added mixer.*;clean olds; added lpf3, etc

2022-09-10 22:38:13 +02:00
parent f3e30f3aa7
commit 13f9b3f8de
6 changed files with 70 additions and 77 deletions
@@ -6,7 +6,7 @@
 #include <math.h>
 #include <filter.h>

-void lpf_init(lpf_t *lpf, double freq) {
+void lpf2_init(lpf2_t *lpf, double freq) {
    lpf->x0 = 0.0;
    lpf->x1 = 0.0;

@@ -16,7 +16,7 @@ void lpf_init(lpf_t *lpf, double freq) {
 }


-double lpf_apply(lpf_t *lpf, double x2, double dt) {
+double lpf2_apply(lpf2_t *lpf, double x2, double dt) {

    double k = dt / (lpf->rc + dt);

@@ -24,3 +24,24 @@ double lpf_apply(lpf_t *lpf, double x2, double dt) {
    lpf->x0 = lpf->x0 + k * (lpf->x1 - lpf->x0);
    return lpf->x0;
 }
+
+
+void lpf3_init(lpf3_t *lpf, double freq) {
+    lpf->x1 = 0.0;
+    lpf->x2 = 0.0;
+    lpf->x3 = 0.0;
+
+    double order = 2.0;
+    double c = 1.0 / sqrt(powf(2.0, 1.0 / order) - 1.0);
+    lpf->rc = 1.0 / (2.0 * c * M_PI * freq);
+}
+
+double lpf3_apply(lpf3_t *lpf, double x0, double dt) {
+
+    double k = dt / (lpf->rc + dt);
+
+    lpf->x1 = lpf->x1 + k * (x0 - lpf->x1);
+    lpf->x2 = lpf->x2 + k * (lpf->x1 - lpf->x2);
+    lpf->x3 = lpf->x3 + k * (lpf->x2 - lpf->x3);
+    return lpf->x3;
+}