text: #!/usr/bin/env python
  #
  # Copyright 2006-2008,2013 Free Software Foundation, Inc.
  # 
  # This file is part of GNU Radio
  # 
  # GNU Radio 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 3, or (at your option)
  # any later version.
  # 
  # GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
  # the Free Software Foundation, Inc., 51 Franklin Street,
  # Boston, MA 02110-1301, USA.
  # 
  
  import math
  from gnuradio import gr, fft
  from gnuradio import blocks
  import digital_swig as digital
  import ofdm_packet_utils
  from ofdm_receiver import ofdm_receiver
  import gnuradio.gr.gr_threading as _threading
  import psk, qam
  
  # /////////////////////////////////////////////////////////////////////////////
  #                   mod/demod with packets as i/o
  # /////////////////////////////////////////////////////////////////////////////
  
  class ofdm_mod(gr.hier_block2):
      """
      Modulates an OFDM stream. Based on the options fft_length, occupied_tones, and
      cp_length, this block creates OFDM symbols using a specified modulation option.
      
      Send packets by calling send_pkt
      """
      def __init__(self, options, msgq_limit=2, pad_for_usrp=True):
          """
  	Hierarchical block for sending packets
  
          Packets to be sent are enqueued by calling send_pkt.
          The output is the complex modulated signal at baseband.
  
          Args:
              options: pass modulation options from higher layers (fft length, occupied tones, etc.)
              msgq_limit: maximum number of messages in message queue (int)
              pad_for_usrp: If true, packets are padded such that they end up a multiple of 128 samples
          """
  
  	gr.hier_block2.__init__(self, "ofdm_mod",
  				gr.io_signature(0, 0, 0),       # Input signature
  				gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
  
          self._pad_for_usrp = pad_for_usrp
          self._modulation = options.modulation
          self._fft_length = options.fft_length
          self._occupied_tones = options.occupied_tones
          self._cp_length = options.cp_length
  
          win = [] #[1 for i in range(self._fft_length)]
  
          # Use freq domain to get doubled-up known symbol for correlation in time domain
          zeros_on_left = int(math.ceil((self._fft_length - self._occupied_tones)/2.0))
          ksfreq = known_symbols_4512_3[0:self._occupied_tones]
          for i in range(len(ksfreq)):
              if((zeros_on_left + i) & 1):
                  ksfreq[i] = 0
  
          # hard-coded known symbols
          preambles = (ksfreq,)
                  
          padded_preambles = list()
          for pre in preambles:
              padded = self._fft_length*[0,]
              padded[zeros_on_left : zeros_on_left + self._occupied_tones] = pre
              padded_preambles.append(padded)
              
          symbol_length = options.fft_length + options.cp_length
          
          mods = {"bpsk": 2, "qpsk": 4, "8psk": 8, "qam8": 8, "qam16": 16, "qam64": 64, "qam256": 256}
          arity = mods[self._modulation]
          
          rot = 1
          if self._modulation == "qpsk":
              rot = (0.707+0.707j)
              
          # FIXME: pass the constellation objects instead of just the points
          if(self._modulation.find("psk") >= 0):
              constel = psk.psk_constellation(arity)
              rotated_const = map(lambda pt: pt * rot, constel.points())
          elif(self._modulation.find("qam") >= 0):
              constel = qam.qam_constellation(arity)
              rotated_const = map(lambda pt: pt * rot, constel.points())
          #print rotated_const
          self._pkt_input = digital.ofdm_mapper_bcv(rotated_const,
                                                    msgq_limit,
                                                    options.occupied_tones,
                                                    options.fft_length)
          
          self.preambles = digital.ofdm_insert_preamble(self._fft_length,
                                                        padded_preambles)
          self.ifft = fft.fft_vcc(self._fft_length, False, win, True)
          self.cp_adder = digital.ofdm_cyclic_prefixer(self._fft_length,
                                                       symbol_length)
          self.scale = blocks.multiply_const_cc(1.0 / math.sqrt(self._fft_length))
          
          self.connect((self._pkt_input, 0), (self.preambles, 0))
          self.connect((self._pkt_input, 1), (self.preambles, 1))
          self.connect(self.preambles, self.ifft, self.cp_adder, self.scale, self)
          
          if options.verbose:
              self._print_verbage()
  
          if options.log:
              self.connect(self._pkt_input, blocks.file_sink(gr.sizeof_gr_complex*options.fft_length,
                                                         "ofdm_mapper_c.dat"))
              self.connect(self.preambles, blocks.file_sink(gr.sizeof_gr_complex*options.fft_length,
                                                        "ofdm_preambles.dat"))
              self.connect(self.ifft, blocks.file_sink(gr.sizeof_gr_complex*options.fft_length,
                                                   "ofdm_ifft_c.dat"))
              self.connect(self.cp_adder, blocks.file_sink(gr.sizeof_gr_complex,
                                                       "ofdm_cp_adder_c.dat"))
  
      def send_pkt(self, payload='', eof=False):
          """
          Send the payload.
  
