130 lines
3.4 KiB
C
130 lines
3.4 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* fir.h - General telephony FIR routines
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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) 2002 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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#if !defined(_FIR_H_)
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#define _FIR_H_
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typedef struct
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{
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int taps;
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int curr_pos;
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int16_t *coeffs;
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int16_t *history;
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} fir16_state_t;
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typedef struct
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{
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int taps;
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int curr_pos;
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int32_t *coeffs;
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int16_t *history;
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} fir32_state_t;
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static inline void fir16_create (fir16_state_t *fir,
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int16_t *coeffs,
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int taps)
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{
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fir->taps = taps;
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fir->curr_pos = taps - 1;
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fir->coeffs = coeffs;
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fir->history = kmalloc(taps*sizeof (int16_t), GFP_KERNEL);
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if (fir->history)
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memset (fir->history, '\0', taps*sizeof (int16_t));
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}
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/*- End of function --------------------------------------------------------*/
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static inline void fir16_free (fir16_state_t *fir)
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{
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kfree(fir->history);
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}
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/*- End of function --------------------------------------------------------*/
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static inline int16_t fir16 (fir16_state_t *fir, int16_t sample)
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{
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int i;
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int offset1;
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int offset2;
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int32_t y;
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fir->history[fir->curr_pos] = sample;
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offset2 = fir->curr_pos + 1;
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offset1 = fir->taps - offset2;
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y = 0;
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for (i = fir->taps - 1; i >= offset1; i--)
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y += fir->coeffs[i]*fir->history[i - offset1];
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for ( ; i >= 0; i--)
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y += fir->coeffs[i]*fir->history[i + offset2];
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if (fir->curr_pos <= 0)
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fir->curr_pos = fir->taps;
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fir->curr_pos--;
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return y >> 15;
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}
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/*- End of function --------------------------------------------------------*/
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static inline void fir32_create (fir32_state_t *fir,
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int32_t *coeffs,
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int taps)
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{
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fir->taps = taps;
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fir->curr_pos = taps - 1;
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fir->coeffs = coeffs;
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fir->history = kmalloc(taps*sizeof (int16_t), GFP_KERNEL);
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if (fir->history)
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memset (fir->history, '\0', taps*sizeof (int16_t));
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}
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/*- End of function --------------------------------------------------------*/
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static inline void fir32_free (fir32_state_t *fir)
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{
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kfree(fir->history);
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}
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/*- End of function --------------------------------------------------------*/
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static inline int16_t fir32 (fir32_state_t *fir, int16_t sample)
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{
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int i;
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int offset1;
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int offset2;
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int32_t y;
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fir->history[fir->curr_pos] = sample;
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offset2 = fir->curr_pos + 1;
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offset1 = fir->taps - offset2;
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y = 0;
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for (i = fir->taps - 1; i >= offset1; i--)
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y += fir->coeffs[i]*fir->history[i - offset1];
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for ( ; i >= 0; i--)
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y += fir->coeffs[i]*fir->history[i + offset2];
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if (fir->curr_pos <= 0)
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fir->curr_pos = fir->taps;
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fir->curr_pos--;
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return y >> 15;
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}
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/*- End of function --------------------------------------------------------*/
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#endif
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/*- End of file ------------------------------------------------------------*/
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