FreeDATA/test/TEST_TX.py

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Python
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2020-12-14 11:44:13 +00:00
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Sun Dec 13 13:45:58 2020
@author: parallels
"""
import ctypes
from ctypes import *
import pathlib
import binascii #required for string.to_bytes() function
#import codecs
import crcengine # required for CRC checksum
#import struct
import sys
#sys.stdout.reconfigure(encoding='utf-8')
def main():
modem = FreeDV() #Load FreeDV Class as "modem"
data = b'TEST' #byte string which will be send
#data = bytes(62) #byte string with XX of zeros
modulated_data = modem.Modulate(data) #Call Modulate function, which returns modulated data
#print(modulated_data)
###################### try: / except necessary beacuse of error 32 - BrokenPipeError while piping data
try:
#print(bytes(8)) #additional zero bytes before modulated data
#sys.stdout.buffer.write(modulated_data) # the normal way of piping data
#sys.stdout.flush() # flushing data
print(bytes(32) + modulated_data, flush=True) #print modulated data with print function
except (BrokenPipeError, IOError):
print ('TEST BrokenPipeError caught', file = sys.stderr)
#sys.stderr.close()
class FreeDV():
def __init__(self):
libname = pathlib.Path().absolute() / "libcodec2.so"
self.c_lib = ctypes.CDLL(libname) # Load FreeDV shared libary
self.freedv = self.c_lib.freedv_open(12) #Set FreeDV waveform ( 10,11,12 --> DATA1-3 )
self.bytes_per_frame = int(self.c_lib.freedv_get_bits_per_modem_frame(self.freedv)/8) #get bytes per frame from selected waveform
self.payload_per_frame = self.bytes_per_frame -2 #get frame payload because of 2byte CRC16 checksum
###################### CHECKSUM COMPARISON FREEDV VS CRCENGINE ########
#https://crccalc.com
teststring = b'test'
#FreeDV crc16 checksum -> c_int16 == c_short
crctest = c_ushort(self.c_lib.freedv_gen_crc16(teststring, 30))
print(crctest.value) #7450
#Python crc16 checksum
crc_algorithm = crcengine.new('crc16-ccitt-false') #load crc16 library
crctest2 = crc_algorithm(teststring)
print(crctest2) #8134
#######################################################################
# MODULATION-OUT OBJECT
def ModulationOut(self):
#return (c_short * self.c_lib.freedv_get_n_nom_modem_samples(self.freedv)) ## all other modes
return (c_ubyte * self.c_lib.freedv_get_n_nom_modem_samples(self.freedv)) ## DATA modes
# Pointer for changing buffer data type
def FrameBytes(self):
return (ctypes.c_ubyte * self.bytes_per_frame)
# Modulate function which returns modulated data
def Modulate(self,data_out):
## mod_out = self.ModulationOut()() # new modulation object and get pointer to it
## #self.freedv_rawdatapreambletx(self.freedv, mod_out) # SEND PREAMBLE
##########################################
mod_out = self.ModulationOut()() # new modulation object and get pointer to it
#buffer = bytearray(self.bytes_per_frame) # use this if no CRC16 checksum is required
buffer = bytearray(self.payload_per_frame) # puse this if CRC16 checksum is required ( DATA1-3)
buffer[:len(data_out)] = data_out # set buffersize to length of data which will be send
#buffer = self.scramble(buffer, packet_num)
crc_algorithm = crcengine.new('crc16-ccitt-false') #load crc16 library
crc = crc_algorithm(buffer) # get new crc16 from buffer
#print(hex(crc))
crc = crc.to_bytes(2, byteorder='big') # convert buffer to byte string
buffer += crc # append crc16 to buffer
#print(buffer)
data = self.FrameBytes().from_buffer_copy(buffer) #change data format form bytearray to ctypes.u_byte
#print(len(data))
self.c_lib.freedv_rawdatatx(self.freedv,mod_out,data) # SEND DATA
return bytes(mod_out) #return modulated data as byte string
main()