1 /* 2 * Copyright (C) 2018 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 import java.math.BigInteger; 18 19 // This is motivated by the assumption that BigInteger allocates malloc memory 20 // underneath. That's true (in 2018) on Android. 21 22 public class Main { main(String[] args)23 public static void main(String[] args) throws Exception { 24 final int nIters = 20_000; // Presumed < 1_000_000. 25 final BigInteger big2_20 = BigInteger.valueOf(1024*1024); // 2^20 26 BigInteger huge = BigInteger.valueOf(1).shiftLeft(4_000_000); // ~0.5MB 27 for (int i = 0; i < nIters; ++i) { // 10 GB total 28 huge = huge.add(BigInteger.ONE); 29 } 30 if (huge.bitLength() != 4_000_001) { 31 System.out.println("Wrong answer length: " + huge.bitLength()); 32 } else if (huge.mod(big2_20).compareTo(BigInteger.valueOf(nIters)) != 0) { 33 System.out.println("Wrong answer: ..." + huge.mod(big2_20)); 34 } else { 35 System.out.println("Test complete"); 36 } 37 } 38 } 39