mainloop/* moved to root

filter.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2022 Oleg Borodin  <borodin@unix7.org>
+ */
+
+#ifndef FILTER_H_QWERTY
+#define FILTER_H_QWERTY
+
+
+typedef struct {
+    double x0;
+    double x1;
+    double rc;
+} lpf2_t;
+
+void lpf2_init(lpf2_t *lpf, double freq);
+double lpf2_apply(lpf2_t *lpf, double x, double dt);
+
+
+typedef struct {
+    double x1;
+    double x2;
+    double x3;
+    double rc;
+} lpf3_t;
+
+void lpf3_init(lpf3_t *lpf, double freq);
+double lpf3_apply(lpf3_t *lpf, double x, double dt);
+
+#endif