From b071fef15c4dbd8c4b66b4f8b97cf1256592966a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20J=C3=B6rdens?= <rj@quartiq.de>
Date: Thu, 25 Feb 2021 16:38:57 +0100
Subject: [PATCH] iir_int: apply rounding bias summarily for speed

---
 dsp/src/lowpass.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dsp/src/lowpass.rs b/dsp/src/lowpass.rs
index 5ab803d..10d5838 100644
--- a/dsp/src/lowpass.rs
+++ b/dsp/src/lowpass.rs
@@ -27,10 +27,10 @@ impl<N: ArrayLength<i32>> Lowpass<N> {
         // Note T-DF-I and the zeros at Nyquist.
         let mut x = x;
         for y in self.y.iter_mut() {
-            let dy = x.saturating_sub(*y).saturating_add(1 << (k - 1)) >> k;
+            let dy = x.saturating_sub(*y) >> k;
             *y += dy;
             x = *y - (dy >> 1);
         }
-        x
+        x.saturating_add((self.y.len() as i32) << (k - 1))
     }
 }