hdl - Add timetag buffer for multi-shot mode
In order to get timetag for each trigger, the driver is using the
trigger interrupt.
But if the shots are close from each other (small number of samples),
the driver can miss interrupts.
The idea would be to implement a timetag buffer in hardware to overcome
this limitation.
With a hw buffer, the driver can get all the timetags at the end of the
acquisition.