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/* Simple DLL
*
* Copyright © 2019 Wim Taymans
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#ifndef SPA_DLL_H
#define SPA_DLL_H
#ifdef __cplusplus
extern "C" {
#endif
#include <stddef.h>
#include <math.h>
#define SPA_DLL_BW_MAX 0.128
#define SPA_DLL_BW_MIN 0.016
struct spa_dll {
double bw;
double z1, z2, z3;
double w0, w1, w2;
};
static inline void spa_dll_init(struct spa_dll *dll)
{
dll->bw = 0.0;
dll->z1 = dll->z2 = dll->z3 = 0.0;
}
static inline void spa_dll_set_bw(struct spa_dll *dll, double bw, unsigned period, unsigned rate)
{
double w = 2 * M_PI * bw * period / rate;
dll->w0 = 1.0 - exp (-20.0 * w);
dll->w1 = w * 1.5 / period;
dll->w2 = w / 1.5;
dll->bw = bw;
}
static inline double spa_dll_update(struct spa_dll *dll, double err)
{
dll->z1 += dll->w0 * (dll->w1 * err - dll->z1);
dll->z2 += dll->w0 * (dll->z1 - dll->z2);
dll->z3 += dll->w2 * dll->z2;
return 1.0 - (dll->z2 + dll->z3);
}
#ifdef __cplusplus
} /* extern "C" */
#endif
#endif /* SPA_DLL_H */
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