com.objsys.asn1j.runtime

Class Asn1DecodeBitBuffer

java.lang.Object

com.objsys.asn1j.runtime.Asn1MessageBufferBase

com.objsys.asn1j.runtime.Asn1MessageBuffer

com.objsys.asn1j.runtime.Asn1DecodeBuffer

com.objsys.asn1j.runtime.Asn1DecodeBitBuffer

All Implemented Interfaces:

Asn1BitMessageBuffer

Direct Known Subclasses:

Asn1NasDecodeBuffer, Asn1OerDecodeBuffer, Asn1PerDecodeBuffer

public class Asn1DecodeBitBuffer
extends Asn1DecodeBuffer
implements Asn1BitMessageBuffer

This class handles handles decoding where the decode buffer is viewed as a set of bits (i.e. a bit offset is maintained).

Field Summary

Fields

Modifier and Type	Field and Description
protected Asn1PerTraceHandler	mTraceHandler

Fields inherited from class com.objsys.asn1j.runtime.Asn1DecodeBuffer

mByteCount

Fields inherited from class com.objsys.asn1j.runtime.Asn1MessageBufferBase

context, mTypeCode

Constructor Summary

Constructors

Constructor and Description
Asn1DecodeBitBuffer(byte[] msgdata) This constructor creates a decode buffer object that references an encoded ASN.1 message.
Asn1DecodeBitBuffer(java.io.InputStream istream) This constructor creates a decode buffer object that references an encoded ASN.1 message.

Method Summary

Modifier and Type	Method and Description
void	binDump(java.io.PrintStream out, java.lang.String varName) This method dumps the encoded message in a human-readable format showing a bit trace of all fields to the given print output stream.
void	binDump(java.lang.String varName) This method invokes an overloaded version of binDump to dump the encoded message to standard output.
void	byteAlign() This methods byte-aligns the buffer.
boolean	decodeBit() This method decodes a single bit value.
int	decodeBitsToInt(int nbits) This method decodes bits from the input stream into a standard integer value.
long	decodeBitsToLong(int nbits) This method decodes bits from the input stream into a long integer value.
void	decodeBitsToOctetArray(byte[] value, int offset, int nbits) This method decodes bits from the input stream into an array of octets.
void	decodeBitsToOctetArray(byte[] value, int offset, int bitOffset, int nbits) This method decodes bits from the input stream into an array of octets.
int	getAvailableBits() Return a number of bits that can definitely be read from this buffer without causing an end of buffer exception.
long	getBitOffset() This method returns the absolute offset to the current bit in the decode buffer.
int	getBitOffsetInByte() Return the bit offset, within the byte, of the next bit to be read.
int	getMsgBitCnt() This method returns the number of bits in the encoded PER message.
Asn1PerTraceHandler	getTraceHandler() This method will return a reference to the internal trace handler object used to trace the bit fields within a PER message.
boolean	hasMoreBits() This method returns true if there are more bits to be read from this buffer.
void	mark(int readLimit) This method is used to mark the current position in the input stream for retry processing.
void	moveBitCursor(long offset) This method moves the bit cursor to the given offset.
int	readByte() This method returns the next available 8-bit value from the input stream.
void	reset() This method is used to reset the current position in the input stream back to the location of the last 'mark' call.
void	setInputStream(byte[] msgdata, int offset, int length) This method will set the input stream from which data is read.
void	skipBits(long bits) Skip the given number of bits.

Methods inherited from class com.objsys.asn1j.runtime.Asn1DecodeBuffer

addCaptureBuffer, capture, decodeIntValue, decodeOIDContents, decodeOIDContentsBig, decodeRelOIDContents, decodeRelOIDContentsBig, getByteCount, getInputStream, getLazyOpenTypeDecode, hexDump, init, read, read, read, read2Bytes, read4Bytes, removeCaptureBuffer, setLazyOpenTypeDecode, skip, skipOIDContents, skipRelOIDContents

Methods inherited from class com.objsys.asn1j.runtime.Asn1MessageBuffer

addNamedEventHandler, getEventHandlerListCount, hasEventHandlers, invokeCharacters, invokeEndElement, invokeStartElement, setEventHandlerList

Methods inherited from class com.objsys.asn1j.runtime.Asn1MessageBufferBase

getContext, hexDump, hexDump, setKey, setTypeCode

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.objsys.asn1j.runtime.Asn1BitMessageBuffer

getInputStream

Field Detail

mTraceHandler

protected Asn1PerTraceHandler mTraceHandler

Constructor Detail

Asn1DecodeBitBuffer

public Asn1DecodeBitBuffer(byte[] msgdata)

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

Parameters:

msgdata - Byte array containing an encoded ASN.1 message.

Asn1DecodeBitBuffer

public Asn1DecodeBitBuffer(java.io.InputStream istream)

This constructor creates a decode buffer object that references an encoded ASN.1 message. In this case, the message is passed in using an InputStream object.

Parameters:

istream - Input stream containing an encoded ASN.1 message.

