What do these codes mean

I want to know what these codes mean

function hmac_sha5(key, data){    if(key.length > 64) key = Coder.sha1(key);    else key = Bytes.create(key);            var hkey = Bytes.create(64);    hkey.copy(key);  var ipad = Bytes.create(64 + data.length);  var opad = Bytes.create(64 + 20);  for(var i = 0; i < 64; i++)  {    ipad[i] = hkey[i] ^ 0x36;    opad[i] = hkey[i] ^ 0x5C;  }  ipad.sets(data, 64);  var hash = Coder.sha1(ipad);  opad.copy(hash, 64);  return Coder.sha1(opad, 64);}function handleMQTTData(data){    //print(JSON.stringify(data));    switch(data.type)    {        case Packet.MQTT.CONNACK:            Net.send(1, Packet.MQTT.subscribe(pkt_id, topic2, 1));            print("aaa");            pkt_id++;            break;        case Packet.MQTT.PUBLISH:            if(data.qos == 1)                Net.send(1, Packet.MQTT.puback(data.id));            break;    }}var mqtt = Packet.MQTT.Parser.create(handleMQTTData);function handleNetEvent(m){    switch(m.event)    {        case Net.READY:            print("csq:", Net.csq());            print("syncTime:", Net.syncTime());            var t = Box.getTime();            print(t.year, t.month, t.day,t.hour, t.minute, t.second);            Net.connect(1, server, port);            break;        case Net.CONN_OK:            Net.send(1, Packet.MQTT.connect(clientid, 60, 1, username, password));            Timer.start(1, 20000);            Timer.start(2, 9000);            //Timer.start(3, 30000);            //Timer.start(4, 50000);            break;        case Net.CONN_FAIL:            print("connect failed");            break;        case Net.CONN_CLOSE:            print("connect closed");            Timer.stop(1);            Timer.stop(2);            break;        case Net.RECV:            print("mqtt_data:");            print(m.data.hex());            mqtt.parse(m.data);            break;    }}function handleTimerOut(id){    switch(id)    {        case 1: //send heartbeat packet            Net.send(1, Packet.MQTT.ping());            Timer.start(1, 30000);            break;        case 2: //send publish packet            var sensor_data = {params:0};            sensor_data.params.CurrentHumidity = 60;            sensor_data.params.CurrentVoltage = 5;            sensor_data.params.CurrentTemperature = 28;            //{CurrentHumidity:10, CurrentVoltage:1, CurrentTemperature:15, color:10}            var str = JSON.stringify(sensor_data);            Net.send(1, Packet.MQTT.publish(topic1, Bytes.create(str), 1, pkt_id));            pkt_id++;            //Timer.start(2, 11000);            break;        case 3: //send unsubscribe packet            Net.send(1, Packet.MQTT.unsubscribe(pkt_id, topic2));            pkt_id++;            break;        case 4: //send disconnect packet            Net.send(1, Packet.MQTT.disconnect());            break;    }}GPIO.set(GPIO.POWER, 1)Net.init()while(true){    var m = Event.get();    switch(m.msg)    {        case Event.NET_EVENT:            handleNetEvent(m);            break;        case Event.TIMER_OUT:            handleTimerOut(m.id);            break;    }}