Helper function for partial pressure calculation

This patch introduces a new structure holding partial pressures (doubles in bar) for
all three gases and a helper function to compute them from gasmix (which holds fractions)
and ambient pressure. Currentlty this works for OC and CCR, to be extended later to PSCR.

Currently the dive_comp_type argument is unused.

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 5 insertions, 17 deletions

diff --git a/deco.c b/deco.c
index ffa8ed4ba..2a0ae940c 100644
--- a/deco.c
+++ b/deco.c
@@ -188,28 +188,16 @@ double add_segment(double pressure, const struct gasmix *gasmix, int period_in_s
 {
 	int ci;
 	int fo2 = get_o2(gasmix), fhe = get_he(gasmix);
-	double pn2 = (pressure - WV_PRESSURE) * (1000 - fo2 - fhe) / 1000.0;
-	double phe = (pressure - WV_PRESSURE) * fhe / 1000.0;
+	struct gas_pressures pressures;
+
+	fill_pressures(&pressures, pressure, gasmix, (double) ccpo2 / 1000.0, dive->dc.dctype);
 
 	if (buehlmann_config.gf_low_at_maxdepth && pressure > gf_low_pressure_this_dive)
 		gf_low_pressure_this_dive = pressure;
 
-	if (ccpo2) { /* CC */
-		double rel_o2_amb, f_dilutent;
-		rel_o2_amb = ccpo2 / pressure / 1000;
-		f_dilutent = (1 - rel_o2_amb) / (1 - fo2 / 1000.0);
-		if (f_dilutent < 0) { /* setpoint is higher than ambient pressure -> pure O2 */
-			pn2 = 0.0;
-			phe = 0.0;
-		} else if (f_dilutent < 1.0) {
-			pn2 *= f_dilutent;
-			phe *= f_dilutent;
-		}
-	}
-
 	for (ci = 0; ci < 16; ci++) {
-		double pn2_oversat = pn2 - tissue_n2_sat[ci];
-		double phe_oversat = phe - tissue_he_sat[ci];
+		double pn2_oversat = pressures.n2 - tissue_n2_sat[ci];
+		double phe_oversat = pressures.he - tissue_he_sat[ci];
 		double n2_f = n2_factor(period_in_seconds, ci);
 		double he_f = he_factor(period_in_seconds, ci);
 		double n2_satmult = pn2_oversat > 0 ? buehlmann_config.satmult : buehlmann_config.desatmult;