private IEnumerable<bool> TerminatorUsingReferenceImplementation(int numDataBits, int numTotalByte)
		{
			BitVector dataBits = new BitVector();
			dataBits.Append(1, numDataBits);
			EncoderInternal.terminateBits(numTotalByte, dataBits);
			return dataBits;
		}

        protected override IEnumerable<bool> EncodeUsingReferenceImplementation(string content)
        {
            // Step 2: Append "bytes" into "dataBits" in appropriate encoding.
            BitVector dataBits = new BitVector();
            EncoderInternal.appendBytes(content, Mode.BYTE, dataBits, "Shift_JIS");


            return dataBits;
        }

		private void ZXEncode(string content, int option)
		{
			System.String encoding = QRCodeConstantVariable.DefaultEncoding;
			ErrorCorrectionLevelInternal m_EcLevelInternal = ErrorCorrectionLevelInternal.H;
			QRCodeInternal qrCodeInternal = new QRCodeInternal();
			
			// Step 1: Choose the mode (encoding).
			Mode mode = EncoderInternal.chooseMode(content, encoding);
			
			// Step 2: Append "bytes" into "dataBits" in appropriate encoding.
			BitVector dataBits = new BitVector();
			EncoderInternal.appendBytes(content, mode, dataBits, encoding);
			// Step 3: Initialize QR code that can contain "dataBits".
			int numInputBytes = dataBits.sizeInBytes();
			EncoderInternal.initQRCode(numInputBytes, m_EcLevelInternal, mode, qrCodeInternal);
			
			// Step 4: Build another bit vector that contains header and data.
			BitVector headerAndDataBits = new BitVector();
			
			// Step 4.5: Append ECI message if applicable
			if (mode == Mode.BYTE && !QRCodeConstantVariable.DefaultEncoding.Equals(encoding))
			{
				CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encoding);
				if (eci != null)
				{
					EncoderInternal.appendECI(eci, headerAndDataBits);
				}
			}
			
			EncoderInternal.appendModeInfo(mode, headerAndDataBits);
			
			int numLetters = mode.Equals(Mode.BYTE)?dataBits.sizeInBytes():content.Length;
			EncoderInternal.appendLengthInfo(numLetters, qrCodeInternal.Version, mode, headerAndDataBits);
			headerAndDataBits.appendBitVector(dataBits);
			
			// Step 5: Terminate the bits properly.
			EncoderInternal.terminateBits(qrCodeInternal.NumDataBytes, headerAndDataBits);
			
			// Step 6: Interleave data bits with error correction code.
			BitVector finalBits = new BitVector();
			EncoderInternal.interleaveWithECBytes(headerAndDataBits, qrCodeInternal.NumTotalBytes, qrCodeInternal.NumDataBytes, qrCodeInternal.NumRSBlocks, finalBits);
			
			if(option == 3)
			{
				return;
			}
			
			// Step 7: Choose the mask pattern and set to "QRCodeInternal".
			ByteMatrix matrix = new ByteMatrix(qrCodeInternal.MatrixWidth, qrCodeInternal.MatrixWidth);
			qrCodeInternal.MaskPattern = EncoderInternal.chooseMaskPattern(finalBits, qrCodeInternal.EcLevelInternal, qrCodeInternal.Version, matrix);
			
			// Step 8.  Build the matrix and set it to "QRCodeInternal".
			MatrixUtil.buildMatrix(finalBits, qrCodeInternal.EcLevelInternal, qrCodeInternal.Version, qrCodeInternal.MaskPattern, matrix);
			qrCodeInternal.Matrix = matrix;
			
		}

 // Build 2D matrix of QR Code from "dataBits" with "ecLevel", "version" and "getMaskPattern". On
 // success, store the result in "matrix" and return true.
 public static void buildMatrix(BitVector dataBits, ErrorCorrectionLevel ecLevel, int version, int maskPattern, ByteMatrix matrix)
 {
     clearMatrix(matrix);
     embedBasicPatterns(version, matrix);
     // Type information appear with any version.
     embedTypeInfo(ecLevel, maskPattern, matrix);
     // Version info appear if version >= 7.
     maybeEmbedVersionInfo(version, matrix);
     // Data should be embedded at end.
     embedDataBits(dataBits, maskPattern, matrix);
 }

		private BitVector GenerateDataCodewords(int numDataCodewords, Random randomizer)
		{
			BitVector result = new BitVector();
			for(int numDC = 0; numDC < numDataCodewords; numDC++)
			{
				result.Append((randomizer.Next(0, 256) & 0xFF), s_bitLengthForByte);
			}
			if(result.sizeInBytes() == numDataCodewords)
				return result;
			else
				throw new Exception("Auto generate data codewords fail");
		}

