/* * Brickworks * * Copyright (C) 2022 Orastron Srl unipersonale * * Brickworks 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, version 3 of the License. * * Brickworks 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 Brickworks. If not, see . * * File author: Stefano D'Angelo */ /*! * module_type {{{ dsp }}} * version {{{ 0.2.0 }}} * requires {{{ bw_config bw_common bw_math }}} * description {{{ * Sawtooth oscillator waveshaper with PolyBLEP antialiasing. * * It turns a normalized phase signal, such as that geneated by * [bw\_phase\_gen](bw_phase_gen), into a sawtooth wave. * }}} * changelog {{{ * * }}} */ #ifndef _BW_OSC_SAW_H #define _BW_OSC_SAW_H #ifdef __cplusplus extern "C" { #endif #include /*! api {{{ * #### bw_osc_saw_coeffs * ```>>> */ typedef struct _bw_osc_saw_coeffs bw_osc_saw_coeffs; /*! <<<``` * Coefficients and related. * * #### bw_osc_saw_init() * ```>>> */ static inline void bw_osc_saw_init(bw_osc_saw_coeffs *BW_RESTRICT coeffs); /*! <<<``` * Initializes input parameter values in `coeffs`. * * #### bw_osc_saw_process1\*() * ```>>> */ static inline float bw_osc_saw_process1(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x); static inline float bw_osc_saw_process1_antialias(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x, float x_phase_inc); /*! <<<``` * These function process one input sample `x`, indicating the normalized * phase, using `coeffs`. They return the corresponding output sample. * * In particular: * * `bw_osc_saw_process1()` assumes that antialiasing is disabled; * * `bw_osc_saw_process1_antialias()` assumes that antialiasing is enabled * and requires the corresponding phase increment value to be passed via * `x_phase_inc`. * * #### bw_osc_saw_process() * ```>>> */ 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); /*! <<<``` * Processes the first `n_samples` of the input buffer `x`, containing the * normalized phase signal, and fills the first `n_samples` of the output * buffer `y`, while using and updating `coeffs`. * * If antialiasing is enabled, `x_phase_inc` must contain phase increment * values, otherwise it is ignored and can be `NULL`. * * #### bw_osc_saw_set_antialiasing() * ```>>> */ static inline void bw_osc_saw_set_antialiasing(bw_osc_saw_coeffs *BW_RESTRICT coeffs, char value); /*! <<<``` * Sets whether the antialiasing is on (`value` non-`0`) or off (`0`) in * `coeffs`. * * Default value: `0` (off). * }}} */ /*** Implementation ***/ /* WARNING: This part of the file is not part of the public API. Its content may * change at any time in future versions. Please, do not use it directly. */ #include struct _bw_osc_saw_coeffs { // Parameters char antialiasing; }; static inline void bw_osc_saw_init(bw_osc_saw_coeffs *BW_RESTRICT coeffs) { coeffs->antialiasing = 0; } static inline float bw_osc_saw_process1(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x) { return x + x - 1.f; } // PolyBLEP residual based on Parzen window (4th-order B-spline), one-sided (x in [0, 2]) static inline float _bw_osc_saw_blep_diff(float x) { return x < 1.f ? x * ((0.25f * x - 0.6666666666666666f) * x * x + 1.333333333333333f) - 1.f : x * (x * ((0.6666666666666666f - 0.08333333333333333f * x) * x - 2.f) + 2.666666666666667f) - 1.333333333333333f; } static inline float bw_osc_saw_process1_antialias(const bw_osc_saw_coeffs *BW_RESTRICT coeffs, float x, float x_phase_inc) { const float s_1_m_phase = 1.f - x; float v = x - s_1_m_phase; if (x_phase_inc != 0.f) { const float phase_inc_2 = x_phase_inc + x_phase_inc; const float phase_inc_rcp = bw_rcpf_2(x_phase_inc); if (s_1_m_phase < phase_inc_2) v += _bw_osc_saw_blep_diff(s_1_m_phase * phase_inc_rcp); if (x < phase_inc_2) v -= _bw_osc_saw_blep_diff(x * phase_inc_rcp); } return v; } 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) { if (coeffs->antialiasing) for (int i = 0; i < n_samples; i++) y[i] = bw_osc_saw_process1_antialias(coeffs, x[i], x_phase_inc[i]); else for (int i = 0; i < n_samples; i++) y[i] = bw_osc_saw_process1(coeffs, x[i]); } static inline void bw_osc_saw_set_antialiasing(bw_osc_saw_coeffs *BW_RESTRICT coeffs, char value) { coeffs->antialiasing = value; } #ifdef __cplusplus } #endif #endif