function Decode(fPort, bytes, variables) {
  var obj = {};
  var offset = 0;
  if(fPort < 10 || fPort > 27){
    obj.msgType = "unknown";
    obj.code = 1;
    obj.error = "Unknown fPort,expect([10,27]),actual(" + fPort + ")";
    return obj;
  }
  
  if(null == bytes){
    return {};
  }

  var indexI, indexJ;
  switch(fPort){
      //It's a heartbeat message.
    case 10:
      {
        obj.msgType = "heartbeat";
        if(bytes.length < 15){
          obj.code = 2;
          obj.error = "Wrong message length,expect(15,18,19),actual(" + bytes.length + ")";
          return obj;
        }
        obj.code = 0;
        
        obj.version = {};
        fwVer = bytes[0]&0x3f;
        obj.version.swVer = ((bytes[0] >> 4) & 0x3).toString(16) + "." + (bytes[0]  & 0xf).toString(16);
        obj.version.hardwareType = (bytes[0] >> 6);// 1: "gateway" , 0: "badge";
        obj.signal = {};
         if (bytes[1] <= 127)
            obj.signal.rssi = bytes[1] - 20;
        else
            obj.signal.rssi = bytes[1] - 275;
        if(bytes[2] <= 127)
           obj.signal.snr = bytes[2];
        else
          obj.signal.snr = bytes[2]- 255;
        obj.status = {};
        //GNSS status
        obj.status.gnss = (bytes[3] >>> 5) & 0x7; //0:off,1:positioning,2:successful,3:failed,4:indoor
        obj.status.battery = (bytes[3] >> 3) & 0x3; //0:not charging,1:charging,2:complete,3:unknown
        //During the heartbeat period, whether the device is moved.
        obj.status.vibstate = (bytes[3] >> 2) & 0x1;//1: moved,0:static;
        /*
         Only used when the hardware type is badge.
         0 indicates it works as a tracker
         1 indicates it works as a BLE gateway
        */
        obj.workmode = (bytes[3] >> 1) & 0x1;//1:gateway,0:tracker;
        //Calculate the available power of the battery.
        var voltage = bytes[4]/ 100.0 + 2;
        if(obj.version.hardwareType == 0)
        {
        if(voltage < 3.3){
           obj.status.soc = 0;
        }
        else if(voltage >= 4.15){
           obj.status.soc = 100;
        }
        else if(voltage >= 4.1){
           obj.status.soc = 99;
       }
       else if(voltage >= 4.04){
             obj.status.soc = Math.round(96 + 3 * (voltage - 4.04) / (4.1 - 4.04));
        }
        else if(voltage >= 3.97){
             obj.status.soc = Math.round(90 + 6 * (voltage - 3.97) / (4.04 - 3.97));
        }
        else if(voltage >= 3.87){
             obj.status.soc = Math.round(69 + 21 * (voltage - 3.87) / (3.97 - 3.87));
        }
        else if(voltage >= 3.69){
             obj.status.soc =Math.round (25 + 44 * (voltage - 3.69) / (3.87 - 3.69));
        }
        else if(voltage >= 3.4){
             obj.status.soc = Math.round(3 + 22 * (voltage - 3.4) / (3.69 - 3.4));
        }
        else if(voltage >= 3.3){
             obj.status.soc =  Math.round(3 * (voltage - 3.3) / (3.4 - 3.3));
        }
        }
        else{
        if(voltage < 3.35){
           obj.status.soc = 0;
        }
        else if(voltage >= 4.1){
           obj.status.soc = 100;
        }
       else if(voltage >= 3.6){
             obj.status.soc = Math.round(50 + 50 * (voltage - 3.6) / (4.1 - 3.6));
        }
        else if(voltage >= 3.35){
             obj.status.soc = Math.round( 50 * (voltage - 3.35) / (3.6 - 3.35));
        }
        }
        //Parse the parameters.
        obj.parameters = {};
        obj.parameters.txPower = bytes[5] >>> 6;
        //Data rate
        obj.parameters.dr = (bytes[5] >> 3) & 0x7;
        //Scheme
        // 0:US915,1:EU868,2:AU915,3:CN470,4:AS923,5:KR920,6:IN865,7:RU864;
        obj.parameters.scheme = bytes[5] & 0x7;
        obj.parameters.ble = {};
        obj.parameters.ble.auReport = bytes[6] >>> 7;//1:enable,0:disable;
        var bleperiod = [0,5,10,20,30,60,120,300,600,900,1200,1800,3600,7200,21600,43200];
        obj.parameters.ble.period = bleperiod[(bytes[6] >> 3) & 0x0f];
        var scan = [1,2,3,6,9,12,15,255];
        obj.parameters.ble.scan = scan[bytes[6] & 0x7];
        obj.parameters.ble.scale = (bytes[7] >> 6) & 0x3;
        obj.parameters.ble.stepsOff = ((bytes[7] >> 3) & 0x7) * 5;
        obj.parameters.ble.bleOff = bytes[7] & 0x7;
        obj.parameters.warning = {};
        //buzzer 0:disable,1:enable;
        obj.parameters.warning.buzzer = (bytes[8] >> 5) & 0x1;
        obj.parameters.warning.vibrator = (bytes[8] >> 4) & 0x1;//1:enabled,0:disabled;
        var distance = [2,4,6,8,10,15,255];
        obj.parameters.warning.distance = distance[(bytes[8] >> 1) & 0x7];
        obj.parameters.warning.proximity = bytes[8] & 0x1;//1:enabled,0:disabled;
        
