qr-code.js

//---------------------------------------------------------------------
//
// QR Code Generator for JavaScript
//
// Copyright (c) 2009 Kazuhiko Arase
//
// URL: http://www.d-project.com/
//
// Licensed under the MIT license:
//  http://www.opensource.org/licenses/mit-license.php
//
// The word 'QR Code' is registered trademark of
// DENSO WAVE INCORPORATED
//  http://www.denso-wave.com/qrcode/faqpatent-e.html
//
//---------------------------------------------------------------------

module.exports = function() {

  //---------------------------------------------------------------------
  // qrcode
  //---------------------------------------------------------------------

  /**
   * qrcode
   * @param typeNumber 1 to 10
   * @param errorCorrectLevel 'L','M','Q','H'
   */
  var qrcode = function(typeNumber, errorCorrectLevel) {

    var PAD0 = 0xEC;
    var PAD1 = 0x11;

    var _typeNumber = typeNumber;
    var _errorCorrectLevel = QRErrorCorrectLevel[errorCorrectLevel];
    var _modules = null;
    var _moduleCount = 0;
    var _dataCache = null;
    var _dataList = new Array();

    var _this = {};

    var makeImpl = function(test, maskPattern) {

      _moduleCount = _typeNumber * 4 + 17;
      _modules = function(moduleCount) {
        var modules = new Array(moduleCount);
        for (var row = 0; row < moduleCount; row += 1) {
          modules[row] = new Array(moduleCount);
          for (var col = 0; col < moduleCount; col += 1) {
            modules[row][col] = null;
          }
        }
        return modules;
      }(_moduleCount);

      setupPositionProbePattern(0, 0);
      setupPositionProbePattern(_moduleCount - 7, 0);
      setupPositionProbePattern(0, _moduleCount - 7);
      setupPositionAdjustPattern();
      setupTimingPattern();
      setupTypeInfo(test, maskPattern);

      if (_typeNumber >= 7) {
        setupTypeNumber(test);
      }

      if (_dataCache == null) {
        _dataCache = createData(_typeNumber, _errorCorrectLevel, _dataList);
      }

      mapData(_dataCache, maskPattern);
    };

    var setupPositionProbePattern = function(row, col) {

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

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

        for (var 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;
          }
        }
      }
    };

    var getBestMaskPattern = function() {

      var minLostPoint = 0;
      var pattern = 0;

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

        makeImpl(true, i);

        var lostPoint = QRUtil.getLostPoint(_this);

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

      return pattern;
    };

    var setupTimingPattern = function() {

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

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

    var setupPositionAdjustPattern = function() {

      var pos = QRUtil.getPatternPosition(_typeNumber);

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

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

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

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

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

            for (var 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;
              }
            }
          }
        }
      }
    };

    var setupTypeNumber = function(test) {

      var bits = QRUtil.getBCHTypeNumber(_typeNumber);

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

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

    var setupTypeInfo = function(test, maskPattern) {

      var data = (_errorCorrectLevel << 3) | maskPattern;
      var bits = QRUtil.getBCHTypeInfo(data);

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

        var 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 (var i = 0; i < 15; i += 1) {

        var 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);
    };

    var mapData = function(data, maskPattern) {

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

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

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

        while (true) {

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

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

              var dark = false;

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

              var 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;
          }
        }
      }
    };

    var createBytes = function(buffer, rsBlocks) {

      var offset = 0;

      var maxDcCount = 0;
      var maxEcCount = 0;

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

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

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

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

        dcdata[r] = new Array(dcCount);

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

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

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

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

      var data = new Array(totalCodeCount);
      var index = 0;

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

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

      return data;
    };

    var createData = function(typeNumber, errorCorrectLevel, dataList) {

      var rsBlocks = QRRSBlock.getRSBlocks(typeNumber, errorCorrectLevel);

      var buffer = qrBitBuffer();

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

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

      if (buffer.getLengthInBits() > totalDataCount * 8) {
        throw new Error('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) {
      var newData = qr8BitByte(data);
      _dataList.push(newData);
      _dataCache = null;
    };

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

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

    _this.make = function() {
      makeImpl(false, getBestMaskPattern() );
    };

    _this.createTableTag = function(cellSize, margin) {

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

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

        qrHtml += '<tr>';

        for (var 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.createImgTag = function(cellSize, margin) {

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

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

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

    return _this;
  };

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

  qrcode.stringToBytes = function(s) {
    var bytes = new Array();
    for (var i = 0; i < s.length; i += 1) {
      var 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.

    var unicodeMap = function() {

      var bin = base64DecodeInputStream(unicodeData);
      var read = function() {
        var b = bin.read();
        if (b == -1) throw new Error();
        return b;
      };

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

      return unicodeMap;
    }();

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

    return function(s) {
      var bytes = new Array();
      for (var i = 0; i < s.length; i += 1) {
        var c = s.charCodeAt(i);
        if (c < 128) {
          bytes.push(c);
        } else {
          var 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
  //---------------------------------------------------------------------

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

  //---------------------------------------------------------------------
  // QRErrorCorrectLevel
  //---------------------------------------------------------------------

  var QRErrorCorrectLevel = {
    L : 1,
    M : 0,
    Q : 3,
    H : 2
  };

