Class TMemBuf

class TMemBuf : public TStreamBuf;

Description

A stream buffer that uses plain memory for its implementation.

A stream of this type is used by RMemWriteStream and RMemReadStream objects. It also has intermediate buffering capabilities.

This is a seekable stream buffer.

Derivation

• MStreamBuf - A stream buffer that provides a generic I/O interface for streamed data.

• TStreamBuf - Adds buffering capabilities to a stream buffer

• TMemBuf - A stream buffer that uses plain memory for its implementation.

Members

Defined in TMemBuf:

• DoSeekL(TMark,TStreamLocation,TInt)
• OverflowL()Empties the intermediate buffer and resets the start and end points of the write...
• Set(TUint8 *,TUint8 *,TInt)Sets up the stream to use the specified area of plain memory.
• TMemBuf()Constructs an empty object.
• UnderflowL(TInt)Re-fills the intermediate buffer and resets the start and end points of the read...

Inherited from MStreamBuf:

• Close()Closes the stream buffer.
• ERead
• EWrite
• PushL()Puts a cleanup item for this object onto the cleanup stack.
• Read(TDes8 &,TInt,TRequestStatus &)Reads data, asynchronously, from the stream buffer into the specified descriptor...
• Read(TDes8 &,TRequestStatus &)Reads data, asynchronously, from the stream buffer into the specified descriptor...
• ReadL(MStreamInput &)Reads data from the stream buffer into the specified data sink.
• ReadL(MStreamInput &,TInt)Reads data from the stream buffer into the specified data sink.
• ReadL(MStreamInput &,TStreamTransfer)Reads data from the stream buffer into the specified data sink.
• ReadL(TAny *,TInt)Reads data from the stream buffer into the specified memory location.
• ReadL(TDes8 &,TInt,TRequestStatus &)Reads data, asynchronously, from the stream buffer into the specified descriptor...
• ReadL(TDes8 &,TRequestStatus &)Reads data, asynchronously, from the stream buffer into the specified descriptor...
• Release()Frees resources before abandoning the stream buffer.
• SeekL(TMark,TStreamLocation,TInt)Moves the position of the read mark or the write mark in the stream.
• SeekL(TMark,TStreamPos)Moves the position of the read or write mark in the stream.
• SeekL(TRead,TInt)Moves the position of the read mark in the stream by the specified offset.
• SeekL(TRead,TStreamLocation,TInt)Moves the position of the read mark in the stream.
• SeekL(TWrite,TInt)Moves the position of the write mark in the stream by the specified offset.
• SeekL(TWrite,TStreamLocation,TInt)Moves the position of the write mark in the stream.
• SizeL()constGets the size of the stream.
• Synch()Synchronises the stream buffer with the stream, returning any error.
• SynchL()Synchronises the stream buffer with the stream, leaving if any error occurs.
• TMarkUsed to identify the type of mark in a stream.
• TReadIndicates that an operation applies to the read mark in a stream or to the read ...
• TWriteIndicates that an operation applies to the write mark in a stream or to the writ...
• TellL(TRead)constGets the position of the read mark within the stream.
• TellL(TWrite)constGets the position of the write mark within the stream.
• Write(const TDesC8 &,TInt,TRequestStatus &)
• Write(const TDesC8 &,TRequestStatus &)Writes data, asynchronously, from the specified descriptor into the stream buffe...
• WriteL(MStreamOutput &)Writes data into the stream buffer from the specified data source.
• WriteL(MStreamOutput &,TInt)Writes data into the stream buffer from the specified data source.
• WriteL(MStreamOutput &,TStreamTransfer)Writes data into the stream buffer from the specified data source.
• WriteL(const TAny *,TInt)Writes data from the specified memory location into the stream buffer.
• WriteL(const TDesC8 &,TInt,TRequestStatus &)Writes data, asynchronously, from the specified descriptor into the stream buffe...
• WriteL(const TDesC8 &,TRequestStatus &)Writes data, asynchronously, from the specified descriptor into the stream buffe...