        //Gnss report period
        var gnssperiod = [0,5,10,15,30,60,150,300,900,1800,3600,5400,10800,21600];
        obj.parameters.gnssPeriod = gnssperiod[(bytes[9] >> 4) & 0xf];
        //Heartbeat report period
        var heartbeatperiod = [60,300,600,1200,1800,3600,7200,21600,43200,86400,86400,86400,86400,86400,86400,86400];
        obj.parameters.heartBeatPeriod = heartbeatperiod[bytes[9] & 0xf];
       
        if(fwVer > 0x18){
            obj.parameters.sleepy = {};
            obj.parameters.sleepy.start =  ((bytes[10] & 0x3) << 3) | ((bytes[11] >> 5) & 0x7);
            obj.parameters.sleepy.end = bytes[11] & 0x1f;
            obj.parameters.sleepy.degree = (bytes[10] >> 2) & 0x7;
          
          if(obj.parameters.sleepy.start != obj.parameters.sleepy.end){
            obj.parameters.timestamp = ((bytes[12] & 0xff) << 24) | ((bytes[13] & 0xff) << 16) | ((bytes[14] & 0xff) << 8) | (bytes[15] & 0xff);
            obj.rmc = (bytes[16] >> 4) & 0x0F;
            obj.bleAck = (bytes[16] >> 3) & 0x01;
            obj.thres =  bytes[16] & 0x07;
            obj.steps = ((bytes[17] & 0xff) << 8) | (bytes[18] & 0xff);
            if(fwVer > 0x19){
              obj.temp = bytes[19] - 50;//Temperature
            }
          }
          else{
            obj.rmc = (bytes[12] >> 4) & 0x0F;
            obj.bleAck = (bytes[12] >> 3) & 0x01;
            obj.thres =  bytes[12] & 0x07;
            obj.steps = ((bytes[13] & 0xff) << 8) | (bytes[14] & 0xff);
            if(fwVer > 0x19){
              obj.temp = bytes[15] - 50;//Temperature
            }
          }
        }
        else{
            obj.parameters.sleepy = {};
            obj.parameters.sleepy.start =  ((bytes[10] & 0x3) << 3) | ((bytes[11] >> 5) & 0x7);
            obj.parameters.sleepy.end = bytes[11] & 0x1f;
            obj.parameters.sleepy.degree = (bytes[10] >> 2) & 0x7;
          
