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TPacketPoker Class Reference

class TPacketPoker

Provides a utility for linear scanning of a chain of RMBuf objects (an RMBufChain ).

An object of this type maintains a current point in the RMBufChain . This point can only move forward, and a leave occurs if the point advances beyond the end of the chain.

Any pointers and aligns arranged before the current point, remain valid: for example, you can save a reference and advance the pointer, and the reference remains usable.

If instead you need to go to a single specified offset, then use RMBufChain::Goto() or RMBufPacketPeek::Access() .

Post-condition: A Generic implementation assert: after construct, iTail == 0 iff iCurrent == 0 (all scanned), or in other words: as long as there are bytes after current point, iTail will be non-zero (and More() returns ETrue). All methods maintain this invariant or leave, if impossible.

Some other utility methods, not directly related to scanning, are also included.

Since: v7.0

Public Member Functions
	TPacketPoker ( RMBufChain &)
TBool	AtBegin ()
IMPORT_C TBool	IsExtensionHeader ( TInt )
TBool	More ()
TUint8 *	Ptr ()
TUint8 *	ReferenceAndSkipL ( TInt )
TUint8 *	ReferenceL ( TInt )
TInt	Remainder ()
void	SkipL ( TInt )

Private Member Functions
IMPORT_C TUint8 *	AdjustL ( TInt )
IMPORT_C void	OverL ( TInt )

Private Attributes
RMBuf *	iCurrent
TInt	iOffset
TInt	iTail

Constructor & Destructor Documentation

TPacketPoker(RMBufChain &)

IMPORT_C

TPacketPoker

(

RMBufChain &

aChain

)

Constructor.

Parameters

RMBufChain & aChain

The RMBuf chain to be poked.

Member Functions Documentation

AdjustL(TInt)

IMPORT_C TUint8 *

AdjustL

(

TInt

aSize

)

[private]

Arrange contiguous run of bytes.

Arragen content of RMBuf chain so that starting from the current offset, a number of bytes is accessible in contiguous memory.

leave: KErrEof, if request cannot be satisfied.

Parameters

TInt aSize

The requested length,

AtBegin()

TBool

AtBegin

(

)

const [inline]

Tests whether the current point is at the beginning of an RMBuf .

IsExtensionHeader(TInt)

IMPORT_C TBool

IsExtensionHeader

(

TInt

aProtocolId

)

[static]

Tests whether a protocol is a known IPv6 extension header using the standard format.

Parameters

TInt aProtocolId

Protocol ID to test.

More()

TBool

(

)

const [inline]

Tests whether there is more data to scan.

OverL(TInt)

IMPORT_C void

OverL

(

TInt

aSize

)

[private]

Skip over bytes.

leave: KErrEof, if skipped past end of chain.

Parameters

TInt aSize

The number of bytes to skip

Ptr()

TUint8 *

Ptr

(

)

const [inline]

Raw pointer to the current point (can be invalid, if iTail = 0).

Note:

Internal "unsafe" method

ReferenceAndSkipL(TInt)

TUint8 *

ReferenceAndSkipL

(

TInt

aSize

)

[inline]

Gets a pointer to the current point, such that at least the specified minimum number of bytes can be read, and moves the point the specified number of bytes forward.

leave: KErrEof if the request cannot be satisfied.

Parameters

TInt aSize

Specified minimum number of bytes to be read through the returned pointer, and the number of bytes to move forward

ReferenceL(TInt)

TUint8 *

ReferenceL

(

TInt

aSize = 1

)

[inline]

Gets a pointer to the current point, such that at least the specified minimum number of bytes can be read.

leave: KErrEof if the request cannot be satisfied.

Parameters

TInt aSize = 1

Specified minimum number of bytes to be read through the returned pointer.

Remainder()

TInt

Remainder

(

)

const [inline]

Gets the length of the contiguous space after the current point.

SkipL(TInt)

void

SkipL

(

TInt

aSize

)

[inline]

Moves the current point forward a specified number of bytes.

leave: KErrEof if the request cannot be satisfied.

Parameters

TInt aSize

Number of bytes to move forward

Member Data Documentation

RMBuf * iCurrent

RMBuf *

iCurrent

[private]

The RMBuf of the current point.

TInt iOffset

TInt

iOffset

[private]

The offset of the current point in the RMBuf .

TInt iTail

TInt

iTail

[private]

Remaining bytes starting from the current point in the RMBuf .