+ else
+ strcpy(buffer, "air");
+
+ g_object_set(renderer, "text", buffer, NULL);
+}
+
+/* Render the SAC data (integer value of "ml / min") */
+static void sac_data_func(GtkTreeViewColumn *col,
+ GtkCellRenderer *renderer,
+ GtkTreeModel *model,
+ GtkTreeIter *iter,
+ gpointer data)
+{
+ int value;
+ const double liters_per_cuft = 28.317;
+ const char *fmt;
+ char buffer[16];
+ double sac;
+
+ gtk_tree_model_get(model, iter, DIVE_SAC, &value, -1);
+
+ if (!value) {
+ g_object_set(renderer, "text", "", NULL);
+ return;
+ }
+
+ sac = value / 1000.0;
+ switch (output_units.volume) {
+ case LITER:
+ fmt = "%4.1f";
+ break;
+ case CUFT:
+ fmt = "%4.2f";
+ sac /= liters_per_cuft;
+ break;
+ }
+ snprintf(buffer, sizeof(buffer), fmt, sac);
+
+ g_object_set(renderer, "text", buffer, NULL);
+}
+
+/*
+ * 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;