263 lines
7.3 KiB
C
263 lines
7.3 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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* One-pole (6 dB/oct) lowpass filter with unitary DC gain, separate attack
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* and decay time constants, and sticky target-reach threshold.
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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 to avoid dynamic memory allocation.</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_ONE_POLE_H
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#define _BW_ONE_POLE_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*! api {{{
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* #### bw_one_pole
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* ```>>> */
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typedef struct _bw_one_pole bw_one_pole;
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/*! <<<```
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* Instance object.
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* >>> */
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/*! ...
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* #### bw_one_pole_sticky_mode
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* ```>>> */
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typedef enum {
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bw_one_pole_sticky_mode_abs,
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bw_one_pole_sticky_mode_rel
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} bw_one_pole_sticky_mode;
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/*! <<<```
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* Distance metrics for sticky behavior:
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* * `bw_one_pole_sticky_mode_abs`: absolute difference (|`out` - `in`|);
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* * `bw_one_pole_sticky_mode_rel`: relative difference with respect to
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* input (|`out` - `in`| / |`in`|);
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* >>> */
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/*! ...
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* #### bw_one_pole_init()
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* ```>>> */
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void bw_one_pole_init(bw_one_pole *instance);
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/*! <<<```
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* Initializes the `instance` object.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_sample_rate()
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* ```>>> */
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void bw_one_pole_set_sample_rate(bw_one_pole *instance, float sample_rate);
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/*! <<<```
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* Sets the `sample_rate` (Hz) value for the given `instance`.
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* >>> */
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/*! ...
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* #### bw_one_pole_reset()
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* ```>>> */
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void bw_one_pole_reset(bw_one_pole *instance);
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/*! <<<```
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* Resets the given `instance` to its initial state.
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* >>> */
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/*! ...
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* #### bw_one_pole_process()
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* ```>>> */
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void bw_one_pole_process(bw_one_pole *instance, const float* x, 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` and fills the corresponding `n_samples` samples in the output
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* buffer `y`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_init_val()
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* ```>>> */
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void bw_one_pole_set_init_val(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the initial/quiescent `value` for the given `instance`.
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*
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* In practice, when processing the first buffer after a reset, the past
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* input and output are both assumed to have virtually been constant and of
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* the specified `value`.
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*
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* Default value: `0.f`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_cutoff()
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* ```>>> */
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void bw_one_pole_set_cutoff(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets both the upgoing (attack) and downgoing (decay) cutoff frequency to
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* the given `value` (Hz) for the given `instance`.
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*
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* This is equivalent to calling both `bw_one_pole_set_cutoff_up()` and
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* `bw_one_pole_set_cutoff_down()` with same `instance` and `value` or
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* calling `bw_one_pole_set_tau()` with same `instance` and
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* value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `INFINITY`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_cutoff_up()
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* ```>>> */
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void bw_one_pole_set_cutoff_up(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the upgoing (attack) cutoff frequency to the given `value` (Hz) for
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* the given `instance`.
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*
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* This is equivalent to calling `bw_one_pole_set_tau_up()` with same
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* `instance` and value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `INFINITY`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_cutoff_down()
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* ```>>> */
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void bw_one_pole_set_cutoff_down(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the downgoing (attack) cutoff frequency to the given `value` (Hz)
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* for the given `instance`.
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*
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* This is equivalent to calling `bw_one_pole_set_tau_down()` with same
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* `instance` and value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `INFINITY`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_tau()
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* ```>>> */
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void bw_one_pole_set_tau(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets both the upgoing (attack) and downgoing (decay) time constant to the
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* given `value` (s) for the given `instance`.
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*
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* This is equivalent to calling both `bw_one_pole_set_tau_up()` and
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* `bw_one_pole_set_tau_down()` with same `instance` and `value` or calling
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* `bw_one_pole_set_cutoff()` with same `instance` and
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* value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `0.f`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_tau_up()
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* ```>>> */
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void bw_one_pole_set_tau_up(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the upgoing (attack) time constant to the given `value` (s) for the
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* given `instance`.
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*
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* This is equivalent to calling `bw_one_pole_set_cutoff_up()` with same
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* `instance` and value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `0.f`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_tau_down()
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* ```>>> */
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void bw_one_pole_set_tau_down(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the downgoing (decay) time constant to the given `value` (s) for the
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* given `instance`.
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*
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* This is equivalent to calling `bw_one_pole_set_cutoff_down()` with same
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* `instance` and value = 1 / (2 * pi * `value`) (net of numerical errors).
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*
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* Default value: `0.f`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_sticky_thresh()
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* ```>>> */
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void bw_one_pole_set_sticky_thresh(bw_one_pole *instance, float value);
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/*! <<<```
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* Sets the target-reach threshold specified by `value` for the given
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* `instance`.
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*
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* When the difference between the output and the input would fall under such
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* threshold according to the current distance metric (see
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* `bw_one_pole_set_sticky_mode()`), the output is forcefully set to be equal
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* to the input value.
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*
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* Default value: `0.f`.
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* >>> */
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/*! ...
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* #### bw_one_pole_set_sticky_mode()
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* ```>>> */
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void bw_one_pole_set_sticky_mode(bw_one_pole *instance, bw_one_pole_sticky_mode value);
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/*! <<<```
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* Sets the current distance metric for sticky behavior.
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* }}} */
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/* WARNING: the internal definition of this struct is not part of the public
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* API. Its content may change at any time in future versions. Please, do not
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* access its members directly. */
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struct _bw_one_pole {
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// Coefficients
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float Ttm2pi;
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float mA1u;
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float mA1d;
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float st2;
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// Parameters
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float init_val;
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float cutoff_up;
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float cutoff_down;
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float sticky_thresh;
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bw_one_pole_sticky_mode sticky_mode;
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int param_changed;
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// State
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char first_run;
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float x_z1;
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float y_z1;
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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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