331 lines
10 KiB
C
331 lines
10 KiB
C
/*
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* Brickworks
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*
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* Copyright (C) 2022, 2023 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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* along with Brickworks. If not, see <http://www.gnu.org/licenses/>.
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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 {{{ 0.3.0 }}}
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* requires {{{
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* bw_config bw_common bw_gain bw_math bw_mm2 bw_one_pole bw_svf
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* }}}
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* description {{{
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* Second-order low shelf filter (12 dB/oct) with gain asymptotically
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* approaching unity as frequency increases.
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*
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* The quality factor can be either directly controlled via the Q parameter
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* or indirectly through the slope parameter, which indicates the "shelf
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* slope" as defined in the "Cookbook formulae for audio EQ biquad filter
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* coefficients" by Robert Bristow-Johnson. The use_slope parameter allows
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* you to choose which parameterization to use.
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* }}}
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* changelog {{{
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* <ul>
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* <li>Version <strong>0.3.0</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_LS2_H
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#define _BW_LS2_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_ls2_coeffs
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* ```>>> */
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typedef struct _bw_ls2_coeffs bw_ls2_coeffs;
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/*! <<<```
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* Coefficients and related.
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*
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* #### bw_ls2_state
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* ```>>> */
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typedef struct _bw_ls2_state bw_ls2_state;
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/*! <<<```
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* Internal state and related.
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*
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* #### bw_ls2_init()
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* ```>>> */
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static inline void bw_ls2_init(bw_ls2_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Initializes input parameter values in `coeffs`.
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*
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* #### bw_ls2_set_sample_rate()
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* ```>>> */
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static inline void bw_ls2_set_sample_rate(bw_ls2_coeffs *BW_RESTRICT coeffs, float sample_rate);
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/*! <<<```
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* Sets the `sample_rate` (Hz) value in `coeffs`.
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*
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* #### bw_ls2_reset_coeffs()
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* ```>>> */
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static inline void bw_ls2_reset_coeffs(bw_ls2_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Resets coefficients in `coeffs` to assume their target values.
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*
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* #### bw_ls2_reset_state()
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* ```>>> */
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static inline void bw_ls2_reset_state(const bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state);
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/*! <<<```
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* Resets the given `state` to its initial values using the given `coeffs`.
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*
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* #### bw_ls2_update_coeffs_ctrl()
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* ```>>> */
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static inline void bw_ls2_update_coeffs_ctrl(bw_ls2_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Triggers control-rate update of coefficients in `coeffs`.
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*
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* #### bw_ls2_update_coeffs_audio()
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* ```>>> */
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static inline void bw_ls2_update_coeffs_audio(bw_ls2_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Triggers audio-rate update of coefficients in `coeffs`.
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*
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* #### bw_ls2_process1()
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* ```>>> */
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static inline float bw_ls2_process1(const bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state, float x);
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/*! <<<```
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* Processes one input sample `x` using `coeffs`, while using and updating
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* `state`. Returns the corresponding output sample.
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*
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* #### bw_ls2_process()
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* ```>>> */
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static inline void bw_ls2_process(bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state, const float *x, float *y, int n_samples);
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/*! <<<```
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* Processes the first `n_samples` of the input buffer `x` and fills the
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* first `n_samples` of the output buffer `y`, while using and updating both
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* `coeffs` and `state` (control and audio rate).
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*
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* #### bw_ls2_set_cutoff()
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* ```>>> */
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static inline void bw_ls2_set_cutoff(bw_ls2_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the cutoff frequency `value` (Hz) in `coeffs`.
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*
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* Default value: `1e3f`.
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*
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* #### bw_ls2_set_Q()
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* ```>>> */
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static inline void bw_ls2_set_Q(bw_mm2_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the quality factor to the given `value` in `coeffs`.
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*
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* `value` must be equal or bigger than `0.5f`.
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*
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* Default value: `0.5f`.
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*
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* #### bw_ls2_set_dc_gain_lin()
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* ```>>> */
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static inline void bw_ls2_set_dc_gain_lin(bw_ls2_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the dc gain parameter to the given `value` (linear gain) in `coeffs`.
