helium mappers decoder

// My Functions > Add a core function
// name: Mappers Decoder
// based on https://github.com/hkicko/CubeCell-GPS-Helium-Mapper
function Decoder(bytes, port) {
  var decoded = {};

  var latitude = ((bytes[0]<<16)>>>0) + ((bytes[1]<<8)>>>0) + bytes[2];
  latitude = (latitude / 16777215.0 * 180) - 90;

  var longitude = ((bytes[3]<<16)>>>0) + ((bytes[4]<<8)>>>0) + bytes[5];
  longitude = (longitude / 16777215.0 * 360) - 180;

  switch (port)
  {
    case 2:
      decoded.latitude = latitude;
      decoded.longitude = longitude;

      var altValue = ((bytes[6]<<8)>>>0) + bytes[7];
      var sign = bytes[6] & (1 << 7);
      if(sign) decoded.altitude = 0xFFFF0000 | altValue;
      else decoded.altitude = altValue;

      decoded.speed = parseFloat((((bytes[8]))/1.609).toFixed(2));
      decoded.battery = parseFloat((bytes[9]/100 + 2).toFixed(2));
      decoded.sats = bytes[10];
      decoded.accuracy = 2.5; // Bogus Accuracy required by Cargo/Mapper integration
      break;
  }

  return decoded;
}