com.webcodepro.shrinkit.io

Class BitInputStream

java.lang.Object

java.io.InputStream

com.webcodepro.shrinkit.io.BitInputStream

All Implemented Interfaces:

BitConstants, java.io.Closeable, java.lang.AutoCloseable

public class BitInputStream
extends java.io.InputStream
implements BitConstants

The BitInputStream allows varying bit sizes to be pulled out of the wrapped InputStream. This is useful for LZW type compression algorithms where 9-12 bit codes are used instead of the 8-bit byte.

Warning: The read(byte[]) and read(byte[], int, int) methods of InputStream will not work appropriately with any bit size > 8 bits.

Field Summary

Fields inherited from interface com.webcodepro.shrinkit.io.BitConstants

BIT_MASKS

Constructor Summary

Constructors

Constructor and Description
BitInputStream(java.io.InputStream is, int startingNumberOfBits) Create a BitInputStream wrapping the given InputStream and reading the number of bits specified.

Method Summary

Modifier and Type	Method and Description
void	clearRemainingBitsOfData() When shifting from buffer to buffer, the input stream also should be reset.
int	getBitMask() Answer with the current bit mask for the current bit size.
void	increaseRequestedNumberOfBits() Increase the requested number of bits by one.
int	read() Read a number of bits off of the wrapped InputStream.
void	setRequestedNumberOfBits(int numberOfBits) Set the number of bits to be read with each call to read().

Methods inherited from class java.io.InputStream

available, close, mark, markSupported, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

BitInputStream

public BitInputStream(java.io.InputStream is,
                      int startingNumberOfBits)

Create a BitInputStream wrapping the given InputStream and reading the number of bits specified.

Method Detail

setRequestedNumberOfBits

public void setRequestedNumberOfBits(int numberOfBits)

Set the number of bits to be read with each call to read().

increaseRequestedNumberOfBits

public void increaseRequestedNumberOfBits()

Increase the requested number of bits by one. This is the general usage and prevents client from needing to track the requested number of bits or from making various method calls.

getBitMask

public int getBitMask()

Answer with the current bit mask for the current bit size.

read

public int read()
         throws java.io.IOException

Read a number of bits off of the wrapped InputStream.

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

clearRemainingBitsOfData

public void clearRemainingBitsOfData()

When shifting from buffer to buffer, the input stream also should be reset. This allows the "left over" bits to be cleared.