		/// <summary>
        /// Combine Gma.QrCodeNet.Encoding input recognition method and version control method
        /// with legacy code. To create expected answer. 
        /// This is base on assume Gma.QrCodeNet.Encoding input recognition and version control sometime
        /// give different result as legacy code. 
        /// </summary>
        /// <param name="content"></param>
        /// <returns></returns>
        internal static BitVector DataEncodeUsingReferenceImplementation(string content, ErrorCorrectionLevel ecLevel, out QRCodeInternal qrInternal)
        {
        	if(string.IsNullOrEmpty(content))
        		throw new ArgumentException("input string content can not be null or empty");
        	
        	//Choose mode
        	RecognitionStruct recognitionResult = InputRecognise.Recognise(content);
        	string encodingName = recognitionResult.EncodingName;
        	Mode mode = ConvertMode(recognitionResult.Mode);
        	
        	//append byte to databits
        	BitVector dataBits = new BitVector();
			EncoderInternal.appendBytes(content, mode, dataBits, encodingName);
			
			int dataBitsLength = dataBits.size();
			VersionControlStruct vcStruct = 
				VersionControl.InitialSetup(dataBitsLength, recognitionResult.Mode, ecLevel, recognitionResult.EncodingName);
			//ECI
			BitVector headerAndDataBits = new BitVector();
			string defaultByteMode = "iso-8859-1";
			if (mode == Mode.BYTE && !defaultByteMode.Equals(encodingName))
			{
				CharacterSetECI eci = CharacterSetECI.getCharacterSetECIByName(encodingName);
				if (eci != null)
				{
					EncoderInternal.appendECI(eci, headerAndDataBits);
				}
			}
			//Mode
			EncoderInternal.appendModeInfo(mode, headerAndDataBits);
			//Char info
			int numLetters = mode.Equals(Mode.BYTE)?dataBits.sizeInBytes():content.Length;
			EncoderInternal.appendLengthInfo(numLetters, vcStruct.VersionDetail.Version, mode, headerAndDataBits);
			//Combine with dataBits
			headerAndDataBits.appendBitVector(dataBits);
			
			// Terminate the bits properly.
			EncoderInternal.terminateBits(vcStruct.VersionDetail.NumDataBytes, headerAndDataBits);
			
			qrInternal = new QRCodeInternal();
			qrInternal.Version = vcStruct.VersionDetail.Version;
			qrInternal.MatrixWidth = vcStruct.VersionDetail.MatrixWidth;
			qrInternal.EcLevelInternal = ErrorCorrectionLevelConverter.ToInternal(ecLevel);
			qrInternal.NumTotalBytes = vcStruct.VersionDetail.NumTotalBytes;
			qrInternal.NumDataBytes = vcStruct.VersionDetail.NumDataBytes;
			qrInternal.NumRSBlocks = vcStruct.VersionDetail.NumECBlocks;
			return headerAndDataBits;
        }

        public static BitMatrix Encode(string content, ErrorCorrectionLevel ecLevel)
        {
			QRCodeInternal qrInternal;
			BitVector headerAndDataBits = DataEncodeUsingReferenceImplementation(content, ecLevel, out qrInternal);
			
			// Step 6: Interleave data bits with error correction code.
			BitVector finalBits = new BitVector();
			EncoderInternal.interleaveWithECBytes(headerAndDataBits, qrInternal.NumTotalBytes, qrInternal.NumDataBytes, qrInternal.NumRSBlocks, finalBits);
			
			// Step 7: Choose the mask pattern and set to "QRCodeInternal".
			ByteMatrix matrix = new ByteMatrix(qrInternal.MatrixWidth, qrInternal.MatrixWidth);
			int MaskPattern = EncoderInternal.chooseMaskPattern(finalBits, qrInternal.EcLevelInternal, qrInternal.Version, matrix);
			
