add pll

lib/filters.h

@@ -14,4 +14,17 @@ typedef struct
 void init_preemphasis(ResistorCapacitor *filter, float tau, float sample_rate);
 float apply_preemphasis(ResistorCapacitor *filter, float sample);
 
-float hard_clip(float sample, float threshold);
+float hard_clip(float sample, float threshold);
+
+typedef struct {
+    float phase;
+    float freq;
+    float ref_freq;
+    float loop_filter_state;
+    float kp;
+    float ki;
+    int sample_rate;
+    int quadrature_mode;
+} PLL;
+void init_pll(PLL *pll, float output_freq, float refrence_freq, float loop_filter_bandwidth, int quadrature_mode, int sample_rate);
+float apply_pll(PLL *pll, float ref_sample, float input_sample);