From 17c70f89e5a954384ce96e99a24c8366ba983e3d Mon Sep 17 00:00:00 2001
From: Stan Grams <sjg@haxx.space>
Date: Sun, 1 Mar 2026 00:41:28 +0100
Subject: [PATCH] [fix](trx-backend-soapysdr): fully reset wfm decoder on tune

Signed-off-by: Stan Grams <sjg@haxx.space>
---
 .../trx-backend-soapysdr/src/demod.rs         | 68 +++++++++++++++++++
 .../trx-backend-soapysdr/src/dsp.rs           |  4 +-
 2 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs b/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
index fed2be1..84e2c39 100644
--- a/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
+++ b/src/trx-server/trx-backend/trx-backend-soapysdr/src/demod.rs
@@ -146,6 +146,11 @@ impl DcBlocker {
         self.y1 = y;
         y
     }
+
+    pub(crate) fn reset(&mut self) {
+        self.x1 = 0.0;
+        self.y1 = 0.0;
+    }
 }
 
 /// Soft AGC with a fast-attack / slow-release envelope follower.
@@ -280,6 +285,13 @@ impl BiquadBandPass {
         self.y1 = y;
         y
     }
+
+    fn reset(&mut self) {
+        self.x1 = 0.0;
+        self.x2 = 0.0;
+        self.y1 = 0.0;
+        self.y2 = 0.0;
+    }
 }
 
 /// 2nd-order IIR low-pass filter (RBJ cookbook).  Use [`BW4_Q1`]/[`BW4_Q2`] in
@@ -323,6 +335,13 @@ impl BiquadLowPass {
         self.y1 = y;
         y
     }
+
+    fn reset(&mut self) {
+        self.x1 = 0.0;
+        self.x2 = 0.0;
+        self.y1 = 0.0;
+        self.y2 = 0.0;
+    }
 }
 
 /// 2nd-order IIR notch (band-reject) filter (RBJ cookbook).
@@ -365,6 +384,13 @@ impl BiquadNotch {
         self.y1 = y;
         y
     }
+
+    fn reset(&mut self) {
+        self.x1 = 0.0;
+        self.x2 = 0.0;
+        self.y1 = 0.0;
+        self.y2 = 0.0;
+    }
 }
 
 impl OnePoleLowPass {
@@ -381,6 +407,10 @@ impl OnePoleLowPass {
         self.y += self.alpha * (x - self.y);
         self.y
     }
+
+    fn reset(&mut self) {
+        self.y = 0.0;
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -401,6 +431,10 @@ impl Deemphasis {
         self.y += self.alpha * (x - self.y);
         self.y
     }
+
+    fn reset(&mut self) {
+        self.y = 0.0;
+    }
 }
 
 #[derive(Debug, Clone)]
@@ -674,6 +708,40 @@ impl WfmStereoDecoder {
         self.prev_iq = None;
     }
 
+    pub fn reset_state(&mut self) {
+        self.rds_decoder.reset();
+        self.rds_bpf.reset();
+        self.rds_dc.reset();
+        self.prev_iq = None;
+        self.pilot_phase = 0.0;
+        self.pilot_i_lp.reset();
+        self.pilot_q_lp.reset();
+        self.pilot_abs_lp.reset();
+        self.pilot_bpf.reset();
+        self.sum_lpf1.reset();
+        self.sum_lpf2.reset();
+        self.sum_notch.reset();
+        self.diff_lpf1.reset();
+        self.diff_lpf2.reset();
+        self.diff_q_lpf1.reset();
+        self.diff_q_lpf2.reset();
+        self.diff_dc.reset();
+        self.diff_q_dc.reset();
+        self.dc_m.reset();
+        self.dc_l.reset();
+        self.dc_r.reset();
+        self.deemph_m.reset();
+        self.deemph_l.reset();
+        self.deemph_r.reset();
+        self.stereo_detect_level = 0.0;
+        self.stereo_detected = false;
+        self.sum_hist = [0.0; WFM_RESAMP_TAPS];
+        self.diff_hist = [0.0; WFM_RESAMP_TAPS];
+        self.diff_q_hist = [0.0; WFM_RESAMP_TAPS];
+        self.prev_blend = 0.0;
+        self.output_phase = 0.0;
+    }
+
     pub fn stereo_detected(&self) -> bool {
         self.stereo_detected
     }
diff --git a/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs b/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
index 7007c4d..47fc663 100644
--- a/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
+++ b/src/trx-server/trx-backend/trx-backend-soapysdr/src/dsp.rs
@@ -603,9 +603,7 @@ impl ChannelDsp {
 
     pub fn reset_wfm_state(&mut self) {
         if let Some(decoder) = &mut self.wfm_decoder {
-            decoder.reset_rds();
-            decoder.reset_stereo_detect();
-            decoder.reset_demod_state();
+            decoder.reset_state();
         }
     }