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CVJDeCompressor Class Reference

class CVJDeCompressor : public CVJDeCompressorIf

Van Jacobson TCP/IP header decompressor (RFC 1144)

Inherits from

CVJDeCompressor
- CVJDeCompressorIf
  - CObject
    - CBase

Public Member Functions
	CVJDeCompressor()
	~CVJDeCompressor()
void	CRCError()
void	ConstructL(CVJCompFactory *, TUint)
TBool	DecompVJComp(RMBufChain &)
TBool	DecompVJUncomp(RMBufChain &)

Private Member Functions
TBool	CheckStoredRxHeader(const TUint)
void	ClearFlag(const TUint)
void	CopyInNewHeaderL(RMBufChain , ThdrIP , ThdrTCP *, TUint, TUint16, TUint16)
void	CopyRecvHeader(const TUint, ThdrIP *)
TUint16	DecodeDelta(TUint8 **)
void	DecompAck(TUint8 *, ThdrTCP )
void	DecompIPId(const TUint, TUint8 *, ThdrIP )
void	DecompPushFlag(const TUint, ThdrTCP *)
void	DecompSWAU(const TUint, TUint8 *, ThdrTCP , TUint16)
void	DecompSeq(TUint8 *, ThdrTCP )
void	DecompUrgent(TUint8 *, ThdrTCP , TUint)
void	DecompWindow(TUint8 *, ThdrTCP )
void	DecompressFrameL(RMBufChain &, TUint8, TUint8, TUint8 *const , TUint, TUint16)
void	DoIPChecksum(ThdrIP *, TUint16)
void	EncodeDelta(TUint8 **, TUint16)
ThdrIP *	GetIPHeader(RMBufChain &)
void	GetStoredRxHeader(const TUint, ThdrIP , ThdrTCP )
TUint8 *	GetVJPtr(RMBufChain &, TUint16 *)
void	SetFlag(const TUint)
TBool	TestFlag(const TUint)

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()
	CObject::AccessCount()const
	CObject::CObject()
	CObject::Close()
	CObject::Dec()
	CObject::Extension_(TUint,TAny &,TAny )
	CObject::FullName()const
	CObject::Inc()
	CObject::Name()const
	CObject::Open()
	CObject::Owner()const
	CObject::SetName(const TDesC *)
	CObject::SetNameL(const TDesC *)
	CObject::SetOwner(CObject *)
	CObject::UniqueID()const
	CObject::~CObject()
	CVJDeCompressorIf::CVJDeCompressorIf()
	CVJDeCompressorIf::~CVJDeCompressorIf()

Private Attributes
TUint	iFlags
TUint	iLastRxConn
TUint	iNumVJSlots
TVJCompHdr *	iRxStates

Inherited Attributes
	CVJDeCompressorIf::iFactory

Constructor & Destructor Documentation

CVJDeCompressor()

CVJDeCompressor

(

)

~CVJDeCompressor()

~CVJDeCompressor

(

)

Member Functions Documentation

CRCError()

void

CRCError

(

)

[virtual]

Sets the discard flag after receiving a bad frame so that future decompressed packets don't get out of sync.

CheckStoredRxHeader(const TUint)

TBool

CheckStoredRxHeader

(

const TUint

aConnection

)

const [private]

Checks if the given VJ connection number has previously been filled in.

Parameters

const TUint aConnection

Valid VJ connection number to check

ClearFlag(const TUint)

void

ClearFlag

(

const TUint

aFlag

)

[private, inline]

Clear an internal flag.

Parameters

const TUint aFlag

Flag value to clear

ConstructL(CVJCompFactory *, TUint)

void	ConstructL	(	CVJCompFactory *	aFactory,
			TUint	aSlots
		)

Construct the CVJDeCompressor object.

Parameters

CVJCompFactory * aFactory	Factory that created this object
TUint aSlots	Value of the highest VJ connection number to be received

CopyInNewHeaderL(RMBufChain , ThdrIP , ThdrTCP *, TUint, TUint16, TUint16)

void	CopyInNewHeaderL	(	RMBufChain *	aPacket,
			ThdrIP *	aIPHeader,
			ThdrTCP *	aTCPHeader,
			TUint	aCompressedHeaderLength,
			TUint16	aIPHeaderLength,
			TUint16	aTCPHeaderLength
		)	[private]

Copy the uncompressed header into the proper location in the packet.

Parameters

RMBufChain * aPacket	MBuf chain containing packet to be updated
ThdrIP * aIPHeader	IP packet header
ThdrTCP * aTCPHeader	TCP header
TUint aCompressedHeaderLength	Length of VJ compression header
TUint16 aIPHeaderLength	Length of IP header
TUint16 aTCPHeaderLength	Length of TCP header

CopyRecvHeader(const TUint, ThdrIP *)

void	CopyRecvHeader	(	const TUint	aConnectionNumber,
			ThdrIP *	aHeader
		)	[private]

Caches a TCP/IP Header to be used as a reference to reconstruct future compressed headers.

