diff options
author | Kevin P. Fleming <kpfleming@digium.com> | 2008-05-21 15:11:48 +0000 |
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committer | Kevin P. Fleming <kpfleming@digium.com> | 2008-05-21 15:11:48 +0000 |
commit | 802b567e6c7ba7803a950324cbed13f7d57944cb (patch) | |
tree | 6b90ca3119aaa2e4073d3b651ac965dea5d3430e /drivers/dahdi/biquad.h | |
parent | ec5ce88e015b41c2f46f6c9b783339b945f9502a (diff) |
start copying kernel bits
git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@4315 a0bf4364-ded3-4de4-8d8a-66a801d63aff
Diffstat (limited to 'drivers/dahdi/biquad.h')
-rw-r--r-- | drivers/dahdi/biquad.h | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/dahdi/biquad.h b/drivers/dahdi/biquad.h new file mode 100644 index 0000000..58458a9 --- /dev/null +++ b/drivers/dahdi/biquad.h @@ -0,0 +1,73 @@ +/* + * 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. + * + * 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. + * + */ + +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 ------------------------------------------------------------*/ |