btk::mmfilebuf Class Reference

File buffer using the the memory mapped mechanism. More...

#include <btkBinaryFileStream_mmfstream.h>

Public Member Functions
mmfilebuf *	close ()
const char *	data () const
bool	is_eob () const
bool	is_open () const
	mmfilebuf ()
mmfilebuf *	open (const char *s, std::ios_base::openmode mode)
std::streampos	pubseekoff (std::streamoff off, std::ios_base::seekdir way, std::ios_base::openmode which=std::ios_base::in|std::ios_base::out)
std::streampos	pubseekpos (std::streampos pos, std::ios_base::openmode which=std::ios_base::in|std::ios_base::out)
std::streamsize	sgetn (char *s, std::streamsize n)
std::streamsize	size () const
std::streamsize	sputn (const char *s, std::streamsize n)
bool	writemode () const
	~mmfilebuf ()

Protected Member Functions
mmfilebuf *	mapfile ()
mmfilebuf *	resizemap ()
std::streampos	seekoff (std::streamoff off, std::ios_base::seekdir way, std::ios_base::openmode which=std::ios_base::in|std::ios_base::out)
std::streampos	seekpos (std::streampos pos, std::ios_base::openmode which=std::ios_base::in|std::ios_base::out)

Static Protected Member Functions
static int	granularity ()

Detailed Description

File buffer using the the memory mapped mechanism.

This class is a low level class used by the class BinaryFileStream when possible (if the OS supports it). It is not advised to use this class directly even if the direct access to the buffer can speed the reading of a file (compared to the use of the class BinaryFileStream).

Constructor & Destructor Documentation

btk::mmfilebuf::mmfilebuf ( )

inline

Constructor.

btk::mmfilebuf::~mmfilebuf ( )

inline

Destructor. Try to close the file if opened.

Member Function Documentation

mmfilebuf * btk::mmfilebuf::close

(

)

Close the file.

Returns

Return 0 is an error happened during the closing.

const char * btk::mmfilebuf::data ( ) const

inline

Returns directly the content of the buffer.

int btk::mmfilebuf::granularity ( )

staticprotected

Return the size of block of memory.

bool btk::mmfilebuf::is_eob ( ) const

inline

Check if the position of the pointer on the data is at the end of the buffer.

bool btk::mmfilebuf::is_open ( ) const

inline

Return true if the file is opened.

mmfilebuf * btk::mmfilebuf::mapfile ( )

protected

Try to map the file into the memory.

Returns

Returns 0 if an error occured.

mmfilebuf * btk::mmfilebuf::open	(	const char *	s,
		std::ios_base::openmode	mode
	)

Open the file with the given filename s and the options mode. From the given options, the option binary is everytime append as this buffer is only for binary file.

std::streampos btk::mmfilebuf::pubseekoff ( std::streamoff  off, std::ios_base::seekdir  way, std::ios_base::openmode  which = std::ios_base::in | std::ios_base::out  )

inline

Sets internal position pointer to relative position.

Returns

The new position value of the modified position pointer.

std::streampos btk::mmfilebuf::pubseekpos ( std::streampos  pos, std::ios_base::openmode  which = std::ios_base::in | std::ios_base::out  )

inline

Sets internal position pointer to absolute position

Returns

The new position value of the modified position pointer.

mmfilebuf * btk::mmfilebuf::resizemap ( )

protected

Try to resize the map to be able to extract more data from the file.

Returns

Returns 0 if an error occured.

std::streampos btk::mmfilebuf::seekoff ( std::streamoff  off, std::ios_base::seekdir  way, std::ios_base::openmode  which = std::ios_base::in | std::ios_base::out  )

protected

Sets internal position pointer to relative position.

Returns

The new position value of the modified position pointer. Errors are expected to be signaled by an invalid position value, like -1.

std::streampos btk::mmfilebuf::seekpos ( std::streampos  pos, std::ios_base::openmode  which = std::ios_base::in | std::ios_base::out  )

protected

Sets internal position pointer to absolute position

Returns

The new position value of the modified position pointer. In case of error, the value returned shall be an invalid position, like -1.

std::streamsize btk::mmfilebuf::sgetn	(	char *	s,
		std::streamsize	n
	)

Get sequence of characters

Returns

The number of characters gotten, returned as a value of type streamsize.

std::streamsize btk::mmfilebuf::size ( ) const

inline

Returns the size of the buffer.

std::streamsize btk::mmfilebuf::sputn	(	const char *	s,
		std::streamsize	n
	)

Write a sequence of characters

Returns

The number of characters written, returned as a value of type streamsize.

bool btk::mmfilebuf::writemode ( ) const

inline

Check if this file buffer is in write mode or not.