1 files changed, 69 insertions, 0 deletions
diff --git a/data_manager.c b/data_manager.c
new file mode 100644
index 0000000..bd34426
--- /dev/null
+++ b/data_manager.c
@@ -0,0 +1,69 @@
+#include <stdbool.h>
+#include <stdlib.h>
+#include <math.h>
+
+#include "data_manager.h"
+#include "barometer.h"
+
+static float pressure[PRESSURE_UNIT_MAX];
+static float setting[PRESSURE_UNIT_MAX];
+static float altitude[ALTITUDE_UNIT_MAX];
+
+/* utility functions */
+static float pressure_to_metres_asl(float real, float setting)
+{
+	return 44330.f*(1.f-powf(real/setting, 1/5.255));
+}
+
+
+/* exported functions */
+#define DATA_MANAGER_GETTER(name, store, bound, enum_type, return_type) \
+float name(enum_type unit) \
+{ \
+	if (unit >= 0 && unit < bound) { \
+		return store[unit]; \
+	} else { \
+		abort(); \
+	} \
+}
+
+DATA_MANAGER_GETTER(
+	data_manager_get_pressure,
+	pressure,
+	PRESSURE_UNIT_MAX,
+	enum pressure_unit,
+	float)
+DATA_MANAGER_GETTER(
+	data_manager_get_setting,
+	setting,
+	PRESSURE_UNIT_MAX,
+	enum pressure_unit,
+	float)
+DATA_MANAGER_GETTER(
+	data_manager_get_altitude,
+	altitude,
+	ALTITUDE_UNIT_MAX,
+	enum altitude_unit,
+	float)
+
+void data_manager_init(void)
+{
+	/* FIXME load initial setting and force a tick synchronously */
+}
+
+void data_manager_tick(void)
+{
+	/* FIXME alt rate */
+	/* FIXME calculate on demand? */
+	/* FIXME hardcoding the conversion factors here is gross */
+	float p = barometer_read();
+	pressure[PRESSURE_UNIT_HPA] = p;
+	pressure[PRESSURE_UNIT_INHG] = p / 3.38639;
+
+	/* FIXME we need atomic access to alt setting once user can set it. Check
+	 * if AVR allows multiple/nested ISRs to run concurrently, pretty sure not
+	 */
+	float a = pressure_to_metres_asl(p, setting[PRESSURE_UNIT_HPA]);
+	altitude[ALTITUDE_UNIT_METRE] = a;
+	altitude[ALTITUDE_UNIT_FT] = a * 3.048;
+}