Re: [Discuss-gnuradio] delete_head_blocking()

[Bastian Bloessl]

Hi,

On 06/27/2013 11:18 PM, Shashank Gaur wrote:
> I have been trying to understand delete_head_blocking() function from
> gr_basic_block, but couldn't understand much clearly. Can anybody shed
> some light on this.

I think this function is useful if you have a block with a message input 
and a stream output (i.e., the block has a work function). To avoid that 
the scheduler has to call the work function all the time even if there 
is no message to handle, you can block in the work with 
delete_head_blocking() until you receive a message.


> Also I want to understand pair(car-cdr as well), any
> info would help.

car and cdr seam to be some old school functions from Lisp times.
They are used to access the first and respectively second element of a 
pair. You might want to use them in conjunction with PDUs, as PDUs are 
pairs of a dictionary with metadata (1st element) and a blob with the 
actual payload (2nd element).

Best,
Bastian