Merge remote-tracking branch 's5p/for-next'
[linux-2.6/next.git] / drivers / isdn / mISDN / dsp_biquad.h
blob038191bc45f5ace94f2bab57910a60f5f8a6ae1a
1 /*
2 * SpanDSP - a series of DSP components for telephony
4 * biquad.h - General telephony bi-quad section routines (currently this just
5 * handles canonic/type 2 form)
7 * Written by Steve Underwood <steveu@coppice.org>
9 * Copyright (C) 2001 Steve Underwood
11 * All rights reserved.
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software
25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
29 struct biquad2_state {
30 int32_t gain;
31 int32_t a1;
32 int32_t a2;
33 int32_t b1;
34 int32_t b2;
36 int32_t z1;
37 int32_t z2;
40 static inline void biquad2_init(struct biquad2_state *bq,
41 int32_t gain, int32_t a1, int32_t a2, int32_t b1, int32_t b2)
43 bq->gain = gain;
44 bq->a1 = a1;
45 bq->a2 = a2;
46 bq->b1 = b1;
47 bq->b2 = b2;
49 bq->z1 = 0;
50 bq->z2 = 0;
53 static inline int16_t biquad2(struct biquad2_state *bq, int16_t sample)
55 int32_t y;
56 int32_t z0;
58 z0 = sample*bq->gain + bq->z1*bq->a1 + bq->z2*bq->a2;
59 y = z0 + bq->z1*bq->b1 + bq->z2*bq->b2;
61 bq->z2 = bq->z1;
62 bq->z1 = z0 >> 15;
63 y >>= 15;
64 return y;