portapack-mayhem/firmware/baseband/dsp_iir.hpp

71 lines
1.8 KiB
C++

/*
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __DSP_IIR_H__
#define __DSP_IIR_H__
#include <array>
#include "dsp_types.hpp"
struct iir_biquad_config_t {
std::array<float, 3> b;
std::array<float, 3> a;
};
constexpr iir_biquad_config_t iir_config_passthrough {
{ { 1.0f, 0.0f, 0.0f } },
{ { 0.0f, 0.0f, 0.0f } },
};
constexpr iir_biquad_config_t iir_config_no_pass {
{ { 0.0f, 0.0f, 0.0f } },
{ { 0.0f, 0.0f, 0.0f } },
};
class IIRBiquadFilter {
public:
// http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
constexpr IIRBiquadFilter(
) : IIRBiquadFilter(iir_config_no_pass)
{
}
// Assume all coefficients are normalized so that a0=1.0
constexpr IIRBiquadFilter(
const iir_biquad_config_t& config
) : config(config)
{
}
void configure(const iir_biquad_config_t& new_config);
void execute(const buffer_f32_t& buffer_in, const buffer_f32_t& buffer_out);
void execute_in_place(const buffer_f32_t& buffer);
private:
iir_biquad_config_t config;
std::array<float, 3> x { { 0.0f, 0.0f, 0.0f } };
std::array<float, 3> y { { 0.0f, 0.0f, 0.0f } };
};
#endif/*__DSP_IIR_H__*/