Profile support for multiple concurrent pressure sensors

This finally handles multiple cylinder pressures, both overlapping and
consecutive, and it seems to work on the nasty cases I've thrown at it.

Want to just track five different cylinders all at once, without any
pesky gas switch events? Sure, you can do that.  It will show five
different gas pressures for your five cylinders, and they will go down
as you breathe down the cylinders.

I obviously don't have any real data for that case, but I do have a test
file with five actual cylinders that all have samples over the whole
course of the dive.  The end result looks messy as hell, but what did
you expect?

HOWEVER.

The only way to do this sanely was

 - actually make the "struct plot_info" have all the cylinder pressures
   (so no "sensor index and pressure" - every cylinder has a pressure for
   every plot info entry)

   This obviously makes the plot_info much bigger. We used to have
   MAX_CYLINDERS be a fairly generous 8, which seems sane. The planning
   code made that 8 be 20. That seems questionable. But whatever.

   The good news is that the plot-info should hopefully get freed, and
   only be allocated one dive at a time, so the fact that it is big and
   nasty shouldn't be a scaling issue, though.

 - the "populate_pressure_information()" function had to be rewritten
   quite a bit. The good news is that it's actually simpler now, although
   I would not go so far as to really call it simple. It's still
   complicated and suble, but now it explicitly just does one cylinder at
   a time.

   It *used* to have this insanely complicated "keep track of the pressure
   ranges for every cylinder at once". I just couldn't stand that model
   and keep my sanity, so it now just tracks one cylinder at a time, and
   doesn't have an array of live data, instead the caller will just call
   it for each cylinder.

 - get rid of some of our hackier stuff, like the code that populates the
   plot_info data code with the currently selected cylinder number, and
   clears out any other pressures. That obviously does *not* work when you
   may not have a single primary cylinder any more.

Now, the above sounds like all good things. Yeah, it mostly is.

BUT.

There's a few big downsides from the above:

 - there's no sane way to do this as a series of small changes.

   The change to make the plot_info take an array of cylinder pressures
   rather than the sensor+pressure model really isn't amenable to "fix up
   one use at a time". When you switch over to the new data structure
   model, you have to switch over to the new way of populating the
   pressure ranges. The two just go hand in hand.

 - Some of our code *depended* on the "sensor+pressure" model. I fixed all
   the ones I could sanely fix. There was one particular case that I just
   couldn't sanely fix, and I didn't care enough about it to do something
   insane.

   So the only _known_ breakage is the "TankItem" profile widget. That's
   the bar at the bottom of the profile that shows which cylinder is in
   use right now. You'd think that would be trivial to fix up, and yes it
   would be - I could just use the regular model of

     firstcyl = explicit_first_cylinder(dive, dc)
     .. then iterate over the gas change events to see the others ..

   but the problem with the "TankItem" widget is that it does its own
   model, and it has thrown away the dive and the dive computer
   information. It just doesn't even know. It only knows what cylinders
   there are, and the plot_info. And it just used to look at the sensor
   number in the plot_info, and be done with that. That number no longer
   exists.

 - I have tested it, and I think the code is better, but hey, it's a
   fairly large patch to some of the more complex code in our code base.
   That "interpolate missing pressure fields" code really isn't pretty. It
   may be prettier, but..

Anyway, without further ado, here's the patch. No sign-off yet, because I
do think people should look and comment. But I think the patch is fine,
and I'll fix anythign that anybody can find, *except* for that TankItem
thing that I will refuse to touch. That class is ugly. It needs to have
access to the actual dive.

Note how it actually does remove more lines than it adds, and that's
despite added comments etc. The code really is simpler, but there may be
cases in there that need more work.