Inherited from TStreamBuf:

• Avail(TArea)constGets the number of bytes available in the read or write area within the intermed...
• Avail(TRead)constGets the number of bytes available in the read area within the intermediate buff...
• Avail(TWrite)constGets the number of bytes available in the write area within the intermediate buf...
• DoReadL(MStreamInput &,TStreamTransfer)Reads data from the intermediate buffer and, if necessary, any remaining data fr...
• DoReadL(TAny *,TInt)Reads data from the intermediate buffer into the specified memory location.
• DoWriteL(MStreamOutput &,TStreamTransfer)
• DoWriteL(const TAny *,TInt)Writes data from the specified memory location into the intermediate buffer.
• End(TArea)constGets the current end point of the read or write area within the intermediate buf...
• End(TRead)constGets the current end point of the read area within the intermediate buffer.
• End(TWrite)constGets the current end point of the write area within the intermediate buffer.
• Ptr(TArea)constGets the current start point of the read or write area within the intermediate b...
• Ptr(TRead)constGets the current start point of the read area within the intermediate buffer.
• Ptr(TWrite)constGets the current start point of the write area within the intermediate buffer.
• SetBuf(TArea,TUint8 *,TUint8 *)Sets the start and end points of the read and/or the write area within the inter...
• SetBuf(TRead,TUint8 *,TUint8 *)Sets the start and end points of the read area within the intermediate buffer.
• SetBuf(TWrite,TUint8 *,TUint8 *)Sets the start and end points of the write area within the intermediate buffer.
• SetEnd(TArea,TUint8 *)
• SetEnd(TRead,TUint8 *)
• SetEnd(TWrite,TUint8 *)
• SetPtr(TArea,TUint8 *)Sets the start point of the read and/or the write area within the intermediate b...
• SetPtr(TRead,TUint8 *)Sets the start point of the write area within the intermediate buffer.
• SetPtr(TWrite,TUint8 *)Sets the start point of the write area within the intermediate buffer.
• TAreaUsed to identify the type of area within an intermediate buffer.

IMPORT_C TMemBuf();

Description

Constructs an empty object.

Call TMemBuf::Set(TUint8 *,TUint8 *,TInt) before using the object.

IMPORT_C void Set(TUint8 *aPtr, TUint8 *anEnd, TInt aMode=ERead|EWrite);

Description

Sets up the stream to use the specified area of plain memory.

Parameters

TUint8 *aPtr The start address for the area of plain memory that hosts the stream and that also acts as the intermediate buffer. TUint8 *anEnd The end address for the area of plain memory that hosts the stream and that also acts as the intermediate buffer. The addressed byte is outside the memory area. TInt aMode The mode in which the stream is to be used. It can be used in either or both read and write modes, represented by ERead and EWrite.

See also:

• MStreamBuf::TReadIndicates that an operation applies to the read mark in a stream or to the read ...
• MStreamBuf::TWriteIndicates that an operation applies to the write mark in a stream or to the writ...

protected: IMPORT_C virtual TInt UnderflowL(TInt aMaxLength);

Description

Re-fills the intermediate buffer and resets the start and end points of the read area.

The implementation of this function depends on the way the stream itself is implemented. For example, the in-memory streams have simple implementations.

Parameters

TInt aMaxLength The maximum amount of data required for the intermediate buffer.

Return value

TInt The amount of data available in the intermediate buffer.

protected: IMPORT_C virtual void OverflowL();

Description

Empties the intermediate buffer and resets the start and end points of the write area.

The implementation of this function depends on the way the stream itself is implemented. For example, the in-memory streams have simple implementations.

protected: IMPORT_C virtual TStreamPos DoSeekL(TMark aMark, TStreamLocation aLocation, TInt anOffset);

Description

Parameters

MStreamBuf::TMark aMark TStreamLocation aLocation TInt anOffset

Return value

TStreamPos