TStreamBuf Class Reference

#include <s32buf.h>

class TStreamBuf : public MStreamBuf

Inherits from

TStreamBuf
- MStreamBuf

Protected Member Type Definitions
typedef	TInt TArea

Protected Member Functions
	TStreamBuf()
IMPORT_C TInt	Avail(TArea)
TInt	Avail(TRead)
TInt	Avail(TWrite)
virtual IMPORT_C TInt	DoReadL(TAny *, TInt)
virtual IMPORT_C TStreamTransfer	DoReadL(MStreamInput &, TStreamTransfer)
virtual IMPORT_C void	DoWriteL(const TAny *, TInt)
virtual IMPORT_C TStreamTransfer	DoWriteL(MStreamOutput &, TStreamTransfer)
IMPORT_C TUint8 *	End(TArea)
TUint8 *	End(TRead)
TUint8 *	End(TWrite)
IMPORT_C TUint8 *	Ptr(TArea)
TUint8 *	Ptr(TRead)
TUint8 *	Ptr(TWrite)
IMPORT_C void	SetBuf(TArea, TUint8 , TUint8 )
void	SetBuf(TRead, TUint8 , TUint8 )
void	SetBuf(TWrite, TUint8 , TUint8 )
IMPORT_C void	SetEnd(TArea, TUint8 *)
void	SetEnd(TRead, TUint8 *)
void	SetEnd(TWrite, TUint8 *)
IMPORT_C void	SetPtr(TArea, TUint8 *)
void	SetPtr(TRead, TUint8 *)
void	SetPtr(TWrite, TUint8 *)

Inherited Enumerations
	MStreamBuf:TRead
	MStreamBuf:TWrite

Inherited Functions
	MStreamBuf::Close()
	MStreamBuf::MStreamBuf()
	MStreamBuf::PushL()
	MStreamBuf::Read(TDes8 &,TInt,TRequestStatus &)
	MStreamBuf::Read(TDes8 &,TRequestStatus &)
	MStreamBuf::ReadL(MStreamInput &)
	MStreamBuf::ReadL(MStreamInput &,TInt)
	MStreamBuf::ReadL(MStreamInput &,TStreamTransfer)
	MStreamBuf::ReadL(TAny *,TInt)
	MStreamBuf::ReadL(TDes8 &,TInt,TRequestStatus &)
	MStreamBuf::ReadL(TDes8 &,TRequestStatus &)
	MStreamBuf::Release()
	MStreamBuf::SeekL(TMark,TStreamLocation,TInt)
	MStreamBuf::SeekL(TMark,TStreamPos)
	MStreamBuf::SeekL(TRead,TInt)
	MStreamBuf::SeekL(TRead,TStreamLocation,TInt)
	MStreamBuf::SeekL(TWrite,TInt)
	MStreamBuf::SeekL(TWrite,TStreamLocation,TInt)
	MStreamBuf::SizeL()const
	MStreamBuf::Synch()
	MStreamBuf::SynchL()
	MStreamBuf::TellL(TRead)const
	MStreamBuf::TellL(TWrite)const
	MStreamBuf::Write(const TDesC8 &,TInt,TRequestStatus &)
	MStreamBuf::Write(const TDesC8 &,TRequestStatus &)
	MStreamBuf::WriteL(MStreamOutput &)
	MStreamBuf::WriteL(MStreamOutput &,TInt)
	MStreamBuf::WriteL(MStreamOutput &,TStreamTransfer)
	MStreamBuf::WriteL(const TAny *,TInt)
	MStreamBuf::WriteL(const TDesC8 &,TInt,TRequestStatus &)
	MStreamBuf::WriteL(const TDesC8 &,TRequestStatus &)

Inherited Type Definitions
	MStreamBuf::TMark

Detailed Description

Adds buffering capabilities to a stream buffer

The class provides pointers to mark out the current read and write areas within the intermediate buffer. The class also defines the pure virtual functions UnderflowL() and OverflowL() which must be provided by a derived class.

Streams which have buffering capabilities derive from this class, otherwise they derive from MStreamBuf.

Note that the class does not provide the buffer; this is left to the class derived from it. For example, the memory buffer classes use the memory area directly, the file buffer class allocate a heap cell to use as a buffer.

Member Type Definition Documentation

Typedef TArea

typedef TInt

TArea

[protected]

Used to identify the type of area within an intermediate buffer.

The type is used by functions of this class that set or get pointers into the intermediate buffer.

The type uses the ERead and EWrite enumeration values, as bit flags, to identify the read and write areas respectively.

ERead is an MStreamBuf::TRead enumerator. EWrite is an MStreamBuf::EWrite enumerator.

Constructor & Destructor Documentation

TStreamBuf ( )

IMPORT_C

TStreamBuf

(

)

[protected]

Sets the pointers that mark out the read and write areas within the intermediate buffer to null.

