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95 lines
2.7 KiB
95 lines
2.7 KiB
/*
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Ported to JavaScript by Lazar Laszlo 2011
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lazarsoft@gmail.com, www.lazarsoft.info
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*/
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/*
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*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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var Decoder={};
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Decoder.rsDecoder = new ReedSolomonDecoder(GF256.QR_CODE_FIELD);
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Decoder.correctErrors=function( codewordBytes, numDataCodewords)
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{
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var numCodewords = codewordBytes.length;
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// First read into an array of ints
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var codewordsInts = new Array(numCodewords);
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for (var i = 0; i < numCodewords; i++)
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{
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codewordsInts[i] = codewordBytes[i] & 0xFF;
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}
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var numECCodewords = codewordBytes.length - numDataCodewords;
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try
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{
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Decoder.rsDecoder.decode(codewordsInts, numECCodewords);
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//var corrector = new ReedSolomon(codewordsInts, numECCodewords);
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//corrector.correct();
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}
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catch ( rse)
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{
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throw rse;
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}
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// Copy back into array of bytes -- only need to worry about the bytes that were data
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// We don't care about errors in the error-correction codewords
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for (var i = 0; i < numDataCodewords; i++)
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{
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codewordBytes[i] = codewordsInts[i];
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}
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}
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Decoder.decode=function(bits)
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{
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var parser = new BitMatrixParser(bits);
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var version = parser.readVersion();
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var ecLevel = parser.readFormatInformation().ErrorCorrectionLevel;
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// Read codewords
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var codewords = parser.readCodewords();
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// Separate into data blocks
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var dataBlocks = DataBlock.getDataBlocks(codewords, version, ecLevel);
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// Count total number of data bytes
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var totalBytes = 0;
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for (var i = 0; i < dataBlocks.length; i++)
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{
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totalBytes += dataBlocks[i].NumDataCodewords;
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}
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var resultBytes = new Array(totalBytes);
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var resultOffset = 0;
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// Error-correct and copy data blocks together into a stream of bytes
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for (var j = 0; j < dataBlocks.length; j++)
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{
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var dataBlock = dataBlocks[j];
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var codewordBytes = dataBlock.Codewords;
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var numDataCodewords = dataBlock.NumDataCodewords;
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Decoder.correctErrors(codewordBytes, numDataCodewords);
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for (var i = 0; i < numDataCodewords; i++)
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{
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resultBytes[resultOffset++] = codewordBytes[i];
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}
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}
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// Decode the contents of that stream of bytes
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var reader = new QRCodeDataBlockReader(resultBytes, version.VersionNumber, ecLevel.Bits);
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return reader;
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//return DecodedBitStreamParser.decode(resultBytes, version, ecLevel);
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}
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