All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.zxing.datamatrix.decoder.DataBlock Maven / Gradle / Ivy

/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.datamatrix.decoder;

/**
 * 

Encapsulates a block of data within a Data Matrix Code. Data Matrix Codes may split their data into * multiple blocks, each of which is a unit of data and error-correction codewords. Each * is represented by an instance of this class.

* * @author [email protected] (Brian Brown) */ final class DataBlock { private final int numDataCodewords; private final byte[] codewords; private DataBlock(int numDataCodewords, byte[] codewords) { this.numDataCodewords = numDataCodewords; this.codewords = codewords; } /** *

When Data Matrix Codes use multiple data blocks, they actually interleave the bytes of each of them. * That is, the first byte of data block 1 to n is written, then the second bytes, and so on. This * method will separate the data into original blocks.

* * @param rawCodewords bytes as read directly from the Data Matrix Code * @param version version of the Data Matrix Code * @return DataBlocks containing original bytes, "de-interleaved" from representation in the * Data Matrix Code */ static DataBlock[] getDataBlocks(byte[] rawCodewords, Version version) { // Figure out the number and size of data blocks used by this version Version.ECBlocks ecBlocks = version.getECBlocks(); // First count the total number of data blocks int totalBlocks = 0; Version.ECB[] ecBlockArray = ecBlocks.getECBlocks(); for (Version.ECB ecBlock : ecBlockArray) { totalBlocks += ecBlock.getCount(); } // Now establish DataBlocks of the appropriate size and number of data codewords DataBlock[] result = new DataBlock[totalBlocks]; int numResultBlocks = 0; for (Version.ECB ecBlock : ecBlockArray) { for (int i = 0; i < ecBlock.getCount(); i++) { int numDataCodewords = ecBlock.getDataCodewords(); int numBlockCodewords = ecBlocks.getECCodewords() + numDataCodewords; result[numResultBlocks++] = new DataBlock(numDataCodewords, new byte[numBlockCodewords]); } } // All blocks have the same amount of data, except that the last n // (where n may be 0) have 1 less byte. Figure out where these start. // TODO(bbrown): There is only one case where there is a difference for Data Matrix for size 144 int longerBlocksTotalCodewords = result[0].codewords.length; //int shorterBlocksTotalCodewords = longerBlocksTotalCodewords - 1; int longerBlocksNumDataCodewords = longerBlocksTotalCodewords - ecBlocks.getECCodewords(); int shorterBlocksNumDataCodewords = longerBlocksNumDataCodewords - 1; // The last elements of result may be 1 element shorter for 144 matrix // first fill out as many elements as all of them have minus 1 int rawCodewordsOffset = 0; for (int i = 0; i < shorterBlocksNumDataCodewords; i++) { for (int j = 0; j < numResultBlocks; j++) { result[j].codewords[i] = rawCodewords[rawCodewordsOffset++]; } } // Fill out the last data block in the longer ones boolean specialVersion = version.getVersionNumber() == 24; int numLongerBlocks = specialVersion ? 8 : numResultBlocks; for (int j = 0; j < numLongerBlocks; j++) { result[j].codewords[longerBlocksNumDataCodewords - 1] = rawCodewords[rawCodewordsOffset++]; } // Now add in error correction blocks int max = result[0].codewords.length; for (int i = longerBlocksNumDataCodewords; i < max; i++) { for (int j = 0; j < numResultBlocks; j++) { int jOffset = specialVersion ? (j + 8) % numResultBlocks : j; int iOffset = specialVersion && jOffset > 7 ? i - 1 : i; result[jOffset].codewords[iOffset] = rawCodewords[rawCodewordsOffset++]; } } if (rawCodewordsOffset != rawCodewords.length) { throw new IllegalArgumentException(); } return result; } int getNumDataCodewords() { return numDataCodewords; } byte[] getCodewords() { return codewords; } }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy