taCache == null) {
      _dataCache = createData(_typeNumber, _errorCorrectionLevel, _dataList);
    }

    mapData(_dataCache, maskPattern);
  };

  const setupPositionProbePattern = function(row, col) {

    for (let r = -1; r <= 7; r += 1) {

      if (row + r <= -1 || _moduleCount <= row + r) continue;

      for (let c = -1; c <= 7; c += 1) {

        if (col + c <= -1 || _moduleCount <= col + c) continue;

        if ( (0 <= r && r <= 6 && (c == 0 || c == 6) )
            || (0 <= c && c <= 6 && (r == 0 || r == 6) )
            || (2 <= r && r <= 4 && 2 <= c && c <= 4) ) {
          _modules[row + r][col + c] = true;
        } else {
          _modules[row + r][col + c] = false;
        }
      }
    }
  };

  const getBestMaskPattern = function() {

    let minLostPoint = 0;
    let pattern = 0;

    for (let i = 0; i < 8; i += 1) {

      makeImpl(true, i);

      const lostPoint = QRUtil.getLostPoint(_this);

      if (i == 0 || minLostPoint > lostPoint) {
        minLostPoint = lostPoint;
        pattern = i;
      }
    }

    return pattern;
  };

  const setupTimingPattern = function() {

    for (let r = 8; r < _moduleCount - 8; r += 1) {
      if (_modules[r][6] != null) {
        continue;
      }
      _modules[r][6] = (r % 2 == 0);
    }

    for (let c = 8; c < _moduleCount - 8; c += 1) {
      if (_modules[6][c] != null) {
        continue;
      }
      _modules[6][c] = (c % 2 == 0);
    }
  };

  const setupPositionAdjustPattern = function() {

    const pos = QRUtil.getPatternPosition(_typeNumber);

    for (let i = 0; i < pos.length; i += 1) {

      for (let j = 0; j < pos.length; j += 1) {

        const row = pos[i];
        const col = pos[j];

        if (_modules[row][col] != null) {
          continue;
        }

        for (let r = -2; r <= 2; r += 1) {

          for (let c = -2; c <= 2; c += 1) {

            if (r == -2 || r == 2 || c == -2 || c == 2
                || (r == 0 && c == 0) ) {
              _modules[row + r][col + c] = true;
            } else {
              _modules[row + r][col + c] = false;
            }
          }
        }
      }
    }
  };

  const setupTypeNumber = function(test) {

    const bits = QRUtil.getBCHTypeNumber(_typeNumber);

    for (let i = 0; i < 18; i += 1) {
      const mod = (!test && ( (bits >> i) & 1) == 1);
      _modules[Math.floor(i / 3)][i % 3 + _moduleCount - 8 - 3] = mod;
    }

    for (let i = 0; i < 18; i += 1) {
      const mod = (!test && ( (bits >> i) & 1) == 1);
      _modules[i % 3 + _moduleCount - 8 - 3][Math.floor(i / 3)] = mod;
    }
  };

  const setupTypeInfo = function(test, maskPattern) {

    const data = (_errorCorrectionLevel << 3) | maskPattern;
    const bits = QRUtil.getBCHTypeInfo(data);

    // vertical
    for (let i = 0; i < 15; i += 1) {

      const mod = (!test && ( (bits >> i) & 1) == 1);

      if (i < 6) {
        _modules[i][8] = mod;
      } else if (i < 8) {
        _modules[i + 1][8] = mod;
      } else {
        _modules[_moduleCount - 15 + i][8] = mod;
      }
    }

    // horizontal
    for (let i = 0; i < 15; i += 1) {

      const mod = (!test && ( (bits >> i) & 1) == 1);

      if (i < 8) {
        _modules[8][_moduleCount - i - 1] = mod;
      } else if (i < 9) {
        _modules[8][15 - i - 1 + 1] = mod;
      } else {
        _modules[8][15 - i - 1] = mod;
      }
    }

    // fixed module
    _modules[_moduleCount - 8][8] = (!test);
  };

  const mapData = function(data, maskPattern) {

    let inc = -1;
    let row = _moduleCount - 1;
    let bitIndex = 7;
    let byteIndex = 0;
    const maskFunc = QRUtil.getMaskFunction(maskPattern);

    for (let col = _moduleCount - 1; col > 0; col -= 2) {

      if (col == 6) col -= 1;

      while (true) {

        for (let c = 0; c < 2; c += 1) {

          if (_modules[row][col - c] == null) {

            let dark = false;

            if (byteIndex < data.length) {
              dark = ( ( (data[byteIndex] >>> bitIndex) & 1) == 1);
            }

            const mask = maskFunc(row, col - c);

            if (mask) {
              dark = !dark;
            }

            _modules[row][col - c] = dark;
            bitIndex -= 1;

            if (bitIndex == -1) {
              byteIndex += 1;
              bitIndex = 7;
            }
          }
        }

        row += inc;

        if (row < 0 || _moduleCount <= row) {
          row -= inc;
          inc = -inc;
          break;
        }
      }
    }
  };

  const createBytes = function(buffer, rsBlocks) {

    let offset = 0;

    let maxDcCount = 0;
    let maxEcCount = 0;

    const dcdata = new Array(rsBlocks.length);
    const ecdata = new Array(rsBlocks.length);

    for (let r = 0; r < rsBlocks.length; r += 1) {

      const dcCount = rsBlocks[r].dataCount;
      const ecCount = rsBlocks[r].totalCount - dcCount;

      maxDcCount = Math.max(maxDcCount, dcCount);
      maxEcCount = Math.max(maxEcCount, ecCount);

      dcdata[r] = new Array(dcCount);

      for (let i = 0; i < dcdata[r].length; i += 1) {
        dcdata[r][i] = 0xff & buffer.getBuffer()[i + offset];
      }
      offset += dcCount;

      const rsPoly = QRUtil.getErrorCorrectPolynomial(ecCount);
      const rawPoly = qrPolynomial(dcdata[r], rsPoly.getLength() - 1);

      const modPoly = rawPoly.mod(rsPoly);
      ecdata[r] = new Array(rsPoly.getLength() - 1);
      for (let i = 0; i < ecdata[r].length; i += 1) {
        const modIndex = i + modPoly.getLength() - ecdata[r].length;
        ecdata[r][i] = (modIndex >= 0)? modPoly.getAt(modIndex) : 0;
      }
    }

    let totalCodeCount = 0;
    for (let i = 0; i < rsBlocks.length; i += 1) {
      totalCodeCount += rsBlocks[i].totalCount;
    }

    const data = new Array(totalCodeCount);
    let index = 0;

    for (let i = 0; i < maxDcCount; i += 1) {
      for (let r = 0; r < rsBlocks.length; r += 1) {
        if (i < dcdata[r].length) {
          data[index] = dcdata[r][i];
          index += 1;
        }
      }
    }

    for (let i = 0; i < maxEcCount; i += 1) {
      for (let r = 0; r < rsBlocks.length; r += 1) {
        if (i < ecdata[r].length) {
          data[index] = ecdata[r][i];
          index += 1;
        }
      }
    }

    return data;
  };

  const createData = function(typeNumber, errorCorrectionLevel, dataList) {

    const rsBlocks = QRRSBlock.getRSBlocks(typeNumber, errorCorrectionLevel);

    const buffer = qrBitBuffer();

    for (let i = 0; i < dataList.length; i += 1) {
      const data = dataList[i];
      buffer.put(data.getMode(), 4);
      buffer.put(data.getLength(), QRUtil.getLengthInBits(data.getMode(), typeNumber) );
      data.write(buffer);
    }

    // calc num max data.
    let totalDataCount = 0;
    for (let i = 0; i < rsBlocks.length; i += 1) {
      totalDataCount += rsBlocks[i].dataCount;
    }

    if (buffer.getLengthInBits() > totalDataCount * 8) {
      throw 'code length overflow. ('
        + buffer.getLengthInBits()
        + '>'
        + totalDataCount * 8
        + ')';
    }

    // end code
    if (buffer.getLengthInBits() + 4 <= totalDataCount * 8) {
      buffer.put(0, 4);
    }

    // padding
    while (buffer.getLengthInBits() % 8 != 0) {
      buffer.putBit(false);
    }

    // padding
    while (true) {

      if (buffer.getLengthInBits() >= totalDataCount * 8) {
        break;
      }
      buffer.put(PAD0, 8);

      if (buffer.getLengthInBits() >= totalDataCount * 8) {
        break;
      }
      buffer.put(PAD1, 8);
    }

    return createBytes(buffer, rsBlocks);
  };

  _this.addData = function(data, mode) {

    mode = mode || 'Byte';

    let newData = null;

    switch(mode) {
    case 'Numeric' :
      newData = qrNumber(data);
      break;
    case 'Alphanumeric' :
      newData = qrAlphaNum(data);
      break;
    case 'Byte' :
      newData = qr8BitByte(data);
      break;
    case 'Kanji' :
      newData = qrKanji(data);
      break;
    default :
      throw 'mode:' + mode;
    }

    _dataList.push(newData);
    _dataCache = null;
  };

  _this.isDark = function(row, col) {
    if (row < 0 || _moduleCount <= row || col < 0 || _moduleCount <= col) {
      throw row + ',' + col;
    }
    return _modules[row][col];
  };

  _this.getModuleCount = function() {
    return _moduleCount;
  };

  _this.make = function() {
    if (_typeNumber < 1) {
      let typeNumber = 1;

      for (; typeNumber < 40; typeNumber++) {
        const rsBlocks = QRRSBlock.getRSBlocks(typeNumber, _errorCorrectionLevel);
        const buffer = qrBitBuffer();

        for (let i = 0; i < _dataList.length; i++) {
          const data = _dataList[i];
          buffer.put(data.getMode(), 4);
          buffer.put(data.getLength(), QRUtil.getLengthInBits(data.getMode(), typeNumber) );
          data.write(buffer);
        }

        let totalDataCount = 0;
        for (let i = 0; i < rsBlocks.length; i++) {
          totalDataCount += rsBlocks[i].dataCount;
        }

        if (buffer.getLengthInBits() <= totalDataCount * 8) {
          break;
        }
      }

      _typeNumber = typeNumber;
    }

    makeImpl(false, getBestMaskPattern() );
  };

  _this.createTableTag = function(cellSize, margin) {

    cellSize = cellSize || 2;
    margin = (typeof margin == 'undefined')? cellSize * 4 : margin;

    let qrHtml = '';

    qrHtml += '<table style="';
    qrHtml += ' border-width: 0px; border-style: none;';
    qrHtml += ' border-collapse: collapse;';
    qrHtml += ' padding: 0px; margin: ' + margin + 'px;';
    qrHtml += '">';
    qrHtml += '<tbody>';

    for (let r = 0; r < _this.getModuleCount(); r += 1) {

      qrHtml += '<tr>';

      for (let c = 0; c < _this.getModuleCount(); c += 1) {
        qrHtml += '<td style="';
        qrHtml += ' border-width: 0px; border-style: none;';
        qrHtml += ' border-collapse: collapse;';
        qrHtml += ' padding: 0px; margin: 0px;';
        qrHtml += ' width: ' + cellSize + 'px;';
        qrHtml += ' height: ' + cellSize + 'px;';
        qrHtml += ' background-color: ';
        qrHtml += _this.isDark(r, c)? '#000000' : '#ffffff';
        qrHtml += ';';
        qrHtml += '"/>';
      }

      qrHtml += '</tr>';
    }

    qrHtml += '</tbody>';
    qrHtml += '</table>';

    return qrHtml;
  };

  _this.createSvgTag = function(cellSize, margin, alt, title) {

    let opts = {};
    if (typeof arguments[0] == 'object') {
      // Called by options.
      opts = arguments[0];
      // overwrite cellSize and margin.
      cellSize = opts.cellSize;
      margin = opts.margin;
      alt = opts.alt;
      title = opts.title;
    }

    cellSize = cellSize || 2;
    margin = (typeof margin == 'undefined')? cellSize * 4 : margin;

    // Compose alt property surrogate
    alt = (typeof alt === 'string') ? {text: alt} : alt || {};
    alt.text = alt.text || null;
    alt.id = (alt.text) ? alt.id || 'qrcode-description' : null;

    // Compose title property surrogate
    title = (typeof title === 'string') ? {text: title} : title || {};
    title.text = title.text || null;
    title.id = (title.text) ? title.id || 'qrcode-title' : null;

    const size = _this.getModuleCount() * cellSize + margin * 2;
    let c, mc, r, mr, qrSvg='', rect;

    rect = 'l' + cellSize + ',0 0,' + cellSize +
      ' -' + cellSize + ',0 0,-' + cellSize + 'z ';

    qrSvg += '<svg version="1.1" xmlns="http://www.w3.org/2000/svg"';
    qrSvg += !opts.scalable ? ' width="' + size + 'px" height="' + size + 'px"' : '';
    qrSvg += ' viewBox="0 0 ' + size + ' ' + size + '" ';
    qrSvg += ' preserveAspectRatio="xMinYMin meet"';
    qrSvg += (title.text || alt.text) ? ' role="img" aria-labelledby="' +
        escapeXml([title.id, alt.id].join(' ').trim() ) + '"' : '';
    qrSvg += '>';
    qrSvg += (title.text) ? '<title id="' + escapeXml(title.id) + '">' +
        escapeXml(title.text) + '</title>' : '';
    qrSvg += (alt.text) ? '<description id="' + escapeXml(alt.id) + '">' +
        escapeXml(alt.text) + '</description>' : '';
    qrSvg += '<rect width="100%" height="100%" fill="white" cx="0" cy="0"/>';
    qrSvg += '<path d="';

    for (r = 0; r < _this.getModuleCount(); r += 1) {
      mr = r * cellSize + margin;
      for (c = 0; c < _this.getModuleCount(); c += 1) {
        if (_this.isDark(r, c) ) {
          mc = c*cellSize+margin;
          qrSvg += 'M' + mc + ',' + mr + rect;
        }
      }
    }

    qrSvg += '" stroke="transparent" fill="black"/>';
    qrSvg += '</svg>';

    return qrSvg;
  };

  _this.createDataURL = function(cellSize, margin) {

    cellSize = cellSize || 2;
    margin = (typeof margin == 'undefined')? cellSize * 4 : margin;

    const size = _this.getModuleCount() * cellSize + margin * 2;
    const min = margin;
    const max = size - margin;

    return createDataURL(size, size, function(x, y) {
      if (min <= x && x < max && min <= y && y < max) {
        const c = Math.floor( (x - min) / cellSize);
        const r = Math.floor( (y - min) / cellSize);
        return _this.isDark(r, c)? 0 : 1;
      } else {
        return 1;
      }
    } );
  };

  _this.createImgTag = function(cellSize, margin, alt) {

    cellSize = cellSize || 2;
    margin = (typeof margin == 'undefined')? cellSize * 4 : margin;

    const size = _this.getModuleCount() * cellSize + margin * 2;

    let img = '';
    img += '<img';
    img += '\u0020src="';
    img += _this.createDataURL(cellSize, margin);
    img += '"';
    img += '\u0020width="';
    img += size;
    img += '"';
    img += '\u0020height="';
    img += size;
    img += '"';
    if (alt) {
      img += '\u0020alt="';
      img += escapeXml(alt);
      img += '"';
    }
    img += '/>';

    return img;
  };

  const escapeXml = function(s) {
    let escaped = '';
    for (let i = 0; i < s.length; i += 1) {
      const c = s.charAt(i);
      switch(c) {
      case '<': escaped += '&lt;'; break;
      case '>': escaped += '&gt;'; break;
      case '&': escaped += '&amp;'; break;
      case '"': escaped += '&quot;'; break;
      default : escaped += c; break;
      }
    }
    return escaped;
  };

  const _createHalfASCII = function(margin) {
    const cellSize = 1;
    margin = (typeof margin == 'undefined')? cellSize * 2 : margin;

    const size = _this.getModuleCount() * cellSize + margin * 2;
    const min = margin;
    const max = size - margin;

    let y, x, r1, r2, p;

    const blocks = {
      '██': '█',
      '█ ': '▀',
      ' █': '▄',
      '  ': ' '
    };

    const blocksLastLineNoMargin = {
      '██': '▀',
      '█ ': '▀',
      ' █': ' ',
      '  ': ' '
    };

    let ascii = '';
    for (y = 0; y < size; y += 2) {
      r1 = Math.floor((y - min) / cellSize);
      r2 = Math.floor((y + 1 - min) / cellSize);
      for (x = 0; x < size; x += 1) {
        p = '█';

        if (min <= x && x < max && min <= y && y < max && _this.isDark(r1, Math.floor((x - min) / cellSize))) {
          p = ' ';
        }

        if (min <= x && x < max && min <= y+1 && y+1 < max && _this.isDark(r2, Math.floor((x - min) / cellSize))) {
          p += ' ';
        }
        else {
          p += '█';
        }

        // Output 2 characters per pixel, to create full square. 1 character per pixels gives only half width of square.
        ascii += (margin < 1 && y+1 >= max) ? blocksLastLineNoMargin[p] : blocks[p];
      }

      ascii += '\n';
    }

    if (size % 2 && margin > 0) {
      return ascii.substring(0, ascii.length - size - 1) + Array(size+1).join('▀');
    }

    return ascii.substring(0, ascii.length-1);
  };

  _this.createASCII = function(cellSize, margin) {
    cellSize = cellSize || 1;

    if (cellSize < 2) {
      return _createHalfASCII(margin);
    }

    cellSize -= 1;
    margin = (typeof margin == 'undefined')? cellSize * 2 : margin;

    const size = _this.getModuleCount() * cellSize + margin * 2;
    const min = margin;
    const max = size - margin;

    let y, x, r, p;

    const white = Array(cellSize+1).join('██');
    const black = Array(cellSize+1).join('  ');

    let ascii = '';
    let line = '';
    for (y = 0; y < size; y += 1) {
      r = Math.floor( (y - min) / cellSize);
      line = '';
      for (x = 0; x < size; x += 1) {
        p = 1;

        if (min <= x && x < max && min <= y && y < max && _this.isDark(r, Math.floor((x - min) / cellSize))) {
          p = 0;
        }

        // Output 2 characters per pixel, to create full square. 1 character per pixels gives only half width of square.
        line += p ? white : black;
      }

      for (r = 0; r < cellSize; r += 1) {
        ascii += line + '\n';
      }
    }

    return ascii.substring(0, ascii.length-1);
  };

  _this.renderTo2dContext = function(context, cellSize) {
    cellSize = cellSize || 2;
    const length = _this.getModuleCount();
    for (let row = 0; row < length; row++) {
      for (let col = 0; col < length; col++) {
        context.fillStyle = _this.isDark(row, col) ? 'black' : 'white';
        context.fillRect(col * cellSize, row * cellSize, cellSize, cellSize);
      }
    }
  }

  return _this;
};

//---------------------------------------------------------------------
// qrcode.stringToBytes
//---------------------------------------------------------------------

qrcode.stringToBytes = function(s) {
  const bytes = [];
  for (let i = 0; i < s.length; i += 1) {
    const c = s.charCodeAt(i);
    bytes.push(c & 0xff);
  }
  return bytes;
};

//---------------------------------------------------------------------
// qrcode.createStringToBytes
//---------------------------------------------------------------------

/**
 * @param unicodeData base64 string of byte array.
 * [16bit Unicode],[16bit Bytes], ...
 * @param numChars
 */
qrcode.createStringToBytes = function(unicodeData, numChars) {

  // create conversion map.

  const unicodeMap = function() {

    const bin = base64DecodeInputStream(unicodeData);
    const read = function() {
      const b = bin.read();
      if (b == -1) throw 'eof';
      return b;
    };

    let count = 0;
    const unicodeMap = {};
    while (true) {
      const b0 = bin.read();
      if (b0 == -1) break;
      const b1 = read();
      const b2 = read();
      const b3 = read();
      const k = String.fromCharCode( (b0 << 8) | b1);
      const v = (b2 << 8) | b3;
      unicodeMap[k] = v;
      count += 1;
    }
    if (count != numChars) {
      throw count + ' != ' + numChars;
    }

    return unicodeMap;
  }();

  const unknownChar = '?'.charCodeAt(0);

  return function(s) {
    const bytes = [];
    for (let i = 0; i < s.length; i += 1) {
      const c = s.charCodeAt(i);
      if (c < 128) {
        bytes.push(c);
      } else {
        const b = unicodeMap[s.charAt(i)];
        if (typeof b == 'number') {
          if ( (b & 0xff) == b) {
            // 1byte
            bytes.push(b);
          } else {
            // 2bytes
            bytes.push(b >>> 8);
            bytes.push(b & 0xff);
          }
        } else {
          bytes.push(unknownChar);
        }
      }
    }
    return bytes;
  };
};

//---------------------------------------------------------------------
// QRMode
//---------------------------------------------------------------------

const QRMode = {
  MODE_NUMBER :    1 << 0,
  MODE_ALPHA_NUM : 1 << 1,
  MODE_8BIT_BYTE : 1 << 2,
  MODE_KANJI :     1 << 3
};

//---------------------------------------------------------------------
// QRErrorCorrectionLevel
//---------------------------------------------------------------------

export const QRErrorCorrectionLevel = {
  L : 1,
  M : 0,
  Q : 3,
  H : 2
};

//---------------------------------------------------------------------
// QRMaskPattern
//---------------------------------------------------------------------

const QRMaskPattern = {
  PATTERN000 : 0,
  PATTERN001 : 1,
  PATTERN010 : 2,
  PATTERN011 : 3,
  PATTERN100 : 4,
  PATTERN101 : 5,
  PATTERN110 : 6,
  PATTERN111 : 7
};

//---------------------------------------------------------------------
// QRUtil
//---------------------------------------------------------------------

const QRUtil = function() {

  const PATTERN_POSITION_TABLE = [
    [],
    [6, 18],
    [6, 22],
    [6, 26],
    [6, 30],
    [6, 34],
    [6, 22, 38],
    [6, 24, 42],
    [6, 26, 46],
    [6, 28, 50],
    [6, 30, 54],
    [6, 32, 58],
    [6, 34, 62],
    [6, 26, 46, 66],
    [6, 26, 48, 70],
    [6, 26, 50, 74],
    [6, 30, 54, 78],
    [6, 30, 56, 82],
    [6, 30, 58, 86],
    [6, 34, 62, 90],
    [6, 28, 50, 72, 94],
    [6, 26, 50, 74, 98],
    [6, 30, 54, 78, 102],
    [6, 28, 54, 80, 106],
    [6, 32, 58, 84, 110],
    [6, 30, 58, 86, 114],
    [6, 34, 62, 90, 118],
    [6, 26, 50, 74, 98, 122],
    [6, 30, 54, 78, 102, 126],
    [6, 26, 52, 78, 104, 130],
    [6, 30, 56, 82, 108, 134],
    [6, 34, 60, 86, 112, 138],
    [6, 30, 58, 86, 114, 142],
    [6, 34, 62, 90, 118, 146],
    [6, 30, 54, 78, 102, 126, 150],
    [6, 24, 50, 76, 102, 128, 154],
    [6, 28, 54, 80, 106, 132, 158],
    [6, 32, 58, 84, 110, 136, 162],
    [6, 26, 54, 82, 110, 138, 166],
    [6, 30, 58, 86, 114, 142, 170]
  ];
  const G15 = (1 << 10) | (1 << 8) | (1 << 5) | (1 << 4) | (1 << 2) | (1 << 1) | (1 << 0);
  const G18 = (1 << 12) | (1 << 11) | (1 << 10) | (1 << 9) | (1 << 8) | (1 << 5) | (1 << 2) | (1 << 0);
  const G15_MASK = (1 << 14) | (1 << 12) | (1 << 10) | (1 << 4) | (1 << 1);

  const _this = {};

  const getBCHDigit = function(data) {
    let digit = 0;
    while (data != 0) {
      digit += 1;
      data >>>= 1;
    }
    return digit;
  };

  _this.getBCHTypeInfo = function(data) {
    let d = data << 10;
    while (getBCHDigit(d) - getBCHDigit(G15) >= 0) {
      d ^= (G15 << (getBCHDigit(d) - getBCHDigit(G15) ) );
    }
    return ( (data << 10) | d) ^ G15_MASK;
  };

  _this.getBCHTypeNumber = function(data) {
    let d = data << 12;
    while (getBCHDigit(d) - getBCHDigit(G18) >= 0) {
      d ^= (G18 << (getBCHDigit(d) - getBCHDigit(G18) ) );
    }
    return (data << 12) | d;
  };

  _this.getPatternPosition = function(typeNumber) {
    return PATTERN_POSITION_TABLE[typeNumber - 1];
  };

  _this.getMaskFunction = function(maskPattern) {

    switch (maskPattern) {

    case QRMaskPattern.PATTERN000 :
      return function(i, j) { return (i + j) % 2 == 0; };
    case QRMaskPattern.PATTERN001 :
      return function(i, j) { return i % 2 == 0; };
    case QRMaskPattern.PATTERN010 :
      return function(i, j) { return j % 3 == 0; };
    case QRMaskPattern.PATTERN011 :
      return function(i, j) { return (i + j) % 3 == 0; };
    case QRMaskPattern.PATTERN100 :
      return function(i, j) { return (Math.floor(i / 2) + Math.floor(j / 3) ) % 2 == 0; };
    case QRMaskPattern.PATTERN101 :
      return function(i, j) { return (i * j) % 2 + (i * j) % 3 == 0; };
    case QRMaskPattern.PATTERN110 :
      return function(i, j) { return ( (i * j) % 2 + (i * j) % 3) % 2 == 0; };
    case QRMaskPattern.PATTERN111 :
      return function(i, j) { return ( (i * j) % 3 + (i + j) % 2) % 2 == 0; };

    default :
      throw 'bad maskPattern:' + maskPattern;
    }
  };

  _this.getErrorCorrectPolynomial = function(errorCorrectLength) {
    let a = qrPolynomial([1], 0);
    for (let i = 0; i < errorCorrectLength; i += 1) {
      a = a.multiply(qrPolynomial([1, QRMath.gexp(i)], 0) );
    }
    return a;
  };

  _this.getLengthInBits = function(mode, type) {

    if (1 <= type && type < 10) {

      // 1 - 9

      switch(mode) {
      case QRMode.MODE_NUMBER    : return 10;
      case QRMode.MODE_ALPHA_NUM : return 9;
      case QRMode.MODE_8BIT_BYTE : return 8;
      case QRMode.MODE_KANJI     : return 8;
      default :
        throw 'mode:' + mode;
      }

    } else if (type < 27) {

      // 10 - 26

      switch(mode) {
      case QRMode.MODE_NUMBER    : return 12;
      case QRMode.MODE_ALPHA_NUM : return 11;
      case QRMode.MODE_8BIT_BYTE : return 16;
      case QRMode.MODE_KANJI     : return 10;
      default :
        throw 'mode:' + mode;
      }

    } else if (type < 41) {

      // 27 - 40

      switch(mode) {
      case QRMode.MODE_NUMBER    : return 14;
      case QRMode.MODE_ALPHA_NUM : return 13;
      case QRMode.MODE_8BIT_BYTE : return 16;
      case QRMode.MODE_KANJI     : return 12;
      default :
        throw 'mode:' + mode;
      }

    } else {
      throw 'type:' + type;
    }
  };

  _this.getLostPoint = function(qrcode) {

    const moduleCount = qrcode.getModuleCount();

    let lostPoint = 0;

    // LEVEL1

    for (let row = 0; row < moduleCount; row += 1) {
      for (let col = 0; col < moduleCount; col += 1) {

        let sameCount = 0;
        const dark = qrcode.isDark(row, col);

        for (let r = -1; r <= 1; r += 1) {

          if (row + r < 0 || moduleCount <= row + r) {
            continue;
          }

          for (let c = -1; c <= 1; c += 1) {

            if (col + c < 0 || moduleCount <= col + c) {
              continue;
            }

            if (r == 0 && c == 0) {
              continue;
            }

            if (dark == qrcode.isDark(row + r, col + c) ) {
              sameCount += 1;
            }
          }
        }

        if (sameCount > 5) {
          lostPoint += (3 + sameCount - 5);
        }
      }
    };

    // LEVEL2

    for (let row = 0; row < moduleCount - 1; row += 1) {
      for (let col = 0; col < moduleCount - 1; col += 1) {
        let count = 0;
        if (qrcode.isDark(row, col) ) count += 1;
        if (qrcode.isDark(row + 1, col) ) count += 1;
        if (qrcode.isDark(row, col + 1) ) count += 1;
        if (qrcode.isDark(row + 1, col + 1) ) count += 1;
        if (count == 0 || count == 4) {
          lostPoint += 3;
        }
      }
    }

    // LEVEL3

    for (let row = 0; row < moduleCount; row += 1) {
      for (let col = 0; col < moduleCount - 6; col += 1) {
        if (qrcode.isDark(row, col)
            && !qrcode.isDark(row, col + 1)
            &&  qrcode.isDark(row, col + 2)
            &&  qrcode.isDark(row, col + 3)
            &&  qrcode.isDark(row, col + 4)
            && !qrcode.isDark(row, col + 5)
            &&  qrcode.isDark(row, col + 6) ) {
          lostPoint += 40;
        }
      }
    }

    for (let col = 0; col < moduleCount; col += 1) {
      for (let row = 0; row < moduleCount - 6; row += 1) {
        if (qrcode.isDark(row, col)
            && !qrcode.isDark(row + 1, col)
            &&  qrcode.isDark(row + 2, col)
            &&  qrcode.isDark(row + 3, col)
            &&  qrcode.isDark(row + 4, col)
            && !qrcode.isDark(row + 5, col)
            &&  qrcode.isDark(row + 6, col) ) {
          lostPoint += 40;
        }
      }
    }

    // LEVEL4

    let darkCount = 0;

    for (let col = 0; col < moduleCount; col += 1) {
      for (let row = 0; row < moduleCount; row += 1) {
        if (qrcode.isDark(row, col) ) {
          darkCount += 1;
        }
      }
    }

    const ratio = Math.abs(100 * darkCount / moduleCount / moduleCount - 50) / 5;
    lostPoint += ratio * 10;

    return lostPoint;
  };

  return _this;
}();

//---------------------------------------------------------------------
// QRMath
//---------------------------------------------------------------------

const QRMath = function() {

  const EXP_TABLE = new Array(256);
  const LOG_TABLE = new Array(256);

  // initialize tables
  for (let i = 0; i < 8; i += 1) {
    EXP_TABLE[i] = 1 << i;
  }
  for (let i = 8; i < 256; i += 1) {
    EXP_TABLE[i] = EXP_TABLE[i - 4]
      ^ EXP_TABLE[i - 5]
      ^ EXP_TABLE[i - 6]
      ^ EXP_TABLE[i - 8];
  }
  for (let i = 0; i < 255; i += 1) {
    LOG_TABLE[EXP_TABLE[i] ] = i;
  }

  const _this = {};

  _this.glog = function(n) {

    if (n < 1) {
      throw 'glog(' + n + ')';
    }

    return LOG_TABLE[n];
  };

  _this.gexp = function(n) {

    while (n < 0) {
      n += 255;
    }

    while (n >= 256) {
      n -= 255;
    }

    return EXP_TABLE[n];
  };

  return _this;
}();

//---------------------------------------------------------------------
// qrPolynomial
//---------------------------------------------------------------------

const qrPolynomial = function(num, shift) {

  if (typeof num.length == 'undefined') {
    throw num.length + '/' + shift;
  }

  const _num = function() {
    let offset = 0;
    while (offset < num.length && num[offset] == 0) {
      offset += 1;
    }
    const _num = new Array(num.length - offset + shift);
    for (let i = 0; i < num.length - offset; i += 1) {
      _num[i] = num[i + offset];
    }
    return _num;
  }();

  const _this = {};

  _this.getAt = function(index) {
    return _num[index];
  };

  _this.getLength = function() {
    return _num.length;
  };

  _this.multiply = function(e) {

    const num = new Array(_this.getLength() + e.getLength() - 1);

    for (let i = 0; i < _this.getLength(); i += 1) {
      for (let j = 0; j < e.getLength(); j += 1) {
        num[i + j] ^= QRMath.gexp(QRMath.glog(_this.getAt(i) ) + QRMath.glog(e.getAt(j) ) );
      }
    }

    return qrPolynomial(num, 0);
  };

  _this.mod = function(e) {

    if (_this.getLength() - e.getLength() < 0) {
      return _this;
    }

    const ratio = QRMath.glog(_this.getAt(0) ) - QRMath.glog(e.getAt(0) );

    const num = new Array(_this.getLength() );
    for (let i = 0; i < _this.getLength(); i += 1) {
      num[i] = _this.getAt(i);
    }

    for (let i = 0; i < e.getLength(); i += 1) {
      num[i] ^= QRMath.gexp(QRMath.glog(e.getAt(i) ) + ratio);
    }

    // recursive call
    return qrPolynomial(num, 0).mod(e);
  };

  return _this;
};

//---------------------------------------------------------------------
// QRRSBlock
//---------------------------------------------------------------------

export const QRRSBlock = function() {

  const RS_BLOCK_TABLE = [

    // L
    // M
    // Q
    // H

    // 1
    [1, 26, 19],
    [1, 26, 16],
    [1, 26, 13],
    [1, 26, 9],

    // 2
    [1, 44, 34],
    [1, 44, 28],
    [1, 44, 22],
    [1, 44, 16],

    // 3
    [1, 70, 55],
    [1, 70, 44],
    [2, 35, 17],
    [2, 35, 13],

    // 4
    [1, 100, 80],
    [2, 50, 32],
    [2, 50, 24],
    [4, 25, 9],

    // 5
    [1, 134, 108],
    [2, 67, 43],
    [2, 33, 15, 2, 34, 16],
    [2, 33, 11, 2, 34, 12],

    // 6
    [2, 86, 68],
    [4, 43, 27],
    [4, 43, 19],
    [4, 43, 15],

    // 7
    [2, 98, 78],
    [4, 49, 31],
    [2, 32, 14, 4, 33, 15],
    [4, 39, 13, 1, 40, 14],

    // 8
    [2, 121, 97],
    [2, 60, 38, 2, 61, 39],
    [4, 40, 18, 2, 41, 19],
    [4, 40, 14, 2, 41, 15],

    // 9
    [2, 146, 116],
    [3, 58, 36, 2, 59, 37],
    [4, 36, 16, 4, 37, 17],
    [4, 36, 12, 4, 37, 13],

    // 10
    [2, 86, 68, 2, 87, 69],
    [4, 69, 43, 1, 70, 44],
    [6, 43, 19, 2, 44, 20],
    [6, 43, 15, 2, 44, 16],

    // 11
    [4, 101, 81],
    [1, 80, 50, 4, 81, 51],
    [4, 50, 22, 4, 51, 23],
    [3, 36, 12, 8, 37, 13],

    // 12
    [2, 116, 92, 2, 117, 93],
    [6, 58, 36, 2, 59, 37],
    [4, 46, 20, 6, 47, 21],
    [7, 42, 14, 4, 43, 15],

    // 13
    [4, 133, 107],
    [8, 59, 37, 1, 60, 38],
    [8, 44, 20, 4, 45, 21],
    [12, 33, 11, 4, 34, 12],

    // 14
    [3, 145, 115, 1, 146, 116],
    [4, 64, 40, 5, 65, 41],
    [11, 36, 16, 5, 37, 17],
    [11, 36, 12, 5, 37, 13],

    // 15
    [5, 109, 87, 1, 110, 88],
    [5, 65, 41, 5, 66, 42],
    [5, 54, 24, 7, 55, 25],
    [11, 36, 12, 7, 37, 13],

    // 16
    [5, 122, 98, 1, 123, 99],
    [7, 73, 45, 3, 74, 46],
    [15, 43, 19, 2, 44, 20],
    [3, 45, 15, 13, 46, 16],

    // 17
    [1, 135, 107, 5, 136, 108],
    [10, 74, 46, 1, 75, 47],
    [1, 50, 22, 15, 51, 23],
    [2, 42, 14, 17, 43, 15],

    // 18
    [5, 150, 120, 1, 151, 121],
    [9, 69, 43, 4, 70, 44],
    [17, 50, 22, 1, 51, 23],
    [2, 42, 14, 19, 43, 15],

    // 19
    [3, 141, 113, 4, 142, 114],
    [3, 70, 44, 11, 71, 45],
    [17, 47, 21, 4, 48, 22],
    [9, 39, 13, 16, 40, 14],

    // 20
    [3, 135, 107, 5, 136, 108],
    [3, 67, 41, 13, 68, 42],
    [15, 54, 24, 5, 55, 25],
    [15, 43, 15, 10, 44, 16],

    // 21
    [4, 144, 116, 4, 145, 117],
    [17, 68, 42],
    [17, 50, 22, 6, 51, 23],
    [19, 46, 16, 6, 47, 17],

    // 22
    [2, 139, 111, 7, 140, 112],
    [17, 74, 46],
    [7, 54, 24, 16, 55, 25],
    [34, 37, 13],

    // 23
    [4, 151, 121, 5, 152, 122],
    [4, 75, 47, 14, 76, 48],
    [11, 54, 24, 14, 55, 25],
    [16, 45, 15, 14, 46, 16],

    // 24
    [6, 147, 117, 4, 148, 118],
    [6, 73, 45, 14, 74, 46],
    [11, 54, 24, 16, 55, 25],
    [30, 46, 16, 2, 47, 17],

    // 25
    [8, 132, 106, 4, 133, 107],
    [8, 75, 47, 13, 76, 48],
    [7, 54, 24, 22, 55, 25],
    [22, 45, 15, 13, 46, 16],

    // 26
    [10, 142, 114, 2, 143, 115],
    [19, 74, 46, 4, 75, 47],
    [28, 50, 22, 6, 51, 23],
    [33, 46, 16, 4, 47, 17],

    // 27
    [8, 152, 122, 4, 153, 123],
    [22, 73, 45, 3, 74, 46],
    [8, 53, 23, 26, 54, 24],
    [12, 45, 15, 28, 46, 16],

    // 28
    [3, 147, 117, 10, 148, 118],
    [3, 73, 45, 23, 74, 46],
    [4, 54, 24, 31, 55, 25],
    [11, 45, 15, 31, 46, 16],

    // 29
    [7, 146, 116, 7, 147, 117],
    [21, 73, 45, 7, 74, 46],
    [1, 53, 23, 37, 54, 24],
    [19, 45, 15, 26, 46, 16],

    // 30
    [5, 145, 115, 10, 146, 116],
    [19, 75, 47, 10, 76, 48],
    [15, 54, 24, 25, 55, 25],
    [23, 45, 15, 25, 46, 16],

    // 31
    [13, 145, 115, 3, 146, 116],
    [2, 74, 46, 29, 75, 47],
    [42, 54, 24, 1, 55, 25],
    [23, 45, 15, 28, 46, 16],

    // 32
    [17, 145, 115],
    [10, 74, 46, 23, 75, 47],
    [10, 54, 24, 35, 55, 25],
    [19, 45, 15, 35, 46, 16],

    // 33
    [17, 145, 115, 1, 146, 116],
    [14, 74, 46, 21, 75, 47],
    [29, 54, 24, 19, 55, 25],
    [11, 45, 15, 46, 46, 16],

    // 34
    [13, 145, 115, 6, 146, 116],
    [14, 74, 46, 23, 75, 47],
    [44, 54, 24, 7, 55, 25],
    [59, 46, 16, 1, 47, 17],

    // 35
    [12, 151, 121, 7, 152, 122],
    [12, 75, 47, 26, 76, 48],
    [39, 54, 24, 14, 55, 25],
    [22, 45, 15, 41, 46, 16],

    // 36
    [6, 151, 121, 14, 152, 122],
    [6, 75, 47, 34, 76, 48],
    [46, 54, 24, 10, 55, 25],
    [2, 45, 15, 64, 46, 16],

    // 37
    [17, 152, 122, 4, 153, 123],
    [29, 74, 46, 14, 75, 47],
    [49, 54, 24, 10, 55, 25],
    [24, 45, 15, 46, 46, 16],

    // 38
    [4, 152, 122, 18, 153, 123],
    [13, 74, 46, 32, 75, 47],
    [48, 54, 24, 14, 55, 25],
    [42, 45, 15, 32, 46, 16],

    // 39
    [20, 147, 117, 4, 148, 118],
    [40, 75, 47, 7, 76, 48],
    [43, 54, 24, 22, 55, 25],
    [10, 45, 15, 67, 46, 16],

    // 40
    [19, 148, 118, 6, 149, 119],
    [18, 75, 47, 31, 76, 48],
    [34, 54, 24, 34, 55, 25],
    [20, 45, 15, 61, 46, 16]
  ];

  const qrRSBlock = function(totalCount, dataCount) {
    const _this = {};
    _this.totalCount = totalCount;
    _this.dataCount = dataCount;
    return _this;
  };

  const _this = {};

  const getRsBlockTable = function(typeNumber, errorCorrectionLevel) {

    switch(errorCorrectionLevel) {
    case QRErrorCorrectionLevel.L :
      return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 0];
    case QRErrorCorrectionLevel.M :
      return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 1];
    case QRErrorCorrectionLevel.Q :
      return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 2];
    case QRErrorCorrectionLevel.H :
      return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 3];
    default :
      return undefined;
    }
  };

  _this.getRSBlocks = function(typeNumber, errorCorrectionLevel) {

    const rsBlock = getRsBlockTable(typeNumber, errorCorrectionLevel);

    if (typeof rsBlock == 'undefined') {
      throw 'bad rs block @ typeNumber:' + typeNumber +
          '/errorCorrectionLevel:' + errorCorrectionLevel;
    }

    const length = rsBlock.length / 3;

    const list = [];

    for (let i = 0; i < length; i += 1) {

      const count = rsBlock[i * 3 + 0];
      const totalCount = rsBlock[i * 3 + 1];
      const dataCount = rsBlock[i * 3 + 2];

      for (let j = 0; j < count; j += 1) {
        list.push(qrRSBlock(totalCount, dataCount) );
      }
    }

    return list;
  };

  return _this;
}();

//---------------------------------------------------------------------
// qrBitBuffer
//---------------------------------------------------------------------

const qrBitBuffer = function() {

  const _buffer = [];
  let _length = 0;

  const _this = {};

  _this.getBuffer = function() {
    return _buffer;
  };

  _this.getAt = function(index) {
    const bufIndex = Math.floor(index / 8);
    return ( (_buffer[bufIndex] >>> (7 - index % 8) ) & 1) == 1;
  };

