blob: ea2c83db458d48e566b268152c9d8dd4447a34e1 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
/*
* SpanDSP - a series of DSP components for telephony
*
* biquad.h - General telephony bi-quad section routines (currently this just
* handles canonic/type 2 form)
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2001 Steve Underwood
*
* All rights reserved.
*
*/
/*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2 as published by the
* Free Software Foundation. See the LICENSE file included with
* this program for more details.
*/
static inline void biquad2_init (biquad2_state_t *bq,
int32_t gain,
int32_t a1,
int32_t a2,
int32_t b1,
int32_t b2)
{
bq->gain = gain;
bq->a1 = a1;
bq->a2 = a2;
bq->b1 = b1;
bq->b2 = b2;
bq->z1 = 0;
bq->z2 = 0;
}
/*- End of function --------------------------------------------------------*/
static inline int16_t biquad2 (biquad2_state_t *bq, int16_t sample)
{
int32_t y;
int32_t z0;
z0 = sample*bq->gain + bq->z1*bq->a1 + bq->z2*bq->a2;
y = z0 + bq->z1*bq->b1 + bq->z2*bq->b2;
bq->z2 = bq->z1;
bq->z1 = z0 >> 15;
y >>= 15;
return y;
}
/*- End of function --------------------------------------------------------*/
/*- End of file ------------------------------------------------------------*/
|