			// Step 8.  Build the matrix and set it to "QRCodeInternal".
			MatrixUtil.buildMatrix(finalBits, qrInternal.EcLevelInternal, qrInternal.Version, MaskPattern, matrix);
			return matrix.ToBitMatrix();
        }

		public void PerformanceTest()
		{
			Random randomizer = new Random();
			BitVector dataCodewordsV = GenerateDataCodewords(s_vcInfo.NumDataBytes, randomizer);
			
			BitList dataCodewordsL = new BitList();
			dataCodewordsL.Add(dataCodewordsV);
			
			Stopwatch sw = new Stopwatch();
			int timesofTest = 1000;
			
			string[] timeElapsed = new string[2];
			
			sw.Start();
			for(int i = 0; i < timesofTest; i++)
			{
				ECGenerator.FillECCodewords(dataCodewordsL, s_vcInfo);
			}
			sw.Stop();
			
			timeElapsed[0] = sw.ElapsedMilliseconds.ToString();
			
			sw.Reset();
			
			sw.Start();
			for(int i = 0; i < timesofTest; i++)
			{
				BitVector finalBits = new BitVector();
				EncoderInternal.interleaveWithECBytes(dataCodewordsV, s_vcInfo.NumTotalBytes, s_vcInfo.NumDataBytes, s_vcInfo.NumECBlocks, finalBits);
			}
			sw.Stop();
			
			timeElapsed[1] = sw.ElapsedMilliseconds.ToString();
			
			
			Assert.Pass("ErrorCorrection performance {0} Tests~ QrCode.Net: {1} ZXing: {2}", timesofTest, timeElapsed[0], timeElapsed[1]);
			
			
			
		}

		public void PerformanceTest()
		{
			Stopwatch sw = new Stopwatch();
			int timesofTest = 1000;
			
			string[] timeElapsed = new string[2];
			
			sw.Start();
			
			for(int i = 0; i < timesofTest; i++)
			{
				BitList list = new BitList();
				list.TerminateBites(0, 400);
			}
			
			sw.Stop();
			
			timeElapsed[0] = sw.ElapsedMilliseconds.ToString();
			
			sw.Reset();
			
			sw.Start();
			
			for(int i = 0; i < timesofTest; i++)
			{
				BitVector headerAndDataBits = new BitVector();
				//headerAndDataBits.Append(1, 1);
				EncoderInternal.terminateBits(400, headerAndDataBits);
			}
			sw.Stop();
			
			timeElapsed[1] = sw.ElapsedMilliseconds.ToString();
			
			
			Assert.Pass("Terminator performance {0} Tests~ QrCode.Net: {1} ZXing: {2}", timesofTest, timeElapsed[0], timeElapsed[1]);
			
		}

		// Append "bits".
		public void  appendBitVector(BitVector bits)
		{
			int size = bits.size();
			for (int i = 0; i < size; ++i)
			{
				appendBit(bits.at(i));
			}
		}

		private static void  appendECI(CharacterSetECI eci, BitVector bits)
		{
			bits.appendBits(Mode.ECI.Bits, 4);
			// This is correct for values up to 127, which is all we need now.
			bits.appendBits(eci.Value, 8);
		}

		internal static void  append8BitBytes(System.String content, BitVector bits, System.String encoding)
		{
			sbyte[] bytes;
			try
			{
				//UPGRADE_TODO: Method 'java.lang.String.getBytes' was converted to 'System.Text.Encoding.GetEncoding(string).GetBytes(string)' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javalangStringgetBytes_javalangString'"
				bytes = SupportClass.ToSByteArray(System.Text.Encoding.GetEncoding(encoding).GetBytes(content));
			}
			catch (System.IO.IOException uee)
			{
				//UPGRADE_TODO: The equivalent in .NET for method 'java.lang.Throwable.toString' may return a different value. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1043'"
				throw new WriterException(uee.ToString());
			}
			for (int i = 0; i < bytes.Length; ++i)
			{
				bits.appendBits(bytes[i], 8);
			}
		}

		internal static void  appendNumericBytes(System.String content, BitVector bits)
		{
			int length = content.Length;
			int i = 0;
			while (i < length)
			{
				int num1 = content[i] - '0';
				if (i + 2 < length)
				{
					// Encode three numeric letters in ten bits.
					int num2 = content[i + 1] - '0';
					int num3 = content[i + 2] - '0';
					bits.appendBits(num1 * 100 + num2 * 10 + num3, 10);
					i += 3;
				}
				else if (i + 1 < length)
				{
					// Encode two numeric letters in seven bits.
					int num2 = content[i + 1] - '0';
					bits.appendBits(num1 * 10 + num2, 7);
					i += 2;
				}
				else
				{
					// Encode one numeric letter in four bits.
					bits.appendBits(num1, 4);
					i++;
				}
			}
		}