  _this.put = function(num, length) {
    for (let i = 0; i < length; i += 1) {
      _this.putBit( ( (num >>> (length - i - 1) ) & 1) == 1);
    }
  };

  _this.getLengthInBits = function() {
    return _length;
  };

  _this.putBit = function(bit) {

    const bufIndex = Math.floor(_length / 8);
    if (_buffer.length <= bufIndex) {
      _buffer.push(0);
    }

    if (bit) {
      _buffer[bufIndex] |= (0x80 >>> (_length % 8) );
    }

    _length += 1;
  };

  return _this;
};

//---------------------------------------------------------------------
// qrNumber
//---------------------------------------------------------------------

const qrNumber = function(data) {

  const _mode = QRMode.MODE_NUMBER;
  const _data = data;

  const _this = {};

  _this.getMode = function() {
    return _mode;
  };

  _this.getLength = function(buffer) {
    return _data.length;
  };

  _this.write = function(buffer) {

    const data = _data;

    let i = 0;

    while (i + 2 < data.length) {
      buffer.put(strToNum(data.substring(i, i + 3) ), 10);
      i += 3;
    }

    if (i < data.length) {
      if (data.length - i == 1) {
        buffer.put(strToNum(data.substring(i, i + 1) ), 4);
      } else if (data.length - i == 2) {
        buffer.put(strToNum(data.substring(i, i + 2) ), 7);
      }
    }
  };

  const strToNum = function(s) {
    let num = 0;
    for (let i = 0; i < s.length; i += 1) {
      num = num * 10 + chatToNum(s.charAt(i) );
    }
    return num;
  };

  const chatToNum = function(c) {
    if ('0' <= c && c <= '9') {
      return c.charCodeAt(0) - '0'.charCodeAt(0);
    }
    throw 'illegal char :' + c;
  };

  return _this;
};

//---------------------------------------------------------------------
// qrAlphaNum
//---------------------------------------------------------------------

const qrAlphaNum = function(data) {

  const _mode = QRMode.MODE_ALPHA_NUM;
  const _data = data;

  const _this = {};

  _this.getMode = function() {
    return _mode;
  };

  _this.getLength = function(buffer) {
    return _data.length;
  };

  _this.write = function(buffer) {

    const s = _data;

    let i = 0;

    while (i + 1 < s.length) {
      buffer.put(
        getCode(s.charAt(i) ) * 45 +
        getCode(s.charAt(i + 1) ), 11);
      i += 2;
    }

    if (i < s.length) {
      buffer.put(getCode(s.charAt(i) ), 6);
    }
  };

  const getCode = function(c) {

    if ('0' <= c && c <= '9') {
      return c.charCodeAt(0) - '0'.charCodeAt(0);
    } else if ('A' <= c && c <= 'Z') {
      return c.charCodeAt(0) - 'A'.charCodeAt(0) + 10;
    } else {
      switch (c) {
      case '\u0020' : return 36;
      case '$' : return 37;
      case '%' : return 38;
      case '*' : return 39;
      case '+' : return 40;
      case '-' : return 41;
      case '.' : return 42;
      case '/' : return 43;
      case ':' : return 44;
      default :
        throw 'illegal char :' + c;
      }
    }
  };

  return _this;
};

//---------------------------------------------------------------------
// qr8BitByte
//---------------------------------------------------------------------

const qr8BitByte = function(data) {

  const _mode = QRMode.MODE_8BIT_BYTE;
  const _data = data;
  const _bytes = qrcode.stringToBytes(data);

  const _this = {};

  _this.getMode = function() {
    return _mode;
  };

  _this.getLength = function(buffer) {
    return _bytes.length;
  };

  _this.write = function(buffer) {
    for (let i = 0; i < _bytes.length; i += 1) {
      buffer.put(_bytes[i], 8);
    }
  };

  return _this;
};

//---------------------------------------------------------------------
// qrKanji
//---------------------------------------------------------------------

const qrKanji = function(data) {

  const _mode = QRMode.MODE_KANJI;
  const _data = data;

  const stringToBytes = qrcode.stringToBytes;
  !function(c, code) {
    // self test for sjis support.
    const test = stringToBytes(c);
    if (test.length != 2 || ( (test[0] << 8) | test[1]) != code) {
      throw 'sjis not supported.';
    }
  }('\u53cb', 0x9746);

  const _bytes = stringToBytes(data);

  const _this = {};

  _this.getMode = function() {
    return _mode;
  };

  _this.getLength = function(buffer) {
    return ~~(_bytes.length / 2);
  };

  _this.write = function(buffer) {

    const data = _bytes;

    let i = 0;

    while (i + 1 < data.length) {

      let c = ( (0xff & data[i]) << 8) | (0xff & data[i + 1]);

      if (0x8140 <= c && c <= 0x9FFC) {
        c -= 0x8140;
      } else if (0xE040 <= c && c <= 0xEBBF) {
        c -= 0xC140;
      } else {
        throw 'illegal char at ' + (i + 1) + '/' + c;
      }

      c = ( (c >>> 8) & 0xff) * 0xC0 + (c & 0xff);

      buffer.put(c, 13);

      i += 2;
    }

    if (i < data.length) {
      throw 'illegal char at ' + (i + 1);
    }
  };

  return _this;
};

//=====================================================================
// GIF Support etc.
//

//---------------------------------------------------------------------
// byteArrayOutputStream
//---------------------------------------------------------------------

const byteArrayOutputStream = function() {

  const _bytes = [];

  const _this = {};

  _this.writeByte = function(b) {
    _bytes.push(b & 0xff);
  };

  _this.writeShort = function(i) {
    _this.writeByte(i);
    _this.writeByte(i >>> 8);
  };

  _this.writeBytes = function(b, off, len) {
    off = off || 0;
    len = len || b.length;
    for (let i = 0; i < len; i += 1) {
      _this.writeByte(b[i + off]);
    }
  };

  _this.writeString = function(s) {
    for (let i = 0; i < s.length; i += 1) {
      _this.writeByte(s.charCodeAt(i) );
    }
  };

  _this.toByteArray = function() {
    return _bytes;
  };

  _this.toString = function() {
    let s = '';
    s += '[';
    for (let i = 0; i < _bytes.length; i += 1) {
      if (i > 0) {
        s += ',';
      }
      s += _bytes[i];
    }
    s += ']';
    return s;
  };

  return _this;
};

//---------------------------------------------------------------------
// base64EncodeOutputStream
//---------------------------------------------------------------------

const base64EncodeOutputStream = function() {

  let _buffer = 0;
  let _buflen = 0;
  let _length = 0;
  let _base64 = '';

  const _this = {};

  const writeEncoded = function(b) {
    _base64 += String.fromCharCode(encode(b & 0x3f) );
  };

  const encode = function(n) {
    if (n < 0) {
      throw 'n:' + n;
    } else if (n < 26) {
      return 0x41 + n;
    } else if (n < 52) {
      return 0x61 + (n - 26);
    } else if (n < 62) {
      return 0x30 + (n - 52);
    } else if (n == 62) {
      return 0x2b;
    } else if (n == 63) {
      return 0x2f;
    } else {
      throw 'n:' + n;
    }
  };