Member Function Documentation

Avail ( TArea )

IMPORT_C TInt

Avail

(

TArea

anArea

)

const [protected]

Gets the number of bytes available in the read or write area within the intermediate buffer.

Parameters
anArea	The area within the intermediate buffer for which the number of available bytes is to be fetched. This can be either the read area or the write area, as indicated by the ERead and EWrite bits. Only one of these can be set, otherwise the function raises a STORE-Stream 17 panic.

Return Value: The number of bytes available.

Avail ( TRead )

TInt

Avail

(

TRead

)

const [protected, inline]

Gets the number of bytes available in the read area within the intermediate buffer.

See also: MStreamBuf::TRead

Return Value: The number of bytes available.

Avail ( TWrite )

TInt

Avail

(

TWrite

)

const [protected, inline]

Gets the number of bytes available in the write area within the intermediate buffer.

See also: MStreamBuf::TWrite

Return Value: The number of bytes available.

DoReadL ( TAny *, TInt )

IMPORT_C TInt	DoReadL	(	TAny *	aPtr,
			TInt	aMaxLength
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoReadL(TAny *,TInt)

Reads data from the intermediate buffer into the specified memory location.

The function calls the virtual function UnderfLowL() to give concrete implementations the chance to refill the intermediate buffer, and satisfy the caller's requirements.

This implementation overrides the one supplied by the base class MStreamBuf, and is called by, MStreamBuf::ReadL(TAny*,TInt).

See also: MStreamBuf::ReadL() MStreamBuf::DoReadL()

Parameters
aPtr	A pointer to the target memory location for the data read from the intermediate buffer.
aMaxLength	The maximum number of bytes to be read.

Return Value: The number of bytes read. This may be less than the amount requested.

DoReadL ( MStreamInput &, TStreamTransfer )

IMPORT_C TStreamTransfer	DoReadL	(	MStreamInput &	anInput,
			TStreamTransfer	aTransfer
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoReadL(MStreamInput &,TStreamTransfer)

Reads data from the intermediate buffer and, if necessary, any remaining data from the stream to the specified target stream input object.

It is called by ReadL(MStreamInput&,TStreamTransfer).

The intermediate buffer is emptied first by calling the target stream input's PushL() function, which performs the read from intermediate buffer operation. Any remaining data is then read from the stream by calling the target stream object's ReadFromL() function, which performs the read from stream operation.

This implementation is called for streams that have buffering capabilities and are derived from this class.

Parameters
anInput	The target stream input object.
aTransfer	A stream transfer object defining the amount of data available to be written.

Return Value: The amount of data that was not consumed.

DoWriteL ( const TAny *, TInt )

IMPORT_C void	DoWriteL	(	const TAny *	aPtr,
			TInt	aLength
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoWriteL(const TAny *,TInt)

Writes data from the specified memory location into the intermediate buffer.

The function calls the virtual function OverfLowL() to give concrete implementations the chance to forward the intermediate buffer content to its destination.

This implementation overrides the one supplied by the base class MStreamBuf, and is called by MStreamBuf::WriteL(const TAny*,TInt).

See also: MStreamBuf::WriteL() MStreamBuf::DoWriteL()

Parameters
aPtr	A pointer to the source memory location for the data to be written to the intermediate buffer.
aLength	The number of bytes to be written.

Return Value: The number of bytes written.

DoWriteL ( MStreamOutput &, TStreamTransfer )

IMPORT_C TStreamTransfer	DoWriteL	(	MStreamOutput &	anOutput,
			TStreamTransfer	aTransfer
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoWriteL(MStreamOutput &,TStreamTransfer)

End ( TArea )

IMPORT_C TUint8 *

End

(

TArea

anArea

)

const [protected]

Gets the current end point of the read or write area within the intermediate buffer.

An end point is always the first byte beyond the end of an area.

Parameters
anArea	The area within the intermediate buffer for which the end point is to be fetched. This can be either the read area or the write area, as indicated by the ERead and EWrite bits. Only one of these can be set, otherwise the function raises a STORE-Stream 17 panic.

Return Value: The end point.

End ( TRead )

TUint8 *

End

(

TRead

)

const [protected, inline]

Gets the current end point of the read area within the intermediate buffer.

An end point is always the first byte beyond the end of an area.

See also: MStreamBuf::TRead

Return Value: The end point.

End ( TWrite )

TUint8 *

End

(

TWrite

)

const [protected, inline]

Gets the current end point of the write area within the intermediate buffer.

An end point is always the first byte beyond the end of an area.

See also: MStreamBuf::TWrite

Return Value: The end point.

Ptr ( TArea )

IMPORT_C TUint8 *

Ptr

(

TArea

anArea

)

const [protected]

Gets the current start point of the read or write area within the intermediate buffer.

Parameters
anArea	The area within the intermediate buffer for which the start point is to be fetched. This can be either the read area or the write area, as indicated by the ERead and EWrite bits. Only one of these can be set, otherwise the function raises a STORE-Stream 17 panic.

