Re: [Discuss-gnuradio] Some doubts in using gr_modtool

[Marcus Müller]

Hi Manu!
> Suppose I don't know the block size before hand, and I want to pass a parameter 
> "x" to toe constructor such that block size can be obtained from x using 
> certain computation (that will be defined inside the constructor). Can I do this? If so 
> how?
 Yes, that's possible *inside the constructor only*. See the 
gr::basic_block::set_{in,out}put_signature(gr::io_signature::sptr) doxygen.
> When I add a new block "encoder", to the module "ldpc", modtool add files "include/ldpc/encoder.h", 
> "lib/encoder_impl.cc", and "lib/encoder_impl.h". And the work function is to be declared and defined in encoder_impl.h and 
> encoder_impl.cc respectively. Consider that I have the function "encode" defined and declared in ldpc.h and ldpc.cc respectively. ldpc.* 
> does not define any signal processing block, so I don't add them using modtool. But they are required as they have the definition for the 
> "encode" function and inside the work function in encoder_impl.cc I just want to call the encode function defined inside this ldpc class.
>
> Am I supposed to put ldpc.h in inlclude/ldpc/ and ldpc.cc in lib/? Or should I 
> put both of them inside lib/ ? Which section of CMakeLists.txt am I supposed to 
> modify?
Yes, that would be the correct structure.
Just add ldpc.cc to lib/CMakeLists.txt:

list_append (APPEND projectname_sources
encoder_impl.cc
...
ldpc.cc )

Happy Hacking!

PS:You should also the include_directuries(${library_INCLUDE_DIR}) for each 
external library you use to that file if you haven't done so; same applies for 
target_link_libraries)