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[Discuss-gnuradio] one question about gr_chunks_to_symbols_bc
From: |
jiangfan shi |
Subject: |
[Discuss-gnuradio] one question about gr_chunks_to_symbols_bc |
Date: |
Thu, 18 Sep 2008 12:16:47 -0500 |
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
- [Discuss-gnuradio] one question about gr_chunks_to_symbols_bc,
jiangfan shi <=