pkt_rcv_epy_block_0.py

import numpy as np
from gnuradio import gr
import pmt
import base64

class blk(gr.sync_block):
    def __init__(self):
        gr.sync_block.__init__(
            self,
            name='EPB: Decode Packet',   # will show up in GRC
            in_sig=None,
            out_sig=None)
        self.message_port_register_in(pmt.intern('msg_in'))
        self.message_port_register_out(pmt.intern('msg_out'))
        self.set_msg_handler(pmt.intern('msg_in'), self.handle_msg)

    def handle_msg(self, msg):
        _debug = 0          # set to zero to turn off diagnostics
        try:
            buff = pmt.to_python(pmt.cdr(msg))
        except Exception as e:
            gr.log.error("Error with message conversion: %s" % str(e))
            return

        b_len = len (buff)
        if (_debug):
            print ("new_val =", buff, b_len)
        u8_data = []
        if (b_len != 52):
            # decode Base64
            data = base64.b64decode(buff)
            i = 0
            while (i < len(data)):
                u8_data.append(pmt.to_pmt (data[i]))
                i += 1
            pdu = pmt.cons(pmt.PMT_NIL,pmt.init_u8vector(len(u8_data), u8_data))
            self.message_port_pub(pmt.intern('msg_out'), pdu)
        elif ((buff[0] != 37) and (buff[51] != 93)):
            # decode Base64
            data = base64.b64decode(buff)
            i = 0
            while (i < len(data)):
                u8_data.append(pmt.to_pmt (data[i]))
                i += 1
            pdu = pmt.cons(pmt.PMT_NIL,pmt.init_u8vector(len(u8_data), u8_data))
            self.message_port_pub(pmt.intern('msg_out'), pdu)