MMDVMHost-Private/IIRDirectForm1Filter.h

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2020-12-15 16:21:07 +00:00
/*
* Copyright (C) 2015-2020 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.
*/
#if !defined(IIRDIRECTFORM1FILTER_H)
#define IIRDIRECTFORM1FILTER_H
class CIIRDirectForm1Filter
{
public:
CIIRDirectForm1Filter(float b0, float b1, float b2, float, float a1, float a2, float additionalGaindB);
float filter(float sample);
void reset();
private:
// delay line
float m_x2; // x[n-2]
float m_y2; // y[n-2]
float m_x1; // x[n-1]
float m_y1; // y[n-1]
// coefficients
// FIR
float m_b0;
float m_b1;
float m_b2;
// IIR
float m_a1;
float m_a2;
float m_additionalGainLin;
};
#endif