text: /***********************************************************************************************************************
  *                                                                                                                      *
  * libscopeprotocols                                                                                                    *
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  * Copyright (c) 2012-2022 Andrew D. Zonenberg and contributors                                                         *
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  #include "../scopehal/scopehal.h"
  #include <complex>
  #include "WindowedAutocorrelationFilter.h"
  
  using namespace std;
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // Construction / destruction
  
  WindowedAutocorrelationFilter::WindowedAutocorrelationFilter(const string& color)
  	: Filter(OscilloscopeChannel::CHANNEL_TYPE_ANALOG, color, CAT_MATH)
  {
  	//Set up channels
  	CreateInput("I");
  	CreateInput("Q");
  
  	m_windowName = "Window";
  	m_parameters[m_windowName] = FilterParameter(FilterParameter::TYPE_INT, Unit(Unit::UNIT_FS));
  	m_parameters[m_windowName].SetFloatVal(400e6);
  
  	m_periodName = "Period";
  	m_parameters[m_periodName] = FilterParameter(FilterParameter::TYPE_INT, Unit(Unit::UNIT_FS));
  	m_parameters[m_periodName].SetFloatVal(3.6e9);
  }
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // Factory methods
  
  bool WindowedAutocorrelationFilter::ValidateChannel(size_t i, StreamDescriptor stream)
  {
  	if(stream.m_channel == NULL)
  		return false;
  
  	if( (i < 2) && (stream.m_channel->GetType() == OscilloscopeChannel::CHANNEL_TYPE_ANALOG) )
  		return true;
  
  	return false;
  }
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // Accessors
  
  string WindowedAutocorrelationFilter::GetProtocolName()
  {
  	return "Windowed Autocorrelation";
  }
  
  ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
  // Actual decoder logic
  
  void WindowedAutocorrelationFilter::Refresh()
  {
  	//Make sure we've got valid inputs
  	if(!VerifyAllInputsOKAndAnalog())
  	{
  		SetData(NULL, 0);
  		return;
  	}
  
  	auto din_i = GetAnalogInputWaveform(0);
  	auto din_q = GetAnalogInputWaveform(1);
  
  	//Copy the units
  	SetYAxisUnits(m_inputs[0].GetYAxisUnits(), 0);
  
  	//Convert window and period to samples
  	int window_ps = m_parameters[m_windowName].GetIntVal();
  	size_t window_samples = window_ps / din_i->m_timescale;
  	int period_ps = m_parameters[m_periodName].GetIntVal();
  	size_t period_samples = period_ps / din_i->m_timescale;
  	window_samples = min(window_samples, period_samples);
  
  	//We need meaningful data, bail if it's too short
  	auto len = min(din_i->m_samples.size(), din_q->m_samples.size());
  	if(len < period_samples)
  	{
  		SetData(NULL, 0);
  		return;
  	}
  
  	//Set up the output waveform
  	auto cap = SetupOutputWaveform(din_i, 0, 0, 2*period_samples);
  
  	size_t end = len - 2*period_samples;
  	for(size_t i=0; i < end; i ++)
  	{
  		complex<float> total = 0;
  		for(size_t j=0; j<window_samples; j++)
  		{
  			size_t first = i + j;
  			size_t second = first + period_samples;
  
  			complex<float> a(din_i->m_samples[first], din_q->m_samples[first]);
  			complex<float> b(din_i->m_samples[second], din_q->m_samples[second]);
  
  			total += a*b;
  		}
  
  		float v = abs(total) / window_samples;
  
  		cap->m_samples[i] = v;
  	}
  }
  