Reformat rational interpolator code

sdrbase/dsp/interpolator.cpp

@@ -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++)
+	for (int n = 0; n < ntaps; n++) {
-		window[n] = 0.54 - 0.46 * cos ((2 * M_PI * n) / (ntaps - 1));
+	    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];
+	for (int n = -M; n <= M; n++)
-			else taps[n + M] =  sin (n * fwT0) / (n * M_PI) * window[n + M];
+	{
+		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++)
+	for (int i = 0; i < ntaps; i++) {
-		taps[i] *= gain;
+	    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++)
+	for (int phase = 0; phase < phaseSteps; phase++)
-			polyphase[phase * m_nTaps + i] = taps[i * 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++) {
-		for(int i = phase * m_nTaps; i < phase * m_nTaps + m_nTaps; i++)
+		    sum += polyphase[i];
-			polyphase[i] /= sum;
+		}
+
+		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;

sdrbase/dsp/interpolator.h

@@ -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)
+		if (phase < 0) {
-			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