diff --git a/control.h b/control.h
new file mode 100644
index 0000000..846c033
--- /dev/null
+++ b/control.h
@@ -0,0 +1,16 @@
+
+struct control_t
+{
+	float value;
+	float step;
+};
+
+static inline void control_setstep(struct control_t *control, float value, uint32_t samples)
+{
+	control->step = (value - control->value) / samples;
+}
+
+static inline void control_tick(struct control_t *control)
+{
+	control->value += control->step;
+}