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      1 /*
      2  * Copyright (C) 2008 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 package android.core;
     18 
     19 import junit.framework.TestCase;
     20 
     21 import java.util.zip.Adler32;
     22 import java.util.zip.CRC32;
     23 import android.test.suitebuilder.annotation.SmallTest;
     24 
     25 /**
     26  * tests for CRC32 and Adler32 checksum algorithms.
     27  */
     28 public class ChecksumTest extends TestCase {
     29 
     30     @SmallTest
     31     public void testChecksum() throws Exception {
     32         /*
     33          * Values computed experimentally, using C interfaces.
     34          */
     35         adler32Test(mTestString, 0x9de210dbL);
     36         cRC32Test(mTestString, 0x939f04afL);
     37 
     38         // Test for issue 1016037
     39         wrongChecksumWithAdler32Test();
     40     }
     41 
     42     private void adler32Test(byte[] values, long expected) {
     43         Adler32 adler = new Adler32();
     44 
     45         // try it all at once
     46         adler.update(values);
     47         assertEquals(adler.getValue(), expected);
     48 
     49         // try resetting and computing one byte at a time
     50         adler.reset();
     51         for (int i = 0; i < values.length; i++) {
     52             adler.update(values[i]);
     53         }
     54         assertEquals(adler.getValue(), expected);
     55     }
     56 
     57     private void cRC32Test(byte[] values, long expected) {
     58         CRC32 crc = new CRC32();
     59 
     60         // try it all at once
     61         crc.update(values);
     62         assertEquals(crc.getValue(), expected);
     63 
     64         // try resetting and computing one byte at a time
     65         crc.reset();
     66         for (int i = 0; i < values.length; i++) {
     67             crc.update(values[i]);
     68         }
     69         assertEquals(crc.getValue(), expected);
     70     }
     71 
     72     // "The quick brown fox jumped over the lazy dogs\n"
     73     private static byte[] mTestString = {
     74             0x54, 0x68, 0x65, 0x20, 0x71, 0x75, 0x69, 0x63,
     75             0x6b, 0x20, 0x62, 0x72, 0x6f, 0x77, 0x6e, 0x20,
     76             0x66, 0x6f, 0x78, 0x20, 0x6a, 0x75, 0x6d, 0x70,
     77             0x65, 0x64, 0x20, 0x6f, 0x76, 0x65, 0x72, 0x20,
     78             0x74, 0x68, 0x65, 0x20, 0x6c, 0x61, 0x7a, 0x79,
     79             0x20, 0x64, 0x6f, 0x67, 0x73, 0x2e, 0x0a
     80     };
     81 
     82 
     83     // Test for issue 1016037
     84     private void wrongChecksumWithAdler32Test() {
     85         byte[] bytes = {1, 0, 5, 0, 15, 0, 1, 11, 0, 1};
     86         Adler32 adler = new Adler32();
     87         adler.update(bytes);
     88         long arrayChecksum = adler.getValue();
     89         adler.reset();
     90         for (int i = 0; i < bytes.length; i++) {
     91             adler.update(bytes[i]);
     92         }
     93         assertEquals("Checksums not equal: expected: " + arrayChecksum +
     94                 " actual: " + adler.getValue(), arrayChecksum, adler.getValue());
     95     }
     96 }
     97 
     98