Known missing pieces that don't currently take advantage of concurrent
cylinder pressure data:

 - the momentary SAC rate coloring for dives will need more work

 - dive merging (but we expect to generally normally not merge dive
   computers, which is the main source of sensor data)

 - actually taking advantage of different sensor data from different
   dive computers

But most of all: Testing.  Lots and lots of testing to find all the
corner cases.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 124 insertions, 81 deletions

diff --git a/core/gaspressures.c b/core/gaspressures.c
index 86ea8de7a..13196b61f 100644
--- a/core/gaspressures.c
+++ b/core/gaspressures.c
@@ -64,18 +64,20 @@ static void list_free(pr_track_t *list)
 }
 
 #ifdef DEBUG_PR_TRACK
-static void dump_pr_track(pr_track_t **track_pr)
+static void dump_pr_track(int cyl, pr_track_t *track_pr)
 {
-	int cyl;
 	pr_track_t *list;
 
-	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
-		list = track_pr[cyl];
-		while (list) {
-			printf("cyl%d: start %d end %d t_start %d t_end %d pt %d\n", cyl,
-			       list->start, list->end, list->t_start, list->t_end, list->pressure_time);
-			list = list->next;
-		}
+	printf("cyl%d:\n", cyl);
+	list = track_pr;
+	while (list) {
+		printf("   start %d end %d t_start %d:%02d t_end %d:%02d pt %d\n",
+		       mbar_to_PSI(list->start),
+		       mbar_to_PSI(list->end),
+		       FRACTION(list->t_start, 60),
+		       FRACTION(list->t_end, 60),
+		       list->pressure_time);
+		list = list->next;
 	}
 }
 #endif
@@ -197,32 +199,28 @@ static struct pr_interpolate_struct get_pr_interpolate_data(pr_track_t *segment,
 	return interpolate;
 }
 
-static void fill_missing_tank_pressures(struct dive *dive, struct plot_info *pi, pr_track_t **track_pr, int sensoridx)
+static void fill_missing_tank_pressures(struct dive *dive, struct plot_info *pi, pr_track_t *track_pr, int cyl)
 {
-	int cyl, i;
+	int i;
 	struct plot_data *entry;
 	pr_interpolate_t interpolate = { 0, 0, 0, 0 };
 	pr_track_t *last_segment = NULL;
-	int cur_pr[MAX_CYLINDERS]; // cur_pr[MAX_CYLINDERS] is the CCR diluent cylinder
+	int cur_pr;
+	enum interpolation_strategy strategy;
 
-	for (cyl = 0; cyl < MAX_CYLINDERS; cyl++) {
-		enum interpolation_strategy strategy;
-		if (!track_pr[cyl]) {
-			/* no segment where this cylinder is used */
-			cur_pr[cyl] = -1;
-			continue;
-		}
-		if (dive->cylinder[cyl].cylinder_use == OC_GAS)
-			strategy = SAC;
-		else
-			strategy = TIME;
-		fill_missing_segment_pressures(track_pr[cyl], strategy); // Interpolate the missing tank pressure values ..
-		cur_pr[cyl] = track_pr[cyl]->start;	       // in the pr_track_t lists of structures
-	}						       // and keep the starting pressure for each cylinder.
+	/* no segment where this cylinder is used */
+	if (!track_pr)
+		return;
 
+	if (dive->cylinder[cyl].cylinder_use == OC_GAS)
+		strategy = SAC;
+	else
+		strategy = TIME;
+	fill_missing_segment_pressures(track_pr, strategy); // Interpolate the missing tank pressure values ..
+	cur_pr = track_pr->start;			       // in the pr_track_t lists of structures
+							       // and keep the starting pressure for each cylinder.
 #ifdef DEBUG_PR_TRACK
-	/* another great debugging tool */
-	dump_pr_track(track_pr);
+	dump_pr_track(cyl, track_pr);
 #endif
 
 	/* Transfer interpolated cylinder pressures from pr_track strucktures to plotdata
@@ -243,27 +241,32 @@ static void fill_missing_tank_pressures(struct dive *dive, struct plot_info *pi,
 
 		entry = pi->entry + i;
 
-		cyl = entry->sensor[sensoridx];
-		if (cyl < 0)
-			continue;
-		save_pressure = &(entry->pressure[sensoridx][SENSOR_PR]);
-		save_interpolated = &(entry->pressure[sensoridx][INTERPOLATED_PR]);
+		save_pressure = &(entry->pressure[cyl][SENSOR_PR]);
+		save_interpolated = &(entry->pressure[cyl][INTERPOLATED_PR]);
 		pressure = *save_pressure ? *save_pressure : *save_interpolated;
 
 		if (pressure) {			// If there is a valid pressure value,
 			last_segment = NULL;	// get rid of interpolation data,
-			cur_pr[cyl] = pressure; // set current pressure
+			cur_pr = pressure; // set current pressure
 			continue;		// and skip to next point.
 		}
 		// If there is NO valid pressure value..
 		// Find the pressure segment corresponding to this entry..
-		segment = track_pr[cyl];
+		segment = track_pr;
 		while (segment && segment->t_end < entry->sec) // Find the track_pr with end time..
 			segment = segment->next;	       // ..that matches the plot_info time (entry->sec)
 
