Using fft::fft_complex in an out-of-tree moudle

GNU Radio
1

Hi all,

I created an out-of-tree module for my personal project.
In one block, I need to perform FFT and IFFF, so I put “#include
<gnuradio/fft/fft.h>” in the header file, and then declare
*fft::fft_complex
d_ifft;
​In the .cc file, I wrote d_ifft = new fft::fft_complex(64, false,
1);​
​Then I can compile without any error messages, but when I run a flow
graph
to ​test the block, it turns out an error message like this:

Traceback (most recent call last):
File “/home/van-ly/sandbox/gnuradio-builds/Test/top_block.py”, line
15,
in
import PNC4TWRN
File
“/opt/gnuradio-3.7.3/lib/python2.7/dist-packages/PNC4TWRN/init.py”,
line 45, in
from PNC4TWRN_swig import *
File
“/opt/gnuradio-3.7.3/lib/python2.7/dist-packages/PNC4TWRN/PNC4TWRN_swig.py”,
line 28, in
_PNC4TWRN_swig = swig_import_helper()
File
“/opt/gnuradio-3.7.3/lib/python2.7/dist-packages/PNC4TWRN/PNC4TWRN_swig.py”,
line 24, in swig_import_helper
_mod = imp.load_module(’_PNC4TWRN_swig’, fp, pathname, description)
ImportError: /opt/gnuradio-3.7.3/lib/libgnuradio-PNC4TWRN.so: undefined
symbol: _ZN2gr3fft11fft_complexC1Eibi

​Could any one please help me with this?
Does any one know how to use the perform FFT ​in an out-of-tree module?

Thank you in advance,
Van-Ly

Van-Ly Nguyen,
Research Assistant,
Signals and Systems Laboratory - SSL
Faculty of Electronics and Telecommunications - FET
University of Engineering and Technology - UET
Vietnam National University, Hanoi - VNU

Phone: (+84) 97 881 9406

2

You have to add FFT to the top level CMakeLists.txt file. Like so:

set(GR_REQUIRED_COMPONENTS RUNTIME FFT)

Ron

3

Thank you Ron,

I got it.

Best Regards,
Van-Ly

Van-Ly Nguyen,
Research Assistant,
Signals and Systems Laboratory - SSL
Faculty of Electronics and Telecommunications - FET
University of Engineering and Technology - UET
Vietnam National University, Hanoi - VNU

Phone: (+84) 97 881 9406