Return Value: The start point.

Ptr ( TRead )

TUint8 *

Ptr

(

TRead

)

const [protected, inline]

Gets the current start point of the read area within the intermediate buffer.

See also: MStreamBuf::TRead

Return Value: The start point.

Ptr ( TWrite )

TUint8 *

Ptr

(

TWrite

)

const [protected, inline]

Gets the current start point of the write area within the intermediate buffer.

See also: MStreamBuf::TWrite

Return Value: The start point.

SetBuf ( TArea, TUint8 , TUint8 )

IMPORT_C void	SetBuf	(	TArea	anArea,
			TUint8 *	aPtr,
			TUint8 *	anEnd
		)	[protected]

Sets the start and end points of the read and/or the write area within the intermediate buffer.

A start point is always within an area; an end point is always the first byte beyond the end of an area.

Parameters
anArea	The areas within the intermediate buffer for which the start and end points are to be set. These can be the read area and/or the write area, as indicated by the ERead and EWrite bits. Only these bits can be set, otherwise the function raises a STORE-Stream 17 panic.
aPtr	The start point.
anEnd	The end point.

SetBuf ( TRead, TUint8 , TUint8 )

void	SetBuf	(	TRead	,
			TUint8 *	aPtr,
			TUint8 *	anEnd
		)	[protected, inline]

Sets the start and end points of the read area within the intermediate buffer.

A start point is always within an area; an end point is always the first byte beyond the end of an area.

See also: MStreamBuf::TRead

Parameters
aPtr	The start point.
anEnd	The end point.

SetBuf ( TWrite, TUint8 , TUint8 )

void	SetBuf	(	TWrite	,
			TUint8 *	aPtr,
			TUint8 *	anEnd
		)	[protected, inline]

Sets the start and end points of the write area within the intermediate buffer.

A start point is always within an area; an end point is always the first byte beyond the end of an area.

See also: MStreamBuf::TWrite

Parameters
aPtr	The start point.
anEnd	The end point.

SetEnd ( TArea, TUint8 * )

IMPORT_C void	SetEnd	(	TArea	anArea,
			TUint8 *	anEnd
		)	[protected]

SetEnd ( TRead, TUint8 * )

void	SetEnd	(	TRead	,
			TUint8 *	anEnd
		)	[protected, inline]

SetEnd ( TWrite, TUint8 * )

void	SetEnd	(	TWrite	,
			TUint8 *	anEnd
		)	[protected, inline]

SetPtr ( TArea, TUint8 * )

IMPORT_C void	SetPtr	(	TArea	anArea,
			TUint8 *	aPtr
		)	[protected]

Sets the start point of the read and/or the write area within the intermediate buffer.

A start point is always within an area.

Parameters
anArea	The areas within the intermediate buffer for which the start point is to be set. These can be the read area and/or the write area, as indicated by the ERead and EWrite bits. Only these bits can be set, otherwise the function raises a STORE-Stream 17 panic.
aPtr	The start point.

SetPtr ( TRead, TUint8 * )

void	SetPtr	(	TRead	,
			TUint8 *	aPtr
		)	[protected, inline]

Sets the start point of the write area within the intermediate buffer.

A start point is always within an area.

See also: MStreamBuf::TWrite

Parameters
aPtr	The start point.

SetPtr ( TWrite, TUint8 * )

void	SetPtr	(	TWrite	,
			TUint8 *	aPtr
		)	[protected, inline]

Sets the start point of the write area within the intermediate buffer.

A start point is always within an area.

See also: MStreamBuf::TWrite

Parameters
aPtr	The start point.

TStreamBuf Class Reference

Inherits from

Detailed Description

Member Type Definition Documentation

Typedef TArea

Constructor & Destructor Documentation

TStreamBuf ( )

Member Function Documentation

Avail ( TArea )

Avail ( TRead )

Avail ( TWrite )

DoReadL ( TAny *, TInt )

DoReadL ( MStreamInput &, TStreamTransfer )

DoWriteL ( const TAny *, TInt )

DoWriteL ( MStreamOutput &, TStreamTransfer )

End ( TArea )

End ( TRead )

End ( TWrite )

Ptr ( TArea )

Ptr ( TRead )

Ptr ( TWrite )

SetBuf ( TArea, TUint8 *, TUint8 * )

SetBuf ( TRead, TUint8 *, TUint8 * )

SetBuf ( TWrite, TUint8 *, TUint8 * )

SetEnd ( TArea, TUint8 * )

SetEnd ( TRead, TUint8 * )

SetEnd ( TWrite, TUint8 * )

SetPtr ( TArea, TUint8 * )

SetPtr ( TRead, TUint8 * )

SetPtr ( TWrite, TUint8 * )

SetBuf ( TArea, TUint8 , TUint8 )

SetBuf ( TRead, TUint8 , TUint8 )

SetBuf ( TWrite, TUint8 , TUint8 )