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use crate::{flatten_stereo, Gain, Sample};
pub trait Signal {
type Frame;
fn sample(&self, interval: f32, out: &mut [Self::Frame]);
#[inline]
fn remaining(&self) -> f32 {
f32::INFINITY
}
fn into_stereo(self) -> MonoToStereo<Self>
where
Self: Signal<Frame = Sample> + Sized,
{
MonoToStereo(self)
}
fn with_gain(self) -> Gain<Self>
where
Self: Sized,
{
Gain::new(self)
}
}
pub struct MonoToStereo<T>(pub T);
impl<T: Signal<Frame = Sample>> Signal for MonoToStereo<T> {
type Frame = [Sample; 2];
fn sample(&self, interval: f32, out: &mut [[Sample; 2]]) {
let n = out.len();
let buf = flatten_stereo(out);
self.0.sample(interval, &mut buf[..n]);
for i in (0..buf.len()).rev() {
buf[i] = buf[i / 2];
}
}
fn remaining(&self) -> f32 {
self.0.remaining()
}
}
#[cfg(test)]
mod tests {
use std::cell::Cell;
use super::*;
struct CountingSignal(Cell<u32>);
impl Signal for CountingSignal {
type Frame = Sample;
fn sample(&self, _: f32, out: &mut [Sample]) {
for x in out {
let i = self.0.get();
*x = i as f32;
self.0.set(i + 1);
}
}
}
#[test]
fn mono_to_stereo() {
let signal = CountingSignal(Cell::new(0)).into_stereo();
let mut buf = [[0.0; 2]; 4];
signal.sample(1.0, (&mut buf[..]).into());
assert_eq!(buf, [[0.0, 0.0], [1.0, 1.0], [2.0, 2.0], [3.0, 3.0]]);
}
}