use super::delay_line::DelayLine;
#[derive(Debug)]
pub struct Comb {
delay_line: DelayLine,
feedback: f64,
filter_state: f64,
dampening: f64,
dampening_inverse: f64,
}
impl Comb {
pub fn new(delay_length: usize) -> Self {
Self {
delay_line: DelayLine::new(delay_length),
feedback: 0.5,
filter_state: 0.0,
dampening: 0.5,
dampening_inverse: 0.5,
}
}
pub fn set_dampening(&mut self, value: f64) {
self.dampening = value;
self.dampening_inverse = 1.0 - value;
}
pub fn set_feedback(&mut self, value: f64) {
self.feedback = value;
}
pub fn tick(&mut self, input: f64) -> f64 {
let output = self.delay_line.read();
self.filter_state = output * self.dampening_inverse + self.filter_state * self.dampening;
self.delay_line
.write_and_advance(input + self.filter_state * self.feedback);
output
}
}
#[cfg(test)]
mod tests {
#[test]
fn basic_ticking() {
let mut comb = super::Comb::new(2);
assert_eq!(comb.tick(1.0), 0.0);
assert_eq!(comb.tick(0.0), 0.0);
assert_eq!(comb.tick(0.0), 1.0);
assert_eq!(comb.tick(0.0), 0.0);
assert_eq!(comb.tick(0.0), 0.25);
assert_eq!(comb.tick(0.0), 0.125);
assert_eq!(comb.tick(0.0), 0.125);
assert_eq!(comb.tick(0.0), 0.09375);
}
}