Profile: fix SAC calculation for air dives

Commit f5b11daffd6f240268ce78d72c64be43670988ea changed gasmix
arguments and return values to be passed by value instead of
using pointers.

Notably, get_gasmix() is fed a default-value and returns a
new value. In the old code, NULL was passed in in a first
loop iteration and non-NULL was always returned in the first
iteration. Thus, an equality comparison of passed-in an
returned gasmix would always fail in the first loop iteration.

The new code passed in air as default. Now if air was also
returned, then the matching gases were not calculated in
calculate_sac(). To revert to the old behavior, pass in
an invalid gasmix.

Moreover, give names to the invalid and air gasmixes.

Reported-by: tormento <turment@gmail.com>
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 8 insertions, 1 deletions

diff --git a/core/dive.c b/core/dive.c
index 53ca49bfd..a8814413a 100644
--- a/core/dive.c
+++ b/core/dive.c
@@ -2205,8 +2205,15 @@ void cylinder_renumber(struct dive *dive, int mapping[])
 		dc_cylinder_renumber(dive, dc, mapping);
 }
 
+static bool gasmix_is_invalid(struct gasmix mix)
+{
+	return mix.o2.permille < 0;
+}
+
 int same_gasmix(struct gasmix a, struct gasmix b)
 {
+	if (gasmix_is_invalid(a) || gasmix_is_invalid(b))
+		return 0;
 	if (gasmix_is_air(a) && gasmix_is_air(b))
 		return 1;
 	return a.o2.permille == b.o2.permille && a.he.permille == b.he.permille;
@@ -4314,6 +4321,6 @@ struct gasmix get_gasmix(const struct dive *dive, const struct divecomputer *dc,
 struct gasmix get_gasmix_at_time(const struct dive *d, const struct divecomputer *dc, duration_t time)
 {
 	const struct event *ev = NULL;
-	struct gasmix gasmix = { 0 };
+	struct gasmix gasmix = gasmix_air;
 	return get_gasmix(d, dc, time.seconds, &ev, gasmix);
 }