mirror of https://gitee.com/openkylin/linux.git
155 lines
3.6 KiB
C
155 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
#if !defined(_FIR_H_)
|
|
#define _FIR_H_
|
|
|
|
/*
|
|
Ideas for improvement:
|
|
|
|
1/ Rewrite filter for dual MAC inner loop. The issue here is handling
|
|
history sample offsets that are 16 bit aligned - the dual MAC needs
|
|
32 bit aligmnent. There are some good examples in libbfdsp.
|
|
|
|
2/ Use the hardware circular buffer facility tohalve memory usage.
|
|
|
|
3/ Consider using internal memory.
|
|
|
|
Using less memory might also improve speed as cache misses will be
|
|
reduced. A drop in MIPs and memory approaching 50% should be
|
|
possible.
|
|
|
|
The foreground and background filters currenlty use a total of
|
|
about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
|
|
can.
|
|
*/
|
|
|
|
/*
|
|
* 16 bit integer FIR descriptor. This defines the working state for a single
|
|
* instance of an FIR filter using 16 bit integer coefficients.
|
|
*/
|
|
struct fir16_state_t {
|
|
int taps;
|
|
int curr_pos;
|
|
const int16_t *coeffs;
|
|
int16_t *history;
|
|
};
|
|
|
|
/*
|
|
* 32 bit integer FIR descriptor. This defines the working state for a single
|
|
* instance of an FIR filter using 32 bit integer coefficients, and filtering
|
|
* 16 bit integer data.
|
|
*/
|
|
struct fir32_state_t {
|
|
int taps;
|
|
int curr_pos;
|
|
const int32_t *coeffs;
|
|
int16_t *history;
|
|
};
|
|
|
|
/*
|
|
* Floating point FIR descriptor. This defines the working state for a single
|
|
* instance of an FIR filter using floating point coefficients and data.
|
|
*/
|
|
struct fir_float_state_t {
|
|
int taps;
|
|
int curr_pos;
|
|
const float *coeffs;
|
|
float *history;
|
|
};
|
|
|
|
static inline const int16_t *fir16_create(struct fir16_state_t *fir,
|
|
const int16_t *coeffs, int taps)
|
|
{
|
|
fir->taps = taps;
|
|
fir->curr_pos = taps - 1;
|
|
fir->coeffs = coeffs;
|
|
fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
|
|
return fir->history;
|
|
}
|
|
|
|
static inline void fir16_flush(struct fir16_state_t *fir)
|
|
{
|
|
memset(fir->history, 0, fir->taps * sizeof(int16_t));
|
|
}
|
|
|
|
static inline void fir16_free(struct fir16_state_t *fir)
|
|
{
|
|
kfree(fir->history);
|
|
}
|
|
|
|
static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample)
|
|
{
|
|
int32_t y;
|
|
int i;
|
|
int offset1;
|
|
int offset2;
|
|
|
|
fir->history[fir->curr_pos] = sample;
|
|
|
|
offset2 = fir->curr_pos;
|
|
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 (int16_t) (y >> 15);
|
|
}
|
|
|
|
static inline const int16_t *fir32_create(struct fir32_state_t *fir,
|
|
const int32_t *coeffs, int taps)
|
|
{
|
|
fir->taps = taps;
|
|
fir->curr_pos = taps - 1;
|
|
fir->coeffs = coeffs;
|
|
fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
|
|
return fir->history;
|
|
}
|
|
|
|
static inline void fir32_flush(struct fir32_state_t *fir)
|
|
{
|
|
memset(fir->history, 0, fir->taps * sizeof(int16_t));
|
|
}
|
|
|
|
static inline void fir32_free(struct fir32_state_t *fir)
|
|
{
|
|
kfree(fir->history);
|
|
}
|
|
|
|
static inline int16_t fir32(struct fir32_state_t *fir, int16_t sample)
|
|
{
|
|
int i;
|
|
int32_t y;
|
|
int offset1;
|
|
int offset2;
|
|
|
|
fir->history[fir->curr_pos] = sample;
|
|
offset2 = fir->curr_pos;
|
|
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 (int16_t) (y >> 15);
|
|
}
|
|
|
|
#endif
|