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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 "UartClockRecoveryFilter.h"

using namespace std;

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Construction / destruction

UartClockRecoveryFilter::UartClockRecoveryFilter(const string& color)
	: Filter(color, CAT_CLOCK)
{
	AddDigitalStream("data");
	CreateInput("din");

	m_baudname = "Baud rate";
	m_parameters[m_baudname] = FilterParameter(FilterParameter::TYPE_INT, Unit(Unit::UNIT_BITRATE));
	m_parameters[m_baudname].SetIntVal(115200);	//115.2 Kbps by default

	m_threshname = "Threshold";
	m_parameters[m_threshname] = FilterParameter(FilterParameter::TYPE_FLOAT, Unit(Unit::UNIT_VOLTS));
	m_parameters[m_threshname].SetFloatVal(0);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Factory methods

bool UartClockRecoveryFilter::ValidateChannel(size_t i, StreamDescriptor stream)
{
	if(stream.m_channel == NULL)
		return false;

	if( (i == 0) && (stream.GetType() == Stream::STREAM_TYPE_ANALOG) )
		return true;

	return false;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Accessors

string UartClockRecoveryFilter::GetProtocolName()
{
	return "Clock Recovery (UART)";
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Actual decoder logic

void UartClockRecoveryFilter::Refresh()
{
	//Make sure we've got valid inputs
	if(!VerifyAllInputsOK())
	{
		SetData(NULL, 0);
		return;
	}

	//Get the input data
	auto din = GetInputWaveform(0);

	//Look up the nominal baud rate and convert to time
	int64_t baud = m_parameters[m_baudname].GetIntVal();
	int64_t fs = static_cast<int64_t>(FS_PER_SECOND / baud);

	//Create the output waveform and copy our timescales
	auto cap = SetupEmptySparseDigitalOutputWaveform(din, 0);
	cap->m_triggerPhase = 0;
	cap->m_timescale = 1;
	cap->PrepareForCpuAccess();

	//Timestamps of the edges
	vector<int64_t> edges;

	//Find times of the zero crossings
	const float threshold = m_parameters[m_threshname].GetFloatVal();
	FindZeroCrossingsBase(din, threshold, edges);

	//Actual DLL logic
	size_t nedge = 0;
	int64_t bcenter = 0;
	size_t elen = edges.size();
	for(; nedge < elen;)
	{
		//The current bit starts half a baud period after the start bit edge
		bcenter = edges[nedge] + fs/2;
		nedge ++;

		//We have ten start/ data/stop bits after this
		for(int i=0; i<10; i++)
		{
			if(nedge >= elen)
				break;

			//If the next edge is around the time of this bit, re-sync to it
			if(edges[nedge] < bcenter + fs/4)
			{
				//bcenter = edges[nedge] + fs/2;
				nedge ++;
			}

			//Emit a sample for this data bit
			cap->m_offsets.push_back(bcenter);
			cap->m_durations.push_back(fs/2);
			cap->m_samples.push_back(1);

			cap->m_offsets.push_back(bcenter + fs/2);
			cap->m_durations.push_back(fs/2);
			cap->m_samples.push_back(0);

			//Next bit starts one baud period later
			bcenter  += fs;
		}
	}

	SetData(cap, 0);
	cap->MarkModifiedFromCpu();
}
