Supplies functionality for timestamping data packets. More...

#include <packetstamper.h>

Classes
struct	DataPair

Public Member Functions
	PacketStamper ()
	Default constructor. More...

void	resetTosEstimation ()
	Reset the Time Of Sampling estimation parameters. More...

int64_t	stampPacket (XsDataPacket &pack, XsDataPacket const &highest)
	Create 64 bit counter for a packet. More...

Static Public Member Functions
static int64_t	calculateLargePacketCounter (int64_t frameCounter, int64_t lastCounter, int64_t boundary)
	Calculate the new large packet counter value based on frameCounter and the lastCounter. More...

static int64_t	calculateLargeSampleTime (int64_t frameTime, int64_t lastTime)
	Calculate the new large sample time value based on frameTime and the lastTime. More...

Static Public Attributes
static const int64_t	AWINDABOUNDARY = 0x100000000LL
	32 bit MT Sample Counter boundary More...

static const int64_t	MTSCBOUNDARY = 0x00010000LL
	16 bit MT Sample Counter boundary More...

static const int64_t	SC8BOUNDARY = 0x00000100LL
	8 bit Sample Counter boundary More...

Protected Member Functions
void	estimateClockParameters ()
	Estimate the clock parameters based on the available data points. More...

void	estimateTos (XsDataPacket &pack)
	Estimate the time of sampling for the supplied packet pack and update it. More...

int64_t	estimateTosInternal (int64_t pid, int64_t toa)
	Estimate the time of sampling for the supplied pid. More...

bool	rejectOutlier ()
	Remove the worst outlier from the known data points. More...

Protected Attributes
std::list< DataPair >	m_dataPoints
	The filtered history of interesting data items. More...

DataPair	m_latest
	Latest known data (later data may arrive with a lower pid, which will not be put in this item) More...

DataPair	m_linearize
	The very first item received, used to normalize to 0,0 so we have less computational issues with large numbers. More...

double	m_rate
	The estimated clock rate per pid. More...

int	m_rejectionCountdown
	A countdown value that is used after the input sanity check rejects input to reject subsequent samples as well. More...

double	m_toa0
	The recomputed Time Of Arrival of PID 0. More...

Detailed Description

Supplies functionality for timestamping data packets.

This class can analyze a data packet and create a proper packet id for it.

Definition at line 73 of file packetstamper.h.

Constructor & Destructor Documentation

◆ PacketStamper()

PacketStamper::PacketStamper ( )

Default constructor.

Definition at line 83 of file packetstamper.cpp.

Member Function Documentation

◆ calculateLargePacketCounter()

int64_t PacketStamper::calculateLargePacketCounter	(	int64_t	frameCounter,
		int64_t	lastCounter,
		int64_t	boundary
	)

static

Calculate the new large packet counter value based on frameCounter and the lastCounter.

Wraparound is at the given boundary

Parameters

[in]	frameCounter	The frame counter
[in]	lastCounter	The last counter
[in]	boundary	the boundary at which to assume a wrap-around

Returns: The computed packet counter value

Note: If lastCounter < 0, returns frameCounter

Definition at line 106 of file packetstamper.cpp.

◆ calculateLargeSampleTime()

int64_t PacketStamper::calculateLargeSampleTime	(	int64_t	frameTime,
		int64_t	lastTime
	)

static

Calculate the new large sample time value based on frameTime and the lastTime.

Wraparound is at 864000000 (1 day @ 10kHz)

Parameters

[in]	frameTime	The frame time
[in]	lastTime	The last time

Returns: The computed packet counter value

Note: If lastTime < 0, returns frameTime

Definition at line 175 of file packetstamper.cpp.

◆ estimateClockParameters()

void PacketStamper::estimateClockParameters ( )

protected

Estimate the clock parameters based on the available data points.

Uses a least-square estimation to fit a line through the known dataset and then shifts the line down to ensure the TOA >= ETOS constraint holds

Definition at line 203 of file packetstamper.cpp.

◆ estimateTos()

void PacketStamper::estimateTos ( XsDataPacket & pack )

protected

Estimate the time of sampling for the supplied packet pack and update it.

