From cd6dca60632b585af3094c673d3dc0c5311526a2 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 10 Sep 2024 17:20:05 +0200
Subject: [PATCH] Allow to query Biquad coefficients

---
 libs/ardour/ardour/dsp_filter.h |  2 ++
 libs/ardour/dsp_filter.cc       | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/libs/ardour/ardour/dsp_filter.h b/libs/ardour/ardour/dsp_filter.h
index 44dc1bbe52..6fdbd6af52 100644
--- a/libs/ardour/ardour/dsp_filter.h
+++ b/libs/ardour/ardour/dsp_filter.h
@@ -272,6 +272,8 @@ namespace ARDOUR { namespace DSP {
 
 			/** reset filter state */
 			void reset () { _z1 = _z2 = 0.0; }
+
+			void coefficients (double& a1, double& a2, double& b0, double& b1, double& b2) const;
 		private:
 			void set_vicanek_poles (const double W0, const double Q, const double A = 1.0);
 			void calc_vicanek (const double W0, double& A0, double& A1, double& A2, double& phi0, double& phi1, double& phi2);
diff --git a/libs/ardour/dsp_filter.cc b/libs/ardour/dsp_filter.cc
index 084541f098..d786ac0ab2 100644
--- a/libs/ardour/dsp_filter.cc
+++ b/libs/ardour/dsp_filter.cc
@@ -212,6 +212,16 @@ Biquad::configure (double a1, double a2, double b0, double b1, double b2)
 	_b2 = b2;
 }
 
+void
+Biquad::coefficients (double& a1, double& a2, double& b0, double& b1, double& b2) const
+{
+	a1 = _a1;
+	a2 = _a2;
+	b0 = _b0;
+	b1 = _b1;
+	b2 = _b2;
+}
+
 void
 Biquad::configure (Biquad const& other)
 {