          if(obj.parameters.sleepy.start != obj.parameters.sleepy.end){
            obj.parameters.timestamp = ((bytes[12] & 0xff) << 24) | ((bytes[13] & 0xff) << 16) | ((bytes[14] & 0xff) << 8) | (bytes[15] & 0xff);
            obj.rmc = (bytes[16] >> 4) & 0x0F;
            obj.bleAck = (bytes[16] >> 3) & 0x01;
            obj.thres =  bytes[16] & 0x07;
            obj.steps = ((bytes[18] & 0xff) << 8) | (bytes[19] & 0xff);
          }
          else{
            obj.rmc = (bytes[12] >> 4) & 0x0F;
            obj.bleAck = (bytes[12] >> 3) & 0x01;
            obj.thres =  bytes[12] & 0x07;
            obj.steps = ((bytes[14] & 0xff) << 8) | (bytes[15] & 0xff);
          }
        }
        return obj;
      }
    case 11:
      {
        obj.msgType = "GNSS coordinate";
        if(bytes.length != 9 && bytes.length != 25){
          obj.code = 2;
          obj.error = "Wrong message length,expect(9,25),actual(" + bytes.length + ")";
          return obj;
        }
        obj.code = 0;
        if(bytes.length == 9)
        {
            obj.longitude = {};
            obj.longitude.orientation = bytes[0] & 0x80  ? "W" : "E";
            var longi = (bytes[0] & 0x7f) << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3];
            obj.longitude.value = (parseInt(longi / 10000000) + (longi % 10000000) / 6000000.0).toFixed(7);
            obj.latitude = {};
            obj.latitude.orientation = bytes[4] & 0x80  ? "S" : "N";
            var lati = (bytes[4] & 0x7f) << 24 | bytes[5] << 16 | bytes[6] << 8 | bytes[7];
            obj.latitude.value = (parseInt(lati / 10000000) + (lati % 10000000) / 6000000.0).toFixed(7);
            obj.time = bytes[8];
        }
        else if(bytes.length == 13)
        {
            obj.longitude = {};
            obj.longitude.orientation = bytes[0] & 0x80  ? "W" : "E";
            var longi = (bytes[0] & 0x7f) << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3];
            obj.longitude.value = (parseInt(longi / 10000000) + (longi % 10000000) / 6000000.0).toFixed(7);
            obj.latitude = {};
            obj.latitude.orientation = bytes[4] & 0x80  ? "S" : "N";
            var lati = (bytes[4] & 0x7f) << 24 | bytes[5] << 16 | bytes[6] << 8 | bytes[7];
            obj.latitude.value = (parseInt(lati / 10000000) + (lati % 10000000) / 6000000.0).toFixed(7);
            var alti =  (bytes[8] & 0x7f) << 24 | bytes[8] << 16 | bytes[10] << 8 | bytes[11];
            obj.altitude = alti / 100.0;
            obj.time = bytes[12];
        }
        return obj;
      }
    case 12:
      {
        obj.msgType = "BLE coordinate";
        if(bytes.length < 7){
          obj.code = 2;
          obj.error = "wrong message length,less than minimum length(10)";
          return obj;
        }
        obj.code = 0;

        var majorLen,majorShift,beaconStart;
        if(bytes[1] == 0)
        {
              obj.step = bytes[0] << 16 | bytes[1] << 8 | bytes[2];
             //How many kinds of Major value of the beacons.
              majorLen = bytes[3] & 0xf;
              majorShift = 4 + majorLen;
              beaconStart = 4;
        }
        else{
             majorLen = bytes[0] & 0xf;
             majorShift = 1 + majorLen;
             beaconStart = 1;
             obj.closecontact = (bytes[0] >> 4) & 0x1;
        }
        
