mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-25 01:18:38 -05:00
256 lines
8.3 KiB
C++
256 lines
8.3 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2018 F4EXB //
|
|
// written by Edouard Griffiths //
|
|
// //
|
|
// Integer half-band FIR based interpolator and decimator //
|
|
// This is the even/odd double buffer variant. Really useful only when SIMD is //
|
|
// used //
|
|
// //
|
|
// 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 //
|
|
// (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 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 SDRBASE_DSP_INTHALFBANDFILTEREOF_H_
|
|
#define SDRBASE_DSP_INTHALFBANDFILTEREOF_H_
|
|
|
|
#include <stdint.h>
|
|
#include <cstdlib>
|
|
#include "dsp/dsptypes.h"
|
|
#include "dsp/hbfiltertraits.h"
|
|
#include "export.h"
|
|
|
|
template<uint32_t HBFilterOrder, bool IQOrder>
|
|
class IntHalfbandFilterEOF {
|
|
public:
|
|
IntHalfbandFilterEOF();
|
|
|
|
bool workDecimateCenter(float *x, float *y)
|
|
{
|
|
// insert sample into ring-buffer
|
|
storeSample(*x, *y);
|
|
|
|
switch(m_state)
|
|
{
|
|
case 0:
|
|
// advance write-pointer
|
|
advancePointer();
|
|
// next state
|
|
m_state = 1;
|
|
// tell caller we don't have a new sample
|
|
return false;
|
|
|
|
default:
|
|
// save result
|
|
doFIR(x, y);
|
|
// advance write-pointer
|
|
advancePointer();
|
|
// next state
|
|
m_state = 0;
|
|
// tell caller we have a new sample
|
|
return true;
|
|
}
|
|
}
|
|
|
|
void myDecimate(float x1, float y1, float *x2, float *y2)
|
|
{
|
|
storeSample(x1, y1);
|
|
advancePointer();
|
|
|
|
storeSample(*x2, *y2);
|
|
doFIR(x2, y2);
|
|
advancePointer();
|
|
}
|
|
|
|
/** Simple zero stuffing and filter */
|
|
void myInterpolateZeroStuffing(float *x1, float *y1, float *x2, float *y2)
|
|
{
|
|
storeSample(*x1, *y1);
|
|
doFIR(x1, y1);
|
|
advancePointer();
|
|
|
|
storeSample(0, 0);
|
|
doFIR(x2, y2);
|
|
advancePointer();
|
|
}
|
|
|
|
/** Optimized upsampler by 2 not calculating FIR with inserted null samples */
|
|
void myInterpolate(float *x1, float *y1, float *x2, float *y2)
|
|
{
|
|
// insert sample into ring double buffer
|
|
m_samples[m_ptr][0] = *x1;
|
|
m_samples[m_ptr][1] = *y1;
|
|
m_samples[m_ptr + HBFIRFilterTraits<HBFilterOrder>::hbOrder/2][0] = *x1;
|
|
m_samples[m_ptr + HBFIRFilterTraits<HBFilterOrder>::hbOrder/2][1] = *y1;
|
|
|
|
// advance pointer
|
|
if (m_ptr < (HBFIRFilterTraits<HBFilterOrder>::hbOrder/2) - 1) {
|
|
m_ptr++;
|
|
} else {
|
|
m_ptr = 0;
|
|
}
|
|
|
|
// first output sample calculated with the middle peak
|
|
*x1 = m_samples[m_ptr + (HBFIRFilterTraits<HBFilterOrder>::hbOrder/4) - 1][0];
|
|
*y1 = m_samples[m_ptr + (HBFIRFilterTraits<HBFilterOrder>::hbOrder/4) - 1][1];
|
|
|
|
// second sample calculated with the filter
|
|
doInterpolateFIR(x2, y2);
|
|
}
|
|
|
|
void myInterpolateInf(float *x1, float *y1, float *x2, float *y2, float *x3, float *y3, float *x4, float *y4)
|
|
{
|
|
myInterpolate(x1, y1, x2, y2);
|
|
myInterpolate(x3, y3, x4, y4);
|
|
// rotation
|
|
qint32 x;
|
|
x = *x1;
|
|
*x1 = *y1;
|
|
*y1 = -x;
|
|
*x2 = -*x2;
|
|
*y2 = -*y2;
|
|
x = *x3;
|
|
*x3 = -*y3;
|
|
*y3 = x;
|
|
}
|
|
|
|
void myInterpolateSup(float *x1, float *y1, float *x2, float *y2, float *x3, float *y3, float *x4, float *y4)
|
|
{
|
|
myInterpolate(x1, y1, x2, y2);
