Asn1PerDecodeBuffer Class Reference

Inheritance diagram for Asn1PerDecodeBuffer:

List of all members.

Public Member Functions
	Asn1PerDecodeBuffer (System.IO.Stream istream, bool aligned)
	Asn1PerDecodeBuffer (byte[] msgdata, bool aligned)
virtual void	BinDump (System.IO.StreamWriter outs, System.String varName)
virtual void	BinDump (System.String varName)
virtual void	ByteAlign ()
virtual bool	DecodeBit ()
virtual bool	DecodeBit (System.String ident)
virtual int	DecodeBitsToInt (int nbits)
virtual int	DecodeBitsToInt (int nbits, System.String ident)
virtual long	DecodeBitsToLong (int nbits)
virtual long	DecodeBitsToLong (int nbits, System.String ident)
virtual void	DecodeBitsToOctetArray (byte[] data, int offset, int nbits)
virtual void	DecodeBitsToOctetArray (byte[] data, int offset, int bitOffset, int nbits, System.String ident)
virtual void	DecodeBitsToOctetArray (byte[] data, int offset, int nbits, System.String ident)
virtual void	DecodeCharString (int nchars, int abpc, int ubpc, Asn1CharSet charSet, System.Text.StringBuilder sbuf)
virtual long	DecodeConsWholeNumber (long rangeValue)
virtual long	DecodeConsWholeNumber (long rangeValue, System.String ident)
virtual long	DecodeExtLength ()
virtual long	DecodeInt (int nocts, bool signExtend)
virtual long	DecodeInt (int nocts, bool signExtend, System.String ident)
virtual long	DecodeLength (long lower, long upper)
virtual long	DecodeLength ()
virtual int	DecodeSmallLength ()
virtual int	DecodeSmallNonNegWholeNumber ()
virtual long	DecodeUnconsLength ()
virtual bool	IsAligned ()
virtual void	MoveBitCursor (long offset)
override int	ReadByte ()
virtual void	SetAligned (bool data)
override void	SetInputStream (byte[] msgdata, int offset, int length)
void	SetSizeConstraint (long lower, long upper)
void	SetSizeConstraintExt (long lower, long upper, long extLower, long extUpper)
Static Public Member Functions
static Asn1PerDecodeBuffer	SetBuffer (Asn1PerDecodeBuffer buffer, byte[] msgdata, bool aligned)
Protected Attributes
internal Asn1PerTraceHandler	mTraceHandler
Properties
virtual long	BitOffset [get]
virtual int	MsgBitCnt [get]
virtual Asn1PerTraceHandler	TraceHandler [get]

---

Detailed Description

This class handles the decoding of ASN.1 messages as specified in the Packed Encoding Rules (PER) ITU-T X.691 standard.

---

Constructor & Destructor Documentation

Asn1PerDecodeBuffer	(	byte[]	msgdata,
		bool	aligned
	)

This constructor creates a PER Decode buffer object that references an encoded ASN.1 message.

Parameters:

	msgdata	Byte array containing an encoded ASN.1 message.
	aligned	true for specifying PER aligned; otherwise false for unaligned encoding.

Asn1PerDecodeBuffer	(	System.IO.Stream	istream,
		bool	aligned
	)

This constructor creates a PER Decode buffer object that references an encoded ASN.1 message. In this case, the message is passed in using an System.IO.Stream object.

Parameters:

	istream	Input stream containing an encoded ASN.1 message.
	aligned	Boolean specifying PER aligned or unaligned encoding.

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Member Function Documentation

virtual void BinDump	(	System.IO.StreamWriter	outs,
		System.String	varName
	)			[virtual]

This method dumps the encoded message in a human-readable format showing a bit trace of all fields to the given output stream.

Parameters:

	outs	StreamWriter object to which output should be written
	varName	Name of top-level message object variable

virtual void BinDump

(

System.String

varName

)

[virtual]

This method invokes an overloaded version of BinDump to dump the encoded message to standard output.

Parameters:

varName

Name of top-level message object variable

virtual void ByteAlign

(

)

[virtual]

This methods byte-aligns the buffer.

Implements Asn1PerMessageBuffer.

virtual bool DecodeBit

(

)

[virtual]

This method decodes a single bit value. The ident argument which is used for tracing is defaulted to 'value'.

Returns:

Boolean value of bit that was decoded.

virtual bool DecodeBit

(

System.String

ident

)

[virtual]

This method decodes a single bit value.

Parameters:

ident

Bit field identifier name for tracing.

Returns:

Boolean value of bit that was decoded.

virtual int DecodeBitsToInt

(

int

nbits

)

[virtual]

This method decodes bits from the input stream into a standard integer value. Up to 32 bits can be decoded. The bits are placed in the least-significant bytes of the integer. The ident argument which is used for tracing is defaulted to 'value'.

