[Discuss-gnuradio] zero ninput_items_required[0]

[Nemanja Savic]

Hi list,

I am designing very simple FSK modulator. The principle of operation is following:

based on symbol value nco generates baseband signa. The problem is somewhere in my forecast function, but I can't figure out where, probably because of misunderstanfing of something.

The body of my forecast function is:

ninput_items_required[0] = noutput_items * d_sym_rate / d_sampling_freq;
printf("ninput_items_required %d, noutput_items %d\n", ninput_items_required[0], noutput_items);

when i run execution, the output is following:

ninput_items_required 8, noutput_items 4096
ninput_items_required 4, noutput_items 2048
ninput_items_required 2, noutput_items 1024
ninput_items_required 1, noutput_items 512
ninput_items_required 0, noutput_items 256
ninput: 0, produced: 0

The last line of the output comes from general_work function and prints number of input items and number of produced output samples.

Can somebody explain me why forecast is called 5 times, till number of input items reach 0, and after that nothing is possible in work function, cause it won't enter the loop since ninput_items = 0;

Thanks,

--
Nemanja Savić