159 lines
4.7 KiB
C
159 lines
4.7 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 bw_rand }}}
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* description {{{
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* Generator of white noise with uniform distribution.
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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_NOISE_GEN_H
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#define _BW_NOISE_GEN_H
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#include <bw_common.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_noise_gen_coeffs
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* ```>>> */
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typedef struct _bw_noise_gen_coeffs bw_noise_gen_coeffs;
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/*! <<<```
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* Coefficients.
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*
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* #### bw_noise_gen_init()
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* ```>>> */
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static inline void bw_noise_gen_init(bw_noise_gen_coeffs *BW_RESTRICT coeffs, uint64_t *BW_RESTRICT state);
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/*! <<<```
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* Initializes `coeffs` and lets it use the given `state` pointer to obtain
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* pseudo-random numbers.
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*
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* #### bw_noise_gen_set_sample_rate()
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* ```>>> */
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static inline void bw_noise_gen_set_sample_rate(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float sample_rate);
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/*! <<<```
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* Sets the `sample_rate` (Hz) value for the given `coeffs`.
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* >>> */
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static inline float bw_noise_gen_process1(const bw_noise_gen_coeffs *BW_RESTRICT coeffs);
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static inline float bw_noise_gen_process1_scaling(const bw_noise_gen_coeffs *BW_RESTRICT coeffs);
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/*! ...
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* #### bw_noise_gen_process()
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* ```>>> */
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static inline void bw_noise_gen_process(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float *BW_RESTRICT y, int n_samples);
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/*! <<<```
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* Lets the given `instance` generate `n_samples` samples and puts them in
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* the output buffer `y`.
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* >>> */
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/*! ...
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* #### bw_noise_gen_set_sample_rate_scaling()
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* ```>>> */
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static inline void bw_noise_gen_set_sample_rate_scaling(bw_noise_gen_coeffs *BW_RESTRICT coeffs, char value);
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/*! <<<```
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* Sets whether the output should be scaled (`value` non-`0`) or not (`0`)
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* according to the sample rate by the given `instance`.
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*
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* In order to maintain the perceived loudness at different sample rates, a
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* white noise signal with uniform distribution should be accordingly scaled.
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* In this module the 44100 Hz sample rate is used as a reference (that is,
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* the scaling factor at that sample rate is `1.f`).
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*
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* Default value: `0`.
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* }}} */
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static inline float bw_noise_gen_get_scaling_k(bw_noise_gen_coeffs *BW_RESTRICT coeffs);
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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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#include <bw_rand.h>
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struct _bw_noise_gen_coeffs {
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// Coefficients
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float scaling_k;
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// Parameters
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uint64_t *state;
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char sample_rate_scaling;
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};
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static inline void bw_noise_gen_init(bw_noise_gen_coeffs *BW_RESTRICT coeffs, uint64_t *BW_RESTRICT state) {
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coeffs->state = state;
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coeffs->sample_rate_scaling = 0;
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}
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static inline void bw_noise_gen_set_sample_rate(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float sample_rate) {
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coeffs->scaling_k = 0.004761904761904762f * bw_sqrtf_2(sample_rate);
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}
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static inline float bw_noise_gen_process1(const bw_noise_gen_coeffs *BW_RESTRICT coeffs) {
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return bw_randf(coeffs->state);
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}
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static inline float bw_noise_gen_process1_scaling(const bw_noise_gen_coeffs *BW_RESTRICT coeffs) {
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return coeffs->scaling_k * bw_randf(coeffs->state);
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}
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static inline void bw_noise_gen_process(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float *BW_RESTRICT y, int n_samples) {
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if (coeffs->sample_rate_scaling)
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for (int i = 0; i < n_samples; i++)
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y[i] = bw_noise_gen_process1(coeffs);
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else
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for (int i = 0; i < n_samples; i++)
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y[i] = bw_noise_gen_process1_scaling(coeffs);
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}
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static inline void bw_noise_gen_set_sample_rate_scaling(bw_noise_gen_coeffs *BW_RESTRICT coeffs, char value) {
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coeffs->sample_rate_scaling = value;
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}
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static inline float bw_noise_gen_get_scaling_k(bw_noise_gen_coeffs *BW_RESTRICT coeffs) {
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return coeffs->scaling_k;
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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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