  _this.writeByte = function(n) {

    _buffer = (_buffer << 8) | (n & 0xff);
    _buflen += 8;
    _length += 1;

    while (_buflen >= 6) {
      writeEncoded(_buffer >>> (_buflen - 6) );
      _buflen -= 6;
    }
  };

  _this.flush = function() {

    if (_buflen > 0) {
      writeEncoded(_buffer << (6 - _buflen) );
      _buffer = 0;
      _buflen = 0;
    }

    if (_length % 3 != 0) {
      // padding
      const padlen = 3 - _length % 3;
      for (let i = 0; i < padlen; i += 1) {
        _base64 += '=';
      }
    }
  };

  _this.toString = function() {
    return _base64;
  };

  return _this;
};

//---------------------------------------------------------------------
// base64DecodeInputStream
//---------------------------------------------------------------------

const base64DecodeInputStream = function(str) {

  const _str = str;
  let _pos = 0;
  let _buffer = 0;
  let _buflen = 0;

  const _this = {};

  _this.read = function() {

    while (_buflen < 8) {

      if (_pos >= _str.length) {
        if (_buflen == 0) {
          return -1;
        }
        throw 'unexpected end of file./' + _buflen;
      }

      const c = _str.charAt(_pos);
      _pos += 1;

      if (c == '=') {
        _buflen = 0;
        return -1;
      } else if (c.match(/^\s$/) ) {
        // ignore if whitespace.
        continue;
      }

      _buffer = (_buffer << 6) | decode(c.charCodeAt(0) );
      _buflen += 6;
    }

    const n = (_buffer >>> (_buflen - 8) ) & 0xff;
    _buflen -= 8;
    return n;
  };

  const decode = function(c) {
    if (0x41 <= c && c <= 0x5a) {
      return c - 0x41;
    } else if (0x61 <= c && c <= 0x7a) {
      return c - 0x61 + 26;
    } else if (0x30 <= c && c <= 0x39) {
      return c - 0x30 + 52;
    } else if (c == 0x2b) {
      return 62;
    } else if (c == 0x2f) {
      return 63;
    } else {
      throw 'c:' + c;
    }
  };

  return _this;
};

//---------------------------------------------------------------------
// gifImage (B/W)
//---------------------------------------------------------------------

const gifImage = function(width, height) {

  const _width = width;
  const _height = height;
  const _data = new Array(width * height);

  const _this = {};

  _this.setPixel = function(x, y, pixel) {
    _data[y * _width + x] = pixel;
  };

  _this.write = function(out) {

    //---------------------------------
    // GIF Signature

    out.writeString('GIF87a');

    //---------------------------------
    // Screen Descriptor

    out.writeShort(_width);
    out.writeShort(_height);

    out.writeByte(0x80); // 2bit
    out.writeByte(0);
    out.writeByte(0);

    //---------------------------------
    // Global Color Map

    // black
    out.writeByte(0x00);
    out.writeByte(0x00);
    out.writeByte(0x00);

    // white
    out.writeByte(0xff);
    out.writeByte(0xff);
    out.writeByte(0xff);

    //---------------------------------
    // Image Descriptor

    out.writeString(',');
    out.writeShort(0);
    out.writeShort(0);
    out.writeShort(_width);
    out.writeShort(_height);
    out.writeByte(0);

    //---------------------------------
    // Local Color Map

    //---------------------------------
    // Raster Data

    const lzwMinCodeSize = 2;
    const raster = getLZWRaster(lzwMinCodeSize);

    out.writeByte(lzwMinCodeSize);

    let offset = 0;

    while (raster.length - offset > 255) {
      out.writeByte(255);
      out.writeBytes(raster, offset, 255);
      offset += 255;
    }

    out.writeByte(raster.length - offset);
    out.writeBytes(raster, offset, raster.length - offset);
    out.writeByte(0x00);

    //---------------------------------
    // GIF Terminator
    out.writeString(';');
  };

  const bitOutputStream = function(out) {

    const _out = out;
    let _bitLength = 0;
    let _bitBuffer = 0;

    const _this = {};

    _this.write = function(data, length) {

      if ( (data >>> length) != 0) {
        throw 'length over';
      }

      while (_bitLength + length >= 8) {
        _out.writeByte(0xff & ( (data << _bitLength) | _bitBuffer) );
        length -= (8 - _bitLength);
        data >>>= (8 - _bitLength);
        _bitBuffer = 0;
        _bitLength = 0;
      }

      _bitBuffer = (data << _bitLength) | _bitBuffer;
      _bitLength = _bitLength + length;
    };

    _this.flush = function() {
      if (_bitLength > 0) {
        _out.writeByte(_bitBuffer);
      }
    };

    return _this;
  };

  const getLZWRaster = function(lzwMinCodeSize) {

    const clearCode = 1 << lzwMinCodeSize;
    const endCode = (1 << lzwMinCodeSize) + 1;
    let bitLength = lzwMinCodeSize + 1;

    // Setup LZWTable
    const table = lzwTable();

    for (let i = 0; i < clearCode; i += 1) {
      table.add(String.fromCharCode(i) );
    }
    table.add(String.fromCharCode(clearCode) );
    table.add(String.fromCharCode(endCode) );

    const byteOut = byteArrayOutputStream();
    const bitOut = bitOutputStream(byteOut);

    // clear code
    bitOut.write(clearCode, bitLength);

    let dataIndex = 0;

    let s = String.fromCharCode(_data[dataIndex]);
    dataIndex += 1;

    while (dataIndex < _data.length) {

      const c = String.fromCharCode(_data[dataIndex]);
      dataIndex += 1;

      if (table.contains(s + c) ) {

        s = s + c;

      } else {

        bitOut.write(table.indexOf(s), bitLength);

        if (table.size() < 0xfff) {

          if (table.size() == (1 << bitLength) ) {
            bitLength += 1;
          }

          table.add(s + c);
        }

        s = c;
      }
    }

    bitOut.write(table.indexOf(s), bitLength);

    // end code
    bitOut.write(endCode, bitLength);

    bitOut.flush();

    return byteOut.toByteArray();
  };

  const lzwTable = function() {

    const _map = {};
    let _size = 0;

    const _this = {};

    _this.add = function(key) {
      if (_this.contains(key) ) {
        throw 'dup key:' + key;
      }
      _map[key] = _size;
      _size += 1;
    };

    _this.size = function() {
      return _size;
    };

    _this.indexOf = function(key) {
      return _map[key];
    };

    _this.contains = function(key) {
      return typeof _map[key] != 'undefined';
    };

    return _this;
  };

  return _this;
};

const createDataURL = function(width, height, getPixel) {
  const gif = gifImage(width, height);
  for (let y = 0; y < height; y += 1) {
    for (let x = 0; x < width; x += 1) {
      gif.setPixel(x, y, getPixel(x, y) );
    }
  }

  const b = byteArrayOutputStream();
  gif.write(b);

  const base64 = base64EncodeOutputStream();
  const bytes = b.toByteArray();
  for (let i = 0; i < bytes.length; i += 1) {
    base64.writeByte(bytes[i]);
  }
  base64.flush();

  return 'data:image/gif;base64,' + base64;
};

export default qrcode;

export const stringToBytes = qrcode.stringToBytes;
PK