Profile: dynamically allocate gases array

To calculate sac rates, an array of used gases for every point on the
profile was used. This was implemented using unsigned int bitfields.

While nobody sane will ever use 32 or even 64 cylinders, for consistency
with the rest of the code, also change this to use dynamically
allocated arrays.

But allocate only once per shown profile, not once per sample.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 45 insertions, 27 deletions

diff --git a/core/profile.c b/core/profile.c
index e27bcfd36..8fd669989 100644
--- a/core/profile.c
+++ b/core/profile.c
@@ -656,7 +656,7 @@ static void populate_plot_entries(struct dive *dive, struct divecomputer *dc, st
  *
  * Everything in between has a cylinder pressure for at least some of the cylinders.
  */
-static int sac_between(struct dive *dive, struct plot_info *pi, int first, int last, unsigned int gases)
+static int sac_between(struct dive *dive, struct plot_info *pi, int first, int last, const bool gases[])
 {
 	int i, airuse;
 	double pressuretime;
@@ -671,7 +671,7 @@ static int sac_between(struct dive *dive, struct plot_info *pi, int first, int l
 		cylinder_t *cyl;
 		int cyluse;
 
-		if (!(gases & (1u << i)))
+		if (!gases[i])
 			continue;
 
 		a.mbar = get_plot_pressure(pi, first, i);
@@ -703,26 +703,40 @@ static int sac_between(struct dive *dive, struct plot_info *pi, int first, int l
 	return lrint(airuse / pressuretime);
 }
 
-/* Which of the set of gases have pressure data */
-static unsigned int have_pressures(struct plot_info *pi, int idx, unsigned int gases)
+/* Is there pressure data for all gases? */
+static bool all_pressures(struct plot_info *pi, int idx, const bool gases[])
 {
 	int i;
 
 	for (i = 0; i < MAX_CYLINDERS; i++) {
-		unsigned int mask = 1 << i;
-		if (gases & mask) {
-			if (!get_plot_pressure(pi, idx, i))
-				gases &= ~mask;
-		}
+		if (gases[i] && !get_plot_pressure(pi, idx, i))
+			return false;
 	}
-	return gases;
+
+	return true;
+}
+
+/* Which of the set of gases have pressure data? Returns false if none of them. */
+static bool filter_pressures(struct plot_info *pi, int idx, const bool gases_in[], bool gases_out[])
+{
+	int i;
+	bool has_pressure = false;
+
+	for (i = 0; i < MAX_CYLINDERS; i++) {
+		gases_out[i] = gases_in[i] && get_plot_pressure(pi, idx, i);
+		has_pressure |= gases_out[i];
+	}
+
+	return has_pressure;
 }
 
 /*
  * Try to do the momentary sac rate for this entry, averaging over one
- * minute.
+ * minute. This is premature optimization, but instead of allocating
+ * an array of gases, the caller passes in scratch memory in the last
+ * argument.
  */
-static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, unsigned int gases)
+static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, const bool gases_in[], bool gases[])
 {
 	struct plot_data *entry = pi->entry + idx;
 	int first, last;
@@ -735,8 +749,7 @@ static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, unsigned
 	 * We may not have pressure data for all the cylinders,
 	 * but we'll calculate the SAC for the ones we do have.
 	 */
-	gases = have_pressures(pi, idx, gases);
-	if (!gases)
+	if (!filter_pressures(pi, idx, gases_in, gases))
 		return;
 
 	/*
@@ -753,7 +766,7 @@ static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, unsigned
 			break;
 		if (prev->sec < time)
 			break;
-		if (have_pressures(pi, idx - 1, gases) != gases)
+		if (!all_pressures(pi, idx - 1, gases))
 			break;
 		idx--;
 		first = idx;
@@ -769,7 +782,7 @@ static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, unsigned
 			break;
 		if (next->sec > time)
 			break;
-		if (have_pressures(pi, idx + 1, gases) != gases)
+		if (!all_pressures(pi, idx + 1, gases))
 			break;
 		last = idx;
 	}
@@ -781,35 +794,40 @@ static void fill_sac(struct dive *dive, struct plot_info *pi, int idx, unsigned
 /*
  * Create a bitmap of cylinders that match our current gasmix
  */
-static unsigned int matching_gases(struct dive *dive, struct gasmix gasmix)
+static void matching_gases(struct dive *dive, struct gasmix gasmix, bool gases[])
 {
 	int i;
-	unsigned int gases = 0;
 
-	for (i = 0; i < MAX_CYLINDERS; i++) {
-		cylinder_t *cyl = dive->cylinder + i;
-		if (same_gasmix(gasmix, cyl->gasmix))
-			gases |= 1 << i;
-	}
-	return gases;
+	for (i = 0; i < MAX_CYLINDERS; i++)
+		gases[i] = same_gasmix(gasmix, dive->cylinder[i].gasmix);
 }
 
 static void calculate_sac(struct dive *dive, struct divecomputer *dc, struct plot_info *pi)
 {
 	struct gasmix gasmix = gasmix_invalid;
 	const struct event *ev = NULL;
-	unsigned int gases = 0;
+	bool *gases, *gases_scratch;
+
+	gases = malloc(MAX_CYLINDERS * sizeof(*gases));
+	memset(gases, 0, MAX_CYLINDERS * sizeof(*gases));
+
+	/* This might be premature optimization, but let's allocate the gas array for
+	 * the fill_sac function only once an not once per sample */
+	gases_scratch = malloc(MAX_CYLINDERS * sizeof(*gases));
 
 	for (int i = 0; i < pi->nr; i++) {
 		struct plot_data *entry = pi->entry + i;
 		struct gasmix newmix = get_gasmix(dive, dc, entry->sec, &ev, gasmix);
 		if (!same_gasmix(newmix, gasmix)) {
 			gasmix = newmix;
-			gases = matching_gases(dive, newmix);
+			matching_gases(dive, newmix, gases);
 		}
 
-		fill_sac(dive, pi, i, gases);
+		fill_sac(dive, pi, i, gases, gases_scratch);
 	}
+
+	free(gases);
+	free(gases_scratch);
 }
 
 static void populate_secondary_sensor_data(const struct divecomputer *dc, struct plot_info *pi)