149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
/*
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* Brickworks
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*
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* Copyright (C) 2022 Orastron Srl unipersonale
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*
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* Brickworks 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, version 3 of the License.
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*
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* Brickworks 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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*
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* File author: Stefano D'Angelo
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*/
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/*!
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* module_type {{{ dsp }}}
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* version {{{ 0.2.0 }}}
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* requires {{{ bw_config bw_common bw_math }}}
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* description {{{
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* Sawtooth oscillator waveshaper with PolyBLEP antialiasing.
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* }}}
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* changelog {{{
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* <ul>
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* <li>Version <strong>0.2.0</strong>:
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* <ul>
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* <li>Refactored API.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.1.0</strong>:
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* <ul>
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* <li>First release.</li>
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* </ul>
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* </li>
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* </ul>
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* }}}
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*/
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#ifndef _BW_OSC_SAW_H
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#define _BW_OSC_SAW_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <bw_common.h>
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/*! api {{{
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* #### bw_osc_saw_coeffs
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* ```>>> */
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typedef struct _bw_osc_saw_coeffs bw_osc_saw_coeffs;
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/*! <<<```
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* Coefficients.
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*
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* #### bw_osc_saw_init()
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* ```>>> */
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static inline void bw_osc_saw_init(bw_osc_saw_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Initializes the `coeffs`.
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* >>> */
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static inline float bw_osc_saw_process1(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x);
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static inline float bw_osc_saw_process1_antialias(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x, float x_phase_inc);
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/*! ...
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* #### bw_osc_saw_process()
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* ```>>> */
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static inline void bw_osc_saw_process(bw_osc_saw_coeffs *BW_RESTRICT coeffs, const float *x, const float *x_phase_inc, float *y, int n_samples);
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/*! <<<```
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* Lets the given `instance` process `n_samples` samples from the input
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* buffer `x` containing the normalized phase signal and fills the
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* corresponding `n_samples` samples in the output buffer `y`.
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* >>> */
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/*! ...
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* #### bw_osc_saw_set_antialiasing()
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* ```>>> */
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static inline void bw_osc_saw_set_antialiasing(bw_osc_saw_coeffs *BW_RESTRICT coeffs, char value);
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/*! <<<```
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* Sets whether the antialiasing is on (`value` non-`0`) or off (`0`) for the
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* given `instance`.
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*
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* Default value: `0`.
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* }}} */
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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#include <bw_math.h>
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struct _bw_osc_saw_coeffs {
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// Parameters
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char antialiasing;
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};
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static inline void bw_osc_saw_init(bw_osc_saw_coeffs *BW_RESTRICT coeffs) {
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coeffs->antialiasing = 0;
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}
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static inline float bw_osc_saw_process1(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x) {
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return x + x - 1.f;
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}
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// PolyBLEP residual based on Parzen window (4th-order B-spline), one-sided (x in [0, 2])
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static inline float _bw_osc_saw_blep_diff(float x) {
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return x < 1.f
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? x * ((0.25f * x - 0.6666666666666666f) * x * x + 1.333333333333333f) - 1.f
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: x * (x * ((0.6666666666666666f - 0.08333333333333333f * x) * x - 2.f) + 2.666666666666667f) - 1.333333333333333f;
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}
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static inline float bw_osc_saw_process1_antialias(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x, float x_phase_inc) {
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const float s_1_m_phase = 1.f - x;
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float v = x - s_1_m_phase;
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if (x_phase_inc != 0.f) {
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const float phase_inc_2 = x_phase_inc + x_phase_inc;
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const float phase_inc_rcp = bw_rcpf_2(x_phase_inc);
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if (s_1_m_phase < phase_inc_2)
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v += _bw_osc_saw_blep_diff(s_1_m_phase * phase_inc_rcp);
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if (x < phase_inc_2)
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v -= _bw_osc_saw_blep_diff(x * phase_inc_rcp);
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}
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return v;
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}
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static inline void bw_osc_saw_process(bw_osc_saw_coeffs *BW_RESTRICT coeffs, const float *x, const float *x_phase_inc, float *y, int n_samples) {
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if (coeffs->antialiasing)
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for (int i = 0; i < n_samples; i++)
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y[i] = bw_osc_saw_process1_antialias(coeffs, x[i], x_phase_inc[i]);
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else
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for (int i = 0; i < n_samples; i++)
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y[i] = bw_osc_saw_process1(coeffs, x[i]);
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}
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static inline void bw_osc_saw_set_antialiasing(bw_osc_saw_coeffs *BW_RESTRICT coeffs, char value) {
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coeffs->antialiasing = value;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif
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