[Discuss-gnuradio] Re: one question about gr_chunks_to_symbols_bc

[jiangfan shi]

Can anyone offer some explanations? Thanks.

Jiangfan

On Thu, Sep 18, 2008 at 12:16 PM, jiangfan shi <address@hidden> wrote:
> Hi, All,
>
> I looked through the gr_chunks_to_symbols_bc code, my understanding is
> that it handles a two-dimension array. Based on the following work()
> function, my understanding is that  each input_items[m] is a list of
> chunk (called stream in this function), and the input_items itself is
> a list of stream. Then the function maps each chunk to a complex based
> on the symbol table.  Am I right?
>
> =============================
> int
> gr_chunks_to_symbols_bc::work (int noutput_items,
>                        gr_vector_const_void_star &input_items,
>                        gr_vector_void_star &output_items)
> {
>  assert (noutput_items % d_D == 0);
>  assert (input_items.size() == output_items.size());
>  int nstreams = input_items.size();
>
>  for (int m=0;m<nstreams;m++) {
>    const unsigned char *in = (unsigned char *) input_items[m];
>    gr_complex *out = (gr_complex *) output_items[m];
>
>    // per stream processing
>    for (int i = 0; i < noutput_items / d_D; i++){
>      assert (((unsigned int)in[i]*d_D+d_D) <= d_symbol_table.size());
>      memcpy(out, &d_symbol_table[(unsigned int)in[i]*d_D],
> d_D*sizeof(gr_complex));
>      out+=d_D;
>    }
>    // end of per stream processing
>
>  }
>  return noutput_items;
> }
>
> ==========================
>
> Another question is that what the gr_chunks_to_symbols_bc constructor
> means? Based on the following code, I do not understand d_D(D) and
> d_symbol_table (symbol_table). I know gr_sync_interpolator() is called
> explicitly in gr_chunks_to_symbols_bc's constructor. are d_D and
> d_symbol_table other classes? or something else?
>
> =========================
> gr_chunks_to_symbols_bc::gr_chunks_to_symbols_bc (const
> std::vector<gr_complex> &symbol_table, const int D)
>  : gr_sync_interpolator ("chunks_to_symbols_bc",
>                          gr_make_io_signature (1, -1, sizeof (unsigned char)),
>                          gr_make_io_signature (1, -1, sizeof (gr_complex)),
>                          D),
>  d_D (D),
>  d_symbol_table (symbol_table)
> {
> }
>
> =========================
>
> Thanks for your help.
>
> Jiangfan
>