diff options
author | markster <markster@5390a7c7-147a-4af0-8ec9-7488f05a26cb> | 2002-03-18 21:33:06 +0000 |
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committer | markster <markster@5390a7c7-147a-4af0-8ec9-7488f05a26cb> | 2002-03-18 21:33:06 +0000 |
commit | 61a5fa55ab854e07d02da2b214561a797b821a44 (patch) | |
tree | 6cac6f1b14ad62b3a3eb7471a7ca3f4ee366d4e5 | |
parent | cc758a980dca142a3cba4a1b24ca77c8e7b8f31f (diff) |
Version 0.2.0 from FTP
git-svn-id: http://svn.digium.com/svn/zaptel/trunk@69 5390a7c7-147a-4af0-8ec9-7488f05a26cb
-rwxr-xr-x | fir.h | 130 |
1 files changed, 130 insertions, 0 deletions
@@ -0,0 +1,130 @@ +/* + * SpanDSP - a series of DSP components for telephony + * + * fir.h - General telephony FIR routines + * + * Written by Steve Underwood <steveu@coppice.org> + * + * Copyright (C) 2002 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. + * + */ + +#if !defined(_FIR_H_) +#define _FIR_H_ + +typedef struct +{ + int taps; + int curr_pos; + int16_t *coeffs; + int16_t *history; +} fir16_state_t; + +typedef struct +{ + int taps; + int curr_pos; + int32_t *coeffs; + int16_t *history; +} fir32_state_t; + +static inline void fir16_create (fir16_state_t *fir, + int16_t *coeffs, + int taps) +{ + fir->taps = taps; + fir->curr_pos = taps - 1; + fir->coeffs = coeffs; + fir->history = MALLOC (taps*sizeof (int16_t)); + if (fir->history) + memset (fir->history, '\0', taps*sizeof (int16_t)); +} +/*- End of function --------------------------------------------------------*/ + +static inline void fir16_free (fir16_state_t *fir) +{ + FREE (fir->history); +} +/*- End of function --------------------------------------------------------*/ + +static inline int16_t fir16 (fir16_state_t *fir, int16_t sample) +{ + int i; + int offset1; + int offset2; + int32_t y; + + fir->history[fir->curr_pos] = sample; + offset2 = fir->curr_pos + 1; + offset1 = fir->taps - offset2; + y = 0; + for (i = fir->taps - 1; i >= offset1; i--) + y += fir->coeffs[i]*fir->history[i - offset1]; + for ( ; i >= 0; i--) + y += fir->coeffs[i]*fir->history[i + offset2]; + if (fir->curr_pos <= 0) + fir->curr_pos = fir->taps; + fir->curr_pos--; + return y >> 15; +} +/*- End of function --------------------------------------------------------*/ + +static inline void fir32_create (fir32_state_t *fir, + int32_t *coeffs, + int taps) +{ + fir->taps = taps; + fir->curr_pos = taps - 1; + fir->coeffs = coeffs; + fir->history = MALLOC (taps*sizeof (int16_t)); + if (fir->history) + memset (fir->history, '\0', taps*sizeof (int16_t)); +} +/*- End of function --------------------------------------------------------*/ + +static inline void fir32_free (fir32_state_t *fir) +{ + FREE (fir->history); +} +/*- End of function --------------------------------------------------------*/ + +static inline int16_t fir32 (fir32_state_t *fir, int16_t sample) +{ + int i; + int offset1; + int offset2; + int32_t y; + + fir->history[fir->curr_pos] = sample; + offset2 = fir->curr_pos + 1; + offset1 = fir->taps - offset2; + y = 0; + for (i = fir->taps - 1; i >= offset1; i--) + y += fir->coeffs[i]*fir->history[i - offset1]; + for ( ; i >= 0; i--) + y += fir->coeffs[i]*fir->history[i + offset2]; + if (fir->curr_pos <= 0) + fir->curr_pos = fir->taps; + fir->curr_pos--; + return y >> 15; +} +/*- End of function --------------------------------------------------------*/ + +#endif +/*- End of file ------------------------------------------------------------*/ |