mdf::MdfReader Class Reference

Reader interface to an MDF file. More...

#include "mdf/mdfreader.h"

Public Member Functions
	MdfReader (const std::string &filename)
virtual	~MdfReader ()
	Destructor that close any open file and destructs.
	MdfReader (const MdfReader &)=delete
	MdfReader (MdfReader &&)=delete
MdfReader &	operator= (const MdfReader &)=delete
MdfReader &	operator= (MdfReader &&)=delete
int64_t	Index () const
void	Index (int64_t index)
bool	IsOk () const
bool	IsFinalized () const
	Return true if the file is marked as finalized.
const MdfFile *	GetFile () const
const IHeader *	GetHeader () const
	Returns the header (HD) block.
IDataGroup *	GetDataGroup (size_t order) const
	Returns the data group (DG) block.
std::string	ShortName () const
	Returns the file name without paths.
bool	Open ()
	Opens the file stream for reading.
void	Close ()
	Closes the file stream.
bool	ReadHeader ()
	Reads the ID and the HD block.
bool	ReadMeasurementInfo ()
	Reads everything but not CG and raw data.
bool	ReadEverythingButData ()
	Reads all blocks but not raw data.
bool	ExportAttachmentData (const IAttachment &attachment, const std::string &dest_file)
	Export the attachment data to a detination file.
bool	ReadData (IDataGroup &data_group)
	Reads all sample, sample reduction and signal data into memory.
bool	ReadPartialData (IDataGroup &data_group, size_t min_sample, size_t max_sample)
	Reads a range of samples.
bool	ReadSrData (ISampleReduction &sr_group)
	Reads in data bytes to a sample reduction (SR) block.
bool	ReadVlsdData (IDataGroup &data_group, IChannel &vlsd_channel, const std::vector< uint64_t > &offset_list, std::function< void(uint64_t, const std::vector< uint8_t > &)> &callback)
	Read in partial variable length data with an offset list.

Detailed Description

This is the main interface when reading MDF3 and MDF4 files.

Constructor & Destructor Documentation

MdfReader()

mdf::MdfReader::MdfReader ( const std::string & filename )

explicit

Constructor that opens the file and read ID and HD block.

Member Function Documentation

GetFile()

const MdfFile * mdf::MdfReader::GetFile ( ) const

inlinenodiscard

Returns a pointer to the MDF file. This file holds references to the MDF blocks.

Returns

Pointer to the MDF file object. Note it may return a null pointer.

Index() [1/2]

int64_t mdf::MdfReader::Index ( ) const

inlinenodiscard

Unique index for this reader. This index is typically used when fetching files from a database. The index itself is not used by the reader.

Returns

An unique index.

Index() [2/2]

void mdf::MdfReader::Index ( int64_t index )

inline

Sets a unique index to this reader or actually its file. This index is typically retrieved from a database and makes finding files much easier than comparing paths.

Parameters

index

Unique index.

IsFinalized()

bool mdf::MdfReader::IsFinalized ( ) const

nodiscard

This function returns true if the file is marked as finalized. This is done by checking the ID block.

Returns

True if the file is marked as finalized.

IsOk()

bool mdf::MdfReader::IsOk ( ) const

inlinenodiscard

Checks if the file was read without errors.

Returns

True if the file was read OK.

ReadData()

bool mdf::MdfReader::ReadData

(

IDataGroup &

data_group

)

Reads in all data bytes that belongs to a data group (DG). The function reads in sample data (DT..) blocks, sample reduction (RD/RV/RI) blocks and signal data (SD) blocks. Note that this function may consume a lot of memory, so remember to call the IDataGroup::ClearData() function when data not are needed anymore.

The attached observers also consumes memory, so remember to delete them when they are no more needed.

Parameters

data_group

Reference to the data group (DG) object.

Returns

True if the read was successful.

ReadPartialData()

bool mdf::MdfReader::ReadPartialData	(	IDataGroup &	data_group,
		size_t	min_sample,
		size_t	max_sample )

Reads in a range of samples a data group (DG). The function reads in sample data (DT..) blocks, sample reduction (RD/RV/RI) blocks and signal data (SD) blocks. The function is faster that reading all data bytes, skipping records it doesn't need to read.

Note that this function still may consume a lot of memory, so remember to call the IDataGroup::ClearData() function when data not are needed anymore.

The attached observers also consumes memory, so remember to delete them when they are no more needed.

Parameters

data_group	Reference to the data group (DG) object.
min_sample	First sample index to read.
max_sample	Last sample index to read.

Returns

True if the read was successful.

ReadSrData()

bool mdf::MdfReader::ReadSrData

(

ISampleReduction &

sr_group

)

To minimíze the use of time and memory, this function reads in data for one sample reduction (SR) block. The function is much faster than to read in all data bytes for a data group (DG).

Parameters

sr_group

Reference to a sample reduction (SR) block.

Returns

True if the read was successful.

ReadVlsdData()

bool mdf::MdfReader::ReadVlsdData	(	IDataGroup &	data_group,
		IChannel &	vlsd_channel,
		const std::vector< uint64_t > &	offset_list,
		std::function< void(uint64_t, const std::vector< uint8_t > &)> &	callback )

This function reads in VLSD stored data according to an offset list. For smaller MDF files that fits in the primary memory, this function is not needed but sometimes the VLSD data sample holds a large amount of data bytes typical a video stream. These files tends to be huge so the application runs out of memory.

This function reads in VLSD stored data in smaller batcher. The application first reads in all offsets to the raw data. Using these offsets the application can read in typically one sample (offset) at a time. This tactic saves primary memory.

Parameters

data_group	Data group to read VLSD data from
vlsd_channel	Which channel that stores the VLSD data
offset_list	List of offsets (samples) to read.
callback	Callback function for each offset/sample data

Returns

Returns true if the read was successful

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

• include/mdf/mdfreader.h