sample and hold node

README.md

@@ -769,6 +769,7 @@ envelopes (all subsampled at ~2 ms)
 other
 - `tick()` one sample delay
 - `shift_reg()` 2 ins (input signal, trigger signal), 8 outs (outputs of the shift register)
+- `snh()` sample and hold node. 2 ins (input signal, trigger signal), 1 out (held signal)
 - `meter(peak/rms, float)` e.g. `meter(rms, 0.5)` `rms(peak, 2)`
 - `chorus(float, float, float, float)` (seed, separation, variation, mod frequency)
 - `declick([float])` e.g. `declick()` 10ms fade in, `declick(2)` 2 second fade in

src/functions.rs

@@ -575,6 +575,7 @@ pub fn str_to_net(op: &str) -> Net {
         // -------------------- other --------------------
         "tick" => return Net::wrap(Box::new(tick())),
         "shift_reg" => return Net::wrap(Box::new(An(ShiftReg::new()))),
+        "snh" => return Net::wrap(Box::new(An(SnH::new()))),
         "meter" => {
             if let (Some(arg), Some(p)) = (args.get(1), p.first()) {
                 if arg.starts_with("peak") {

src/nodes.rs

@@ -776,3 +776,36 @@ impl AudioNode for BuffOut {
         [self.r.try_recv().unwrap_or(0.)].into()
     }
 }
+
+/// sample and hold
+/// - input 0: input signal
+/// - input 1: trigger
+/// - output 0: held signal
+#[derive(Clone)]
+pub struct SnH {
+    val: f32,
+}
+
+impl SnH {
+    pub fn new() -> Self {
+        SnH { val: 0. }
+    }
+}
+
+impl AudioNode for SnH {
+    const ID: u64 = 1125;
+    type Inputs = U2;
+    type Outputs = U1;
+
+    #[inline]
+    fn tick(&mut self, input: &Frame<f32, Self::Inputs>) -> Frame<f32, Self::Outputs> {
+        if input[1] != 0. {
+            self.val = input[0];
+        }
+        [self.val].into()
+    }
+
+    fn reset(&mut self) {
+        self.val = 0.;
+    }
+}