Re: [Discuss-gnuradio] First line of Work Confusion

[Marcus Müller]

Hi Rich,

two cases here:
a) Either the block doesn't actually do the casting (ie. it doesn't care for the data type), and the drop down menu just selects a item size (useful for things that just memcpy things over etc), or
b) the dropdown menu actually selects one of multiple different blocks.

Cheers,
Marcus

On 21.07.2015 01:35, Richard Bell wrote:

So, the first line of work and general_work functions is usually something of the form

const unsigned char *in = (const unsigned char *) input_items[0];
unsigned char *out = (unsigned char *) output_items[0];

or

gr_complex *in = (gr_complex *) input_items[0];
gr_complex *out = (gr_complex *) output_items[0];

or other input/output types.

The confusion comes when I make blocks that have user selectable types through GRC. I see from built-ins that developers use the unsigned char pointers for this usually. What I can't figure out is how this works when a user selects gr_complex as an input/output type. It seems to me that these pointers to unsigned chars should fail dramatically. But they don't! In fact, I can use either of the two forms I presented above and my flow graph "works", quotes because there maybe a fail case I haven't found yet, so far they just work either way.

Rich

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