Jeff Epler
ce0c1c77a4
BlockBiquad takes kind, f0 (center frequency) & Q (sharpness) block type arguments and calculates the actual filter coefficients every frame. This allows the filter characteristics f0 and Q to be changed dynamically from LFOs & arithmetic blocks. A new manual test demonstrates this on a host computer, playing a simple tone that is dynamically filtered.
20 lines
592 B
C
20 lines
592 B
C
// This file is part of the CircuitPython project: https://circuitpython.org
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//
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// SPDX-FileCopyrightText: Copyright (c) 2023 Jeff Epler for Adafruit Industries
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//
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// SPDX-License-Identifier: MIT
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#pragma once
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#include "py/obj.h"
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#define BIQUAD_SHIFT (15)
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typedef struct {
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int32_t a1, a2, b0, b1, b2;
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int32_t x[2], y[2];
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} biquad_filter_state;
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void synthio_biquad_filter_assign(biquad_filter_state *st, mp_obj_t biquad_obj);
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void synthio_biquad_filter_reset(biquad_filter_state *st);
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void synthio_biquad_filter_samples(biquad_filter_state *st, int32_t *buffer, size_t n_samples);
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