On 03/11/2014 09:48, Miika Turkia wrote:
On Mon, Nov 3, 2014 at 3:02 PM, Willem Ferguson
<[email protected]
<mailto:[email protected]>> wrote:
Calculate correct nitrogen and helium gas pressures for CCR after
import from CSV.
Currently the gas pressures stored in structures of pressure are
calculated using the gasmix composition of the currently selected
cylinder. But with CCR dives the default cylinder is the oxygen
cylinder (cylinder index 0). However, the gas pressures need to
be calculated using gasmix data from cylinder 1 (the diluent
cylinder). This patch allows setting the appropriate cylinder
for calculating the values in the structures of pressure. It
also allows for correctly calculating gas pressures for any
open circuit cylinders (e.g. bailout) that a CCR diver may
use. These open circuit cylinders would have cylinder indices
of 2 and larger.
Will hard coding the diluent cylinder index be sufficient for us? If
we have always oxygen cylinder on index 0 and diluent on cylinder 1,
then I guess hard coding might be sufficient, but if there can be
variation with different rebreathers, then it would make sense to have
the diluent and oxygen cylinders assigned dynamically per dive.
Otherwise we should probably just use define to have the diluent and
oxygen cylinders named properly so one don't need to guess what the
numbers mean.
miika
Thanks, Miika,
It is a difficult question to answer because there are different
approaches that could be adopted.
One could have coded:
if (dc->dctype==CCR etc.) cylinderindex=1; // MUCH simpler than the
current patch.
But this is obscure code for someone else doing code development later
on and who does not understand the existing logic. Therefore the way it
is implemented in the current code, which is (I hope) much more
understandable. But your argument is to get the existing logic clear in
the first place.
In a way, one wants to leave as much flexibility because one is not
sure, in expanding this code, what problems will arise in future. My
personal suspicion is that for all CCR with a 100% oxygen cylinder and a
diluent cylinde , the cylinder assignments will be as they are at
present (and with my very limited knowledge and experience I do not know
of a CCR system that is configured otherwise). This would favour a more
hard coded approach.
You guys have the experience. Please advise?? Robert, your opinion?
Kind regards,
willem
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