Fix the pO2 calculation when diving with air

So few of my dives are on air that at first I didn't notice - but for
those dives we set the o2 permille to 0 - which of course causes incorrect
(and extremely deadly) pO2 of 0...

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/profile.c b/profile.c
index d32224190..82b7dd0f1 100644
--- a/profile.c
+++ b/profile.c
@@ -1298,8 +1298,8 @@ static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, str
 	lastindex = 0;
 	lastdepth = -1;
 	for (i = 0; i < nr_samples; i++) {
-		int depth;
-		double fo2, pressure;
+		int depth, fo2;
+		double pressure;
 		int delay = 0;
 		struct sample *sample = dive_sample+i;
 
@@ -1341,8 +1341,10 @@ static struct plot_info *create_plot_info(struct dive *dive, int nr_samples, str
 		entry->cylinderindex = sample->cylinderindex;
 		SENSOR_PRESSURE(entry) = sample->cylinderpressure.mbar;
 		pressure = (depth + 10000) / 10000.0 * 1.01325;
-		fo2 = dive->cylinder[sample->cylinderindex].gasmix.o2.permille / 1000.0;
-		entry->po2 = fo2 * pressure;
+		fo2 = dive->cylinder[sample->cylinderindex].gasmix.o2.permille;
+		if (!fo2)
+			fo2 = AIR_PERMILLE;
+		entry->po2 = fo2 / 1000.0 * pressure;
 
 		entry->temperature = sample->temperature.mkelvin;