          Args:
              payload: data to send (string)
          """
          if eof:
              msg = gr.message(1) # tell self._pkt_input we're not sending any more packets
          else:
              # print "original_payload =", string_to_hex_list(payload)
              pkt = ofdm_packet_utils.make_packet(payload, 1, 1,
                                                  self._pad_for_usrp,
                                                  whitening=True)
              
              #print "pkt =", string_to_hex_list(pkt)
              msg = gr.message_from_string(pkt)
          self._pkt_input.msgq().insert_tail(msg)
  
      @staticmethod
      def add_options(normal, expert):
          """
          Adds OFDM-specific options to the Options Parser
          """
          normal.add_option("-m", "--modulation", type="string", default="bpsk",
                            help="set modulation type (bpsk, qpsk, 8psk, qam{16,64}) [default=%default]")
          expert.add_option("", "--fft-length", type="intx", default=512,
                            help="set the number of FFT bins [default=%default]")
          expert.add_option("", "--occupied-tones", type="intx", default=200,
                            help="set the number of occupied FFT bins [default=%default]")
          expert.add_option("", "--cp-length", type="intx", default=128,
                            help="set the number of bits in the cyclic prefix [default=%default]")
  
      def _print_verbage(self):
          """
          Prints information about the OFDM modulator
          """
          print "\nOFDM Modulator:"
          print "Modulation Type: %s"    % (self._modulation)
          print "FFT length:      %3d"   % (self._fft_length)
          print "Occupied Tones:  %3d"   % (self._occupied_tones)
          print "CP length:       %3d"   % (self._cp_length)
  
  
  class ofdm_demod(gr.hier_block2):
      """
      Demodulates a received OFDM stream. Based on the options fft_length, occupied_tones, and
      cp_length, this block performs synchronization, FFT, and demodulation of incoming OFDM
      symbols and passes packets up the a higher layer.
  
      The input is complex baseband.  When packets are demodulated, they are passed to the
      app via the callback.
      """
  
      def __init__(self, options, callback=None):
          """
  	Hierarchical block for demodulating and deframing packets.
  
  	The input is the complex modulated signal at baseband.
          Demodulated packets are sent to the handler.
  
          Args:
              options: pass modulation options from higher layers (fft length, occupied tones, etc.)
              callback: function of two args: ok, payload (ok: bool; payload: string)
  	"""
  	gr.hier_block2.__init__(self, "ofdm_demod",
  				gr.io_signature(1, 1, gr.sizeof_gr_complex), # Input signature
  				gr.io_signature(1, 1, gr.sizeof_gr_complex)) # Output signature
  
  
          self._rcvd_pktq = gr.msg_queue()          # holds packets from the PHY
  
          self._modulation = options.modulation
          self._fft_length = options.fft_length
          self._occupied_tones = options.occupied_tones
          self._cp_length = options.cp_length
          self._snr = options.snr
  
          # Use freq domain to get doubled-up known symbol for correlation in time domain
          zeros_on_left = int(math.ceil((self._fft_length - self._occupied_tones)/2.0))
          ksfreq = known_symbols_4512_3[0:self._occupied_tones]
          for i in range(len(ksfreq)):
              if((zeros_on_left + i) & 1):
                  ksfreq[i] = 0
  
          # hard-coded known symbols
          preambles = (ksfreq,)
  
          symbol_length = self._fft_length + self._cp_length
          self.ofdm_recv = ofdm_receiver(self._fft_length,
                                         self._cp_length,
                                         self._occupied_tones,
                                         self._snr, preambles,
                                         options.log)
  
          mods = {"bpsk": 2, "qpsk": 4, "8psk": 8, "qam8": 8, "qam16": 16, "qam64": 64, "qam256": 256}
          arity = mods[self._modulation]
          
          rot = 1
          if self._modulation == "qpsk":
              rot = (0.707+0.707j)
  
