tonic-gate  * SORTS UP.
197c478bd9Sstevel@tonic-gate  * IF THERE ARE NO EXCHANGES (IEX=0) ON A SWEEP
207c478bd9Sstevel@tonic-gate  * THE COMPARISON GAP (IGAP) IS HALVED FOR THE NEXT SWEEP
217c478bd9Sstevel@tonic-gate  */
22*11a8fa6cSceastha void
23*11a8fa6cSceastha shell(int n, int (*comp)(), int (*exch)())
247c478bd9Sstevel@tonic-gate {
257c478bd9Sstevel@tonic-gate 	int igap, iplusg, iex, i, imax;
267c478bd9Sstevel@tonic-gate 	igap = n;
27*11a8fa6cSceastha 	while (igap > 1) {
287c478bd9Sstevel@tonic-gate 		igap /= 2;
297c478bd9Sstevel@tonic-gate 		imax = n-igap;
30*11a8fa6cSceastha 		do {
317c478bd9Sstevel@tonic-gate 			iex = 0;
32*11a8fa6cSceastha 			for (i = 0; i < imax; i++) {
337c478bd9Sstevel@tonic-gate 				iplusg = i + igap;
347c478bd9Sstevel@tonic-gate 				if ((*comp)(i, iplusg)) continue;
357c478bd9Sstevel@tonic-gate 				(*exch) (i, iplusg);
367c478bd9Sstevel@tonic-gate 				iex = 1;
377c478bd9Sstevel@tonic-gate 			}
387c478bd9Sstevel@tonic-gate 		}
39*11a8fa6cSceastha 		while (iex > 0)
40*11a8fa6cSceastha 			;
417c478bd9Sstevel@tonic-gate 	}
427c478bd9Sstevel@tonic-gate }
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