+void update_air_info(char *buffer)
+{
+ char markup[120];
+
+ if (! buffer)
+ buffer = EMPTY_AIRCONSUMPTION;
+ snprintf(markup, sizeof(markup), "<span font=\"8\">%s</span>",buffer);
+ gtk_label_set_markup(GTK_LABEL(airconsumption), markup);
+}
+
+/*
+ * Return air usage (in liters).
+ */
+static double calculate_airuse(struct dive *dive)
+{
+ double airuse = 0;
+ int i;
+
+ for (i = 0; i < MAX_CYLINDERS; i++) {
+ cylinder_t *cyl = dive->cylinder + i;
+ int size = cyl->type.size.mliter;
+ double kilo_atm;
+
+ if (!size)
+ continue;
+
+ kilo_atm = (cyl->start.mbar - cyl->end.mbar) / 1013250.0;
+
+ /* Liters of air at 1 atm == milliliters at 1k atm*/
+ airuse += kilo_atm * size;
+ }
+ return airuse;
+}
+
+static void update_air_info_frame(struct dive *dive)
+{
+ const double liters_per_cuft = 28.317;
+ const char *unit, *format, *desc;
+ double airuse;
+ char buffer1[80];
+ char buffer2[80];
+ int len;
+
+ airuse = calculate_airuse(dive);
+ if (!airuse) {
+ update_air_info(NULL);
+ return;
+ }
+ switch (output_units.volume) {
+ case LITER:
+ unit = "l";
+ format = "vol: %4.0f %s";
+ break;
+ case CUFT:
+ unit = "cuft";
+ format = "vol: %4.2f %s";
+ airuse /= liters_per_cuft;
+ break;
+ }
+ len = snprintf(buffer1, sizeof(buffer1), format, airuse, unit);
+ if (dive->duration.seconds) {
+ double pressure = 1 + (dive->meandepth.mm / 10000.0);
+ double sac = airuse / pressure * 60 / dive->duration.seconds;
+ snprintf(buffer1+len, sizeof(buffer1)-len,
+ "\nSAC: %4.2f %s/min", sac, unit);
+ }
+ len = 0;
+ desc = dive->cylinder[0].type.description;
+ if (desc || dive->cylinder[0].gasmix.o2.permille) {
+ int o2 = dive->cylinder[0].gasmix.o2.permille / 10;
+ if (!desc)
+ desc = "";
+ if (!o2)
+ o2 = 21;
+ len = snprintf(buffer2, sizeof(buffer2), "%s (%d%%): used ", desc, o2);
+ }
+ snprintf(buffer2+len, sizeof(buffer2)-len, buffer1);
+ update_air_info(buffer2);
+}
+