From 960366cf8dbb3359afaca30cf7fdbf69a6d6dda7 Mon Sep 17 00:00:00 2001 From: Karsten Keil Date: Sun, 27 Jul 2008 01:56:38 +0200 Subject: Add mISDN DSP Enable support for digital audio processing capability. This module may be used for special applications that require cross connecting of bchannels, conferencing, dtmf decoding echo cancelation, tone generation, and Blowfish encryption and decryption. It may use hardware features if available. Signed-off-by: Karsten Keil --- drivers/isdn/mISDN/dsp_biquad.h | 65 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 drivers/isdn/mISDN/dsp_biquad.h (limited to 'drivers/isdn/mISDN/dsp_biquad.h') diff --git a/drivers/isdn/mISDN/dsp_biquad.h b/drivers/isdn/mISDN/dsp_biquad.h new file mode 100644 index 000000000000..038191bc45f5 --- /dev/null +++ b/drivers/isdn/mISDN/dsp_biquad.h @@ -0,0 +1,65 @@ +/* + * 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 + * + * Copyright (C) 2001 Steve Underwood + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + */ + +struct biquad2_state { + int32_t gain; + int32_t a1; + int32_t a2; + int32_t b1; + int32_t b2; + + int32_t z1; + int32_t z2; +}; + +static inline void biquad2_init(struct biquad2_state *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; +} + +static inline int16_t biquad2(struct biquad2_state *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; +} -- cgit v1.2.3