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*
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* Default value: `0.f`.
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*
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* #### bw_ls2_set_dc_gain_dB()
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* ```>>> */
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static inline void bw_ls2_set_dc_gain_dB(bw_ls2_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the dc gain parameter to the given `value` (dB) in `coeffs`.
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*
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* Default value: `-INFINITY`.
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*
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* #### bw_ls2_set_slope()
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* ```>>> */
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static inline void bw_ls2_set_slope(bw_ls2_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the shelf slope `value` in `coeffs`.
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*
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* Default value: `0.5f`.
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*
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* #### bw_ls2_set_use_slope()
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* ```>>> */
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static inline void bw_ls2_set_use_slope(bw_mm2_coeffs *BW_RESTRICT coeffs, char value);
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/*! <<<```
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* Sets whether the quality factor should be controlled via the slope
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* parameter (`value` non-`0`) or via the Q parameter (`0`).
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*
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* Default value: non-`0` (use slope parameter).
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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_mm2.h>
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#include <bw_math.h>
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struct _bw_ls2_coeffs {
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// Sub-components
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bw_mm2_coeffs mm2_coeffs;
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// Coefficients
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float sg;
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float isg;
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float issg;
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// Parameters
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float dc_gain;
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float cutoff;
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float Q;
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float slope;
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char use_slope;
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int param_changed;
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};
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struct _bw_ls2_state {
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bw_mm2_state mm2_state;
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};
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#define _BW_LS2_PARAM_DC_GAIN 1
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#define _BW_LS2_PARAM_CUTOFF (1<<1)
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#define _BW_LS2_PARAM_Q (1<<2)
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#define _BW_LS2_PARAM_SLOPE (1<<3)
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static inline void bw_ls2_init(bw_ls2_coeffs *BW_RESTRICT coeffs) {
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bw_mm2_init(&coeffs->mm2_coeffs);
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bw_mm2_set_prewarp_at_cutoff(&coeffs->mm2_coeffs, 0);
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coeffs->dc_gain = 1.f;
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coeffs->cutoff = 1e3f;
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coeffs->Q = 0.5f;
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coeffs->slope = 0.5f;
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coeffs->use_slope = 1;
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}
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static inline void bw_ls2_set_sample_rate(bw_ls2_coeffs *BW_RESTRICT coeffs, float sample_rate) {
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bw_mm2_set_sample_rate(&coeffs->mm2_coeffs, sample_rate);
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}
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static inline void _bw_ls2_update_mm2_params(bw_ls1_coeffs *BW_RESTRICT coeffs) {
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if (coeffs->param_changed) {
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if (coeffs->param_changed & (_BW_LS2_PARAM_DC_GAIN | _BW_LS2_PARAM_CUTOFF)) {
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if (coeffs->param_changed & _BW_LS2_PARAM_DC_GAIN) {
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coeffs->sg = bw_sqrtf_2(coeffs->dc_gain);
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coeffs->isg = bw_rcpf_2(coeffs->sg);
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coeffs->issg = bw_sqrtf_2(coeffs->isg);
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bw_mm2_set_coeff_x(&coeffs->mm2_coeffs, coeffs->sg);
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bw_mm2_set_coeff_lp(&coeffs->mm2_coeffs, coeffs->dc_gain - coeffs->sg);
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bw_mm2_set_coeff_hp(&coeffs->mm2_coeffs, 1.f - coeffs->sg);
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}
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if (coeffs->param_changed & _BW_LS2_PARAM_CUTOFF)
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bw_mm2_set_prewarp_freq(&coeffs->mm2_coeffs, coeffs->cutoff);
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bw_mm2_set_cutoff(&coeffs->mm2_coeffs, coeffs->cutoff * coeffs->issg);
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}
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if (coeffs->use_slope) {
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if (coeffs->param_changed & (_BW_LS2_PARAM_DC_GAIN | _BW_LS2_PARAM_SLOPE)) {
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const float k = coeffs->sg + coeffs->isg;