-		if (!segment || !segment->pressure_time) { // No (or empty) segment?
-			*save_pressure = cur_pr[cyl];      // Just use our current pressure
-			continue;			   // and skip to next point.
+		// After last segment? All done.
+		if (!segment)
+			break;
+
+		// Before first segment, or between segments.. Go on, no interpolation.
+		if (segment->t_start > entry->sec)
+			continue;
+
+		if (!segment->pressure_time) {		// Empty segment?
+			*save_pressure = cur_pr;	// Just use our current pressure
+			continue;			// and skip to next point.
 		}
 
 		// If there is a valid segment but no tank pressure ..
@@ -283,13 +286,13 @@ static void fill_missing_tank_pressures(struct dive *dive, struct plot_info *pi,
 				magic = (interpolate.end - interpolate.start) / (double)interpolate.pressure_time;
 
 				/* Use that overall pressure change to update the current pressure */
-				cur_pr[cyl] = lrint(interpolate.start + magic * interpolate.acc_pressure_time);
+				cur_pr = lrint(interpolate.start + magic * interpolate.acc_pressure_time);
 			}
 		} else {
 			magic = (interpolate.end - interpolate.start) /  (segment->t_end - segment->t_start);
-			cur_pr[cyl] = lrint(segment->start + magic * (entry->sec - segment->t_start));
+			cur_pr = lrint(segment->start + magic * (entry->sec - segment->t_start));
 		}
-		*save_interpolated = cur_pr[cyl]; // and store the interpolated data in plot_info
+		*save_interpolated = cur_pr; // and store the interpolated data in plot_info
 	}
 }
 
@@ -328,6 +331,8 @@ static void debug_print_pressures(struct plot_info *pi)
 }
 #endif
 
+extern bool has_gaschange_event(struct dive *dive, struct divecomputer *dc, int idx);
+
 /* This function goes through the list of tank pressures, either SENSOR_PRESSURE(entry) or O2CYLINDER_PRESSURE(entry),
  * of structure plot_info for the dive profile where each item in the list corresponds to one point (node) of the
  * profile. It finds values for which there are no tank pressures (pressure==0). For each missing item (node) of
@@ -338,78 +343,116 @@ static void debug_print_pressures(struct plot_info *pi)
  * in the pr_track_alloc structures. If diluent_flag = 1, then DILUENT_PRESSURE(entry) is used instead of SENSOR_PRESSURE.
  * This function is called by create_plot_info_new() in profile.c
  */
-void populate_pressure_information(struct dive *dive, struct divecomputer *dc, struct plot_info *pi, int sensoridx)
+void populate_pressure_information(struct dive *dive, struct divecomputer *dc, struct plot_info *pi, int sensor)
 {
 	(void) dc;
-	int i, cylinderid, cylinderindex = -1;
-	pr_track_t *track_pr[MAX_CYLINDERS] = { NULL, };
+	int first, last, cyl;
+	cylinder_t *cylinder = dive->cylinder + sensor;
+	pr_track_t *track = NULL;
 	pr_track_t *current = NULL;
-	bool missing_pr = false;
-	bool found_any_pr_data = false;
+	struct plot_data *entry;
+	struct event *ev;
+	int missing_pr = 0, dense = 1;
 
 	/* if we have no pressure data whatsoever, this is pointless, so let's just return */
-	for (i = 0; i < MAX_CYLINDERS; i++) {
-		if (dive->cylinder[i].start.mbar || dive->cylinder[i].sample_start.mbar ||
-		    dive->cylinder[i].end.mbar || dive->cylinder[i].sample_end.mbar) {
-			found_any_pr_data = true;
-			break;
-		}
-	}
-	if (!found_any_pr_data)
+	if (!cylinder->start.mbar && !cylinder->end.mbar &&
+	    !cylinder->sample_start.mbar && !cylinder->sample_end.mbar)
 		return;
 