		/// <summary> Append length info. On success, store the result in "bits".</summary>
		internal static void  appendLengthInfo(int numLetters, int version, Mode mode, BitVector bits)
		{
			int numBits = mode.getCharacterCountBits(Version.getVersionForNumber(version));
			if (numLetters > ((1 << numBits) - 1))
			{
				throw new WriterException(numLetters + "is bigger than" + ((1 << numBits) - 1));
			}
			bits.appendBits(numLetters, numBits);
		}

		/// <summary> Interleave "bits" with corresponding error correction bytes. On success, store the result in
		/// "result". The interleave rule is complicated. See 8.6 of JISX0510:2004 (p.37) for details.
		/// </summary>
		internal static void  interleaveWithECBytes(BitVector bits, int numTotalBytes, int numDataBytes, int numRSBlocks, BitVector result)
		{
			
			// "bits" must have "getNumDataBytes" bytes of data.
			if (bits.sizeInBytes() != numDataBytes)
			{
				throw new WriterException("Number of bits and data bytes does not match");
			}
			
			// Step 1.  Divide data bytes into blocks and generate error correction bytes for them. We'll
			// store the divided data bytes blocks and error correction bytes blocks into "blocks".
			int dataBytesOffset = 0;
			int maxNumDataBytes = 0;
			int maxNumEcBytes = 0;
			
			// Since, we know the number of reedsolmon blocks, we can initialize the vector with the number.
			System.Collections.ArrayList blocks = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(numRSBlocks));
			
			for (int i = 0; i < numRSBlocks; ++i)
			{
				int[] numDataBytesInBlock = new int[1];
				int[] numEcBytesInBlock = new int[1];
				getNumDataBytesAndNumECBytesForBlockID(numTotalBytes, numDataBytes, numRSBlocks, i, numDataBytesInBlock, numEcBytesInBlock);
				
				ByteArray dataBytes = new ByteArray();
				dataBytes.set_Renamed(bits.Array, dataBytesOffset, numDataBytesInBlock[0]);
				ByteArray ecBytes = generateECBytes(dataBytes, numEcBytesInBlock[0]);
				blocks.Add(new BlockPair(dataBytes, ecBytes));
				
				maxNumDataBytes = System.Math.Max(maxNumDataBytes, dataBytes.size());
				maxNumEcBytes = System.Math.Max(maxNumEcBytes, ecBytes.size());
				dataBytesOffset += numDataBytesInBlock[0];
			}
			if (numDataBytes != dataBytesOffset)
			{
				throw new WriterException("Data bytes does not match offset");
			}
			
			// First, place data blocks.
			for (int i = 0; i < maxNumDataBytes; ++i)
			{
				for (int j = 0; j < blocks.Count; ++j)
				{
					ByteArray dataBytes = ((BlockPair) blocks[j]).DataBytes;
					if (i < dataBytes.size())
					{
						result.appendBits(dataBytes.at(i), 8);
					}
				}
			}
			// Then, place error correction blocks.
			for (int i = 0; i < maxNumEcBytes; ++i)
			{
				for (int j = 0; j < blocks.Count; ++j)
				{
					ByteArray ecBytes = ((BlockPair) blocks[j]).ErrorCorrectionBytes;
					if (i < ecBytes.size())
					{
						result.appendBits(ecBytes.at(i), 8);
					}
				}
			}
			if (numTotalBytes != result.sizeInBytes())
			{
				// Should be same.
				throw new WriterException("Interleaving error: " + numTotalBytes + " and " + result.sizeInBytes() + " differ.");
			}
		}

		private static int chooseMaskPattern(BitVector bits, ErrorCorrectionLevel ecLevel, int version, ByteMatrix matrix)
		{
			
			int minPenalty = System.Int32.MaxValue; // Lower penalty is better.
			int bestMaskPattern = - 1;
			// We try all mask patterns to choose the best one.
			for (int maskPattern = 0; maskPattern < QRCode.NUM_MASK_PATTERNS; maskPattern++)
			{
				MatrixUtil.buildMatrix(bits, ecLevel, version, maskPattern, matrix);
				int penalty = calculateMaskPenalty(matrix);
				if (penalty < minPenalty)
				{
					minPenalty = penalty;
					bestMaskPattern = maskPattern;
				}
			}
			return bestMaskPattern;
		}