        obj.beaconList = [];
    
        
        for(indexI = 0; indexI < majorLen; indexI++){
          var beaconNum = bytes[beaconStart + indexI];
          var major = (bytes[majorShift]  << 8 | bytes[majorShift + 1]).toString(16);
          
          var minorShift = majorShift + 2;
          for(indexJ = 0; indexJ < beaconNum; indexJ++){
            //var minorShift = majorShift + 2 + indexJ *3;
            var beaconObj = {};
            beaconObj.major = major;
            beaconObj.minor = ((bytes[minorShift] << 8) | bytes[minorShift + 1]).toString(16);
            beaconObj.type = (bytes[minorShift + 2] >> 5) & 0x3;//0:locator,1:asset,2:alarm,3:proximity
            beaconObj.rssi = -(bytes[minorShift + 2] & 0x1f) - 59;
            minorShift += 2;
            if(bytes[minorShift] >> 7){
              beaconObj.battery = bytes[minorShift + 1] & 0x7f;
              minorShift += 1;
            }
            minorShift += 1;
            obj.beaconList.push(beaconObj);
          } 
          majorShift = minorShift;
        }
        return obj;       
      }
    case 13:
      {
        obj.msgType = "alarm";
        if(bytes.length != 2){
          obj.code = 2;
          obj.error = "Wrong message length,expect(2),actual(" + bytes.length + ")";
          return obj;
        }

        obj.code = 0;
        obj.msgId = bytes[0];
        obj.ack = (bytes[1] >> 4) & 0x1;// 1:true,0:false;
		//0:SOS,1:SOS dismissed,2:power off,3:BLE disable,4:LoRa disable,5:GPS disable,6:Enter hazardous area,7:Unknown
        obj.alarm = bytes[1] & 0x7;
        
        return obj;
      }
    case 14:
      {
        obj.msgType = "ack";
        if(bytes.length != 2){
          obj.code = 2;
          obj.error = "Wrong message length,expect(2),actual(" + bytes.length + ")";
          return obj;
        }
        
        obj.code = 0;
        obj.msgId = bytes[0];
        //0:succeed,1:parameter not supported,2:parameter out of range,3:unknown;
        obj.result = bytes[1] & 0x3;
        