Parameters

const TUint aConnectionNumber	Valid VJ connection number
ThdrIP * aHeader	TCP/IP header

DecodeDelta(TUint8 **)

TUint16

DecodeDelta

(

TUint8 **

aVJCompHeader

)

[private]

Decodes a compressed delta value.

Parameters

TUint8 ** aVJCompHeader

Pointer to pointer into VJ header buffer holding encoded value; returns with pointer incremented one past end of value

DecompAck(TUint8 **, ThdrTCP *)

void	DecompAck	(	TUint8 **	aVJCompHeader,
			ThdrTCP *	aTCPHeader
		)	[private]

Decompresses the Acknowledgement Number field.

Parameters

TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrTCP * aTCPHeader	TCP header to be updated

DecompIPId(const TUint, TUint8 **, ThdrIP *)

void	DecompIPId	(	const TUint	aChanges,
			TUint8 **	aVJCompHeader,
			ThdrIP *	aIPHeader
		)	[private]

Decompresses the IP Identification field.

Parameters

const TUint aChanges	The VJ change mask
TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrIP * aIPHeader	IP packet header to be updated

DecompPushFlag(const TUint, ThdrTCP *)

void	DecompPushFlag	(	const TUint	aChanges,
			ThdrTCP *	aHeader
		)	[private]

Decompresses the Push flag.

Parameters

const TUint aChanges	The VJ change mask
ThdrTCP * aHeader	TCP header to be updated

DecompSWAU(const TUint, TUint8 **, ThdrTCP *, TUint16)

void	DecompSWAU	(	const TUint	aChanges,
			TUint8 **	aVJCompHeader,
			ThdrTCP *	aTCPHeader,
			TUint16	aPreviousFrameLength
		)	[private]

Decompresses the special case SWAU type packet.

Parameters

const TUint aChanges	The VJ change mask
TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrTCP * aTCPHeader	TCP header to be updated
TUint16 aPreviousFrameLength	Length of cached packet for this VJ connection

DecompSeq(TUint8 **, ThdrTCP *)

void	DecompSeq	(	TUint8 **	aVJCompHeader,
			ThdrTCP *	aTCPHeader
		)	[private]

Decompresses the Sequence Number field.

Parameters

TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrTCP * aTCPHeader	TCP header to be updated

DecompUrgent(TUint8 **, ThdrTCP *, TUint)

void	DecompUrgent	(	TUint8 **	aVJCompHeader,
			ThdrTCP *	aTCPHeader,
			TUint	aChanges
		)	[private]

Decompresses the Urgent field.

Parameters

TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrTCP * aTCPHeader	TCP header to be updated
TUint aChanges	The VJ change mask

DecompVJComp(RMBufChain &)

TBool

DecompVJComp

(

RMBufChain &

aPacket

)

[virtual]

Decompresses a VJ compressed packet in place.

DecompVJUncomp

Parameters

RMBufChain & aPacket

MBuf chain containing packet

DecompVJUncomp(RMBufChain &)

TBool

DecompVJUncomp

(

RMBufChain &

aPacket

)

[virtual]

Handles a VJ uncompressed packet. Stores the packet header in the appropriate VJ connection slot.

DecompVJComp

Parameters

RMBufChain & aPacket

MBuf chain containing packet

DecompWindow(TUint8 **, ThdrTCP *)

void	DecompWindow	(	TUint8 **	aVJCompHeader,
			ThdrTCP *	aTCPHeader
		)	[private]

Decompresses the Window field.

Parameters

TUint8 ** aVJCompHeader	Pointer to the pointer to the VJ compressed header
ThdrTCP * aTCPHeader	TCP header to be updated

DecompressFrameL(RMBufChain &, TUint8, TUint8, TUint8 *const, TUint, TUint16)

void	DecompressFrameL	(	RMBufChain &	aPacket,
			TUint8	aConnection,
			TUint8	aChanges,
			TUint8 *const	aInitialHeaderPtr,
			TUint	Offset,
			TUint16	aCurrentFrameLength
		)	[private]

Uncompresses a VJ compressed TCP/IP header.

leave: KErrCorrupt if aPacket is corrupt

Parameters

RMBufChain & aPacket	MBuf chain containing packet to be updated
TUint8 aConnection	VJ connection number
TUint8 aChanges	The VJ change mask
TUint8 *const aInitialHeaderPtr	Beginning of the compressed VJ header
TUint Offset	Offset from start of packet to TCP checksum field
TUint16 aCurrentFrameLength	Length of the compressed packet

DoIPChecksum(ThdrIP *, TUint16)

void	DoIPChecksum	(	ThdrIP *	aIPHeader,
			TUint16	aIPHeaderLength
		)	[private]

Calculate the IP checksum and store it in the given IP packet header. See RFC 1071.

