91 lines
2.2 KiB
C++
91 lines
2.2 KiB
C++
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/*
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __DSP_IIR_H__
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#define __DSP_IIR_H__
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#include <array>
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#include "dsp_types.hpp"
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struct iir_biquad_config_t {
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std::array<float, 3> b;
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std::array<float, 3> a;
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};
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// 0..2 - b, 3..5 - a
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typedef std::array<float, 6> iir_biquad_df2_config_t;
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constexpr iir_biquad_config_t iir_config_passthrough {
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{ { 1.0f, 0.0f, 0.0f } },
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{ { 0.0f, 0.0f, 0.0f } },
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};
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constexpr iir_biquad_config_t iir_config_no_pass {
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{ { 0.0f, 0.0f, 0.0f } },
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{ { 0.0f, 0.0f, 0.0f } },
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};
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class IIRBiquadFilter {
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public:
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// http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
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constexpr IIRBiquadFilter(
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) : IIRBiquadFilter(iir_config_no_pass)
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{
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}
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// Assume all coefficients are normalized so that a0=1.0
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constexpr IIRBiquadFilter(
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const iir_biquad_config_t& config
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) : config(config)
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{
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}
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void configure(const iir_biquad_config_t& new_config);
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void execute(const buffer_f32_t& buffer_in, const buffer_f32_t& buffer_out);
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void execute_in_place(const buffer_f32_t& buffer);
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private:
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iir_biquad_config_t config;
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std::array<float, 3> x { { 0.0f, 0.0f, 0.0f } };
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std::array<float, 3> y { { 0.0f, 0.0f, 0.0f } };
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};
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class IIRBiquadDF2Filter {
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public:
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void configure(const iir_biquad_df2_config_t& config);
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float execute(float z);
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private:
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float b0 = 0;
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float b1 = 0;
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float b2 = 0;
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float a1 = 0;
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float a2 = 0;
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float z0 = 0;
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float z1 = 0;
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};
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#endif/*__DSP_IIR_H__*/
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