text: from __future__ import print_function
  from time import sleep
  import sys
  import serial
  import threading
  import time
  import math
  
  class KISS():
  	FEND			= chr(0xC0)
  	FESC			= chr(0xDB)
  	TFEND			= chr(0xDC)
  	TFESC			= chr(0xDD)
  	
  	CMD_UNKNOWN		= chr(0xFE)
  	CMD_DATA		= chr(0x00)
  	CMD_FREQUENCY	= chr(0x01)
  	CMD_BANDWIDTH	= chr(0x02)
  	CMD_TXPOWER		= chr(0x03)
  	CMD_SF			= chr(0x04)
  	CMD_CR          = chr(0x05)
  	CMD_RADIO_STATE = chr(0x06)
  	CMD_RADIO_LOCK	= chr(0x07)
  	CMD_DETECT		= chr(0x08)
  	CMD_PROMISC		= chr(0x0E)
  	CMD_READY       = chr(0x0F)
  	CMD_STAT_RX		= chr(0x21)
  	CMD_STAT_TX		= chr(0x22)
  	CMD_STAT_RSSI	= chr(0x23)
  	CMD_STAT_SNR	= chr(0x24)
  	CMD_BLINK		= chr(0x30)
  	CMD_RANDOM		= chr(0x40)
  	CMD_FW_VERSION  = chr(0x50)
  	CMD_ROM_READ    = chr(0x51)
  
  	DETECT_REQ      = chr(0x73)
  	DETECT_RESP     = chr(0x46)
  	
  	RADIO_STATE_OFF = chr(0x00)
  	RADIO_STATE_ON	= chr(0x01)
  	RADIO_STATE_ASK = chr(0xFF)
  	
  	CMD_ERROR		    = chr(0x90)
  	ERROR_INITRADIO     = chr(0x01)
  	ERROR_TXFAILED	    = chr(0x02)
  	ERROR_EEPROM_LOCKED	= chr(0x03)
  
  	@staticmethod
  	def escape(data):
  		data = data.replace(chr(0xdb), chr(0xdb)+chr(0xdd))
  		data = data.replace(chr(0xc0), chr(0xdb)+chr(0xdc))
  		return data
  	
  
  class RNodeInterface():
  	MTU = 500
  	MAX_CHUNK = 32768
  	FREQ_MIN  = 137000000
  	FREQ_MAX  = 1020000000
  
  	LOG_CRITICAL = 0
  	LOG_ERROR    = 1
  	LOG_WARNING  = 2
  	LOG_NOTICE   = 3
  	LOG_INFO     = 4
  	LOG_VERBOSE  = 5
  	LOG_DEBUG    = 6
  	LOG_EXTREME  = 7
  
  	RSSI_OFFSET  = 157
  	SNR_OFFSET  = 128
  
  	def __init__(self, callback, name, port, frequency = None, bandwidth = None, txpower = None, sf = None, cr = None, loglevel = -1, flow_control = True):
  		self.serial      = None
  		self.loglevel    = loglevel
  		self.callback    = callback
  		self.name        = name
  		self.port        = port
  		self.speed       = 115200
  		self.databits    = 8
  		self.parity      = serial.PARITY_NONE
  		self.stopbits    = 1
  		self.timeout     = 100
  		self.online      = False
  
  		self.frequency   = frequency
  		self.bandwidth   = bandwidth
  		self.txpower     = txpower
  		self.sf          = sf
  		self.cr          = cr
  		self.state       = KISS.RADIO_STATE_OFF
  		self.bitrate     = 0
  
  		self.r_frequency = None
  		self.r_bandwidth = None
  		self.r_txpower   = None
  		self.r_sf        = None
  		self.r_cr        = None
  		self.r_state     = None
  		self.r_lock      = None
  		self.r_stat_rx   = None
  		self.r_stat_tx   = None
  		self.r_stat_rssi = None
  		self.r_stat_snr  = None
  		self.r_random	 = None
  
  		self.packet_queue    = []
  		self.flow_control    = flow_control
  		self.interface_ready = False
  
  		self.validcfg  = True
  		if (self.frequency < RNodeInterface.FREQ_MIN or self.frequency > RNodeInterface.FREQ_MAX):
  			self.log("Invalid frequency configured for "+str(self), RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  
  		if (self.txpower < 0 or self.txpower > 17):
  			self.log("Invalid TX power configured for "+str(self), RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  
  		if (self.bandwidth < 7800 or self.bandwidth > 500000):
  			self.log("Invalid bandwidth configured for "+str(self), RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  
  		if (self.sf < 7 or self.sf > 12):
  			self.log("Invalid spreading factor configured for "+str(self), RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  
  		if (not self.validcfg):
  			raise ValueError("The configuration for "+str(self)+" contains errors, interface is offline")
  