        return obj;
       }
    case 15:
      {
        obj.msgType = "Positioning UUID list";
        obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.uuidList = [];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var uuid = {};
          uuid.index = bytes[1 + 17 * indexI];
          var str = "";
          for(indexJ = 2 + 17 * indexI; indexJ < 18 + 17 * indexI; indexJ++){
            var tmp = bytes[indexJ].toString(16);
            if(tmp.length == 1){
               tmp = "0" + tmp;
            } 
            str += tmp;
          }
          uuid.uuid = str;
          obj.uuidList.push(uuid);
        }
        return obj;
      }
    case 16:
      {
        obj.msgType = "Asset UUID list";
        obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.uuidList = [];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var uuidAsset = {};
          uuidAsset.index = bytes[1 + 17 * indexI];
          var strAsset = "";
          for(indexJ = 2 + 17 * indexI; indexJ < 18 + 17 * indexI; indexJ++){
            var tmpAsset = bytes[indexJ].toString(16);
            if(tmpAsset.length == 1){
               tmpAsset = "0" + tmpAsset;
            } 
            strAsset += tmpAsset;
          }
          uuidAsset.uuid = strAsset;
          obj.uuidList.push(uuidAsset);
        }
        return obj;
      }
    case 17:
      {
        obj.msgType = "Pass-through filter list";
        obj.code = 0;
        if(bytes[0] == 0){
          return obj;
        }
        obj.filterList = [];
        var pos = 1;
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var filterPosPass = {};
          filterPosPass.port = bytes[pos];
          filterPosPass.start = bytes[pos+1];
          filterPosPass.end = bytes[pos+2];
          filterPosPass.filterStart = bytes[pos + 3];
          filterPosPass.filterLen= bytes[pos+4];
          var filterLen = bytes[pos+4];
          var strPosPass = "";
          for(indexJ = 0; indexJ < filterLen; indexJ++){
            var tmpPosPass = bytes[pos+5+indexJ].toString(16);
            if(tmpPosPass.length == 1){
               tmpPosPass = "0" + tmpPosPass;
            } 
            strPosPass += tmpPosPass;
          }
          pos = pos + 5 + filterLen;
          filterPosPass.filter = strPosPass;
          obj.filterList.push(filterPosPass);
        }
        return obj;
      }
    case 18:
    {
        obj.msgType = "History Beacon Config List";
         obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.number = bytes[0];
        obj.beaconList = [];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var beacon= {};
          offset = 5 * indexI;
          beacon.index = bytes[1 + offset];
          beacon.major =  (bytes[2 + offset]  << 8 | bytes[3 + offset]).toString(16);
          beacon.minor =  (bytes[4 + offset]  << 8 | bytes[5 + offset]).toString(16);
          obj.beaconList.push(beacon);
        }
        return obj;
    }
    case 19:
    {
        obj.msgType = "History Beacon Info List";
         obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.number = bytes[0];
        obj.beaconList = [];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var bea= {};
          offset = 9 * indexI;
          bea.major =  (bytes[1 + offset]  << 8 | bytes[2 + offset]).toString(16);
          bea.minor =  (bytes[3 + offset]  << 8 | bytes[4 + offset]).toString(16);
          bea.rssi = -((bytes[5 + offset] & 0x1f) + 59);
          bea.frmOff =  (bytes[6 + offset]  << 8 | bytes[7 + offset]);
          bea.timeOff =  (bytes[8 + offset]  << 8 | bytes[9 + offset]);
          obj.beaconList.push(bea);
        }
        return obj;
    }
    case 20:
    {
        obj.msgType = "History GNSS Info List";
         obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.number = bytes[0];
        obj.gnssList = [];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var gnss = {};
          offset = 12 * indexI;
          gnss.longitude = {};
          gnss.longitude.orientation = bytes[1+offset] & 0x80  ? "W" : "E";
        var longiH = (bytes[1+offset] & 0x7f) << 24 | bytes[2+offset] << 16 | bytes[3+offset] << 8 | bytes[4+offset];
        gnss.longitude.value = (parseInt(longiH / 10000000) + (longiH % 10000000) / 6000000.0).toFixed(7);
        gnss.latitude = {};
        gnss.latitude.orientation = bytes[5+offset] & 0x80  ? "S" : "N";
        var latiH = (bytes[5+offset] & 0x7f) << 24 | bytes[6+offset] << 16 | bytes[7+offset] << 8 | bytes[8+offset];
        gnss.latitude.value = (parseInt(latiH / 10000000) + (latiH % 10000000) / 6000000.0).toFixed(7);
        gnss.frmOff = (bytes[9 + offset]  << 8 | bytes[10 + offset]);
        gnss.timeoff =  (bytes[11 + offset]  << 8 | bytes[12 + offset]);
          obj.gnssList.push(gnss);
        }
        return obj;
    }
    case 21:
	{   //Only used for RCT platform, should be removed if not needed.
        //Or you can modify according to your BLE devices.
        obj.msgType = "Pass-through data list";
		obj.subType = "BLE Sensor";
        obj.port = fPort;
        obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.dataList = [];
        var macList = new Array();
        var dataLen = (bytes.length - 1)/bytes[0];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var passData = {};
          passData.index =  indexI;
          var strDataPass = "";
          for(indexJ = 1 + dataLen * indexI; indexJ < 1 + dataLen + dataLen * indexI; indexJ++){
            var tmpDataPass = bytes[indexJ].toString(16);
            if(tmpDataPass.length == 1){
               tmpDataPass = "0" + tmpDataPass;
            } 
            strDataPass += tmpDataPass;
          }
          passData.payload = strDataPass;
		  
