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Reformat rational interpolator code

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f4exb 2018-12-09 22:11:39 +01:00
parent c546e40191
commit f2e3059099
2 changed files with 96 additions and 38 deletions
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90
sdrbase/dsp/interpolator.cpp
View File

@ -28,31 +28,43 @@ void Interpolator::createPolyphaseLowPass(
{
int ntaps = (int)(nbTapsPerPhase * phaseSteps);
qDebug("Interpolator::createPolyphaseLowPass: ntaps: %d", ntaps);
if((ntaps % 2) != 0)
ntaps++;
if ((ntaps % 2) != 0) {
ntaps++;
}
ntaps *= phaseSteps;
taps.resize(ntaps);
std::vector<float> window(ntaps);
for(int n = 0; n < ntaps; n++)
window[n] = 0.54 - 0.46 * cos ((2 * M_PI * n) / (ntaps - 1));
for (int n = 0; n < ntaps; n++) {
window[n] = 0.54 - 0.46 * cos ((2 * M_PI * n) / (ntaps - 1));
}
int M = (ntaps - 1) / 2;
double fwT0 = 2 * M_PI * cutoffFreqHz / sampleRateHz;
for(int n = -M; n <= M; n++) {
if(n == 0) taps[n + M] = fwT0 / M_PI * window[n + M];
else taps[n + M] = sin (n * fwT0) / (n * M_PI) * window[n + M];
for (int n = -M; n <= M; n++)
{
if (n == 0) {
taps[n + M] = fwT0 / M_PI * window[n + M];
} else {
taps[n + M] = sin (n * fwT0) / (n * M_PI) * window[n + M];
}
}
double max = taps[0 + M];
for(int n = 1; n <= M; n++)
max += 2.0 * taps[n + M];
for (int n = 1; n <= M; n++) {
max += 2.0 * taps[n + M];
}
gain /= max;
for(int i = 0; i < ntaps; i++)
taps[i] *= gain;
for (int i = 0; i < ntaps; i++) {
taps[i] *= gain;
}
}
Interpolator::Interpolator() :
@ -90,39 +102,60 @@ void Interpolator::create(int phaseSteps, double sampleRate, double cutoff, doub
m_nTaps = taps.size() / phaseSteps;
m_phaseSteps = phaseSteps;
m_samples.resize(m_nTaps + 2);
for(int i = 0; i < m_nTaps + 2; i++)
m_samples[i] = 0;
for (int i = 0; i < m_nTaps + 2; i++) {
m_samples[i] = 0;
}
// reorder into polyphase
std::vector<Real> polyphase(taps.size());
for(int phase = 0; phase < phaseSteps; phase++) {
for(int i = 0; i < m_nTaps; i++)
polyphase[phase * m_nTaps + i] = taps[i * phaseSteps + phase];
for (int phase = 0; phase < phaseSteps; phase++)
{
for (int i = 0; i < m_nTaps; i++) {
polyphase[phase * m_nTaps + i] = taps[i * phaseSteps + phase];
}
}
// normalize phase filters
for(int phase = 0; phase < phaseSteps; phase++) {
for (int phase = 0; phase < phaseSteps; phase++)
{
Real sum = 0;
for(int i = phase * m_nTaps; i < phase * m_nTaps + m_nTaps; i++)
sum += polyphase[i];
for(int i = phase * m_nTaps; i < phase * m_nTaps + m_nTaps; i++)
polyphase[i] /= sum;
for (int i = phase * m_nTaps; i < phase * m_nTaps + m_nTaps; i++) {
sum += polyphase[i];
}
for (int i = phase * m_nTaps; i < phase * m_nTaps + m_nTaps; i++) {
polyphase[i] /= sum;
}
}
// move taps around to match sse storage requirements
m_taps = new float[2 * taps.size() + 8];
for(uint i = 0; i < 2 * taps.size() + 8; ++i)
m_taps[i] = 0;
for (uint i = 0; i < 2 * taps.size() + 8; ++i) {
m_taps[i] = 0;
}
m_alignedTaps = (float*)((((quint64)m_taps) + 15) & ~15);
for(uint i = 0; i < taps.size(); ++i) {
for (uint i = 0; i < taps.size(); ++i)
{
m_alignedTaps[2 * i + 0] = polyphase[i];
m_alignedTaps[2 * i + 1] = polyphase[i];
}
m_taps2 = new float[2 * taps.size() + 8];
for(uint i = 0; i < 2 * taps.size() + 8; ++i)
m_taps2[i] = 0;
for (uint i = 0; i < 2 * taps.size() + 8; ++i) {
m_taps2[i] = 0;
}
m_alignedTaps2 = (float*)((((quint64)m_taps2) + 15) & ~15);
for(uint i = 1; i < taps.size(); ++i) {
for (uint i = 1; i < taps.size(); ++i)
{
m_alignedTaps2[2 * (i - 1) + 0] = polyphase[i];
m_alignedTaps2[2 * (i - 1) + 1] = polyphase[i];
}
@ -130,7 +163,8 @@ void Interpolator::create(int phaseSteps, double sampleRate, double cutoff, doub
void Interpolator::free()
{
if(m_taps != NULL) {
if (m_taps != NULL)
{
delete[] m_taps;
m_taps = NULL;
m_alignedTaps = NULL;

44
sdrbase/dsp/interpolator.h
View File

@ -1,3 +1,19 @@
///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015 Edouard Griffiths, F4EXB. //
// //
// 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 as version 3 of the License, or //
// //
// 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 V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#ifndef INCLUDE_INTERPOLATOR_H
#define INCLUDE_INTERPOLATOR_H
@ -17,13 +33,13 @@ public:
void free();
// Original code allowed for upsampling, but was never used that way
// The decimation factor should always be lower than 2 for proper work
bool decimate(Real *distance, const Complex& next, Complex* result)
{
advanceFilter(next);
*distance -= 1.0;
if (*distance >= 1.0)
{
if (*distance >= 1.0) {
return false;
}
@ -53,9 +69,9 @@ public:
// sampling frequency must be the highest of the two
bool resample(Real* distance, const Complex& next, bool* consumed, Complex* result)
{
while(*distance >= 1.0)
while (*distance >= 1.0)
{
if(!(*consumed))
if (!(*consumed))
{
advanceFilter(next);
*distance -= 1.0;
@ -104,24 +120,31 @@ private:
void advanceFilter(const Complex& next)
{
m_ptr--;
if(m_ptr < 0)
m_ptr = m_nTaps - 1;
if (m_ptr < 0) {
m_ptr = m_nTaps - 1;
}
m_samples[m_ptr] = next;
}
void advanceFilter()
{
m_ptr--;
if(m_ptr < 0)
if (m_ptr < 0) {
m_ptr = m_nTaps - 1;
}
m_samples[m_ptr].real(0.0);
m_samples[m_ptr].imag(0.0);
}
void doInterpolate(int phase, Complex* result)
{
if (phase < 0)
phase = 0;
if (phase < 0) {
phase = 0;
}
#if USE_SSE2
// beware of the ringbuffer
if(m_ptr == 0) {
@ -182,12 +205,13 @@ private:
Real rAcc = 0;
Real iAcc = 0;
for(int i = 0; i < m_nTaps; i++) {
for (int i = 0; i < m_nTaps; i++) {
rAcc += *coeff * m_samples[sample].real();
iAcc += *coeff * m_samples[sample].imag();
sample = (sample + 1) % m_nTaps;
coeff += 2;
}
*result = Complex(rAcc, iAcc);
#endif