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/*
* 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.
*/
typedef struct
{
int32_t gain;
int32_t a1;
int32_t a2;
int32_t b1;
int32_t b2;
int32_t z1;
int32_t z2;
} biquad2_state_t;
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 ------------------------------------------------------------*/
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