|
|
myInterpolate(x3, y3, x4, y4);
|
|
// rotation
|
|
qint32 x;
|
|
x = *x1;
|
|
*x1 = -*y1;
|
|
*y1 = x;
|
|
*x2 = -*x2;
|
|
*y2 = -*y2;
|
|
x = *x3;
|
|
*x3 = *y3;
|
|
*y3 = -x;
|
|
}
|
|
|
|
protected:
|
|
float m_even[2][HBFIRFilterTraits<HBFilterOrder>::hbOrder]; // double buffer technique
|
|
float m_odd[2][HBFIRFilterTraits<HBFilterOrder>::hbOrder]; // double buffer technique
|
|
float m_samples[HBFIRFilterTraits<HBFilterOrder>::hbOrder][2]; // double buffer technique
|
|
|
|
int m_ptr;
|
|
int m_size;
|
|
int m_state;
|
|
|
|
void storeSample(float x, float y)
|
|
{
|
|
if ((m_ptr % 2) == 0)
|
|
{
|
|
m_even[0][m_ptr/2] = IQOrder ? x : y;
|
|
m_even[1][m_ptr/2] = IQOrder ? y : x;
|
|
m_even[0][m_ptr/2 + m_size] = IQOrder ? x : y;
|
|
m_even[1][m_ptr/2 + m_size] = IQOrder ? y : x;
|
|
}
|
|
else
|
|
{
|
|
m_odd[0][m_ptr/2] = IQOrder ? x : y;
|
|
m_odd[1][m_ptr/2] = IQOrder ? y : x;
|
|
m_odd[0][m_ptr/2 + m_size] = IQOrder ? x : y;
|
|
m_odd[1][m_ptr/2 + m_size] = IQOrder ? y : x;
|
|
}
|
|
}
|
|
|
|
void advancePointer()
|
|
{
|
|
m_ptr = m_ptr + 1 < 2*m_size ? m_ptr + 1: 0;
|
|
}
|
|
|
|
void doFIR(float *x, float *y)
|
|
{
|
|
float iAcc = 0;
|
|
float qAcc = 0;
|
|
|
|
int a = m_ptr/2 + m_size; // tip pointer
|
|
int b = m_ptr/2 + 1; // tail pointer
|
|
|
|
for (int i = 0; i < HBFIRFilterTraits<HBFilterOrder>::hbOrder / 4; i++)
|
|
{
|
|
if ((m_ptr % 2) == 0)
|
|
{
|
|
iAcc += (m_even[0][a] + m_even[0][b]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
qAcc += (m_even[1][a] + m_even[1][b]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
}
|
|
else
|
|
{
|
|
iAcc += (m_odd[0][a] + m_odd[0][b]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
qAcc += (m_odd[1][a] + m_odd[1][b]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
}
|
|
|
|
a -= 1;
|
|
b += 1;
|
|
}
|
|
|
|
if ((m_ptr % 2) == 0)
|
|
{
|
|
iAcc += m_odd[0][m_ptr/2 + m_size/2] * 0.5f;
|
|
qAcc += m_odd[1][m_ptr/2 + m_size/2] * 0.5f;
|
|
}
|
|
else
|
|
{
|
|
iAcc += m_even[0][m_ptr/2 + m_size/2 + 1] * 0.5f;
|
|
qAcc += m_even[1][m_ptr/2 + m_size/2 + 1] * 0.5f;
|
|
}
|
|
|
|
*x = iAcc; // HB_SHIFT incorrect do not loose the gained bit
|
|
*y = qAcc;
|
|
}
|
|
|
|
void doInterpolateFIR(float *x, float *y)
|
|
{
|
|
qint32 iAcc = 0;
|
|
qint32 qAcc = 0;
|
|
|
|
qint16 a = m_ptr;
|
|
qint16 b = m_ptr + (HBFIRFilterTraits<HBFilterOrder>::hbOrder / 2) - 1;
|
|
|
|
// go through samples in buffer
|
|
for (int i = 0; i < HBFIRFilterTraits<HBFilterOrder>::hbOrder / 4; i++)
|
|
{
|
|
iAcc += (m_samples[a][0] + m_samples[b][0]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
qAcc += (m_samples[a][1] + m_samples[b][1]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffsF[i];
|
|
a++;
|
|
b--;
|
|
}
|
|
|
|
*x = iAcc * SDR_RX_SCALED;
|
|
*y = qAcc * SDR_RX_SCALED;
|
|
}
|
|
};
|
|
|
|
template<uint32_t HBFilterOrder, bool IQOrder>
|
|
IntHalfbandFilterEOF<HBFilterOrder, IQOrder>::IntHalfbandFilterEOF()
|
|
{
|
|
m_size = HBFIRFilterTraits<HBFilterOrder>::hbOrder/2;
|
|
|
|
for (int i = 0; i < 2*m_size; i++)
|
|
{
|
|
m_even[0][i] = 0.0f;
|
|
m_even[1][i] = 0.0f;
|
|
m_odd[0][i] = 0.0f;
|
|
m_odd[1][i] = 0.0f;
|
|
m_samples[i][0] = 0.0f;
|
|
m_samples[i][1] = 0.0f;
|
|
}
|
|
|
|
m_ptr = 0;
|
|
m_state = 0;
|
|
}
|
|
|
|
#endif /* SDRBASE_DSP_INTHALFBANDFILTEREOF_H_ */
|