implementation of DAFX one pole

src/dsp/mod.rs

@@ -582,7 +582,7 @@ macro_rules! node_list {
             sfilter => SFilter UIType::Generic UICategory::Signal
                (0  inp   n_id      d_id  r_id   f_def stp_d -1.0, 1.0, 0.0)
                (1 freq  n_pit      d_pit r_fq  f_freq  stp_d -1.0, 0.5647131, 1000.0)
-               {2 0 ftype setting(0) fa_sfilter_type 0 1}
+               {2 0 ftype setting(0) fa_sfilter_type 0 2}
                [0 sig],
             test => Test UIType::Generic UICategory::IOUtil
                (0 f     n_id      d_id   r_id   f_def stp_d 0.0, 1.0, 0.5)

src/dsp/node_sfilter.rs

@@ -109,6 +109,22 @@ impl DspNode for SFilter {
                     out.write(frame, (m0 * input + m1 * v2) as f32);
                 }
             },
+            // from DAFX by will pirkle:
+            2 => {
+                for frame in 0..ctx.nframes() {
+                    let input = inp.read(frame) as f64;
+                    let o =
+                        (-std::f64::consts::TAU
+                         * (denorm::SFilter::freq(freq, frame) as f64)
+                         * self.israte).cos();
+                    let y = 2.0 - o;
+                    let b = (y * y - 1.0).sqrt() - y;
+                    let a = 1.0 + b;
+
+                    self.z = a * input - b * self.z;
+                    out.write(frame, self.z as f32);
+                }
+            }
             _ => {},
         }
     }

tests/node_sfilter.rs

@@ -44,10 +44,19 @@ fn check_node_sfilter_compare() {
     let ta = std::time::Instant::now().duration_since(ta);
     println!("ta2 Elapsed: {:?}", ta);
 
-    let fft = run_and_get_fft4096(&mut node_exec, 5, 1000.0);
-    for (fq, lvl) in fft {
-        println!("{:5}: {}", fq, lvl);
-    }
+
+    pset_s(&mut matrix, sf, "ftype", 2);
+
+    let ta = std::time::Instant::now();
+    let (out_l, _) = run_for_ms(&mut node_exec, 10000.0);
+    save_wav("check_noise_sfilt3.wav", &out_l);
+    let ta = std::time::Instant::now().duration_since(ta);
+    println!("ta3 Elapsed: {:?}", ta);
+
+//    let fft = run_and_get_fft4096(&mut node_exec, 5, 1000.0);
+//    for (fq, lvl) in fft {
+//        println!("{:5}: {}", fq, lvl);
+//    }
 
 //    let fft = run_and_get_fft4096(&mut node_exec, 50, 1000.0);
 //    assert!(fft.len() == 0);