Function vec_comb 

pub fn vec_comb(
    buf: &mut [f32],
    pos: &mut usize,
    damp: &mut OnePoleState,
    dst: &mut [f32],
    src: &[f32],
    time: &[f32],
    feedback: f32,
    damping: f32,
)

Single comb filter: one delay line with feedback and damping.

Reads from the delay line with interpolated modulated delay time, applies one-pole damping, outputs the result, and writes input + feedback * damped back into the buffer.

Use for: echo, flanger, chorus with feedback, karplus-strong strings, single delay with feedback.