Rename the IIR filter class.

IIR.cpp

@@ -0,0 +1,61 @@
+/*
+ *   Copyright (C) 2015-2020,2024 by Jonathan Naylor G4KLX
+ *   Copyright (C) 2020 by Geoffrey Merck - F4FXL KC3FRA
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include "IIR.h"
+
+#include <cmath>
+
+CIIR::CIIR(float b0, float b1, float b2, float , float a1, float a2, float addtionalGaindB) :
+m_x2(0.0F),
+m_y2(0.0F),
+m_x1(0.0F),
+m_y1(0.0F),
+m_b0(b0),
+m_b1(b1),
+m_b2(b2),
+m_a1(a1),
+m_a2(a2),
+m_additionalGainLin(0.0F)
+{
+    m_additionalGainLin = ::powf(10.0F, addtionalGaindB / 20.0F);
+}
+
+CIIR::~CIIR()
+{
+}
+
+float CIIR::filter(float sample)
+{
+    float output = m_b0 * sample + m_b1 * m_x1 + m_b2 * m_x2 - m_a1 * m_y1 - m_a2 * m_y2;
+
+    m_x2 = m_x1;
+    m_y2 = m_y1;  
+    m_x1 = sample;
+    m_y1 = output;
+
+    return output * m_additionalGainLin;
+}
+
+void CIIR::reset()
+{
+    m_x1 = 0.0F;
+    m_x2 = 0.0F;
+    m_y1 = 0.0F;
+    m_y2 = 0.0F;
+}