          # FIXME: pass the constellation objects instead of just the points
          if(self._modulation.find("psk") >= 0):
              constel = psk.psk_constellation(arity)
              rotated_const = map(lambda pt: pt * rot, constel.points())
          elif(self._modulation.find("qam") >= 0):
              constel = qam.qam_constellation(arity)
              rotated_const = map(lambda pt: pt * rot, constel.points())
          #print rotated_const
  
          phgain = 0.25
          frgain = phgain*phgain / 4.0
          self.ofdm_demod = digital.ofdm_frame_sink(rotated_const, range(arity),
                                                    self._rcvd_pktq,
                                                    self._occupied_tones,
                                                    phgain, frgain)
  
          self.connect(self, self.ofdm_recv)
          self.connect((self.ofdm_recv, 0), (self.ofdm_demod, 0))
          self.connect((self.ofdm_recv, 1), (self.ofdm_demod, 1))
  
          # added output signature to work around bug, though it might not be a bad
          # thing to export, anyway
          self.connect(self.ofdm_recv.chan_filt, self)
  
          if options.log:
              self.connect(self.ofdm_demod,
                           blocks.file_sink(gr.sizeof_gr_complex*self._occupied_tones,
                                        "ofdm_frame_sink_c.dat"))
          else:
              self.connect(self.ofdm_demod,
                           blocks.null_sink(gr.sizeof_gr_complex*self._occupied_tones))
  
          if options.verbose:
              self._print_verbage()
              
          self._watcher = _queue_watcher_thread(self._rcvd_pktq, callback)
  
      @staticmethod
      def add_options(normal, expert):
          """
          Adds OFDM-specific options to the Options Parser
          """
          normal.add_option("-m", "--modulation", type="string", default="bpsk",
                            help="set modulation type (bpsk or qpsk) [default=%default]")
          expert.add_option("", "--fft-length", type="intx", default=512,
                            help="set the number of FFT bins [default=%default]")
          expert.add_option("", "--occupied-tones", type="intx", default=200,
                            help="set the number of occupied FFT bins [default=%default]")
          expert.add_option("", "--cp-length", type="intx", default=128,
                            help="set the number of bits in the cyclic prefix [default=%default]")
          expert.add_option("", "--snr", type="float", default=30.0,
                            help="SNR estimate [default=%default]")
  
      def _print_verbage(self):
          """
          Prints information about the OFDM demodulator
          """
          print "\nOFDM Demodulator:"
          print "Modulation Type: %s"    % (self._modulation)
          print "FFT length:      %3d"   % (self._fft_length)
          print "Occupied Tones:  %3d"   % (self._occupied_tones)
          print "CP length:       %3d"   % (self._cp_length)
  
  
  
  class _queue_watcher_thread(_threading.Thread):
      def __init__(self, rcvd_pktq, callback):
          _threading.Thread.__init__(self)
          self.setDaemon(1)
          self.rcvd_pktq = rcvd_pktq
          self.callback = callback
          self.keep_running = True
          self.start()
  
  
      def run(self):
          while self.keep_running:
              msg = self.rcvd_pktq.delete_head()
              ok, payload = ofdm_packet_utils.unmake_packet(msg.to_string())
              if self.callback:
                  self.callback(ok, payload)
  
  # Generating known symbols with:
  # i = [2*random.randint(0,1)-1 for i in range(4512)]
  
  known_symbols_4512_3 = [-1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, 1, -1, 1, -1, 1, 1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, 1, 1, -1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, 1, -1, -1, -1, 1, 1, 1, -1, -1, -1, -1, -1, -1, -1, 1, -1, -1, 1, -1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, 1, -1, 1, 1, 1, -1, -1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, -1, 1, 1, 1, -1, -1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, 1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, 1, -1, -1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, -1, 1, -1, 1, 1, -1, -1, -1, 1, 1, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1, 1, 1, -1, 1, 1, 1, -1, 1, -1, 1, 1, -1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, -1, -1, 1, 1, -1, 1, -1, 1, -1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, 1, -1, 1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, -1, -1, -1, 1, -1, -1, 1, 1, 1, -1, 1, -1, 1, 1, -1, -1, -1, -1, 1, -1, 1, -1, -1, -1, 1, 1, -1, -1, 1, -1, -1, 1, 1, -1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, 1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1, 1, 1, 1, 1, 1, -1, 1, -1, -1, -1, -1, -1, -1, 1, 1, -1, -1, 1, -1, 1, 1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, -1, -1, -1, 1, 1, -1, 1, 1, 1, -1, -1, 1, 1, 1, -1, -1, -1, -1, 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