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