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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 version 2 as published by the free software foundation 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-only has been chosen to replace the boilerplate/reference in 44 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Steve Winslow <swinslow@gmail.com> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190528170025.980374610@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
154 lines
3.6 KiB
C
154 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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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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#if !defined(_FIR_H_)
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#define _FIR_H_
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/*
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Ideas for improvement:
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1/ Rewrite filter for dual MAC inner loop. The issue here is handling
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history sample offsets that are 16 bit aligned - the dual MAC needs
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32 bit aligmnent. There are some good examples in libbfdsp.
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2/ Use the hardware circular buffer facility tohalve memory usage.
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3/ Consider using internal memory.
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Using less memory might also improve speed as cache misses will be
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reduced. A drop in MIPs and memory approaching 50% should be
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possible.
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The foreground and background filters currenlty use a total of
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about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
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can.
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*/
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/*
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* 16 bit integer FIR descriptor. This defines the working state for a single
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* instance of an FIR filter using 16 bit integer coefficients.
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*/
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struct fir16_state_t {
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int taps;
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int curr_pos;
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const int16_t *coeffs;
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int16_t *history;
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};
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/*
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* 32 bit integer FIR descriptor. This defines the working state for a single
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* instance of an FIR filter using 32 bit integer coefficients, and filtering
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* 16 bit integer data.
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*/
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struct fir32_state_t {
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int taps;
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int curr_pos;
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const int32_t *coeffs;
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int16_t *history;
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};
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/*
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* Floating point FIR descriptor. This defines the working state for a single
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* instance of an FIR filter using floating point coefficients and data.
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*/
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struct fir_float_state_t {
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int taps;
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int curr_pos;
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const float *coeffs;
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float *history;
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};
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static inline const int16_t *fir16_create(struct fir16_state_t *fir,
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const int16_t *coeffs, 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 = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
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return fir->history;
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}
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static inline void fir16_flush(struct fir16_state_t *fir)
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{
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memset(fir->history, 0, fir->taps * sizeof(int16_t));
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}
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static inline void fir16_free(struct fir16_state_t *fir)
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{
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kfree(fir->history);
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}
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static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample)
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{
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int32_t y;
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int i;
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int offset1;
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int offset2;
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fir->history[fir->curr_pos] = sample;
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offset2 = fir->curr_pos;
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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 (int16_t) (y >> 15);
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}
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static inline const int16_t *fir32_create(struct fir32_state_t *fir,
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const int32_t *coeffs, 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 = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
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return fir->history;
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}
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static inline void fir32_flush(struct fir32_state_t *fir)
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{
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memset(fir->history, 0, fir->taps * sizeof(int16_t));
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}
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static inline void fir32_free(struct fir32_state_t *fir)
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{
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kfree(fir->history);
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}
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static inline int16_t fir32(struct fir32_state_t *fir, int16_t sample)
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{
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int i;
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int32_t y;
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int offset1;
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int offset2;
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fir->history[fir->curr_pos] = sample;
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offset2 = fir->curr_pos;
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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 (int16_t) (y >> 15);
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}
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#endif
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