Move setup of channels and trigger masks to the new probe
configuration callback. Although the actual hardware setup
still happens just before acquisition, the new approach
already has the advantage that invalid settings are caught
early.
Also, it turns out that the LWLA1034 allows triggering on
channels which are not enabled for data acquisition. This
feature is now supported as well.
(process_sample_data): When expanding run-length samples into
session packets, calculate the number of samples to write in
advance while honoring all constraints. This is cleaner than
checking constraints within the expansion loop. Also, the new
logic always fills up packets exactly to whatever limit applies
first, thereby removing the need for truncation after the fact.
Allow the acquisition to be constrained by time in addition to
a sample count limit. Since the LWLA protocol actually provides
only a duration natively, implement the sample count limit on top
of the new duration limit.
With this change, limiting an acquisition in external clock mode
should finally work properly.
Daniel Elstner