Add support for RBT reported sample value

RBT (Remaining Bottom Time) is a value calculated on the fly by some air
integrated divecomputers, for example Uwatec devices. This value is an
estimation based in some heuristic around time function pressure
gradients. This way, RBT would be the time a diver can spend at actual
depth without running out of gas (taking account of ascent, deco, if
required, and rock bottom gas reserve, if set).
Older Uwatec devices just made the calculus and only stored alarm events
if this time value reached zero, but modern devices store the value each
sample, in minutes.
It seems that Suunto Eon Steel is storing RBT values too, in seconds.

Libdivecomputer has supported RBT for a while, but Subsurface just
printed it to stdout and dropped it.

This adds support for RBT value on subsurface sample structure and shows
it in the profile's info box, right under TTS(calc), if selected, where
these two values can be easily compared by humans.

Signed-off-by: Salvador Cuñat <salvador.cunat@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

4 files changed, 8 insertions, 3 deletions

diff --git a/dive.h b/dive.h
index e61d1e917..69a01125e 100644
--- a/dive.h
+++ b/dive.h
@@ -176,6 +176,7 @@ struct sample                         // BASE TYPE BYTES  UNITS    RANGE      DE
 	duration_t stoptime;           // uint32_t   4  seconds  (0-18 h)     time duration of next deco stop
 	duration_t ndl;                // uint32_t   4  seconds  (0-18 h)     time duration before no-deco limit
 	duration_t tts;                // uint32_t   4  seconds  (0-18 h)     time duration to reach the surface
+	duration_t rbt;                // uint32_t   4  seconds  (0-18 h)     remaining bottom time
 	depth_t depth;                 // int32_t    4    mm     (0-2000 km)  dive depth of this sample
 	depth_t stopdepth;             // int32_t    4    mm     (0-2000 km)  depth of next deco stop
 	temperature_t temperature;     // int32_t    4  mdegrK   (0-2 MdegK)  ambient temperature
@@ -191,7 +192,7 @@ struct sample                         // BASE TYPE BYTES  UNITS    RANGE      DE
 	bool in_deco;                  // bool       1    y/n      y/n        this sample is part of deco
 	bool manually_entered;         // bool       1    y/n      y/n        this sample was entered by the user,
 				       //                                     not calculated when planning a dive
-};                      // Total size of structure: 53 bytes, excluding padding at end
+};                      // Total size of structure: 57 bytes, excluding padding at end
 
 struct divetag {
 	/*
diff --git a/libdivecomputer.c b/libdivecomputer.c
index edefaab14..64e76e389 100644
--- a/libdivecomputer.c
+++ b/libdivecomputer.c
@@ -246,7 +246,7 @@ sample_cb(dc_sample_type_t type, dc_sample_value_t value, void *userdata)
 		handle_event(dc, sample, value);
 		break;
 	case DC_SAMPLE_RBT:
-		printf("   <rbt>%u</rbt>\n", value.rbt);
+		sample->rbt.seconds = (!strncasecmp(dc->model, "suunto", 6)) ? value.rbt : value.rbt * 60;
 		break;
 	case DC_SAMPLE_HEARTBEAT:
 		sample->heartbeat = value.heartbeat;
diff --git a/profile.c b/profile.c
index 74382b074..51f322cfd 100644
--- a/profile.c
+++ b/profile.c
@@ -637,7 +637,8 @@ struct plot_data *populate_plot_entries(struct dive *dive, struct divecomputer *
 		entry->heartbeat = sample->heartbeat;
 		entry->bearing = sample->bearing.degrees;
 		entry->sac = sample->sac.mliter;
-
+		if (sample->rbt.seconds)
+			entry->rbt = sample->rbt.seconds;
 		/* skip events that happened at this time */
 		while (ev && ev->time.seconds == time)
 			ev = ev->next;
@@ -1197,6 +1198,8 @@ static void plot_string(struct plot_info *pi, struct plot_data *entry, struct me
 	}
 	if (entry->tts_calc)
 		put_format(b, translate("gettextFromC", "TTS: %umin (calc)\n"), DIV_UP(entry->tts_calc, 60));
+	if (entry->rbt)
+		put_format(b, translate("gettextFromC", "RBT: %umin\n"), DIV_UP(entry->rbt, 60));
 	if (entry->ceiling) {
 		depthvalue = get_depth_units(entry->ceiling, NULL, &depth_unit);
 		put_format(b, translate("gettextFromC", "Calculated ceiling %.0f%s\n"), depthvalue, depth_unit);
diff --git a/profile.h b/profile.h
index 36b8aa767..a6dbfcf5f 100644
--- a/profile.h
+++ b/profile.h
@@ -34,6 +34,7 @@ struct plot_data {
 	int percentages[16];
 	int ndl;
 	int tts;
+	int rbt;
 	int stoptime;
 	int stopdepth;
 	int cns;