  		try:
  			self.log("Opening serial port "+self.port+"...")
  			self.serial = serial.Serial(
  				port = self.port,
  				baudrate = self.speed,
  				bytesize = self.databits,
  				parity = self.parity,
  				stopbits = self.stopbits,
  				xonxoff = False,
  				rtscts = False,
  				timeout = 0,
  				inter_byte_timeout = None,
  				write_timeout = None,
  				dsrdtr = False,
  			)
  		except Exception as e:
  			self.log("Could not open serial port for interface "+str(self), RNodeInterface.LOG_ERROR)
  			raise e
  
  		if self.serial.is_open:
  			sleep(2.0)
  			thread = threading.Thread(target=self.readLoop)
  			thread.setDaemon(True)
  			thread.start()
  			self.online = True
  			self.log("Serial port "+self.port+" is now open")
  			self.log("Configuring RNode interface...", RNodeInterface.LOG_VERBOSE)
  			self.initRadio()
  			if (self.validateRadioState()):
  				self.interface_ready = True
  				self.log(str(self)+" is configured and powered up")
  				sleep(1.0)
  			else:
  				self.log("After configuring "+str(self)+", the actual radio parameters did not match your configuration.", RNodeInterface.LOG_ERROR)
  				self.log("Make sure that your hardware actually supports the parameters specified in the configuration", RNodeInterface.LOG_ERROR)
  				self.log("Aborting RNode startup", RNodeInterface.LOG_ERROR)
  				self.serial.close()
  				raise IOError("RNode interface did not pass validation")
  		else:
  			raise IOError("Could not open serial port")
  
  	def log(self, message, level):
  		pass
  
  	def initRadio(self):
  		self.setFrequency()
  		self.setBandwidth()
  		self.setTXPower()
  		self.setSpreadingFactor()
  		self.setRadioState(KISS.RADIO_STATE_ON)
  
  	def setFrequency(self):
  		c1 = self.frequency >> 24
  		c2 = self.frequency >> 16 & 0xFF
  		c3 = self.frequency >> 8 & 0xFF
  		c4 = self.frequency & 0xFF
  		data = KISS.escape(chr(c1)+chr(c2)+chr(c3)+chr(c4))
  
  		kiss_command = KISS.FEND+KISS.CMD_FREQUENCY+data+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring frequency for "+self(str))
  
  	def setBandwidth(self):
  		c1 = self.bandwidth >> 24
  		c2 = self.bandwidth >> 16 & 0xFF
  		c3 = self.bandwidth >> 8 & 0xFF
  		c4 = self.bandwidth & 0xFF
  		data = KISS.escape(chr(c1)+chr(c2)+chr(c3)+chr(c4))
  
  		kiss_command = KISS.FEND+KISS.CMD_BANDWIDTH+data+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring bandwidth for "+self(str))
  
  	def setTXPower(self):
  		txp = chr(self.txpower)
  		kiss_command = KISS.FEND+KISS.CMD_TXPOWER+txp+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring TX power for "+self(str))
  
  	def setSpreadingFactor(self):
  		sf = chr(self.sf)
  		kiss_command = KISS.FEND+KISS.CMD_SF+sf+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring spreading factor for "+self(str))
  
  	def setCodingRate(self):
  		cr = chr(self.cr)
  		kiss_command = KISS.FEND+KISS.CMD_CR+cr+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring coding rate for "+self(str))
  
  	def setRadioState(self, state):
  		kiss_command = KISS.FEND+KISS.CMD_RADIO_STATE+state+KISS.FEND
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring radio state for "+self(str))
  
  	def validateRadioState(self):
  		self.log("Validating radio configuration for "+str(self)+"...", RNodeInterface.LOG_VERBOSE)
  		sleep(0.25);
  		if (self.frequency != self.r_frequency):
  			self.log("Frequency mismatch", RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  		if (self.bandwidth != self.r_bandwidth):
  			self.log("Bandwidth mismatch", RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  		if (self.txpower != self.r_txpower):
  			self.log("TX power mismatch", RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  		if (self.sf != self.r_sf):
  			self.log("Spreading factor mismatch", RNodeInterface.LOG_ERROR)
  			self.validcfg = False
  