Definition at line 191 of file packetstamper.cpp.

◆ estimateTosInternal()

int64_t PacketStamper::estimateTosInternal	(	int64_t	pid,
		int64_t	toa
	)

protected

Estimate the time of sampling for the supplied pid.

This function will estimate the time of samplinmg based on the supplied PID. If both PID and TOA are acceptable values, they will be used to update the estimation parameters.

The current algorithm expects the values to be estimated to be constant for the lifetime of the object.

Parameters

pid	The packet ID to estimate the time of sampling for.
toa	The time of arrival associated with this pid

Returns: The estimated time of sampling.

Definition at line 284 of file packetstamper.cpp.

◆ rejectOutlier()

bool PacketStamper::rejectOutlier ( )

protected

Remove the worst outlier from the known data points.

Only items that are more than the estimated rate off from the current estimation are considered outliers

Returns: true if anything was rejected, false otherwise

Definition at line 252 of file packetstamper.cpp.

◆ resetTosEstimation()

void PacketStamper::resetTosEstimation ( )

Reset the Time Of Sampling estimation parameters.

Definition at line 89 of file packetstamper.cpp.

◆ stampPacket()

int64_t PacketStamper::stampPacket	(	XsDataPacket &	pack,
		XsDataPacket const &	highestPacket
	)

Create 64 bit counter for a packet.

Wrap when new XsDataPacket is too far away from the previous XsDataPacket in time. Use half cache size as reasonable time difference When infinite cache, simply wrap when new is lower than old

Parameters

pack	The XsDataPacket that needs its 64-bit sample counter updated
highestPacket	The highest packet available for the current device, it will be updated if the new counter is higher than the stored value.

Returns: The computed counter for the packet.

Definition at line 133 of file packetstamper.cpp.

Member Data Documentation

◆ AWINDABOUNDARY

const int64_t PacketStamper::AWINDABOUNDARY = 0x100000000LL

static

32 bit MT Sample Counter boundary

Definition at line 79 of file packetstamper.h.

◆ m_dataPoints

std::list<DataPair> PacketStamper::m_dataPoints

protected

The filtered history of interesting data items.

Definition at line 102 of file packetstamper.h.

◆ m_latest

DataPair PacketStamper::m_latest

protected

Latest known data (later data may arrive with a lower pid, which will not be put in this item)

Definition at line 100 of file packetstamper.h.

◆ m_linearize

DataPair PacketStamper::m_linearize

protected

The very first item received, used to normalize to 0,0 so we have less computational issues with large numbers.

Definition at line 101 of file packetstamper.h.

◆ m_rate

double PacketStamper::m_rate

protected

The estimated clock rate per pid.

Definition at line 105 of file packetstamper.h.

◆ m_rejectionCountdown

int PacketStamper::m_rejectionCountdown

protected

A countdown value that is used after the input sanity check rejects input to reject subsequent samples as well.

Definition at line 106 of file packetstamper.h.

◆ m_toa0

double PacketStamper::m_toa0

protected

The recomputed Time Of Arrival of PID 0.

Definition at line 104 of file packetstamper.h.

◆ MTSCBOUNDARY

const int64_t PacketStamper::MTSCBOUNDARY = 0x00010000LL

static

16 bit MT Sample Counter boundary

Definition at line 80 of file packetstamper.h.

◆ SC8BOUNDARY

const int64_t PacketStamper::SC8BOUNDARY = 0x00000100LL

static

8 bit Sample Counter boundary

Definition at line 81 of file packetstamper.h.

The documentation for this class was generated from the following files:

Classes

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ PacketStamper()

Member Function Documentation

◆ calculateLargePacketCounter()

◆ calculateLargeSampleTime()

◆ estimateClockParameters()

◆ estimateTos()

◆ estimateTosInternal()

◆ rejectOutlier()

◆ resetTosEstimation()

◆ stampPacket()

Member Data Documentation

◆ AWINDABOUNDARY

◆ m_dataPoints

◆ m_latest

◆ m_linearize

◆ m_rate

◆ m_rejectionCountdown

◆ m_toa0

◆ MTSCBOUNDARY

◆ SC8BOUNDARY