[Discuss-gnuradio] Problem using FFT-class in my own written block (part II)

[Jeroen Boschma]

Hello all,

In order to keep discussions separated (I apparently did something 
stupid which mixed up 2 threads), I start a new thread here.

Summarizing: when writing my own out of tree block in C++ using FFTs 
(including the 'fft/fft.h' header) and following the tutorial 
"Out-of-tree modules", I get an error when I want to use the block in 
GNU Radio Companion:

    ImportError /usr/local/libgnuradio-MY_MODULE.so: undefined symbol: 
fft_complex

According to Tom Rondeau the FFT-library is not included in the link 
process, and he suggested the following tutorial:

http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModulesConfig

I started following that tutorial, setting some environment variables 
first, and I found out that I am using version 3.6.5git (on an Ettus 
Research USB stick) while I suspect that the suggested tutorial only 
covers versions >= 3.7.

Even when I only changed the following (as suggested by the tutorial):

    find_package(GnuradioCore)

into:

    set(GR_REQUIRED_COMPONENTS CORE)
    find_package(Gnuradio "3.6.5" REQUIRED)

I get the following error when I run "cmake ../" from the build-directory:

=================================================
-- Build type not specified: defaulting to release.
-- Boost version: 1.49.0
-- Found the following Boost libraries:
--   filesystem
--   system
CMake Error at CMakeLists.txt:92 (find_package):
  By not providing "FindGnuradio.cmake" in CMAKE_MODULE_PATH this 
project has
  asked CMake to find a package configuration file provided by "Gnuradio",
  but CMake did not find one.

  Could not find a package configuration file provided by "Gnuradio"
  (requested version 3.6.5) with any of the following names:

    GnuradioConfig.cmake
    gnuradio-config.cmake

  Add the installation prefix of "Gnuradio" to CMAKE_PREFIX_PATH or set
  "Gnuradio_DIR" to a directory containing one of the above files. If
  "Gnuradio" provides a separate development package or SDK, be sure it has
  been installed.
=================================================

So I tried (as suggested by the error message):

    1) set CMAKE_MODULE_PATH to the path where "FindGnuradio.cmake"resides
    2) add the installation prefix of "Gnuradio" to CMAKE_PREFIX_PATH

The two mentioned config .cmake files are not even present on the 
environment I am working on (not found by a search at the GNU radio 
installation prefix which is usr/local).

So I am pretty stuck here.  My goal is to get this working in my current 
environment before trying to port my blocks to the latest version > 3.7. 
Any help is greatly appreciated.

Best regards,

    Jeroen Boschma