Parameters

ThdrIP * aIPHeader	IP packet header
TUint16 aIPHeaderLength	Length of IP header in bytes (must be even)

EncodeDelta(TUint8 **, TUint16)

void	EncodeDelta	(	TUint8 **	aVJCompHeader,
			TUint16	aValue
		)	[private]

Parameters

TUint8 ** aVJCompHeader
TUint16 aValue

GetIPHeader(RMBufChain &)

ThdrIP *

GetIPHeader

(

RMBufChain &

aChain

)

[private]

Extracts the IP Header from the packet even though there is a buffer of Info on the front. This is used in VJ, to avoid the awful hack in the main receive path. PRR 20-11-97

Parameters

RMBufChain & aChain

MBuf chain containing packet

GetStoredRxHeader(const TUint, ThdrIP , ThdrTCP )

void	GetStoredRxHeader	(	const TUint	aConnectionNumber,
			ThdrIP *	aIPHeader,
			ThdrTCP *	aTCPHeader
		)	[private]

Retrieves a packet header from the VJ connection cache.

Parameters

const TUint aConnectionNumber	Valid VJ connection number to retrieve
ThdrIP * aIPHeader	IP packet header
ThdrTCP * aTCPHeader	TCP header

GetVJPtr(RMBufChain &, TUint16 *)

TUint8 *	GetVJPtr	(	RMBufChain &	aChain,
			TUint16 *	aCurrentFrameLength
		)	[private]

Gets a pointer to the VJ Header even though there is a pseudo (Adam) buffer of Info on the front.

Parameters

RMBufChain & aChain	MBuf chain containing packet
TUint16 * aCurrentFrameLength	Returns the length of the packet

SetFlag(const TUint)

void

SetFlag

(

const TUint

aFlag

)

[private, inline]

Set an internal flag.

Parameters

const TUint aFlag

Flag value to set

TestFlag(const TUint)

TBool

TestFlag

(

const TUint

aFlag

)

[private, inline]

Test if an internal flag is set.

Parameters

const TUint aFlag

Flag value to test

Member Data Documentation

TUint iFlags

TUint

iFlags

[private]

Set to KVJDiscard while discarding received packets due to lost synchronization

TUint iLastRxConn

TUint

iLastRxConn

[private]

VJ connection number of the last valid packet received

TUint iNumVJSlots

TUint

iNumVJSlots

[private]

Index of the highest-numbered VJ connection

TVJCompHdr * iRxStates

TVJCompHdr *

iRxStates

[private]

Pointer to start of array of VJ connections

CVJDeCompressor Class Reference

Inherits from

Constructor & Destructor Documentation

CVJDeCompressor()

~CVJDeCompressor()

Member Functions Documentation

CRCError()

CheckStoredRxHeader(const TUint)

Parameters

ClearFlag(const TUint)

Parameters

ConstructL(CVJCompFactory *, TUint)

Parameters

CopyInNewHeaderL(RMBufChain *, ThdrIP *, ThdrTCP *, TUint, TUint16, TUint16)

Parameters

CopyRecvHeader(const TUint, ThdrIP *)

Parameters

DecodeDelta(TUint8 **)

Parameters

DecompAck(TUint8 **, ThdrTCP *)

Parameters

DecompIPId(const TUint, TUint8 **, ThdrIP *)

Parameters

DecompPushFlag(const TUint, ThdrTCP *)

Parameters

DecompSWAU(const TUint, TUint8 **, ThdrTCP *, TUint16)

Parameters

DecompSeq(TUint8 **, ThdrTCP *)

Parameters

DecompUrgent(TUint8 **, ThdrTCP *, TUint)

Parameters

DecompVJComp(RMBufChain &)

Parameters

DecompVJUncomp(RMBufChain &)

Parameters

DecompWindow(TUint8 **, ThdrTCP *)

Parameters

DecompressFrameL(RMBufChain &, TUint8, TUint8, TUint8 *const, TUint, TUint16)

Parameters

DoIPChecksum(ThdrIP *, TUint16)

Parameters

EncodeDelta(TUint8 **, TUint16)

Parameters

GetIPHeader(RMBufChain &)

Parameters

GetStoredRxHeader(const TUint, ThdrIP *, ThdrTCP *)

Parameters

GetVJPtr(RMBufChain &, TUint16 *)

Parameters

SetFlag(const TUint)

Parameters

TestFlag(const TUint)

Parameters

Member Data Documentation

TUint iFlags

TUint iLastRxConn

TUint iNumVJSlots

TVJCompHdr * iRxStates

CopyInNewHeaderL(RMBufChain , ThdrIP , ThdrTCP *, TUint, TUint16, TUint16)

GetStoredRxHeader(const TUint, ThdrIP , ThdrTCP )