mirror of
https://git.vladimir.cc/vladimir/wdsp.git
synced 2026-08-25 17:27:33 +00:00
Uladzimir KarpenkaandClaude Opus 4.8
9960a1d0e3
The tap loop wrapped the ring with a test on every tap:
if ((idx_out = idx_in + j) >= ringsize) idx_out -= ringsize;
which made the address non-affine and stopped the vectorizer. Split the
walk at the wrap point instead, so both halves are unit-stride, and split
the complex ring into separate I/Q arrays so the taps load contiguously
rather than through a de-interleaving ld2.
The dot product also could not be vectorized as written: reassociating an
fp reduction needs -ffast-math, which this library must not enable (it
relies on IEEE semantics for 0/0 = NaN and x/0 = Inf, see linux_port.h).
Carry four independent accumulator pairs instead, which both breaks the
FMA dependency chain and lets the vectorizer in on any compiler.
Measured on an Apple M1 Pro, 512-sample DSP buffers, best of 5:
xresample, decimation to 48 kHz before after speedup
192k -> 48k (561 taps) 342.0 us 84.2 us 4.06x
384k -> 48k (1121 taps) 708.9 us 175.1 us 4.05x
576k -> 48k (1681 taps) 1074.4 us 266.9 us 4.03x
768k -> 48k (2241 taps) 1438.9 us 360.0 us 4.00x
full xrxa() chain, 576k input 1148.2 us 337.6 us 3.40x
10.76% 3.16% of one core
xresampleF (float, host audio) 2.6x - 3.4x
Summation order changes, so the double path is not bit-identical: over
400 buffers of the full RX chain the worst deviation is 1.1e-12, an SNR
of 251 dB. The float path is bit-identical, as the cast to float absorbs
the difference. With the resampler bypassed (48k in, 48k out) the chain
is unchanged bit-for-bit.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
123 lines
3.8 KiB
C
123 lines
3.8 KiB
C
/* resample.h
|
|
|
|
This file is part of a program that implements a Software-Defined Radio.
|
|
|
|
Copyright (C) 2013 Warren Pratt, NR0V
|
|
|
|
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
|
|
The author can be reached by email at
|
|
|
|
warren@wpratt.com
|
|
|
|
*/
|
|
|
|
/************************************************************************************************
|
|
* *
|
|
* VERSION FOR COMPLEX DOUBLE-PRECISION *
|
|
* *
|
|
************************************************************************************************/
|
|
|
|
#ifndef _resample_h
|
|
#define _resample_h
|
|
|
|
typedef struct _resample
|
|
{
|
|
int run; // run
|
|
int size; // number of input samples per buffer
|
|
double* in; // input buffer for resampler
|
|
double* out; // output buffer for resampler
|
|
int in_rate;
|
|
int out_rate;
|
|
double fcin;
|
|
double fc;
|
|
double fc_low;
|
|
double gain;
|
|
int idx_in; // index for input into ring
|
|
int ncoefin;
|
|
int ncoef; // number of coefficients
|
|
int L; // interpolation factor
|
|
int M; // decimation factor
|
|
double* h; // coefficients
|
|
int ringsize; // number of complex pairs the ring buffer holds
|
|
double* ringI; // ring buffer, in-phase
|
|
double* ringQ; // ring buffer, quadrature (split from I so the tap loop
|
|
// reads unit-stride and vectorizes)
|
|
int cpp; // coefficients of the phase
|
|
int phnum; // phase number
|
|
} resample, *RESAMPLE;
|
|
|
|
__declspec (dllexport)
|
|
RESAMPLE create_resample (int run, int size, double* in, double* out, int in_rate, int out_rate, double fc, int ncoef, double gain);
|
|
|
|
__declspec (dllexport)
|
|
void destroy_resample (RESAMPLE a);
|
|
|
|
__declspec (dllexport)
|
|
void flush_resample (RESAMPLE a);
|
|
|
|
__declspec (dllexport)
|
|
int xresample (RESAMPLE a);
|
|
|
|
extern void setBuffers_resample (RESAMPLE a, double* in, double* out);
|
|
|
|
extern void setSize_resample(RESAMPLE a, int size);
|
|
|
|
extern void setInRate_resample(RESAMPLE a, int rate);
|
|
|
|
extern void setOutRate_resample(RESAMPLE a, int rate);
|
|
|
|
extern void setFCLow_resample (RESAMPLE a, double fc_low);
|
|
|
|
extern void setBandwidth_resample (RESAMPLE a, double fc_low, double fc_high);
|
|
|
|
#endif
|
|
|
|
/************************************************************************************************
|
|
* *
|
|
* VERSION FOR NON-COMPLEX FLOATS *
|
|
* *
|
|
************************************************************************************************/
|
|
|
|
#ifndef _resampleF_h
|
|
#define _resampleF_h
|
|
|
|
typedef struct _resampleF
|
|
{
|
|
int run; // run
|
|
int size; // number of input samples per buffer
|
|
float* in; // input buffer for resampler
|
|
float* out; // output buffer for resampler
|
|
int idx_in; // index for input into ring
|
|
int ncoef; // number of coefficients
|
|
int L; // interpolation factor
|
|
int M; // decimation factor
|
|
double* h; // coefficients
|
|
int ringsize; // number of values the ring buffer holds
|
|
double* ring; // ring buffer
|
|
int cpp; // coefficients of the phase
|
|
int phnum; // phase number
|
|
} resampleF, *RESAMPLEF;
|
|
|
|
extern RESAMPLEF create_resampleF (int run, int size, float* in, float* out, int in_rate, int out_rate);
|
|
|
|
extern void destroy_resampleF (RESAMPLEF a);
|
|
|
|
extern void flush_resampleF (RESAMPLEF a);
|
|
|
|
extern int xresampleF (RESAMPLEF a);
|
|
|
|
#endif
|