From 8d68504026f33f6fb18481f7487489a541741a43 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20J=C3=B6rdens?= <rj@quartiq.de>
Date: Wed, 10 Feb 2021 13:31:41 +0100
Subject: [PATCH] lowpass: symmetric code

---
 dsp/src/lowpass.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dsp/src/lowpass.rs b/dsp/src/lowpass.rs
index b85e2ed..24832a8 100644
--- a/dsp/src/lowpass.rs
+++ b/dsp/src/lowpass.rs
@@ -25,7 +25,7 @@ impl<N: ArrayLength<i32>> Lowpass<N> {
         // Note the zero(s) at Nyquist and the benign overflow (DF-I).
         let mut x0 = x;
         let mut x1 = self.xy[0];
-        self.xy[0] = x;
+        self.xy[0] = x0;
         for y1 in self.xy[1..].iter_mut() {
             x0 = *y1 + (((x0 >> 1) + (x1 >> 1) - *y1 + (1 << (k - 1))) >> k);
             x1 = *y1;