2 * Licensed under the Apache License, Version 2.0 (the "License");
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3 * you may not use this file except in compliance with the License.
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4 * You may obtain a copy of the License at
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6 * http://www.apache.org/licenses/LICENSE-2.0
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8 * Unless required by applicable law or agreed to in writing, software
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9 * distributed under the License is distributed on an "AS IS" BASIS,
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10 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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11 * See the License for the specific language governing permissions and
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12 * limitations under the License.
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16 namespace com.google.zxing.qrcode.decoder
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19 /// <summary> <p>Encapsulates a block of data within a QR Code. QR Codes may split their data into
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20 /// multiple blocks, each of which is a unit of data and error-correction codewords. Each
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21 /// is represented by an instance of this class.</p>
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24 /// <author> srowen@google.com (Sean Owen)
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26 public sealed class DataBlock
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28 internal int NumDataCodewords
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32 return numDataCodewords;
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36 internal sbyte[] Codewords
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45 //UPGRADE_NOTE: Final was removed from the declaration of 'numDataCodewords '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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46 private int numDataCodewords;
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47 //UPGRADE_NOTE: Final was removed from the declaration of 'codewords '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
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48 private sbyte[] codewords;
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50 public DataBlock(int numDataCodewords, sbyte[] codewords)
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52 this.numDataCodewords = numDataCodewords;
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53 this.codewords = codewords;
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56 /// <summary> <p>When QR Codes use multiple data blocks, they are actually interleave the bytes of each of them.
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57 /// 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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58 /// method will separate the data into original blocks.</p>
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61 /// <param name="rawCodewords">bytes as read directly from the QR Code
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63 /// <param name="version">version of the QR Code
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65 /// <param name="ecLevel">error-correction level of the QR Code
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67 /// <returns> {@link DataBlock}s containing original bytes, "de-interleaved" from representation in the
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70 internal static DataBlock[] getDataBlocks(sbyte[] rawCodewords, Version version, ErrorCorrectionLevel ecLevel)
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72 // Figure out the number and size of data blocks used by this version and
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73 // error correction level
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74 Version.ECBlocks ecBlocks = version.getECBlocksForLevel(ecLevel);
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76 // First count the total number of data blocks
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77 int totalBlocks = 0;
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78 Version.ECB[] ecBlockArray = ecBlocks.getECBlocks();
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79 for (int i = 0; i < ecBlockArray.Length; i++)
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81 totalBlocks += ecBlockArray[i].getCount();
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84 // Now establish DataBlocks of the appropriate size and number of data codewords
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85 DataBlock[] result = new DataBlock[totalBlocks];
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86 int numResultBlocks = 0;
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87 for (int j = 0; j < ecBlockArray.Length; j++)
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89 Version.ECB ecBlock = ecBlockArray[j];
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90 for (int i = 0; i < ecBlock.getCount(); i++)
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92 int numDataCodewords = ecBlock.getDataCodewords();
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93 int numBlockCodewords = ecBlocks.getTotalECCodewords() + numDataCodewords;
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94 result[numResultBlocks++] = new DataBlock(numDataCodewords, new sbyte[numBlockCodewords]);
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98 // All blocks have the same amount of data, except that the last n
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99 // (where n may be 0) have 1 more byte. Figure out where these start.
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100 int shorterBlocksTotalCodewords = result[0].codewords.Length;
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101 int longerBlocksStartAt = result.Length - 1;
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102 while (longerBlocksStartAt >= 0)
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104 int numCodewords = result[longerBlocksStartAt].codewords.Length;
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105 if (numCodewords == shorterBlocksTotalCodewords)
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109 if (numCodewords != shorterBlocksTotalCodewords + 1)
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111 throw new System.SystemException("Data block sizes differ by more than 1");
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113 longerBlocksStartAt--;
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115 longerBlocksStartAt++;
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117 int shorterBlocksNumDataCodewords = shorterBlocksTotalCodewords - ecBlocks.getTotalECCodewords();
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118 // The last elements of result may be 1 element longer;
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119 // first fill out as many elements as all of them have
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120 int rawCodewordsOffset = 0;
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121 for (int i = 0; i < shorterBlocksNumDataCodewords; i++)
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123 for (int j = 0; j < numResultBlocks; j++)
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125 result[j].codewords[i] = rawCodewords[rawCodewordsOffset++];
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128 // Fill out the last data block in the longer ones
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129 for (int j = longerBlocksStartAt; j < numResultBlocks; j++)
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131 result[j].codewords[shorterBlocksNumDataCodewords] = rawCodewords[rawCodewordsOffset++];
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133 // Now add in error correction blocks
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134 int max = result[0].codewords.Length;
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135 for (int i = shorterBlocksNumDataCodewords; i < max; i++)
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137 for (int j = 0; j < numResultBlocks; j++)
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139 int iOffset = j < longerBlocksStartAt ? i : i + 1;
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140 result[j].codewords[iOffset] = rawCodewords[rawCodewordsOffset++];
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144 if (rawCodewordsOffset != rawCodewords.Length)
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146 throw new System.SystemException();
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