1 /*************************************************************************/
2 /* audio_filter_sw.h */
3 /*************************************************************************/
4 /* This file is part of: */
5 /* GODOT ENGINE */
6 /* https://godotengine.org */
7 /*************************************************************************/
8 /* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */
9 /* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md) */
10 /* */
11 /* Permission is hereby granted, free of charge, to any person obtaining */
12 /* a copy of this software and associated documentation files (the */
13 /* "Software"), to deal in the Software without restriction, including */
14 /* without limitation the rights to use, copy, modify, merge, publish, */
15 /* distribute, sublicense, and/or sell copies of the Software, and to */
16 /* permit persons to whom the Software is furnished to do so, subject to */
17 /* the following conditions: */
18 /* */
19 /* The above copyright notice and this permission notice shall be */
20 /* included in all copies or substantial portions of the Software. */
21 /* */
22 /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
23 /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
24 /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
25 /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
26 /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
27 /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
28 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
29 /*************************************************************************/
30 #ifndef AUDIO_FILTER_SW_H
31 #define AUDIO_FILTER_SW_H
32
33 #include "math_funcs.h"
34
35 class AudioFilterSW {
36 public:
37 struct Coeffs {
38
39 float a1, a2;
40 float b0, b1, b2;
41
42 //bool operator==(const Coeffs &p_rv) { return (FLOATS_EQ(a1,p_rv.a1) && FLOATS_EQ(a2,p_rv.a2) && FLOATS_EQ(b1,p_rv.b1) && FLOATS_EQ(b2,p_rv.b2) && FLOATS_EQ(b0,p_rv.b0) ); }
CoeffsCoeffs43 Coeffs() { a1 = a2 = b0 = b1 = b2 = 0.0; }
44 };
45
46 enum Mode {
47 BANDPASS,
48 HIGHPASS,
49 LOWPASS,
50 NOTCH,
51 PEAK,
52 BANDLIMIT,
53 LOWSHELF,
54 HIGHSHELF
55
56 };
57
58 class Processor { // simple filter processor
59
60 AudioFilterSW *filter;
61 Coeffs coeffs;
62 float ha1, ha2, hb1, hb2; //history
63 public:
64 void set_filter(AudioFilterSW *p_filter);
65 void process(float *p_samples, int p_amount, int p_stride = 1);
66 void update_coeffs();
67 inline void process_one(float &p_sample);
68
69 Processor();
70 };
71
72 private:
73 float cutoff;
74 float resonance;
75 float gain;
76 float sampling_rate;
77 int stages;
78 Mode mode;
79
80 public:
81 float get_response(float p_freq, Coeffs *p_coeffs);
82
83 void set_mode(Mode p_mode);
84 void set_cutoff(float p_cutoff);
85 void set_resonance(float p_resonance);
86 void set_gain(float p_gain);
87 void set_sampling_rate(float p_srate);
88 void set_stages(int p_stages); //adjust for multiple stages
89
90 void prepare_coefficients(Coeffs *p_coeffs);
91
92 AudioFilterSW();
93 };
94
95 /* inline methods */
96
process_one(float & p_val)97 void AudioFilterSW::Processor::process_one(float &p_val) {
98
99 float pre = p_val;
100 p_val = (p_val * coeffs.b0 + hb1 * coeffs.b1 + hb2 * coeffs.b2 + ha1 * coeffs.a1 + ha2 * coeffs.a2);
101 ha2 = ha1;
102 hb2 = hb1;
103 hb1 = pre;
104 ha1 = p_val;
105 }
106
107 #endif // AUDIO_FILTER_SW_H
108