390: lowpass: make it work for k=0 r=jordens a=jordens



Co-authored-by: Robert Jördens <rj@quartiq.de>
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bors[bot] 2021-06-23 06:57:53 +00:00 committed by GitHub
commit c935f97752
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1 changed files with 1 additions and 2 deletions

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@ -25,7 +25,6 @@ impl<const N: usize> Lowpass<N> {
/// Filtered output y.
pub fn update(&mut self, x: i32, k: u8) -> i32 {
debug_assert!(k & 31 == k);
debug_assert!((k - 1) & 31 == k - 1);
// This is an unrolled and optimized first-order IIR loop
// that works for all possible time constants.
// Note T-DF-I and the zeros at Nyquist.
@ -35,6 +34,6 @@ impl<const N: usize> Lowpass<N> {
*y += dy;
x = *y - (dy >> 1);
}
x.saturating_add((self.y.len() as i32) << (k - 1))
x.saturating_add((self.y.len() as i32) << (k - 1).max(0))
}
}