Returns:

Integer value containing decoded bits

Parameters:

nbits

Number of bits to Decode

virtual int DecodeBitsToInt	(	int	nbits,
		System.String	ident
	)			[virtual]

This method decodes bits from the input stream into a standard integer value. Up to 32 bits can be decoded. The bits are placed in the least-significant bytes of the integer.

Parameters:

	nbits	Number of bits to Decode
	ident	Bit field identifier name for tracing.

Returns:

Integer value containing decoded bits

virtual long DecodeBitsToLong

(

int

nbits

)

[virtual]

This method decodes bits from the input stream into a long integer value. Up to 64 bits can be decoded. The bits are placed in the least-significant bytes of the long integer. The ident argument which is used for tracing is defaulted to 'value'.

Parameters:

nbits

Number of bits to Decode

Returns:

Long integer value containing decoded bits

virtual long DecodeBitsToLong	(	int	nbits,
		System.String	ident
	)			[virtual]

This method decodes bits from the input stream into a long integer value. Up to 64 bits can be decoded. The bits are placed in the least-significant bytes of the long integer.

Returns:

Long integer value containing decoded bits

Parameters:

	nbits	Number of bits to Decode
	ident	Bit field identifier name for tracing.

virtual void DecodeBitsToOctetArray	(	byte[]	data,
		int	offset,
		int	nbits
	)			[virtual]

This method decodes bits from the input stream into an array of octets. The user is expected to have provided an array large enough to hold the number of bits requested to be decoded. The ident argument which is used for tracing is defaulted to 'value'.

Parameters:

	data	Octet array for decoded data
	offset	Starting byte offset into array
	nbits	Number of bits to Decode

virtual void DecodeBitsToOctetArray	(	byte[]	data,
		int	offset,
		int	bitOffset,
		int	nbits,
		System.String	ident
	)			[virtual]

This method decodes bits from the input stream into an array of octets. The user is expected to have provided an array large enough to hold the number of bits requested to be decoded.

The first bit is decoded into the given offset byte at the MSB if bitOffset == 0, and at the LSB if bitOffset == 7.

Parameters:

	data	Octet array for decoded data
	offset	Starting byte offset into array
	bitOffset	Where in first byte the first bit goes
	nbits	Number of bits to Decode
	ident	Bit field identifier name for tracing.

virtual void DecodeBitsToOctetArray	(	byte[]	data,
		int	offset,
		int	nbits,
		System.String	ident
	)			[virtual]

This method decodes bits from the input stream into an array of octets. The user is expected to have provided an array large enough to hold the number of bits requested to be decoded.

Parameters:

	data	Octet array for decoded data
	offset	Starting byte offset into array
	nbits	Number of bits to Decode
	ident	Bit field identifier name for tracing.

virtual void DecodeCharString	(	int	nchars,
		int	abpc,
		int	ubpc,
		Asn1CharSet	charSet,
		System.Text.StringBuilder	sbuf
	)			[virtual]

This method decodes the contents of a known-multiplier character string. This version of the method assumes a permitted alphabet constraint is in place.

Parameters:

	nchars	Number of characters
	abpc	Number of bits per character (aligned)
	ubpc	Number of bits per character (unaligned)
	charSet	Object representing the permitted alphabet constraint character set (optional)
	sbuf	String buffer to receive decoded result

virtual long DecodeConsWholeNumber

(

long

rangeValue

)

[virtual]

This method implements the rules to Decode a constrained whole number as specified in section 10.5 of the X.691 standard. The ident argument which is used for tracing is defaulted to 'value'.

Parameters:

rangeValue

lower - upper + 1

Returns:

Decoded adjusted value = value - lower range endpoint value

virtual long DecodeConsWholeNumber	(	long	rangeValue,
		System.String	ident
	)			[virtual]

This method implements the rules to Decode a constrained whole number as specified in section 10.5 of the X.691 standard.

Parameters:

	rangeValue	upper - lower + 1. Treated as unsigned, with 0 representing 2^64.
	ident	Tracing identifier

Returns:

Decoded adjusted value = value - lower range endpoint value

virtual long DecodeExtLength

(

)

[virtual]

This method decodes an extension length value. Note that the decoded length is not what is returned. The bit offset to the start of the next element within the Decode buffer is returned.

Returns:

Bit offset to next element in buffer

virtual long DecodeInt	(	int	nocts,
		bool	signExtend
	)			[virtual]

This method implements the rules to Decode an unconstrained integer value. The ident argument which is used for tracing is defaulted to 'value'.

Returns:

Decoded long integer value

Parameters:

	nocts	Number of octets to Decode
	signExtend	Sign extend resulting value

virtual long DecodeInt	(	int	nocts,
		bool	signExtend,
		System.String	ident
	)			[virtual]

This method implements the rules to Decode an unconstrained integer value.