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bw_mm2_set_Q(&coeffs->mm2_coeffs, bw_sqrtf_2(coeffs->slope * bw_rcpf_2(coeffs->slope + coeffs->slope + k - k * coeffs->slope)));
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}
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}
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else {
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if (coeffs->param_changed & _BW_LS2_PARAM_Q)
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bw_mm2_set_Q(&coeffs->mm2_coeffs, coeffs->Q);
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}
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coeffs->param_changed = 0;
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}
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}
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static inline void bw_ls2_reset_coeffs(bw_ls2_coeffs *BW_RESTRICT coeffs) {
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coeffs->param_changed = ~0;
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_bw_ls2_update_mm2_params(coeffs);
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bw_mm2_reset_coeffs(&coeffs->mm2_coeffs);
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}
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static inline void bw_ls2_reset_state(const bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state) {
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bw_mm2_reset_state(&coeffs->mm2_coeffs, &state->mm2_state);
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}
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static inline void bw_ls2_update_coeffs_ctrl(bw_ls2_coeffs *BW_RESTRICT coeffs) {
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_bw_ls2_update_mm2_params(coeffs);
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bw_mm2_update_coeffs_ctrl(&coeffs->mm2_coeffs);
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}
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static inline void bw_ls2_update_coeffs_audio(bw_ls2_coeffs *BW_RESTRICT coeffs) {
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bw_mm2_update_coeffs_audio(&coeffs->mm2_coeffs);
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}
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static inline float bw_ls2_process1(const bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state, float x) {
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return bw_mm2_process1(&coeffs->mm2_coeffs, &state->mm2_state, x);
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}
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static inline void bw_ls2_process(bw_ls2_coeffs *BW_RESTRICT coeffs, bw_ls2_state *BW_RESTRICT state, const float *x, float *y, int n_samples) {
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bw_ls2_update_coeffs_ctrl(coeffs);
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for (int i = 0; i < n_samples; i++) {
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bw_ls2_update_coeffs_audio(coeffs);
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y[i] = bw_ls2_process1(coeffs, state, x[i]);
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}
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}
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static inline void bw_ls2_set_cutoff(bw_ls2_coeffs *BW_RESTRICT coeffs, float value) {
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if (coeffs->cutoff != value) {
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coeffs->cutoff = value;
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coeffs->param_changed |= _BW_LS2_PARAM_CUTOFF;
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}
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}
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static inline void bw_ls2_set_Q(bw_mm2_coeffs *BW_RESTRICT coeffs, float value) {
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if (coeffs->Q != value) {
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coeffs->Q = value;
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coeffs->param_changed |= _BW_LS2_PARAM_Q;
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}
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}
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static inline void bw_ls2_set_dc_gain_lin(bw_ls2_coeffs *BW_RESTRICT coeffs, float value) {
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if (coeffs->dc_gain != value) {
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coeffs->dc_gain = value;
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coeffs->param_changed |= _BW_LS2_PARAM_DC_GAIN;
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}
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}
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static inline void bw_ls2_set_dc_gain_dB(bw_ls2_coeffs *BW_RESTRICT coeffs, float value) {
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bw_ls2_set_dc_gain_lin(coeffs, bw_dB2linf_3(value));
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}
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static inline void bw_ls2_set_slope(bw_ls2_coeffs *BW_RESTRICT coeffs, float value) {
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if (coeffs->slope != value) {
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coeffs->slope = value;
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coeffs->param_changed |= _BW_LS2_PARAM_SLOPE;
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}
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}
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static inline void bw_ls2_set_use_slope(bw_mm2_coeffs *BW_RESTRICT coeffs, char value) {
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if ((coeffs->use_slope && !value) || (!coeffs->use_slope && value)) {
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coeffs->use_slope = value;
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coeffs->param_changed |= _BW_LS2_PARAM_Q | _BW_LS2_PARAM_SLOPE;
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}
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}
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#undef _BW_LS2_PARAM_DC_GAIN
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#undef _BW_LS2_PARAM_CUTOFF
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#undef _BW_LS2_PARAM_Q
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#undef _BW_LS2_PARAM_SLOPE
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#ifdef __cplusplus
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}
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#endif
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#endif
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