Method Detail

getTraceHandler

public Asn1PerTraceHandler getTraceHandler()

This method will return a reference to the internal trace handler object used to trace the bit fields within a PER message.

Specified by:

getTraceHandler in interface Asn1BitMessageBuffer

binDump

public void binDump(java.lang.String varName)

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

binDump

public void binDump(java.io.PrintStream out,
                    java.lang.String varName)

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

Parameters:

out - PrintStream object to which output should be written

varName - Name of top-level message object variable

byteAlign

public void byteAlign()

This methods byte-aligns the buffer.

Specified by:

byteAlign in interface Asn1BitMessageBuffer

decodeBit

public boolean decodeBit()
                  throws Asn1EndOfBufferException,
                         java.io.IOException

This method decodes a single bit value.

Returns:

Boolean value of bit that was decoded.

Throws:

Asn1EndOfBufferException

java.io.IOException

decodeBitsToLong

public long decodeBitsToLong(int nbits)
                      throws Asn1Exception,
                             java.io.IOException

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.

Parameters:

nbits - Number of bits to decode

Returns:

Long integer value containing decoded bits

Throws:

Asn1Exception

java.io.IOException

decodeBitsToInt

public int decodeBitsToInt(int nbits)
                    throws Asn1Exception,
                           java.io.IOException

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

Returns:

Integer value containing decoded bits

Throws:

Asn1Exception

java.io.IOException

decodeBitsToOctetArray

public void decodeBitsToOctetArray(byte[] value,
                                   int offset,
                                   int nbits)
                            throws Asn1Exception,
                                   java.io.IOException

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:

value - Octet array for decoded data

offset - Starting byte offset into array

nbits - Number of bits to decode

Throws:

Asn1Exception

java.io.IOException

decodeBitsToOctetArray

public void decodeBitsToOctetArray(byte[] value,
                                   int offset,
                                   int bitOffset,
                                   int nbits)
                            throws Asn1Exception,
                                   java.io.IOException

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:

value - 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

Throws:

Asn1Exception

java.io.IOException

getBitOffsetInByte

public final int getBitOffsetInByte()

Return the bit offset, within the byte, of the next bit to be read. The returns 7 for the most significant bit, and 0 for the least significant bit.

Returns:

getBitOffset

public final long getBitOffset()

This method returns the absolute offset to the current bit in the decode buffer. This returns 0 when the first bit of the message is the next bit to be decoded.

Returns:

Offset to current bit in decode buffer

getMsgBitCnt

public final int getMsgBitCnt()

This method returns the number of bits in the encoded PER message.

Specified by:

getMsgBitCnt in interface Asn1BitMessageBuffer

Returns:

Count of bits in encoded message

getAvailableBits

public final int getAvailableBits()

Return a number of bits that can definitely be read from this buffer without causing an end of buffer exception. This only returns zero when the end of the buffer has been reached (or there is some error trying to read from the stream). There may be many more bits available in the underlying stream than what is returned by this function. This might need to read a byte from the underlying stream to determine whether there are more bytes or not. If it cannot read from the stream, this will return 0.

Returns:

hasMoreBits

public final boolean hasMoreBits()

This method returns true if there are more bits to be read from this buffer. This might need to read a byte from the underlying stream to determine whether there are more bytes or not. If it cannot do so, this will return false;

mark

public void mark(int readLimit)

This method is used to mark the current position in the input stream for retry processing. It is equivalent to the Java InputStream 'mark' method.

Overrides:

mark in class Asn1DecodeBuffer

Parameters:

readLimit - Max number of bytes that can be read before mark becomes invalid.

moveBitCursor

public final void moveBitCursor(long offset)
                         throws Asn1EndOfBufferException,
                                java.io.IOException

This method moves the bit cursor to the given offset.

Parameters:

offset - Absolute bit offset value

Throws:

Asn1EndOfBufferException

java.io.IOException

readByte

public final int readByte()
                   throws Asn1Exception,
                          java.io.IOException

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.

Specified by:

readByte in class Asn1DecodeBuffer

Returns:

Next 8-bit byte value from input stream

Throws:

Asn1Exception

java.io.IOException

reset

public void reset()

This method is used to reset the current position in the input stream back to the location of the last 'mark' call. It is equivalent to the Java InputStream 'reset' method. This does NOT restore the container stack to its state at the last mark(). It seems unlikely the container stack would be changed between a mark() and a reset().

Overrides:

reset in class Asn1DecodeBuffer

setInputStream

public final void setInputStream(byte[] msgdata,
                                 int offset,
                                 int length)

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.

Overrides:

setInputStream in class Asn1DecodeBuffer

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

skipBits

public final void skipBits(long bits)
                    throws java.io.IOException,
                           Asn1EndOfBufferException

Skip the given number of bits. This many bits must be present or else this will throw Asn1EndOfBufferException.

Parameters:

bits -

Throws:

java.io.IOException

Asn1EndOfBufferException