Review request: mCCR diving with OSTC3 fixed setpoints

[Jef Driesen]

On 2017-04-28 14:12, Jan Mulder wrote:
> Let me first explain the use case. I (and some fellow cave explorers I
> dive with) dive mCCR units (Kiss Classic specifically) in its most
> primitive form. No attached divecomputer to the mCCR, but only some
> analog po2 devices to fly the unit. This obviously results in no
> logging from po2 sensors. I use a OSTC3, and most of my buddies some
> Shearwater divecomputer. As I am (at this point), not aware how a
> Shearwater handles this use case, I consider only an OSTC3 for now.
> 
> it appears, in the current code, the manual changes of setpoint on the
> divecomputer are correctly recorded (as events) and are correctly
> handled on import from the OSTC3 in to Subsurface. The initial
> setpoint  at the start of the dive is, however, a little bit  a can of
> worms. The OSCTS3 does not record a setpoint change at the beginning
> of the dive, and the recorded po2 values are from the diluent (so not
> very useful).
> 
> To deal with this use case, had to adapt libdivecomputer (see my
> branch https://github.com/janmulder/libdc/tree/ostc3-upd), and after
> that Subsurface
> (https://github.com/janmulder/subsurface/tree/ccr-po2-issue-2).
> 
> As libdivecomputer did not interface the fixed setpoints (including
> the initial one at the start of the dive), I had to add those. After
> that, Subsurface can determine the initial setpoint. For completeness,
> this setpoint is added to the XML and git storage backends as well.
> 
> I would really appreciate a review for this change.

For the initial setpoint, you can simply emit a setpoint value on the 
first sample. I'm already doing that for the initial gas mix too.

Jef