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

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

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

  var QRUtil = function() {

    var 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]
    ];
    var G15 = (1 << 10) | (1 << 8) | (1 << 5) | (1 << 4) | (1 << 2) | (1 << 1) | (1 << 0);
    var G18 = (1 << 12) | (1 << 11) | (1 << 10) | (1 << 9) | (1 << 8) | (1 << 5) | (1 << 2) | (1 << 0);
    var G15_MASK = (1 << 14) | (1 << 12) | (1 << 10) | (1 << 4) | (1 << 1);

    var _this = {};

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

    _this.getBCHTypeInfo = function(data) {
      var 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) {
      var 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 new Error('bad maskPattern:' + maskPattern);
      }
    };

    _this.getErrorCorrectPolynomial = function(errorCorrectLength) {
      var a = qrPolynomial([1], 0);
      for (var 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 new Error('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 new Error('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 new Error('mode:' + mode);
        }

      } else {
        throw new Error('type:' + type);
      }
    };

    _this.getLostPoint = function(qrcode) {

      var moduleCount = qrcode.getModuleCount();

      var lostPoint = 0;

      // LEVEL1

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

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

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

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

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

      var darkCount = 0;

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

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

      return lostPoint;
    };

    return _this;
  }();

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

  var QRMath = function() {

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

    // initialize tables
    for (var i = 0; i < 8; i += 1) {
      EXP_TABLE[i] = 1 << i;
    }
    for (var 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 (var i = 0; i < 255; i += 1) {
      LOG_TABLE[EXP_TABLE[i] ] = i;
    }

    var _this = {};

    _this.glog = function(n) {

      if (n < 1) {
        throw new Error('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
  //---------------------------------------------------------------------

  function qrPolynomial(num, shift) {

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

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

    var _this = {};

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

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

    _this.multiply = function(e) {

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

      for (var i = 0; i < _this.getLength(); i += 1) {
        for (var 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;
      }

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

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

      for (var 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
  //---------------------------------------------------------------------

  var QRRSBlock = function() {

    var 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]
    ];

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

    var _this = {};

    var getRsBlockTable = function(typeNumber, errorCorrectLevel) {

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

    _this.getRSBlocks = function(typeNumber, errorCorrectLevel) {

      var rsBlock = getRsBlockTable(typeNumber, errorCorrectLevel);

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

      var length = rsBlock.length / 3;

      var list = new Array();

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

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

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

      return list;
    };

    return _this;
  }();

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

  var qrBitBuffer = function() {

    var _buffer = new Array();
    var _length = 0;

    var _this = {};

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

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

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

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

    _this.putBit = function(bit) {

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

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

      _length += 1;
    };

    return _this;
  };

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

  var qr8BitByte = function(data) {

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

    var _this = {};

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

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

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

    return _this;
  };

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

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

  var byteArrayOutputStream = function() {

    var _bytes = new Array();

    var _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 (var i = 0; i < len; i += 1) {
        _this.writeByte(b[i + off]);
      }
    };

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

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

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

    return _this;
  };

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

  var base64EncodeOutputStream = function() {

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

    var _this = {};

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

    var encode = function(n) {
      if (n < 0) {
        // error.
      } 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;
      }
      throw new Error('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
        var padlen = 3 - _length % 3;
        for (var i = 0; i < padlen; i += 1) {
          _base64 += '=';
        }
      }
    };

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

    return _this;
  };

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

  var base64DecodeInputStream = function(str) {

    var _str = str;
    var _pos = 0;
    var _buffer = 0;
    var _buflen = 0;

    var _this = {};

    _this.read = function() {

      while (_buflen < 8) {

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

        var 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;
      }

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

    var 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 new Error('c:' + c);
      }
    };

    return _this;
  };

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

  var gifImage = function(width, height) {

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

    var _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

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

      out.writeByte(lzwMinCodeSize);

      var 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(';');
    };

    var bitOutputStream = function(out) {

      var _out = out;
      var _bitLength = 0;
      var _bitBuffer = 0;

      var _this = {};

      _this.write = function(data, length) {

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

    var getLZWRaster = function(lzwMinCodeSize) {

      var clearCode = 1 << lzwMinCodeSize;
      var endCode = (1 << lzwMinCodeSize) + 1;
      var bitLength = lzwMinCodeSize + 1;

      // Setup LZWTable
      var table = lzwTable();

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

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

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

      var dataIndex = 0;

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

      while (dataIndex < _data.length) {

        var 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();
    };

    var lzwTable = function() {

      var _map = {};
      var _size = 0;

      var _this = {};

      _this.add = function(key) {
        if (_this.contains(key) ) {
          throw new Error('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;
  };

  var createImgTag = function(width, height, getPixel, alt) {

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

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

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

    var img = '';
    img += '<img';
    img += '\u0020src="';
    img += 'data:image/gif;base64,';
    img += base64;
    img += '"';
    img += '\u0020width="';
    img += width;
    img += '"';
    img += '\u0020height="';
    img += height;
    img += '"';
    if (alt) {
      img += '\u0020alt="';
      img += alt;
      img += '"';
    }
    img += '/>';

    return img;
  };

  //---------------------------------------------------------------------
  // returns qrcode function.

  return qrcode;
}();