mirror of
https://github.com/f4exb/sdrangel.git
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493 lines
14 KiB
C++
493 lines
14 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2016 F4EXB //
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// written by Edouard Griffiths //
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// //
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// Integer half-band FIR based interpolator and decimator //
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// This is the double buffer variant //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation as version 3 of the License, or //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License V3 for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with this program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#ifndef INCLUDE_INTHALFBANDFILTER_DB_H
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#define INCLUDE_INTHALFBANDFILTER_DB_H
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#include <stdint.h>
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#include "dsp/dsptypes.h"
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#include "dsp/hbfiltertraits.h"
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#include "util/export.h"
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template<uint32_t HBFilterOrder>
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class SDRANGEL_API IntHalfbandFilterDB {
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public:
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IntHalfbandFilterDB();
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// downsample by 2, return center part of original spectrum
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bool workDecimateCenter(Sample* sample)
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{
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// insert sample into ring-buffer
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storeSample((FixReal) sample->real(), (FixReal) sample->imag());
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switch(m_state)
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{
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case 0:
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we don't have a new sample
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return false;
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default:
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// save result
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doFIR(sample);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we have a new sample
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return true;
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}
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}
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// upsample by 2, return center part of original spectrum - double buffer variant
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bool workInterpolateCenter(Sample* sampleIn, Sample *SampleOut)
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{
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switch(m_state)
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{
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case 0:
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// insert sample into ring-buffer
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storeSample(0, 0);
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// save result
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doFIR(SampleOut);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we didn't consume the sample
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return false;
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default:
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// insert sample into ring-buffer
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storeSample((FixReal) sampleIn->real(), (FixReal) sampleIn->imag());
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// save result
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doFIR(SampleOut);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we consumed the sample
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return true;
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}
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}
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bool workDecimateCenter(qint32 *x, qint32 *y)
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{
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// insert sample into ring-buffer
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storeSample(*x, *y);
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switch(m_state)
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{
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case 0:
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we don't have a new sample
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return false;
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default:
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// save result
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doFIR(x, y);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we have a new sample
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return true;
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}
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}
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// downsample by 2, return lower half of original spectrum
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bool workDecimateLowerHalf(Sample* sample)
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{
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switch(m_state)
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{
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case 0:
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// insert sample into ring-buffer
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storeSample((FixReal) -sample->imag(), (FixReal) sample->real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we don't have a new sample
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return false;
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case 1:
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// insert sample into ring-buffer
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storeSample((FixReal) -sample->real(), (FixReal) -sample->imag());
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// save result
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doFIR(sample);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 2;
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// tell caller we have a new sample
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return true;
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case 2:
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// insert sample into ring-buffer
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storeSample((FixReal) sample->imag(), (FixReal) -sample->real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 3;
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// tell caller we don't have a new sample
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return false;
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default:
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// insert sample into ring-buffer
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storeSample((FixReal) sample->real(), (FixReal) sample->imag());
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// save result
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doFIR(sample);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we have a new sample
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return true;
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}
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}
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// upsample by 2, from lower half of original spectrum - double buffer variant
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bool workInterpolateLowerHalf(Sample* sampleIn, Sample *sampleOut)
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{
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Sample s;
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switch(m_state)
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{
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case 0:
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// insert sample into ring-buffer
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storeSample(0, 0);
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// save result
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doFIR(&s);
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sampleOut->setReal(s.imag());
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sampleOut->setImag(-s.real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we didn't consume the sample
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return false;
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case 1:
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// insert sample into ring-buffer
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storeSample((FixReal) sampleIn->real(), (FixReal) sampleIn->imag());
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// save result
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doFIR(&s);
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sampleOut->setReal(-s.real());
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sampleOut->setImag(-s.imag());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 2;
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// tell caller we consumed the sample
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return true;
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case 2:
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// insert sample into ring-buffer
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storeSample(0, 0);
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// save result
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doFIR(&s);
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sampleOut->setReal(-s.imag());
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sampleOut->setImag(s.real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 3;
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// tell caller we didn't consume the sample
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return false;
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default:
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// insert sample into ring-buffer
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storeSample((FixReal) sampleIn->real(), (FixReal) sampleIn->imag());
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// save result
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doFIR(&s);
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sampleOut->setReal(s.real());
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sampleOut->setImag(s.imag());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we consumed the sample
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return true;
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}
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}
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// downsample by 2, return upper half of original spectrum
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bool workDecimateUpperHalf(Sample* sample)
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{
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switch(m_state)
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{
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case 0:
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// insert sample into ring-buffer
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storeSample((FixReal) sample->imag(), (FixReal) -sample->real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we don't have a new sample
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return false;
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case 1:
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// insert sample into ring-buffer
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storeSample((FixReal) -sample->real(), (FixReal) -sample->imag());
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// save result
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doFIR(sample);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 2;