Returns:

Decoded long integer value

Parameters:

	nocts	Number of octets to Decode
	signExtend	Sign extend resulting value
	ident	Tracing identifier

virtual long DecodeLength	(	long	lower,
		long	upper
	)			[virtual]

This method decodes a constrained length determinant value.

Parameters:

	lower	Lower bound (inclusive) of length value range
	upper	Upper bound (inclusive) of length value range

Returns:

Decoded length value

virtual long DecodeLength

(

)

[virtual]

This method decodes either a constrained or unconstrained length depending on whether a size constraint object is set in this object.

Returns:

Decoded length value.

virtual int DecodeSmallLength

(

)

[virtual]

This method implements the rules to Decode a normally small length as specified in section 11.9 of the X.691 standard.

Returns:

Decoded int value

virtual int DecodeSmallNonNegWholeNumber

(

)

[virtual]

This method implements the rules to Decode a small non-negative whole number as specified in section 10.6 of the X.691 standard.

Returns:

Decoded int value

virtual long DecodeUnconsLength

(

)

[virtual]

This method decodes a general (unconstrained) length determinant value as described in section 11.9 of the 2008 X.691 standard. The maximum value that will be returned is 64K which is the largest length fragment size defined for PER. If a value of 16K or larger is returned, the user must repeat this call to fully Decode the fragmented contents.

Returns:

Decoded length value. If the returned value is >= 16k, this indicates a fragmented length was decoded. The user must call this method again after the data fragment is decoded to get the next fragment length.

virtual bool IsAligned

(

)

[virtual]

This method tests if PER alignment is turned on or off.

Returns:

true for PER aligned encoding or false for unaligned encoding.

Implements Asn1PerMessageBuffer.

virtual void MoveBitCursor

(

long

offset

)

[virtual]

This method moves the bit cursor to the given offset.

Parameters:

offset

Absolute bit offset value

override int ReadByte

(

)

[virtual]

This method returns the next available 8-bit value from the input stream. It is implemented differently for BER/DER and PER to take into account odd alignments in PER.

Returns:

Next 8-bit byte value from input stream

Implements Asn1DecodeBuffer.

virtual void SetAligned

(

bool

data

)

[virtual]

This method is used to turn PER aligned encoding on or off.

Parameters:

data

true for PER aligned encoding or false for unaligned encoding.

static Asn1PerDecodeBuffer SetBuffer	(	Asn1PerDecodeBuffer	buffer,
		byte[]	msgdata,
		bool	aligned
	)			[static]

This method will create or reinitialize a PER Decode message buffer object to read data from the given byte array. If the existing buffer reference is null, a new buffer will be created; otherwise, the existing buffer will be reused.

Parameters:

	buffer	Existing message buffer object
	msgdata	Byte array containing message data
	aligned	true specifying PER aligned or false for unaligned encoding.

Returns:

Asn1PerDecodeBuffer to read data from the given byte array

override void SetInputStream	(	byte[]	msgdata,
		int	offset,
		int	length
	)			[virtual]

This method will set the input stream from which data is read. This version of the method allows a byte array containing encoded data to be specified.

Parameters:

	msgdata	Byte array containing encoded message data
	offset	Starting offset of data in the byte array
	length	Length (in bytes) of the encoded data

Reimplemented from Asn1DecodeBuffer.

void SetSizeConstraint	(	long	lower,
		long	upper
	)

This method is used to set a size constraint within the buffer object. The constraint will only be set if an existing constraint is not already in place (i.e. if the existing reference is not null). This is used for length decoding of SEQUENCE OF objects to pass constraints applied to referenced objects to the base object.

void SetSizeConstraintExt	(	long	lower,
		long	upper,
		long	extLower,
		long	extUpper
	)

This method is used to set an extensible size constraint in the buffer object. The constraint will only be set if an existing constraint is not already in place (i.e. if the existing reference is not null). This is used for length encoding of SEQUENCE OF objects to pass constraints applied to referenced objects to the base object.

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Member Data Documentation

internal Asn1PerTraceHandler mTraceHandler [protected]

Variable holds the PER message trace handler

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Property Documentation

virtual long BitOffset [get]

Gets the absolute offset to the current bit in the Decode buffer.

Value: offset to current bit in Decode buffer

virtual int MsgBitCnt [get]

Gets the number of bits in the encoded PER message.

Value: count of bits in encoded message

Implements Asn1PerMessageBuffer.

virtual Asn1PerTraceHandler TraceHandler [get]

Gets a reference to the internal trace handler object used to trace the bit fields within a PER message.

Value: Asn1PerTraceHandler object

Implements Asn1PerMessageBuffer.