Hi Dave,
fortunately, the process got simpler.
For now, let's assume the library you want to use supports CMake. In my
experience, every library you can install via `sudo apt install
lib...-dev` supports CMake.
Let's assume you want to use libfmt, then you need:
`find_package(fmt REQUIRED)`
in your top-level CMakeLists.txt.
In your `/lib/CMakeLists.txt` you need to add:
`target_link_libraries({YOUROOTMODULENAME} gnuradio::gnuradio-runtime
fmt::fmt)`.
That's it.
In case of VOLK, the 2 entries are:
`find_package(Volk REQUIRED)`
and
`Volk::volk`
The `REQUIRED` option let's CMake fail if it can't find the necessary
information. Otherwise, you'd have to check everything yourself.
You might have noticed that you can e.g. use VOLK without the CMake
entries in your OOT. That's because you include it with the GNU Radio
CMake config.
Cheers
Johannes
On 22.02.22 19:06, Ryan Volz wrote:
Hi Dave,
On 2/22/22 11:34 AM, David Cherkus wrote:
So, I found
https://stackoverflow.com/questions/48562304/gnuradio-c-oot-extrernal-so-library
<https://stackoverflow.com/questions/48562304/gnuradio-c-oot-extrernal-so-library>
which is a very good answer to how to get your OOT block to link to a
shared library from another package.
/As pointed out by the answer of Marcus Müller below I did not
link properly. In fact *one has to edit three different cmake files in
three places to add an external dynamically loaded library (.so) to an
OOT module in GNURadio*. I try to explain briefly what to do:
/
1. /Put a find_package(LIBNAME) in the CMakeLists.txt in the
base directory of the OOT module./
2. /Corresponding to that a FindLIBNAME.cmake file in the
cmake module path is necessary. This file has the purpose to implement
the search for include directories and library files (.so files)./
3. /Once found the path to the library has to be used with
target_link_libraries(...) in lib/CMakeLists.txt (linking)./
4. /The include file path, i.e. LIBNAME.h has to be added as
include directory using include_directories(...) in the CMakeLists.txt
in the base directory of the module.
/
/With ldd it is possible to find out if the external library
is linked correctly./
/
*ldd /usr/local/lib/YOURLIB.so*/
Am wondering if this is documented on the GNUradio web site? I could
use a bit more info, but will give it a go anyway. I did the C++
tutorial (
https://wiki.gnuradio.org/index.php?title=Guided_Tutorial_GNU_Radio_in_C%2B%2B
<https://wiki.gnuradio.org/index.php?title=Guided_Tutorial_GNU_Radio_in_C%2B%2B>
) and this was the very next thing I wanted to do, and I presume many
others as well. I know it's hard to know where to draw the line on
teaching enough vs too much, but I think this is a pretty frequent use
case, no? Note that I am teaching myself cmake on the fly. That's
OK, I just taught myself enough C++ to understand the tutorial on the
fly as well.
Regards,
Dave.
This can be easier or harder depending on how well the library you want
to link with supports CMake. In more detail, you may or may not have to
do step 2 of the instructions above, and it may be possible to skip 4 as
well if the library's include paths are part of the target that you
"link" with in step 3. So I think it is most helpful to ask: what
library specifically are you needing to link with?
In general I think covering how to use CMake is best left to the CMake
documentation, but the GNU Radio tutorials could probably benefit from a
simple example of linking with a "nice" external library. (That's if
they don't already include that somewhere, and I can't say that I've
looked!)
Cheers,
Ryan