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// tell caller we have a new sample
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return true;
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case 2:
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// insert sample into ring-buffer
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storeSample((FixReal) -sample->imag(), (FixReal) sample->real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 3;
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// tell caller we don't have a new sample
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return false;
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default:
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// insert sample into ring-buffer
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storeSample((FixReal) sample->real(), (FixReal) sample->imag());
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// save result
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doFIR(sample);
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we have a new sample
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return true;
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}
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}
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// upsample by 2, move original spectrum to upper half - double buffer variant
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bool workInterpolateUpperHalf(Sample* sampleIn, Sample *sampleOut)
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{
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Sample s;
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switch(m_state)
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{
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case 0:
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// insert sample into ring-buffer
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storeSample(0, 0);
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// save result
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doFIR(&s);
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sampleOut->setReal(-s.imag());
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sampleOut->setImag(s.real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 1;
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// tell caller we didn't consume the sample
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return false;
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case 1:
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// insert sample into ring-buffer
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storeSample((FixReal) sampleIn->real(), (FixReal) sampleIn->imag());
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// save result
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doFIR(&s);
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sampleOut->setReal(-s.real());
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sampleOut->setImag(-s.imag());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 2;
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// tell caller we consumed the sample
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return true;
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case 2:
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// insert sample into ring-buffer
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storeSample(0, 0);
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// save result
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doFIR(&s);
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sampleOut->setReal(s.imag());
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sampleOut->setImag(-s.real());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 3;
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// tell caller we didn't consume the sample
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return false;
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default:
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// insert sample into ring-buffer
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storeSample((FixReal) sampleIn->real(), (FixReal) sampleIn->imag());
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// save result
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doFIR(&s);
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sampleOut->setReal(s.real());
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sampleOut->setImag(s.imag());
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// advance write-pointer
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advancePointer();
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// next state
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m_state = 0;
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// tell caller we consumed the sample
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return true;
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}
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}
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void myDecimate(const Sample* sample1, Sample* sample2)
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{
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storeSample((FixReal) sample1->real(), (FixReal) sample1->imag());
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advancePointer();
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storeSample((FixReal) sample2->real(), (FixReal) sample2->imag());
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doFIR(sample2);
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advancePointer();
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}
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void myDecimate(qint32 x1, qint32 y1, qint32 *x2, qint32 *y2)
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{
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storeSample(x1, y1);
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advancePointer();
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storeSample(*x2, *y2);
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doFIR(x2, y2);
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advancePointer();
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}
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protected:
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qint32 m_samplesDB[2*(HBFIRFilterTraits<HBFilterOrder>::hbOrder - 1)][2]; // double buffer technique
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int m_ptr;
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int m_size;
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int m_state;
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void storeSample(const FixReal& sampleI, const FixReal& sampleQ)
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{
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m_samplesDB[m_ptr][0] = sampleI;
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m_samplesDB[m_ptr][1] = sampleQ;
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m_samplesDB[m_ptr + m_size][0] = sampleI;
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m_samplesDB[m_ptr + m_size][1] = sampleQ;
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}
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void storeSample(qint32 x, qint32 y)
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{
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m_samplesDB[m_ptr][0] = x;
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m_samplesDB[m_ptr][1] = y;
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m_samplesDB[m_ptr + m_size][0] = x;
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m_samplesDB[m_ptr + m_size][1] = y;
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}
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void advancePointer()
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{
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m_ptr = m_ptr + 1 < m_size ? m_ptr + 1: 0;
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}
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void doFIR(Sample* sample)
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{
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int a = m_ptr + m_size; // tip pointer
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int b = m_ptr + 1; // tail pointer
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qint32 iAcc = 0;
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qint32 qAcc = 0;
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for (int i = 0; i < HBFIRFilterTraits<HBFilterOrder>::hbOrder / 4; i++)
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{
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iAcc += (m_samplesDB[a][0] + m_samplesDB[b][0]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffs[i];
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qAcc += (m_samplesDB[a][1] + m_samplesDB[b][1]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffs[i];
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a -= 2;
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b += 2;
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}
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iAcc += ((qint32)m_samplesDB[b-1][0]) << (HBFIRFilterTraits<HBFilterOrder>::hbShift - 1);
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qAcc += ((qint32)m_samplesDB[b-1][1]) << (HBFIRFilterTraits<HBFilterOrder>::hbShift - 1);
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sample->setReal(iAcc >> (HBFIRFilterTraits<HBFilterOrder>::hbShift -1));
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sample->setImag(qAcc >> (HBFIRFilterTraits<HBFilterOrder>::hbShift -1));
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}
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void doFIR(qint32 *x, qint32 *y)
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{
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int a = m_ptr + m_size; // tip pointer
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int b = m_ptr + 1; // tail pointer
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qint32 iAcc = 0;
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qint32 qAcc = 0;
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for (int i = 0; i < HBFIRFilterTraits<HBFilterOrder>::hbOrder / 4; i++)
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{
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iAcc += (m_samplesDB[a][0] + m_samplesDB[b][0]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffs[i];
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qAcc += (m_samplesDB[a][1] + m_samplesDB[b][1]) * HBFIRFilterTraits<HBFilterOrder>::hbCoeffs[i];
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a -= 2;
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b += 2;
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}
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iAcc += ((qint32)m_samplesDB[b-1][0]) << (HBFIRFilterTraits<HBFilterOrder>::hbShift - 1);
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qAcc += ((qint32)m_samplesDB[b-1][1]) << (HBFIRFilterTraits<HBFilterOrder>::hbShift - 1);
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*x = iAcc >> (HBFIRFilterTraits<HBFilterOrder>::hbShift -1); // HB_SHIFT incorrect do not loose the gained bit
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*y = qAcc >> (HBFIRFilterTraits<HBFilterOrder>::hbShift -1);
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}
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};
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template<uint32_t HBFilterOrder>
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IntHalfbandFilterDB<HBFilterOrder>::IntHalfbandFilterDB()
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{
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m_size = HBFIRFilterTraits<HBFilterOrder>::hbOrder - 1;
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for (int i = 0; i < m_size; i++)
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{
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m_samplesDB[i][0] = 0;
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m_samplesDB[i][1] = 0;
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}
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m_ptr = 0;
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m_state = 0;
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}
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#endif // INCLUDE_INTHALFBANDFILTER_DB_H
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