linux/drivers/isdn/mISDN/dsp_biquad.h
Thomas Gleixner 74ba9207e1 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 441 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520071858.739733335@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:36:45 +02:00

52 lines
977 B
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* 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.
*/
struct biquad2_state {
int32_t gain;
int32_t a1;
int32_t a2;
int32_t b1;
int32_t b2;
int32_t z1;
int32_t z2;
};
static inline void biquad2_init(struct biquad2_state *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;
}
static inline int16_t biquad2(struct biquad2_state *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;
}