/* * 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 bw_rand }}} * description {{{ * Generator of white noise with uniform distribution. * * This module has no internal state, rather its state is stored into a * `uint64_t` value to which the API user supplies a pointer (as in * [bw\_rand](bw_rand)). * }}} * changelog {{{ * * }}} */ #ifndef _BW_NOISE_GEN_H #define _BW_NOISE_GEN_H #include #ifdef __cplusplus extern "C" { #endif /*! api {{{ * #### bw_noise_gen_coeffs * ```>>> */ typedef struct _bw_noise_gen_coeffs bw_noise_gen_coeffs; /*! <<<``` * Coefficients and related. * * #### bw_noise_gen_init() * ```>>> */ static inline void bw_noise_gen_init(bw_noise_gen_coeffs *BW_RESTRICT coeffs, uint64_t *BW_RESTRICT state); /*! <<<``` * Initializes input parameter values and sets the `state` pointer to obtain * pseudo-random numbers in `coeffs`. * * #### bw_noise_gen_set_sample_rate() * ```>>> */ static inline void bw_noise_gen_set_sample_rate(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float sample_rate); /*! <<<``` * Sets the `sample_rate` (Hz) value in `coeffs`. * * #### bw_noise_gen_process1\*() * ```>>> */ static inline float bw_noise_gen_process1(const bw_noise_gen_coeffs *BW_RESTRICT coeffs); static inline float bw_noise_gen_process1_scaling(const bw_noise_gen_coeffs *BW_RESTRICT coeffs); /*! <<<``` * These functions generate and return one sample using `coeffs`, where: * * `bw_noise_gen_process1()` assumes that sample rate scaling is disabled; * * `bw_noise_gen_process1_scaling()` assumes that sample rate scaling is * enabled. * * #### bw_noise_gen_process() * ```>>> */ static inline void bw_noise_gen_process(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float *BW_RESTRICT y, int n_samples); /*! <<<``` * Generates and fills the first `n_samples` of the output buffer `y` using * `coeffs`. * * #### bw_noise_gen_set_sample_rate_scaling() * ```>>> */ static inline void bw_noise_gen_set_sample_rate_scaling(bw_noise_gen_coeffs *BW_RESTRICT coeffs, char value); /*! <<<``` * Sets whether the output should be scaled (`value` non-`0`) or not (`0`) * according to the sample rate in `coeffs`. * * In order to maintain the same perceived loudness at different sample * rates, a white noise signal with uniform distribution should be * accordingly scaled. The 44100 Hz sample rate is used as a reference (that * is, the scaling factor at that sample rate is `1.f`). * * Default value: `0` (off). * * #### bw_noise_gen_get_scaling_k() * ```>>> */ static inline float bw_noise_gen_get_scaling_k(const bw_noise_gen_coeffs *BW_RESTRICT coeffs); /*! <<<``` * Returns the sample rate scaling factor that is applied or would be applied * if sample rate scaling were enabled, as stored in `coeffs`. * }}} */ /*** 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 #include struct _bw_noise_gen_coeffs { // Coefficients float scaling_k; // Parameters uint64_t *state; char sample_rate_scaling; }; static inline void bw_noise_gen_init(bw_noise_gen_coeffs *BW_RESTRICT coeffs, uint64_t *BW_RESTRICT state) { coeffs->state = state; coeffs->sample_rate_scaling = 0; } static inline void bw_noise_gen_set_sample_rate(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float sample_rate) { coeffs->scaling_k = 0.004761904761904762f * bw_sqrtf_2(sample_rate); } static inline float bw_noise_gen_process1(const bw_noise_gen_coeffs *BW_RESTRICT coeffs) { return bw_randf(coeffs->state); } static inline float bw_noise_gen_process1_scaling(const bw_noise_gen_coeffs *BW_RESTRICT coeffs) { return coeffs->scaling_k * bw_randf(coeffs->state); } static inline void bw_noise_gen_process(bw_noise_gen_coeffs *BW_RESTRICT coeffs, float *BW_RESTRICT y, int n_samples) { if (coeffs->sample_rate_scaling) for (int i = 0; i < n_samples; i++) y[i] = bw_noise_gen_process1(coeffs); else for (int i = 0; i < n_samples; i++) y[i] = bw_noise_gen_process1_scaling(coeffs); } static inline void bw_noise_gen_set_sample_rate_scaling(bw_noise_gen_coeffs *BW_RESTRICT coeffs, char value) { coeffs->sample_rate_scaling = value; } static inline float bw_noise_gen_get_scaling_k(const bw_noise_gen_coeffs *BW_RESTRICT coeffs) { return coeffs->scaling_k; } #ifdef __cplusplus } #endif #endif