jrtechs-sugarizer-lite/activities/QRCode.activity/js/decoder.js

/*
  Ported to JavaScript by Lazar Laszlo 2011 
  
  lazarsoft@gmail.com, www.lazarsoft.info
  
*/

/*
*
* Copyright 2007 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.
*/


var Decoder={};
Decoder.rsDecoder = new ReedSolomonDecoder(GF256.QR_CODE_FIELD);

Decoder.correctErrors=function( codewordBytes,  numDataCodewords)
{
	var numCodewords = codewordBytes.length;
	// First read into an array of ints
	var codewordsInts = new Array(numCodewords);
	for (var i = 0; i < numCodewords; i++)
	{
		codewordsInts[i] = codewordBytes[i] & 0xFF;
	}
	var numECCodewords = codewordBytes.length - numDataCodewords;
	try
	{
		Decoder.rsDecoder.decode(codewordsInts, numECCodewords);
		//var corrector = new ReedSolomon(codewordsInts, numECCodewords);
		//corrector.correct();
	}
	catch ( rse)
	{
		throw rse;
	}
	// Copy back into array of bytes -- only need to worry about the bytes that were data
	// We don't care about errors in the error-correction codewords
	for (var i = 0; i < numDataCodewords; i++)
	{
		codewordBytes[i] =  codewordsInts[i];
	}
}

Decoder.decode=function(bits)
{
	var parser = new BitMatrixParser(bits);
	var version = parser.readVersion();
	var ecLevel = parser.readFormatInformation().ErrorCorrectionLevel;
	
	// Read codewords
	var codewords = parser.readCodewords();

	// Separate into data blocks
	var dataBlocks = DataBlock.getDataBlocks(codewords, version, ecLevel);
	
	// Count total number of data bytes
	var totalBytes = 0;
	for (var i = 0; i < dataBlocks.length; i++)
	{
		totalBytes += dataBlocks[i].NumDataCodewords;
	}
	var resultBytes = new Array(totalBytes);
	var resultOffset = 0;
	
	// Error-correct and copy data blocks together into a stream of bytes
	for (var j = 0; j < dataBlocks.length; j++)
	{
		var dataBlock = dataBlocks[j];
		var codewordBytes = dataBlock.Codewords;
		var numDataCodewords = dataBlock.NumDataCodewords;
		Decoder.correctErrors(codewordBytes, numDataCodewords);
		for (var i = 0; i < numDataCodewords; i++)
		{
			resultBytes[resultOffset++] = codewordBytes[i];
		}
	}
	
	// Decode the contents of that stream of bytes
	var reader = new QRCodeDataBlockReader(resultBytes, version.VersionNumber, ecLevel.Bits);
	return reader;
	//return DecodedBitStreamParser.decode(resultBytes, version, ecLevel);
}