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* 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(color, CAT_MATH)
{
	AddStream(Unit(Unit::UNIT_VOLTS), "data", Stream::STREAM_TYPE_ANALOG);
	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.GetType() == Stream::STREAM_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(!VerifyAllInputsOKAndUniformAnalog())
	{
		SetData(NULL, 0);
		return;
	}

	auto din_i = dynamic_cast<UniformAnalogWaveform*>(GetInputWaveform(0));
	auto din_q = dynamic_cast<UniformAnalogWaveform*>(GetInputWaveform(1));
	din_i->PrepareForCpuAccess();
	din_q->PrepareForCpuAccess();

	//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 = SetupEmptyUniformAnalogOutputWaveform(din_i, 0);
	size_t end = len - 2*period_samples;
	cap->PrepareForCpuAccess();
	cap->Resize(end);

	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;
	}

	cap->MarkModifiedFromCpu();
}