  		if (self.validcfg):
  			return True
  		else:
  			return False
  
  	def setPromiscuousMode(self, state):
  		if state == True:
  			kiss_command = KISS.FEND+KISS.CMD_PROMISC+chr(0x01)+KISS.FEND
  		else:
  			kiss_command = KISS.FEND+KISS.CMD_PROMISC+chr(0x00)+KISS.FEND
  
  		written = self.serial.write(kiss_command)
  		if written != len(kiss_command):
  			raise IOError("An IO error occurred while configuring promiscuous mode for "+self(str))
  
  
  	def updateBitrate(self):
  		try:
  			self.bitrate = self.r_sf * ( (4.0/self.cr) / (math.pow(2,self.r_sf)/(self.r_bandwidth/1000)) ) * 1000
  			self.bitrate_kbps = round(self.bitrate/1000.0, 2)
  			self.log(str(self)+" On-air bitrate is now "+str(self.bitrate_kbps)+ " kbps", RNodeInterface.LOG_DEBUG)
  		except:
  			self.bitrate = 0
  
  	def processIncoming(self, data):
  		self.callback(data, self)
  
  	def send(self, data):
  		self.processOutgoing(data)
  
  	def processOutgoing(self,data):
  		if self.online:
  			if self.interface_ready:
  				if self.flow_control:
  					self.interface_ready = False
  
  				data = KISS.escape(data)
  				frame = chr(0xc0)+chr(0x00)+data+chr(0xc0)
  				written = self.serial.write(frame)
  				if written != len(frame):
  					raise IOError("Serial interface only wrote "+str(written)+" bytes of "+str(len(data)))
  			else:
  				self.queue(data)
  
  	def queue(self, data):
  		self.packet_queue.append(data)
  
  	def process_queue(self):
  		if len(self.packet_queue) > 0:
  			data = self.packet_queue.pop(0)
  			self.interface_ready = True
  			self.processOutgoing(data)
  		elif len(self.packet_queue) == 0:
  			self.interface_ready = True
  
  	def readLoop(self):
  		try:
  			in_frame = False
  			escape = False
  			command = KISS.CMD_UNKNOWN
  			data_buffer = ""
  			command_buffer = ""
  			last_read_ms = int(time.time()*1000)
  
  			while self.serial.is_open:
  				if self.serial.in_waiting:
  					byte = self.serial.read(1)
  					
  					last_read_ms = int(time.time()*1000)
  
  					if (in_frame and byte == KISS.FEND and command == KISS.CMD_DATA):
  						in_frame = False
  						self.processIncoming(data_buffer)
  						data_buffer = ""
  						command_buffer = ""
  					elif (byte == KISS.FEND):
  						in_frame = True
  						command = KISS.CMD_UNKNOWN
  						data_buffer = ""
  						command_buffer = ""
  					elif (in_frame and len(data_buffer) < RNodeInterface.MTU):
  						if (len(data_buffer) == 0 and command == KISS.CMD_UNKNOWN):
  							command = byte
  						elif (command == KISS.CMD_DATA):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								data_buffer = data_buffer+byte
  						elif (command == KISS.CMD_FREQUENCY):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								command_buffer = command_buffer+byte
  								if (len(command_buffer) == 4):
  									self.r_frequency = ord(command_buffer[0]) << 24 | ord(command_buffer[1]) << 16 | ord(command_buffer[2]) << 8 | ord(command_buffer[3])
  									self.log(str(self)+" Radio reporting frequency is "+str(self.r_frequency/1000000.0)+" MHz", RNodeInterface.LOG_DEBUG)
  									self.updateBitrate()
  
  						elif (command == KISS.CMD_BANDWIDTH):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								command_buffer = command_buffer+byte
  								if (len(command_buffer) == 4):
  									self.r_bandwidth = ord(command_buffer[0]) << 24 | ord(command_buffer[1]) << 16 | ord(command_buffer[2]) << 8 | ord(command_buffer[3])
  									self.log(str(self)+" Radio reporting bandwidth is "+str(self.r_bandwidth/1000.0)+" KHz", RNodeInterface.LOG_DEBUG)
  									self.updateBitrate()
  