-	for (i = 0; i < pi->nr; i++) {
+	/* Get a rough range of where we have any pressures at all */
+	first = last = -1;
+	for (int i = 0; i < pi->nr; i++) {
 		struct plot_data *entry = pi->entry + i;
-		unsigned pressure;
+		unsigned pressure = SENSOR_PRESSURE(entry, sensor);
+
+		if (!pressure)
+			continue;
+		if (first < 0)
+			first = i;
+		last = i;
+	}
 
-		pressure = SENSOR_PRESSURE(entry, sensoridx);
-		cylinderid = entry->sensor[sensoridx];
-		if (cylinderid < 0)
-			goto GIVE_UP;
+	/* No sensor data at all? */
+	if (first == last)
+		return;
+
+	/*
+	 * Split the range:
+	 *  - missing pressure data
+	 *  - gas change events to other cylinders
+	 *
+	 * Note that we only look at gas switches if this cylinder
+	 * itself has a gas change event.
+	 */
+	cyl = sensor;
+	ev = NULL;
+	if (has_gaschange_event(dive, dc, sensor))
+		ev = get_next_event(dc->events, "gaschange");
+
+	for (int i = first; i <= last; i++) {
+		struct plot_data *entry = pi->entry + i;
+		unsigned pressure = SENSOR_PRESSURE(entry, sensor);
+		int time = entry->sec;
+
+		while (ev && ev->time.seconds <= time) {
+			cyl = get_cylinder_index(dive, ev);
+			if (cyl < 0)
+				cyl = sensor;
+			ev = get_next_event(ev->next, "gaschange");
+		}
 
-		/* If track_pr structure already exists, then update it: */
-		/* discrete integration of pressure over time to get the SAC rate equivalent */
 		if (current) {
 			entry->pressure_time = calc_pressure_time(dive, entry - 1, entry);
 			current->pressure_time += entry->pressure_time;
 			current->t_end = entry->sec;
+			if (pressure)
+				current->end = pressure;
 		}
 
-		/* If 1st record or different cylinder: Create a new track_pr structure: */
-		/* track the segments per cylinder and their pressure/time integral */
-		if (cylinderid != cylinderindex) {
-			cylinderindex = entry->sensor[sensoridx];
-			current = pr_track_alloc(pressure, entry->sec);
-			track_pr[cylinderindex] = list_add(track_pr[cylinderindex], current);
+		// If we have no pressure information, we will need to
+		// continue with or without a tracking entry. Mark any
+		// existing tracking entry as non-dense, and remember
+		// to fill in interpolated data.
+		if (!pressure) {
+			missing_pr = 1;
+			dense = 0;
 			continue;
 		}
 
-		if (!pressure) {
-			missing_pr = 1;
+		// We have a final pressure for 'current'
+		// If a gas switch has occurred, finish the
+		// current pressure track entry and continue
+		// until we get back to this cylinder.
+		if (cyl != sensor) {
+			current = NULL;
+			SENSOR_PRESSURE(entry, sensor) = 0;
 			continue;
 		}
-		if (current)
-			current->end = pressure;
 
-		/* Was it continuous? */
-		if (SENSOR_PRESSURE(entry - 1, sensoridx))
+		// If we already have a pressure tracking entry, and
+		// it has not had any missing samples, just continue
+		// using it - there's nothing to interpolate yet.
+		if (current && dense)
 			continue;
 
-		/* transmitter stopped transmitting cylinder pressure data */
+		// We need to start a new tracking entry, either
+		// because the previous was interrupted by a gas
+		// switch event, or because the previous one has
+		// missing entries that need to be interpolated.
+		// Or maybe we didn't have a previous one at all,
+		// and this is the first pressure entry.
 		current = pr_track_alloc(pressure, entry->sec);
-		if (cylinderindex >= 0)
-			track_pr[cylinderindex] = list_add(track_pr[cylinderindex], current);
+		track = list_add(track, current);
+		dense = 1;
 	}
 
 	if (missing_pr) {
-		fill_missing_tank_pressures(dive, pi, track_pr, sensoridx);
+		fill_missing_tank_pressures(dive, pi, track, sensor);
 	}
 
 #ifdef PRINT_PRESSURES_DEBUG
 	debug_print_pressures(pi);
 #endif
 
-GIVE_UP:
-	for (i = 0; i < MAX_CYLINDERS; i++)
-		list_free(track_pr[i]);
+	list_free(track);
 }