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dll.h
1/* Simple DLL */
2/* SPDX-FileCopyrightText: Copyright © 2019 Wim Taymans */
3/* SPDX-License-Identifier: MIT */
4
5#ifndef SPA_DLL_H
6#define SPA_DLL_H
7
8#include <stddef.h>
9#include <math.h>
10
11#include <spa/utils/defs.h>
12
13#ifdef __cplusplus
14 extern "C" {
15#endif
16
17#ifndef SPA_API_DLL
18 #ifdef SPA_API_IMPL
19 #define SPA_API_DLL SPA_API_IMPL
20 #else
21 #define SPA_API_DLL static inline
22 #endif
23#endif
24
25#define SPA_DLL_BW_MAX 0.128
26#define SPA_DLL_BW_MIN 0.016
27
28 struct spa_dll {
29 double bw;
30 double z1, z2, z3;
31 double w0, w1, w2;
32};
33
34SPA_API_DLL void spa_dll_init(struct spa_dll *dll)
35{
36 dll->bw = 0.0;
37 dll->z1 = dll->z2 = dll->z3 = 0.0;
38}
39
40SPA_API_DLL void spa_dll_set_bw(struct spa_dll *dll, double bw, unsigned period, unsigned rate)
41{
42 double w = 2 * M_PI * bw * period / rate;
43 dll->w0 = 1.0 - exp (-20.0 * w);
44 dll->w1 = w * 1.5 / period;
45 dll->w2 = w / 1.5;
46 dll->bw = bw;
47}
48
49SPA_API_DLL double spa_dll_update(struct spa_dll *dll, double err)
50{
51 dll->z1 += dll->w0 * (dll->w1 * err - dll->z1);
52 dll->z2 += dll->w0 * (dll->z1 - dll->z2);
53 dll->z3 += dll->w2 * dll->z2;
54 return 1.0 - (dll->z2 + dll->z3);
55}
56
57#ifdef __cplusplus
58} /* extern "C" */
59#endif
60
61#endif /* SPA_DLL_H */
defs.h
spa/utils/defs.h
spa_dll
Definition dll.h:36
spa_dll::z2
double z2
Definition dll.h:38
spa_dll::z1
double z1
Definition dll.h:38
spa_dll::w2
double w2
Definition dll.h:39
spa_dll::z3
double z3
Definition dll.h:38
spa_dll::w0
double w0
Definition dll.h:39
spa_dll::bw
double bw
Definition dll.h:37
spa_dll::w1
double w1
Definition dll.h:39