Re: [Discuss-gnuradio] call the work() method

[Marcus Müller]

Hi Xianda,

> I just want to write c++ code to realize ("fft" block+"OFDM Cyclic
Prefixer").

Sorry, I still did not understand. I only understand your C++, so here's
my comments:

The code you posted has really nothing to do with gr::block;
gr::fft:fft_complex is *not* a gr::block, and has no work()!
http://gnuradio.org/doc/doxygen/classgr_1_1fft_1_1fft__complex.html

Also, I don't see the need to #include
<gnuradio/digital/ofdm_cyclic_prefixer.h>. Is this a mistake or was it
intentional?

fft_complex really just a convenience wrapper around FFTW.
I haven't tried to test your code, and you could read() directly into
the get_inbuf() buffer, and write directly from your get_outbuf()
buffer, but it looks ok.

Again: gr::fft:fft_complex is not a block! it is used from within
fft_complex_vcc (which is a block).
All it does is use the FFTW library to perform FFTs, you can do that
yourself without using GNU Radio at all. Only use it when you are
developing a GNU Radio program!

Greetings,
Marcus


On 31.05.2014 13:21, xianda wrote:
> Hi:
> Thank you so much.
> I just want to write c++ code to realize ("fft" block+"OFDM Cyclic Prefixer").
> And I attached my code which just realize ifft but the "OFDM Cyclic Prefixer" 
> has it's work function.
> #include <fstream>
> #include <vector>
> #include <gnuradio/gr_complex.h>
> #include <gnuradio/fft/fft.h>
> #include <gnuradio/digital/ofdm_cyclic_prefixer.h>
>
> std::vector<std::complex<float> *> buff1(64);//read data
> std::vector<std::complex<float> *> buff2(64);//write data
>
> std::ifstream infile("a.dat",std::ifstream::binary);
> std::ofstream outfile("b.dat",std::ofstream::binary);
>
> int main(){
> while(not infile.eof())
> {
> infile.read((char*)&buff1.front(),buff1.size()*sizeof(std::complex<float>));
>
> gr::fft::fft_complex *buff=new gr::fft::fft_complex(64,0);
> gr_complex *bu=buff->get_inbuf();
> memcpy(bu,&buff1.front(),buff1.size()*sizeof(std::complex<float>));
> buff->execute();
> gr_complex *out=buff->get_outbuf();
> memcpy(&buff2.front(),out,buff2.size()*sizeof(std::complex<float>));
>
> outfile.write((char*)&buff2.front(),buff2.size()*sizeof(std::complex<float>));
> }
>
> infile.close();
> outfile.close();
> }
>
> Thank you.
> Best regards,
> xianda
>
> At 2014-05-31 06:33:35, "Martin Braun" <address@hidden> wrote:
>
>
>
> On 31 May 2014 11:57, "Marcus Müller" <address@hidden> wrote:
>> Hi Xianda,
>>
>>
>>>          I know every block should have it's work or general_work 
>>> function.And i know it's used by scheduler
> For the record, a block that only uses message passing doesn't need a work 
> function - not that that's what you're looking for here.
>
>
> M
>
>
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