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//! Delay stream. Good for syncing up streams.
use log::debug;
use crate::block::{Block, BlockRet};
use crate::stream::{ReadStream, WriteStream};
use crate::{Result, Sample};
/// Delay stream. Good for syncing up streams.
#[derive(rustradio_macros::Block)]
#[rustradio(crate)]
pub struct Delay<T: Sample> {
delay: usize,
current_delay: usize,
// Skip is the number of samples we're needlessly ahead. This can happen
// when the delay changes mid stream.
skip: usize,
#[rustradio(in)]
src: ReadStream<T>,
#[rustradio(out)]
dst: WriteStream<T>,
}
impl<T: Sample> Delay<T> {
/// Create new Delay block.
#[must_use]
pub fn new(src: ReadStream<T>, delay: usize) -> (Self, ReadStream<T>) {
let (dst, dr) = crate::stream::new_stream();
(
Self {
src,
dst,
delay,
current_delay: delay,
skip: 0,
},
dr,
)
}
/// Change the delay.
pub fn set_delay(&mut self, delay: usize) {
if delay > self.delay {
self.current_delay += delay - self.delay;
} else {
let reduce = self.delay - delay;
let cdskip = std::cmp::min(self.current_delay, reduce);
self.current_delay -= cdskip;
self.skip += reduce - cdskip;
}
self.delay = delay;
}
}
impl<T: Sample> Block for Delay<T> {
fn work(&mut self) -> Result<BlockRet<'_>> {
loop {
// Check if we need to catch up.
let (input, tags) = self.src.read_buf()?;
if self.skip > 0 {
let n = std::cmp::min(input.len(), self.skip);
if n == 0 {
return Ok(BlockRet::WaitForStream(&self.src, 1));
}
input.consume(n);
debug!("Delay: skipped {n}");
self.skip -= n;
continue;
}
// Everything except catch-up requires output space.
let mut o = self.dst.write_buf()?;
if o.is_empty() {
return Ok(BlockRet::WaitForStream(&self.dst, 1));
}
// Check if we're still delaying, thus filling with default.
if self.current_delay > 0 {
let n = std::cmp::min(self.current_delay, o.len());
o.slice()[..n].fill(T::default());
o.produce(n, &[]);
self.current_delay -= n;
continue;
}
// Neither skipping nor delaying. just plain copy.
if input.is_empty() {
return Ok(BlockRet::WaitForStream(&self.src, 1));
}
let n = std::cmp::min(input.len(), o.len());
assert_ne!(
n, 0,
"can't happen: we already checked both input and output"
);
o.fill_from_slice(&input.slice()[..n]);
let tags = tags
.into_iter()
.filter(|tag| tag.pos() < n)
.collect::<Vec<_>>();
o.produce(n, &tags);
input.consume(n);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
// TODO: test tag propagation.
#[test]
fn delay_zero() -> Result<()> {
let s = ReadStream::from_slice(&[1.0f32, 2.0, 3.0]);
let (mut delay, o) = Delay::new(s, 0);
delay.work()?;
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![1.0f32, 2.0, 3.0]);
Ok(())
}
#[test]
fn delay_one() -> Result<()> {
let s = ReadStream::from_slice(&[1.0f32, 2.0, 3.0]);
let (mut delay, o) = Delay::new(s, 1);
delay.work()?;
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![0.0f32, 1.0, 2.0, 3.0]);
Ok(())
}
#[test]
fn delay_increase_before_work_extends_remaining_delay() -> Result<()> {
let s = ReadStream::from_slice(&[1u32, 2]);
let (mut delay, o) = Delay::new(s, 1);
delay.set_delay(2);
delay.work()?;
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), &[0, 0, 1, 2]);
Ok(())
}
#[test]
fn delay_decrease_before_work_reduces_remaining_delay() -> Result<()> {
let s = ReadStream::from_slice(&[1u32, 2]);
let (mut delay, o) = Delay::new(s, 3);
delay.set_delay(1);
delay.work()?;
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), &[0, 1, 2]);
Ok(())
}
#[test]
fn delay_reduced_twice_accumulates_pending_skip() -> Result<()> {
let cap = crate::stream::DEFAULT_STREAM_SIZE / std::mem::size_of::<u32>();
let input = (0..cap as u32).collect::<Vec<_>>();
let s = ReadStream::from_slice(&input);
let (mut delay, o) = Delay::new(s, cap + 10);
delay.work()?;
{
let (res, _) = o.read_buf()?;
let len = res.len();
assert_eq!(len, cap);
assert!(res.iter().all(|v| *v == 0));
res.consume(len);
}
delay.set_delay(cap - 1);
delay.set_delay(cap - 2);
delay.work()?;
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), &input[2..]);
Ok(())
}
#[test]
fn delay_change() -> Result<()> {
let s = ReadStream::from_slice(&[1u32, 2]);
let (mut delay, o) = Delay::new(s, 1);
delay.work()?;
{
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![0, 1, 2]);
}
// TODO: fix
/*
// 3,4 => 0,3,4
{
let mut b = s.write_buf()?;
b.fill_from_slice(&[3, 4]);
b.produce(2, &[]);
}
delay.set_delay(2);
delay.work()?;
{
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![0, 1, 2, 0, 3, 4]);
}
// 5,6 => 0,3,4
{
let mut b = s.write_buf()?;
b.fill_from_slice(&[5, 6]);
b.produce(2, &[]);
}
delay.set_delay(0);
delay.work()?;
{
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![0, 1, 2, 0, 3, 4]);
}
// 7 => 7
{
let mut b = s.write_buf()?;
b.slice()[0] = 7;
b.produce(1, &[]);
}
delay.set_delay(0);
delay.work()?;
{
let (res, _) = o.read_buf()?;
assert_eq!(res.slice(), vec![0, 1, 2, 0, 3, 4, 7]);
}
*/
Ok(())
}
}