If salinity is not density, add density of fresh water

There was a reported case of an import of a dive that gave a salinity of
35g/l. This is an actual salinity (an amount of salt in the water) but
for subsurface the salinity is actually the density of the water. So for
too small values of the salinity add the density of fresh water.

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

2 files changed, 4 insertions, 0 deletions

diff --git a/dive.c b/dive.c
index bb35f4454..83ec161c6 100644
--- a/dive.c
+++ b/dive.c
@@ -1116,6 +1116,8 @@ static void fixup_water_salinity(struct dive *dive)
 
 	for_each_dc (dive, dc) {
 		if (dc->salinity) {
+			if (dc->salinity < 500)
+				dc->salinity += FRESHWATER_SALINITY;
 			sum += dc->salinity;
 			nr++;
 		}
diff --git a/dive.h b/dive.h
index ccb12e9be..cf9b19f82 100644
--- a/dive.h
+++ b/dive.h
@@ -409,6 +409,8 @@ static inline int calculate_depth_to_mbar(int depth, pressure_t surface_pressure
 		mbar = SURFACE_PRESSURE;
 	if (!salinity)
 		salinity = SEAWATER_SALINITY;
+	if (salinity < 500)
+		salinity += FRESHWATER_SALINITY;
 	specific_weight = salinity / 10000.0 * 0.981;
 	mbar += rint(depth / 10.0 * specific_weight);
 	return mbar;