61 lines
1.6 KiB
C
61 lines
1.6 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* biquad.h - General telephony bi-quad section routines (currently this just
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* handles canonic/type 2 form)
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2001 Steve Underwood
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*
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* All rights reserved.
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*
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*/
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/*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2 as published by the
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* Free Software Foundation. See the LICENSE file included with
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* this program for more details.
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*/
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static inline void biquad2_init (biquad2_state_t *bq,
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int32_t gain,
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int32_t a1,
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int32_t a2,
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int32_t b1,
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int32_t b2)
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{
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bq->gain = gain;
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bq->a1 = a1;
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bq->a2 = a2;
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bq->b1 = b1;
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bq->b2 = b2;
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bq->z1 = 0;
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bq->z2 = 0;
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}
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/*- End of function --------------------------------------------------------*/
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static inline int16_t biquad2 (biquad2_state_t *bq, int16_t sample)
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{
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int32_t y;
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int32_t z0;
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z0 = sample*bq->gain + bq->z1*bq->a1 + bq->z2*bq->a2;
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y = z0 + bq->z1*bq->b1 + bq->z2*bq->b2;
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bq->z2 = bq->z1;
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bq->z1 = z0 >> 15;
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y >>= 15;
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return y;
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}
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/*- End of function --------------------------------------------------------*/
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/*- End of file ------------------------------------------------------------*/
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