2 * Copyright 2008 ZXing authors
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 package com.google.zxing.common.reedsolomon;
19 import junit.framework.TestCase;
21 import java.util.BitSet;
22 import java.util.Random;
25 * @author srowen@google.com (Sean Owen)
27 public final class ReedSolomonDecoderQRCodeTestCase extends TestCase {
29 /** See ISO 18004, Appendix I, from which this example is taken. */
30 private static final int[] QR_CODE_TEST =
31 { 0x10, 0x20, 0x0C, 0x56, 0x61, 0x80, 0xEC, 0x11, 0xEC,
32 0x11, 0xEC, 0x11, 0xEC, 0x11, 0xEC, 0x11, 0xA5 };
33 private static final int[] QR_CODE_TEST_WITH_EC =
34 { 0x10, 0x20, 0x0C, 0x56, 0x61, 0x80, 0xEC, 0x11, 0xEC,
35 0x11, 0xEC, 0x11, 0xEC, 0x11, 0xEC, 0x11, 0xA5, 0x24,
36 0xD4, 0xC1, 0xED, 0x36, 0xC7, 0x87, 0x2C, 0x55 };
37 private static final int QR_CODE_CORRECTABLE = (QR_CODE_TEST_WITH_EC.length - QR_CODE_TEST.length) / 2;
39 private final ReedSolomonDecoder qrRSDecoder = new ReedSolomonDecoder(GF256.QR_CODE_FIELD);
41 public void testNoError() throws ReedSolomonException {
42 int[] received = new int[QR_CODE_TEST_WITH_EC.length];
43 System.arraycopy(QR_CODE_TEST_WITH_EC, 0, received, 0, received.length);
45 checkQRRSDecode(received);
48 public void testOneError() throws ReedSolomonException {
49 int[] received = new int[QR_CODE_TEST_WITH_EC.length];
50 Random random = new Random(0xDEADBEEFL);
51 for (int i = 0; i < received.length; i++) {
52 System.arraycopy(QR_CODE_TEST_WITH_EC, 0, received, 0, received.length);
53 received[i] = random.nextInt(256);
54 checkQRRSDecode(received);
58 public void testMaxErrors() throws ReedSolomonException {
59 int[] received = new int[QR_CODE_TEST_WITH_EC.length];
60 Random random = new Random(0xDEADBEEFL);
61 for (int i = 0; i < QR_CODE_TEST.length; i++) { // # iterations is kind of arbitrary
62 System.arraycopy(QR_CODE_TEST_WITH_EC, 0, received, 0, received.length);
63 corrupt(received, QR_CODE_CORRECTABLE, random);
64 checkQRRSDecode(received);
68 public void testTooManyErrors() {
69 int[] received = new int[QR_CODE_TEST_WITH_EC.length];
70 System.arraycopy(QR_CODE_TEST_WITH_EC, 0, received, 0, received.length);
71 Random random = new Random(0xDEADBEEFL);
72 corrupt(received, QR_CODE_CORRECTABLE + 1, random);
74 checkQRRSDecode(received);
75 fail("Should not have decoded");
76 } catch (ReedSolomonException rse) {
81 private void checkQRRSDecode(int[] received) throws ReedSolomonException {
82 qrRSDecoder.decode(received, 2*QR_CODE_CORRECTABLE, false);
83 for (int i = 0; i < QR_CODE_TEST.length; i++) {
84 assertEquals(received[i], QR_CODE_TEST[i]);
88 private static void corrupt(int[] received, int howMany, Random random) {
89 BitSet corrupted = new BitSet(received.length);
90 for (int j = 0; j < howMany; j++) {
91 int location = random.nextInt(received.length);
92 if (corrupted.get(location)) {
95 corrupted.set(location);
96 int newByte = random.nextInt(256);
97 received[location] = newByte;