Re: [Discuss-gnuradio] gr.file_sink() or connect() limitations?

[Francesco B.]

Thanks for the tip regarding fork(). I'll use popen() instead. :)


Still need to deal with the file_sink issue, though... fork() was only an
idea for later. Will investigate this further.

~ Francesco



Eric Blossom wrote:
> 
> On Thu, Mar 05, 2009 at 10:35:37PM -0800, Francesco B. wrote:
>> 
>> Below is a short GNU Radio pipeline. Its purpose is to write an impulse
>> response to a character device node representing an FPGA (which contains
>> a
>> 4-coefficient lowpass filter), read the FPGA's output, and store said
>> output
>> in a file. 
> 
> FWIW, the comment about os.fork() concerns me.  If you are expecting
> both parent and child to continue running GNU Radio code after
> os.fork, you have a misunderstanding of our code, and possibly of fork
> in general. (I'm not certain that this is what you're trying to do,
> but if it is, it won't work.)  There's a bunch of shared state behind
> the scenes that will end up "copy-on-write" after fork, leaving the
> no-longer-shared state inconsistent.  A standalone call to fork is
> almost never the answer to any problem.  If you're trying to run an
> external program from within python, consider using os.system or
> os.popen.
> 
>> At least, it'd be appreciated if someone could point me to the code for
>> gr.file_sink() itself. I get lost in the mass of processing blocks that
>> make
>> use of it when I try to search for it, and can't find the file_sink()
>> block
>> itself.
> 
> Using common command line tools will allow you to find the source for
> any block.  E.g.,
> 
>   $ find . -print | grep -v \.svn | xargs grep -l file_sink
> 
> 
>   ./gnuradio-core/src/lib/io/gr_file_sink.h
>   ./gnuradio-core/src/lib/io/gr_file_sink_base.cc
> 
> 
> The etags and/or ctags command are helpful too.
> 
>   $ man ctags
> 
> Eric
> 
> 
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> 

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