2009/3/27 Mikhail Tadjikov <mtadji...@ucla.edu>
> Hello,
>
> I'm trying to build several signal processing blocks for a project that
> I'm doing using USRP2. I was going through the examples and sample code
> along with browsing the source code and I can't seem to find exactly what I
> need. I'm trying to do an average of a vector of length N:
>
> Input vector size N
> Output vector size 1
> I'm doing it for floats.
>
> ------------------------------
> #ifndef INCLUDED_CORES_WEIGHTED_AVG_FF_H
> #define INCLUDED_CORES_WEIGHTED_AVG_FF_H
> #include <gr_sync_block.h>
> class cores_weighted_avg_ff;
>
> typedef boost::shared_ptr<cores_weighted_avg_ff>
> cores_weighted_avg_ff_sptr;
> cores_weighted_avg_ff_sptr cores_make_weighted_avg_ff (unsigned int vlen);
>
> class cores_weighted_avg_ff : public gr_sync_block
> {
> private:
> friend cores_weighted_avg_ff_sptr cores_make_weighted_avg_ff (unsigned
> int vlen);
> cores_weighted_avg_ff (unsigned int vlen); // private constructor
> unsigned int d_vlen;
>
> public:
> int general_work (int noutput_items,
> gr_vector_int &ninput_items,
> gr_vector_const_void_star &input_items,
> gr_vector_void_star &output_items);
> };
> #endif
>
> ----------------------------------------------------------------------------------------------------------
> and source
>
> -------------------------------------------------------------------------------------------
> #ifdef HAVE_CONFIG_H
> #include "config.h"
> #endif
> #include <cores_weighted_avg_ff.h>
> #include <gr_io_signature.h>
>
> cores_weighted_avg_ff_sptr
> cores_make_weighted_avg_ff (unsigned int vlen)
> { return cores_weighted_avg_ff_sptr (new cores_weighted_avg_ff (vlen));}
>
> cores_weighted_avg_ff::cores_weighted_avg_ff (unsigned int vlen)
> : gr_decimator_block ("weighed_avg_ff",
> gr_make_io_signature (1, 1, sizeof (float) * vlen),
> gr_make_io_signature (1, 1, sizeof (float))),
> d_vlen(vlen)
> {
> }
> int
> cores_weighted_avg_ff::int general_work (int noutput_items,
> gr_vector_int &ninput_items,
> gr_vector_const_void_star &input_items,
> gr_vector_void_star &output_items);
> {
> const float *in = (const float *) input_items[0];
> float *out = (float *) output_items[0];
> int noi = noutput_items * d_vlen;
>
> for (int i = 0; i < noi; i++){
> out += in[i]*i;
> }
> out /= d_vlen;
> consume(noutput_items,d_vlen)
>
> return noutput_items;
> }
>
> ------------------------------------------------------------------------------------------------
>
> I'm not sure if the code is correct what I want to do (input is more than
> welcome), when I compile this code I get a weird error:
> cores_weighted_avg_ff.h: In function ‘PyObject*
> _wrap_weighted_avg_ff(PyObject*, PyObject*)’:
> cores_weighted_avg_ff.h:63: error: too few arguments to function
> ‘cores_weighted_avg_ff_sptr cores_make_weighted_avg_ff(unsigned int)’
> cores.cc:4326: error: at this point in file
> make[4]: *** [cores.lo] Error 1
>
> Any help would be greatly appreciated.
With gr_sync_block you only need to write work() and not general_work(). The
example at the end of this tutorial will be helpful
http://www.gnu.org/software/gnuradio/doc/howto-write-a-block.html. Also,
there is a "#endif" sitting in the middle of your code, it might be a typo.
btw, if you are trying to get moving averages, there is a block already
available gr_moving_averages()
Karthik
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