  						elif (command == KISS.CMD_TXPOWER):
  							self.r_txpower = ord(byte)
  							self.log(str(self)+" Radio reporting TX power is "+str(self.r_txpower)+" dBm", RNodeInterface.LOG_DEBUG)
  						elif (command == KISS.CMD_SF):
  							self.r_sf = ord(byte)
  							self.log(str(self)+" Radio reporting spreading factor is "+str(self.r_sf), RNodeInterface.LOG_DEBUG)
  							self.updateBitrate()
  						elif (command == KISS.CMD_CR):
  							self.r_cr = ord(byte)
  							self.log(str(self)+" Radio reporting coding rate is "+str(self.r_cr), RNodeInterface.LOG_DEBUG)
  							self.updateBitrate()
  						elif (command == KISS.CMD_RADIO_STATE):
  							self.r_state = ord(byte)
  						elif (command == KISS.CMD_RADIO_LOCK):
  							self.r_lock = ord(byte)
  						elif (command == KISS.CMD_STAT_RX):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								command_buffer = command_buffer+byte
  								if (len(command_buffer) == 4):
  									self.r_stat_rx = ord(command_buffer[0]) << 24 | ord(command_buffer[1]) << 16 | ord(command_buffer[2]) << 8 | ord(command_buffer[3])
  
  						elif (command == KISS.CMD_STAT_TX):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								command_buffer = command_buffer+byte
  								if (len(command_buffer) == 4):
  									self.r_stat_tx = ord(command_buffer[0]) << 24 | ord(command_buffer[1]) << 16 | ord(command_buffer[2]) << 8 | ord(command_buffer[3])
  
  						elif (command == KISS.CMD_STAT_RSSI):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								self.r_stat_rssi = ord(byte)-self.RSSI_OFFSET
  
  						elif (command == KISS.CMD_STAT_SNR):
  							if (byte == KISS.FESC):
  								escape = True
  							else:
  								if (escape):
  									if (byte == KISS.TFEND):
  										byte = KISS.FEND
  									if (byte == KISS.TFESC):
  										byte = KISS.FESC
  									escape = False
  								self.r_stat_snr  = ord(byte)-self.SNR_OFFSET
  
  						elif (command == KISS.CMD_RANDOM):
  							self.r_random = ord(byte)
  						elif (command == KISS.CMD_ERROR):
  							if (byte == KISS.ERROR_INITRADIO):
  								self.log(str(self)+" hardware initialisation error (code "+self.hexrep(byte)+")", RNodeInterface.LOG_ERROR)
  							elif (byte == KISS.ERROR_INITRADIO):
  								self.log(str(self)+" hardware TX error (code "+self.hexrep(byte)+")", RNodeInterface.LOG_ERROR)
  							else:
  								self.log(str(self)+" hardware error (code "+self.hexrep(byte)+")", RNodeInterface.LOG_ERROR)
  						elif (command == KISS.CMD_READY):
  							# TODO: add timeout and reset if ready
  							# command never arrives
  							self.process_queue()
  						
  				else:
  					time_since_last = int(time.time()*1000) - last_read_ms
  					if len(data_buffer) > 0 and time_since_last > self.timeout:
  						self.log(str(self)+" serial read timeout", RNodeInterface.LOG_DEBUG)
  			 			data_buffer = ""
  			 			in_frame = False
  			 			command = KISS.CMD_UNKNOWN
  			 			escape = False
  			 		sleep(0.08)
  
  		except Exception as e:
  			self.online = False
  			self.log("A serial port error occurred, the contained exception was: "+str(e), RNodeInterface.LOG_ERROR)
  			self.log("The interface "+str(self.name)+" is now offline.", RNodeInterface.LOG_ERROR)
  
  	def log(self, msg, level=3):
  		logtimefmt   = "%Y-%m-%d %H:%M:%S"
  		if self.loglevel >= level:
  			timestamp = time.time()
  			logstring = "["+time.strftime(logtimefmt)+"] ["+self.loglevelname(level)+"] "+msg
  			print(logstring)
  
  	def loglevelname(self, level):
  		if (level == RNodeInterface.LOG_CRITICAL):
  			return "Critical"
  		if (level == RNodeInterface.LOG_ERROR):
  			return "Error"
  		if (level == RNodeInterface.LOG_WARNING):
  			return "Warning"
  		if (level == RNodeInterface.LOG_NOTICE):
  			return "Notice"
  		if (level == RNodeInterface.LOG_INFO):
  			return "Info"
  		if (level == RNodeInterface.LOG_VERBOSE):
  			return "Verbose"
  		if (level == RNodeInterface.LOG_DEBUG):
  			return "Debug"
  		if (level == RNodeInterface.LOG_EXTREME):
  			return "Extra"
  
  	def hexrep(data, delimit=True):
  		delimiter = ":"
  		if not delimit:
  			delimiter = ""
  		hexrep = delimiter.join("{:02x}".format(ord(c)) for c in data)
  		return hexrep
  
  	def __str__(self):
  		return "RNodeInterface["+self.name+"]"
  
  