1 /*
 2  * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  */
23 package org.openjdk.bench.valhalla.util;
24 
25 import java.util.Random;
26 
27 public class Utils {
28 
29     public static void shuffle(int[] a, Random rnd) {
30         for (int i = a.length; i > 1; i--) {
31             int idx = rnd.nextInt(i);
32             int tmp = a[i - 1];
33             a[i - 1] = a[idx];
34             a[idx] = tmp;
35         }
36 
37     }
38 
39     public static int[] makeRandomRing(int size) {
40         int[] A = new int[size - 1];
41         for (int i = 0; i < A.length; i++) {
42             A[i] = i + 1;
43         }
44         shuffle(A, new Random(42));
45         int[] a = new int[size];
46         int x = 0;
47         for (int i = 0; i < A.length; i++) {
48             x = a[x] = A[i];
49         }
50         a[x] = 0;
51         return a;
52     }
53 }