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Fix pO2 for CCR at shallow depths

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Even when diving a CCR, the pO2 cannot exceed ambient
pressure. This only makes a difference at shallow depths.

Fix this in the calculation of OTUs and CNS.

This affects some tests that now have slightly different CNS and OTU values.

Suggested-by: Justin Ashworth
Signed-off-by: Robert C. Helling <helling@atdotde.de>
This commit is contained in:
Robert C. Helling 2021-02-23 11:36:00 +01:00 • committed by Dirk Hohndel
parent 6b8a07f0d9
commit 2064ce06cc
11 changed files with 35 additions and 31 deletions
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20
core/divelist.c
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@ -109,12 +109,14 @@ static int calculate_otu(const struct dive *dive)
po2f = sample->o2sensor[0].mbar; // ... use data from the first o2 sensor
} else {
if (dc->divemode == CCR) {
po2i = psample->setpoint.mbar; // if CCR has no o2 sensors then use setpoint
po2f = sample->setpoint.mbar;
po2i = MIN((int) psample->setpoint.mbar,
depth_to_mbar(psample->depth.mm, dive)); // if CCR has no o2 sensors then use setpoint
po2f = MIN((int) sample->setpoint.mbar,
depth_to_mbar(sample->depth.mm, dive));
} else { // For OC and rebreather without o2 sensor/setpoint
int o2 = active_o2(dive, dc, psample->time); // ... calculate po2 from depth and FiO2.
po2i = lrint(o2 * depth_to_atm(psample->depth.mm, dive)); // (initial) po2 at start of segment
po2f = lrint(o2 * depth_to_atm(sample->depth.mm, dive)); // (final) po2 at end of segment
po2i = lrint(o2 * depth_to_bar(psample->depth.mm, dive)); // (initial) po2 at start of segment
po2f = lrint(o2 * depth_to_bar(sample->depth.mm, dive)); // (final) po2 at end of segment
}
}
if ((po2i > 500) || (po2f > 500)) { // If PO2 in segment is above 500 mbar then calculate otu
@ -164,14 +166,16 @@ static double calculate_cns_dive(const struct dive *dive)
trueo2 = true;
}
if ((dc->divemode == CCR) && (!trueo2)) {
po2i = psample->setpoint.mbar; // if CCR has no o2 sensors then use setpoint
po2f = sample->setpoint.mbar;
po2i = MIN((int) psample->setpoint.mbar,
depth_to_mbar(psample->depth.mm, dive)); // if CCR has no o2 sensors then use setpoint
po2f = MIN((int) sample->setpoint.mbar,
depth_to_mbar(sample->depth.mm, dive));
trueo2 = true;
}
if (!trueo2) {
int o2 = active_o2(dive, dc, psample->time); // For OC and rebreather without o2 sensor:
po2i = lrint(o2 * depth_to_atm(psample->depth.mm, dive)); // (initial) po2 at start of segment
po2f = lrint(o2 * depth_to_atm(sample->depth.mm, dive)); // (final) po2 at end of segment
po2i = lrint(o2 * depth_to_bar(psample->depth.mm, dive)); // (initial) po2 at start of segment
po2f = lrint(o2 * depth_to_bar(sample->depth.mm, dive)); // (final) po2 at end of segment
}
po2i = (po2i + po2f) / 2; // po2i now holds the mean po2 of initial and final po2 values of segment.
/* Don't increase CNS when po2 below 500 matm */