Re: [Discuss-gnuradio] Trouble with block output

[Eric Blossom]

On Sun, Jul 25, 2010 at 12:13:38PM -0700, Thunder87 wrote:
> 
> This block should take a bit from chunk, and produce an output (d_phase)
> which would hold until next chunk comes in. Right now it does take chunk,
> extract this bit, produce correct phase, but next moment block output drops
> to 0+0j.
> 
> It gives me feeling that block is producing output all the time, while
> making decision only when input chunk is present. And when there is no input
> chunk no output decision is being made, and output is being set by default
> 0+0j.
> 
> Could this be? Is there any block that uses same method (holding output
> until next input), so I could learn from it's source?
> 

(1) You should probably derive from gr_sync_block, instead of gr_block.
(2) general_work is missing it's for loop, and is writing only a
    single output sample, but saying it produced noutput_items.


Eric


> 
> howto_diffconst_bc.h
> 
> #ifndef INCLUDED_HOWTO_DIFFCONST_BC_H
> #define INCLUDED_HOWTO_DIFFCONST_BC_H
> 
> #include <gr_block.h>
> #include <iostream>
> using namespace std;
> 
> 
> class howto_diffconst_bc;
> 
> typedef boost::shared_ptr<howto_diffconst_bc> howto_diffconst_bc_sptr;
> 
> howto_diffconst_bc_sptr howto_make_diffconst_bc ();
> 
> class howto_diffconst_bc : public gr_block
> {
>   private:
>     friend howto_diffconst_bc_sptr howto_make_diffconst_bc ();
>     howto_diffconst_bc ();
>     int d_phase;
>   public:
>     ~howto_diffconst_bc ();
>     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
> 
> howto_diffconst_bc.cc
> 
> #ifdef HAVE_CONFIG_H
> #include "config.h"
> #endif
> 
> #include <howto_diffconst_bc.h>
> #include <gr_io_signature.h>
> #include <iostream>
> using namespace std;
> 
> 
> howto_diffconst_bc_sptr howto_make_diffconst_bc ()
>      {return howto_diffconst_bc_sptr (new howto_diffconst_bc ());}
> 
> howto_diffconst_bc::howto_diffconst_bc (): gr_block ("diffconst_bc",
>                                            gr_make_io_signature (1, 1,
> sizeof (unsigned char)),
>                                            gr_make_io_signature (1, 1,
> sizeof (gr_complex))){d_phase=0;}
> 
> howto_diffconst_bc::~howto_diffconst_bc () {}
> 
> 
> int howto_diffconst_bc::general_work (int noutput_items, gr_vector_int
> &ninput_items,
>                                       gr_vector_const_void_star
> &input_items,
>                                       gr_vector_void_star &output_items)
> 
> {
> const unsigned char *in  = (const unsigned char *) input_items [0];
> gr_complex          *out = (gr_complex          *) output_items[0];
> 
> if ((int)(in[0])%2==1) {d_phase++; if (d_phase>3) d_phase=0;}
> else {d_phase--; if (d_phase<0) d_phase=3;}
> 
> if      (d_phase==0) {out[0]=gr_complex( 1.0, 0.0);}
> else if (d_phase==1) {out[0]=gr_complex( 0.0, 1.0);}
> else if (d_phase==2) {out[0]=gr_complex(-1.0, 0.0);}
> else if (d_phase==3) {out[0]=gr_complex( 0.0,-1.0);}
> 
> consume_each (noutput_items);
> return noutput_items;
> }
> 
> -- 
> View this message in context: 
> http://old.nabble.com/Trouble-with-block-output-tp29261420p29261420.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
> 
> 
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