1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3 * SpanDSP - a series of DSP components for telephony
5 * biquad.h - General telephony bi-quad section routines (currently this just
6 * handles canonic/type 2 form)
8 * Written by Steve Underwood <steveu@coppice.org>
10 * Copyright (C) 2001 Steve Underwood
12 * All rights reserved.
15 struct biquad2_state {
26 static inline void biquad2_init(struct biquad2_state *bq,
27 int32_t gain, int32_t a1, int32_t a2, int32_t b1, int32_t b2)
39 static inline int16_t biquad2(struct biquad2_state *bq, int16_t sample)
44 z0 = sample * bq->gain + bq->z1 * bq->a1 + bq->z2 * bq->a2;
45 y = z0 + bq->z1 * bq->b1 + bq->z2 * bq->b2;