Re: Running C++ program from octave ??

[Quentin Spencer]

Robert A. Macy wrote:

> Is it possible to run a C++ program from octave?  With it
> continually running while data keeps coming back?
>
> To clarify, the program is a real time audio interface
> called ASIO from Steinberg.  Picture it's like the
> "recorded" sound.  
>
> The program runs for some long time, continually creating
> rather large data sets as input buffers which are filled
> regularly [then hopefully picked up by octave.  For
> example, 24 bits at 192Kb/s with 50 mS latency is like 9600
> of 4 bytes each, because the data is "long".  
>
> Or, am I supposed to compile my octave program to run in
> C++??  
>
> Probably simple for all of you octave/C++ gurus.  
>  

How to do this depends on how you plan to communicate with the external 
program. I've done something like this where the data is tranferred via 
a file, but that is obviously slower than passing the data directly. I 
also killed the external process under certain conditions if necessary. 
Below is a bit of the code I used:


%% define variables 'command' and 'results_file'

PID = system(mindist_cmd, 1, 'async');
while(waitpid(PID,1)~=PID)
 sleep(1);
 results = [];
 while(isempty(results))
   F = fopen(results_file, 'rt');
   %% perform some operation that loads the file into the variable 
'results'
   fclose(F);
   if(isempty(results))  sleep(0.1);  end
 end
 %% kill the external process
 if(  <some condition is met> )
   kill(PID,SIG.QUIT);
   waitpid(PID);
   break;
 end
end


Hope this helps.

-Quentin



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