add delay

lib/filters.c

@@ -38,4 +38,44 @@ float apply_low_pass_filter(LowPassFilter *lp, float sample) {
         index = (index + 1) % FIR_TAPS;
     }
     return result*6;
+}
+
+void init_delay_line(DelayLine *delay_line, int max_delay) {
+    delay_line->buffer = (float *)calloc(max_delay, sizeof(float));
+    delay_line->size = max_delay;
+    delay_line->write_idx = 0;
+    delay_line->read_idx = 0;
+    delay_line->delay = 0;
+}
+
+void set_delay_line(DelayLine *delay_line, int new_delay) {
+    if (new_delay >= delay_line->size) {
+        new_delay = delay_line->size - 1;
+    }
+    if (new_delay < 0) {
+        new_delay = 0;
+    }
+    
+    delay_line->delay = new_delay;
+    delay_line->read_idx = (delay_line->write_idx - new_delay + delay_line->size) % delay_line->size;
+}
+
+float delay_line(DelayLine *delay_line, float in) {
+    float out;
+    
+    // Read the delayed sample
+    out = delay_line->buffer[delay_line->read_idx];
+    
+    // Write the new sample
+    delay_line->buffer[delay_line->write_idx] = in;
+    
+    // Update indices
+    delay_line->write_idx = (delay_line->write_idx + 1) % delay_line->size;
+    delay_line->read_idx = (delay_line->read_idx + 1) % delay_line->size;
+    
+    return out;
+}
+
+void exit_delay_line(DelayLine *delay_line) {
+    free(delay_line->buffer);
 }

lib/filters.h

@@ -20,4 +20,18 @@ typedef struct {
 } LowPassFilter;
 
 void init_low_pass_filter(LowPassFilter *lp, float cutoff_frequency, float sample_rate);
-float apply_low_pass_filter(LowPassFilter *lp, float sample);
+float apply_low_pass_filter(LowPassFilter *lp, float sample);
+
+
+typedef struct {
+    float *buffer;
+    int write_idx;  // Write position
+    int read_idx;   // Read position
+    int size;       // Total buffer size
+    int delay;      // Delay in samples
+} DelayLine;
+
+void init_delay_line(DelayLine *delay_line, int max_delay);
+void set_delay_line(DelayLine *delay_line, int new_delay);
+float delay_line(DelayLine *delay_line, float in);
+void exit_delay_line(DelayLine *delay_line);