		private void EmbedAlignmentPattern(ByteMatrix matrix, int version, BitVector codewords)
        {
            matrix.Clear(-1);
            MatrixUtil.embedBasicPatterns(version, matrix);
            MatrixUtil.embedDataBits(codewords, -1, matrix);
        }

	    internal static int TryEmbedDataBits(ByteMatrix matrix, BitVector dataBits, int maskPattern)
	    {
	        int bitIndex = 0;
	        int direction = - 1;
	        // Start from the right bottom cell.
	        int x = matrix.Width - 1;
	        int y = matrix.Height - 1;
	        while (x > 0)
	        {
	            // Skip the vertical timing pattern.
	            if (x == 6)
	            {
	                x -= 1;
	            }
	            while (y >= 0 && y < matrix.Height)
	            {
	                for (int i = 0; i < 2; ++i)
	                {
	                    int xx = x - i;
	                    // Skip the cell if it's not empty.
	                    if (!isEmpty(matrix[y, xx]))
	                    {
	                        continue;
	                    }
	                    int bit;
	                    if (bitIndex < dataBits.size())
	                    {
	                        bit = dataBits.at(bitIndex);
	                        ++bitIndex;
	                    }
	                    else
	                    {
	                        // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described
	                        // in 8.4.9 of JISX0510:2004 (p. 24).
	                        bit = 0;
	                    }
						
	                    // Skip masking if mask_pattern is -1.
	                    if (maskPattern != - 1)
	                    {
	                        if (MaskUtil.getDataMaskBit(maskPattern, xx, y))
	                        {
	                            bit ^= 0x1;
	                        }
	                    }
	                    matrix[y, xx] = (sbyte)bit;
	                }
	                y += direction;
	            }
	            direction = - direction; // Reverse the direction.
	            y += direction;
	            x -= 2; // Move to the left.
	        }
	        return bitIndex;
	    }

		/// <summary> Terminate bits as described in 8.4.8 and 8.4.9 of JISX0510:2004 (p.24).</summary>
		internal static void  terminateBits(int numDataBytes, BitVector bits)
		{
			int capacity = numDataBytes << 3;
			if (bits.size() > capacity)
			{
				throw new WriterException("data bits cannot fit in the QR Code" + bits.size() + " > " + capacity);
			}
			// Append termination bits. See 8.4.8 of JISX0510:2004 (p.24) for details.
			// TODO: srowen says we can remove this for loop, since the 4 terminator bits are optional if
			// the last byte has less than 4 bits left. So it amounts to padding the last byte with zeroes
			// either way.
			for (int i = 0; i < 4 && bits.size() < capacity; ++i)
			{
				bits.appendBit(0);
			}
			int numBitsInLastByte = bits.size() % 8;
			// If the last byte isn't 8-bit aligned, we'll add padding bits.
			if (numBitsInLastByte > 0)
			{
				int numPaddingBits = 8 - numBitsInLastByte;
				for (int i = 0; i < numPaddingBits; ++i)
				{
					bits.appendBit(0);
				}
			}
			// Should be 8-bit aligned here.
			if (bits.size() % 8 != 0)
			{
				throw new WriterException("Number of bits is not a multiple of 8");
			}
			// If we have more space, we'll fill the space with padding patterns defined in 8.4.9 (p.24).
			int numPaddingBytes = numDataBytes - bits.sizeInBytes();
			for (int i = 0; i < numPaddingBytes; ++i)
			{
				if (i % 2 == 0)
				{
					bits.appendBits(0xec, 8);
				}
				else
				{
					bits.appendBits(0x11, 8);
				}
			}
			if (bits.size() != capacity)
			{
				throw new WriterException("Bits size does not equal capacity");
			}
		}

		// Modify the bit vector by XOR'ing with "other"
		public void  xor(BitVector other)
		{
			if (sizeInBits != other.size())
			{
				throw new System.ArgumentException("BitVector sizes don't match");
			}
			int sizeInBytes = (sizeInBits + 7) >> 3;
			for (int i = 0; i < sizeInBytes; ++i)
			{
				// The last byte could be incomplete (i.e. not have 8 bits in
				// it) but there is no problem since 0 XOR 0 == 0.
				array[i] ^= other.array[i];
			}
		}