org.limitless.util
Class BitDestination

java.lang.Object
  org.limitless.util.BitDestination

public class BitDestination
extends java.lang.Object

This class provides a 'sink' for data trickled in a bit or bits at a time, instead of bytes at a time. This is especially useful for protocols that have complex headers with binary-packed fields. Once all the bits have been processed through this, it provides an array of bytes or ints as desired.

Version:

$Header: /repository/nmc/java/org/limitless/util/BitDestination.java,v 1.2 2004/07/08 18:17:39 brianj Exp $

Author:

Brian Jones

Field Summary

private int	bitIndex where the next bit will go in the last byte
private int	byteIndex depth used
private int	currentInt the int being built (bitIndex is how far from the left the next bit will go)
(package private) static org.apache.log4j.Logger	logger Log4J Logger
private static long[]	maskHighOrder The index value to the array indicates the number of bits that you want to REMAIN (it masks off the bits HIGHER than the chosen)
private java.util.List	values this holds each byte as it fills

Constructor Summary

BitDestination()

Method Summary

void	addBits(boolean value) Add a boolean, if it's true, a 1 is added, and if false, a 0 is added.
void	addBits(int value, int bits) Add 'bits' of value into the stream.
void	addBits(long value, int bits) Add 'bits' of value into the stream.
void	addBytes(byte[] value) This adds all the bytes in 'value' to the end of the buffer
void	addBytes(byte[] value, int startingByte, int bytesToFill) This adds a sub-set of all the bytes in value to the end of the buffer
void	addBytes(java.lang.String value, int bytesToFill) This adds the binary representation of the string in 'value' and pads it or chops it as needed to fit into bytesToFill bytes ensuring that the resulting block of data added is exactly bytesToFill bytes long.
private void	addRawBits(long value, int bits) This does the shifting and applying of a portion of value bits wide into the system.
byte[]	asBytes() Fetch the data as an array of bytes
int[]	asInts() Fetch teh data as an array of ints
int	getCurrentBitPosition() This is seldom used and is how many bits of the last byte have been used so far.
int	getCurrentBytePosition() This is seldom used and is which byte will be used to write the next bits into.
static void	main(java.lang.String[] args) This exercises the class

Methods inherited from class java.lang.Object

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

Field Detail

logger

static org.apache.log4j.Logger logger

Log4J Logger

maskHighOrder

private static long[] maskHighOrder

The index value to the array indicates the number of bits that you want to REMAIN (it masks off the bits HIGHER than the chosen)

byteIndex

private int byteIndex

depth used

bitIndex

private int bitIndex

where the next bit will go in the last byte

currentInt

private int currentInt

the int being built (bitIndex is how far from the left the next bit will go)

values

private java.util.List values

this holds each byte as it fills

Constructor Detail

BitDestination

public BitDestination()

Method Detail

asBytes

public byte[] asBytes()

Fetch the data as an array of bytes

asInts

public int[] asInts()

Fetch teh data as an array of ints

addBits

public void addBits(int value,
                    int bits)

Add 'bits' of value into the stream. For instance, if value were '13' and bits were '3' then the lower 3 bits of 13 would be added (1101 -> 1(101) -> 101 )

addBits

public void addBits(long value,
                    int bits)

Add 'bits' of value into the stream. For instance, if value were '13' and bits were '3' then the lower 3 bits of 13 would be added (1101 -> 1(101) -> 101 )

addBits

public void addBits(boolean value)

Add a boolean, if it's true, a 1 is added, and if false, a 0 is added.

addBytes

public void addBytes(byte[] value)

This adds all the bytes in 'value' to the end of the buffer

addBytes

public void addBytes(byte[] value,
                     int startingByte,
                     int bytesToFill)

This adds a sub-set of all the bytes in value to the end of the buffer

addBytes

public void addBytes(java.lang.String value,
                     int bytesToFill)

This adds the binary representation of the string in 'value' and pads it or chops it as needed to fit into bytesToFill bytes ensuring that the resulting block of data added is exactly bytesToFill bytes long. The first bytesToFill bytes are used if the string is too long (thus, it discards extra from the RIGHT of the string). If the buffer has any bits unfilled in the current byte, then the string is 'broken' by bits and wrapped across them--not normally what's desired, but it would make for a bizarre ultra-light encryption.

getCurrentBytePosition

public int getCurrentBytePosition()

This is seldom used and is which byte will be used to write the next bits into.

getCurrentBitPosition

public int getCurrentBitPosition()

This is seldom used and is how many bits of the last byte have been used so far.

addRawBits

private void addRawBits(long value,
                        int bits)

This does the shifting and applying of a portion of value bits wide into the system.

main

public static void main(java.lang.String[] args)

This exercises the class