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// license:BSD-3-Clause
// copyright-holders:K.Wilkins,Couriersud,Derrick Renaud,Frank Palazzolo,Jonathan Gevaryahu
#ifndef MAME_SOUND_FLT_BIQUAD_H
#define MAME_SOUND_FLT_BIQUAD_H
#pragma once
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
// ======================> filter_biquad_device
class filter_biquad_device : public device_t, public device_sound_interface
{
public:
enum class biquad_type : int
{
LOWPASS1P = 0,
HIGHPASS1P,
LOWPASS,
HIGHPASS,
BANDPASS,
NOTCH,
PEAK,
LOWSHELF,
HIGHSHELF
};
filter_biquad_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
// set up the filter with the specified filter parameters and return a pointer to the new device
filter_biquad_device& setup(biquad_type type, double fc, double q, double gain);
// update an existing instance with new filter parameters
void update_params(biquad_type type, double fc, double q, double gain);
// helper setup functions to create common filters representable by biquad filters
// Sallen-Key low-pass
filter_biquad_device& opamp_sk_lowpass_setup(double r1, double r2, double r3, double r4, double c1, double c2);
// TODO when needed: Sallen-Key band-pass
// TODO when needed: Sallen-Key high-pass
// Multiple-Feedback low-pass
filter_biquad_device& opamp_mfb_lowpass_setup(double r1, double r2, double r3, double c1, double c2);
// Multiple-Feedback band-pass
filter_biquad_device& opamp_mfb_bandpass_setup(double r1, double r2, double r3, double c1, double c2);
// Multiple-Feedback high-pass
filter_biquad_device& opamp_mfb_highpass_setup(double r1, double r2, double c1, double c2, double c3);
protected:
// device-level overrides
virtual void device_start() override;
// sound stream update overrides
virtual void sound_stream_update(sound_stream &stream, std::vector<read_stream_view> const &inputs, std::vector<write_stream_view> &outputs) override;
private:
void recalc();
void step();
sound_stream* m_stream;
biquad_type m_type;
int m_last_sample_rate;
double m_fc;
double m_q;
double m_gain;
stream_buffer::sample_t m_input;
double m_w0, m_w1, m_w2; /* w[k], w[k-1], w[k-2], current and previous intermediate values */
stream_buffer::sample_t m_output;
double m_a1, m_a2; /* digital filter coefficients, denominator */
double m_b0, m_b1, m_b2; /* digital filter coefficients, numerator */
};
DECLARE_DEVICE_TYPE(FILTER_BIQUAD, filter_biquad_device)
#endif // MAME_SOUND_FLT_BIQUAD_H
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