#!/usr/bin/env python2
# -*- coding: utf-8 -*-

# GR-GSM based transceiver
# Follow graph implementation
#
# (C) 2016-2017 by Vadim Yanitskiy <axilirator@gmail.com>
#
# All Rights Reserved
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

import pmt
import time
import grgsm
import osmosdr

from math import pi

from gnuradio import blocks
from gnuradio import gr

class radio_if(gr.top_block):
	# PHY specific variables
	shiftoff = 400e3
	fc = 941.6e6 # TODO: set ARFCN to 0?

	# Application state flags
	trx_started = False
	fc_set = False

	def __init__(self, phy_args, phy_sample_rate,
			phy_rx_gain, phy_tx_gain, phy_ppm,
			phy_rx_antenna, phy_tx_antenna,
			trx_remote_addr, trx_base_port):

		print("[i] Init Radio interface")

		# PHY specific variables
		self.rx_gain = phy_rx_gain
		self.tx_gain = phy_tx_gain

		gr.top_block.__init__(self, "GR-GSM TRX")
		shift_fc = self.fc - self.shiftoff

		##################################################
		# PHY Definition
		##################################################
		self.phy = osmosdr.source(args = "numchan=%d %s" % (1, phy_args))

		self.phy.set_bandwidth(250e3 + abs(self.shiftoff), 0)
		self.phy.set_center_freq(shift_fc, 0)
		self.phy.set_sample_rate(phy_sample_rate)
		self.phy.set_freq_corr(phy_ppm, 0)
		self.phy.set_iq_balance_mode(2, 0)
		self.phy.set_dc_offset_mode(2, 0)
		self.phy.set_gain_mode(False, 0)
		self.phy.set_gain(self.rx_gain, 0)
		self.phy.set_if_gain(20, 0)
		self.phy.set_bb_gain(20, 0)
		self.phy.set_antenna(phy_rx_antenna, 0)

		##################################################
		# GR-GSM Magic
		##################################################
		self.blocks_rotator = blocks.rotator_cc(
			-2 * pi * self.shiftoff / phy_sample_rate)

		self.gsm_input = grgsm.gsm_input(
			ppm = phy_ppm, osr = 4, fc = self.fc,
			samp_rate_in = phy_sample_rate)

		self.gsm_receiver = grgsm.receiver(4, ([0]), ([]))

		self.gsm_clck_ctrl = grgsm.clock_offset_control(
			shift_fc, phy_sample_rate, osr = 4)

		self.gsm_ts_filter = grgsm.burst_timeslot_filter(0)
		self.gsm_ts_filter.set_policy(grgsm.FILTER_POLICY_DROP_ALL)

		self.gsm_trx_burst_if = grgsm.trx_burst_if(
			trx_remote_addr, str(trx_base_port))

		##################################################
		# Connections
		##################################################
		self.connect((self.phy, 0), (self.blocks_rotator, 0))
		self.connect((self.blocks_rotator, 0), (self.gsm_input, 0))
		self.connect((self.gsm_input, 0), (self.gsm_receiver, 0))

		self.msg_connect((self.gsm_receiver, 'measurements'),
			(self.gsm_clck_ctrl, 'measurements'))

		self.msg_connect((self.gsm_clck_ctrl, 'ctrl'),
			(self.gsm_input, 'ctrl_in'))

		self.msg_connect((self.gsm_receiver, 'C0'),
			(self.gsm_ts_filter, 'in'))

		self.msg_connect((self.gsm_ts_filter, 'out'),
			(self.gsm_trx_burst_if, 'bursts'))

	def check_available(self):
		return self.fc_set

	def shutdown(self):
		print("[i] Shutdown Radio interface")
		self.stop()
		self.wait()

	def set_fc(self, fc):
		self.phy.set_center_freq(fc - self.shiftoff, 0)
		self.gsm_input.set_fc(fc)
		self.fc_set = True
		self.fc = fc

	def set_rx_gain(self, gain):
		self.phy.set_gain(gain, 0)
		self.rx_gain = gain

	def set_tx_gain(self, gain):
		# TODO: TX chain not implemented yet
		self.tx_gain = gain