		  if(bytes[1 + dataLen * indexI] < 128)
		    passData.x = bytes[1 + dataLen * indexI] + bytes[2 + dataLen * indexI] / 256.0;
		  else
		    passData.x = bytes[1 + dataLen * indexI] - 256 + bytes[2 + dataLen * indexI] / 256.0;
		  
		  if(bytes[3 + dataLen * indexI] < 128)
		    passData.y = bytes[3 + dataLen * indexI] + bytes[4 + dataLen * indexI] / 256.0;
		  else
		    passData.y = bytes[3 + dataLen * indexI] - 256 + bytes[4 + dataLen * indexI] / 256.0;
			
		  if(bytes[5 + dataLen * indexI] < 128)
		    passData.z = bytes[5 + dataLen * indexI] + bytes[6 + dataLen * indexI] / 256.0;
		  else
		    passData.z = bytes[5 + dataLen * indexI] - 256 + bytes[6 + dataLen * indexI] / 256.0;

		  passData.mac = "";
          for(indexJ = 12 + dataLen * indexI; indexJ > 6 + dataLen * indexI; indexJ--){
            var tmpDataPass = bytes[indexJ].toString(16);
            if(tmpDataPass.length == 1){
               tmpDataPass = "0" + tmpDataPass;
            } 
            passData.mac += tmpDataPass;
          }	
          var macExist = 0;
          for(var macIndex=0; macIndex<macList.length; macIndex++)
          {
             if(passData.mac == macList[macIndex])
             {
                macExist = 1;
                break;
             }
          }
          if(macExist == 1)
          {
            break;
          }
          else{
            macList.push(passData.mac);
          }
          passData.rssi = bytes[13 + dataLen * indexI] - 255;
          if(passData.y < -0.8 && Math.abs(passData.x) <= 0.1 && Math.abs(passData.z) < 0.1)
		    passData.state = 0;//正常
		  else if(Math.abs(passData.y) < 0.1){
                  passData.state = 2;
          }
          else
		    passData.state = 1;//倾斜
		
          obj.dataList.push(passData);
        }
        return obj;        
      }
    case 22:
    case 23:
    case 24:
    case 25:
      {
        obj.msgType = "Pass-through data list";
        obj.port = fPort;
        obj.code = 0;
        if(bytes[0] == 0){
          return {};
        }
        obj.dataList = [];
        var dataLen = (bytes.length - 1)/bytes[0];
        for(indexI = 0; indexI <  bytes[0]; indexI++){
          var passData = {};
          passData.index =  indexI;
          var strDataPass = "";
          for(indexJ = 1 + dataLen * indexI; indexJ < 1 + dataLen + dataLen * indexI; indexJ++){
            var tmpDataPass = bytes[indexJ].toString(16);
            if(tmpDataPass.length == 1){
               tmpDataPass = "0" + tmpDataPass;
            } 
            strDataPass += tmpDataPass;
          }
          passData.payload = strDataPass;
          obj.dataList.push(passData);
        }
        return obj;        
      }
case 26:
      {
          var ii = 0;
          var len = bytes.length;
          var out = {access_points: []};

         for (; ii < len ;) {
        out.access_points.push({macAddress: bytes.slice(ii, ii + 6), signalStrength: int8(bytes[ii+6])});
        ii += 7;
        }
       return out;
      }
    case 27:
      {
        return {
           "sat_count": bytes[0],
           "lr1110_gnss": bytes.slice(2, bytes.length)
          };
      }
  default:
      return {};
  }
  return {};
}

// convert a byte value to signed int8
function int8(byte) {
  var sign = byte & (1 << 7);
  if (sign) {
    return 0xFFFFFF00 | byte;
  }
  return byte;
}