2 * Copyright 2008 Google Inc.
\r
4 * Licensed under the Apache License, Version 2.0 (the "License");
\r
5 * you may not use this file except in compliance with the License.
\r
6 * You may obtain a copy of the License at
\r
8 * http://www.apache.org/licenses/LICENSE-2.0
\r
10 * Unless required by applicable law or agreed to in writing, software
\r
11 * distributed under the License is distributed on an "AS IS" BASIS,
\r
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
\r
13 * See the License for the specific language governing permissions and
\r
14 * limitations under the License.
\r
17 package com.google.zxing.datamatrix.decoder;
\r
20 * <p>Encapsulates a block of data within a Data Matrix Code. Data Matrix Codes may split their data into
\r
21 * multiple blocks, each of which is a unit of data and error-correction codewords. Each
\r
22 * is represented by an instance of this class.</p>
\r
24 * @author bbrown@google.com (Brian Brown)
\r
26 final class DataBlock {
\r
28 private final int numDataCodewords;
\r
29 private final byte[] codewords;
\r
31 private DataBlock(int numDataCodewords, byte[] codewords) {
\r
32 this.numDataCodewords = numDataCodewords;
\r
33 this.codewords = codewords;
\r
37 * <p>When Data Matrix Codes use multiple data blocks, they actually interleave the bytes of each of them.
\r
38 * That is, the first byte of data block 1 to n is written, then the second bytes, and so on. This
\r
39 * method will separate the data into original blocks.</p>
\r
41 * @param rawCodewords bytes as read directly from the Data Matrix Code
\r
42 * @param version version of the Data Matrix Code
\r
43 * @return {@link DataBlock}s containing original bytes, "de-interleaved" from representation in the
\r
46 static DataBlock[] getDataBlocks(byte[] rawCodewords,
\r
48 // Figure out the number and size of data blocks used by this version
\r
49 Version.ECBlocks ecBlocks = version.getECBlocks();
\r
51 // First count the total number of data blocks
\r
52 int totalBlocks = 0;
\r
53 Version.ECB[] ecBlockArray = ecBlocks.getECBlocks();
\r
54 for (int i = 0; i < ecBlockArray.length; i++) {
\r
55 totalBlocks += ecBlockArray[i].getCount();
\r
58 // Now establish DataBlocks of the appropriate size and number of data codewords
\r
59 DataBlock[] result = new DataBlock[totalBlocks];
\r
60 int numResultBlocks = 0;
\r
61 for (int j = 0; j < ecBlockArray.length; j++) {
\r
62 Version.ECB ecBlock = ecBlockArray[j];
\r
63 for (int i = 0; i < ecBlock.getCount(); i++) {
\r
64 int numDataCodewords = ecBlock.getDataCodewords();
\r
65 int numBlockCodewords = ecBlocks.getECCodewords() + numDataCodewords;
\r
66 result[numResultBlocks++] = new DataBlock(numDataCodewords, new byte[numBlockCodewords]);
\r
70 // All blocks have the same amount of data, except that the last n
\r
71 // (where n may be 0) have 1 less byte. Figure out where these start.
\r
72 // TODO(bbrown): There is only one case where there is a difference for Data Matrix for size 144
\r
73 int longerBlocksTotalCodewords = result[0].codewords.length;
\r
74 int shorterBlocksTotalCodewords = longerBlocksTotalCodewords - 1;
\r
76 int longerBlocksNumDataCodewords = longerBlocksTotalCodewords - ecBlocks.getECCodewords();
\r
77 int shorterBlocksNumDataCodewords = longerBlocksNumDataCodewords - 1;
\r
78 // The last elements of result may be 1 element shorter for 144 matrix
\r
79 // first fill out as many elements as all of them have minus 1
\r
80 int rawCodewordsOffset = 0;
\r
81 for (int i = 0; i < shorterBlocksNumDataCodewords; i++) {
\r
82 for (int j = 0; j < numResultBlocks; j++) {
\r
83 result[j].codewords[i] = rawCodewords[rawCodewordsOffset++];
\r
87 // Fill out the last data block in the longer ones
\r
88 boolean specialVersion = version.getVersionNumber() == 24;
\r
89 int numLongerBlocks = specialVersion ? 8 : numResultBlocks;
\r
90 for (int j = 0; j < numLongerBlocks; j++) {
\r
91 result[j].codewords[longerBlocksNumDataCodewords - 1] = rawCodewords[rawCodewordsOffset++];
\r
94 // Now add in error correction blocks
\r
95 int max = result[0].codewords.length;
\r
96 for (int i = longerBlocksNumDataCodewords; i < max; i++) {
\r
97 for (int j = 0; j < numResultBlocks; j++) {
\r
98 int iOffset = (specialVersion && j > 7) ? i - 1 : i;
\r
99 result[j].codewords[iOffset] = rawCodewords[rawCodewordsOffset++];
\r
103 if (rawCodewordsOffset != rawCodewords.length) {
\r
104 throw new IllegalStateException();
\r
110 int getNumDataCodewords() {
\r
111 return numDataCodewords;
\r
114 byte[] getCodewords() {
\r