Re: [Discuss-gnuradio] gr_delay

[Johnathan Corgan]

On Wed, Nov 2, 2011 at 16:43, Marcus D. Leech <address@hidden> wrote:

To be clear, the problem appears to be with the block itself.   GRC correctly adds the "set_delay" callback spooge.

But calling that callback in the C++ code doesn't appear to affect the delay.

Changing the delay via the callback changes the history requirements of the block, which will not take effect until the thread executing the work() function returns, and could be hundreds or thousands of items in the future.  But it does take effect eventually.

One way to change this behavior would be to implement the pattern used in the FIR blocks for when the number of taps changes.  Changing the delay would set a flag that the work function could check for and return immediately.  However, this wold come a high price, as the work() function currently uses memcpy to move data from the input to the output, and instead you'd have to have an iterative loop with a conditional equality check in the middle.

Johnathan