pt.tumba.ngram.compression
Class BitOutput

java.lang.Object
  pt.tumba.ngram.compression.BitOutput

public final class BitOutput
extends java.lang.Object

Writes to an underlying output stream a bit at a time. A bit is can be input as a boolean, with true=1 and false=0, or as a number, in which case any non-zero input will be converted to 1. If the number of bits written before closing the output does not land on a byte boundary, the remaining fractional byte is filled with 0 bits.

Author:

Bruno Martins

See Also:

BitInput

Field Summary

private int	_nextBitIndex The indexof the next bit to write into the next byte.
private int	_nextByte Buffering for output.
private java.io.OutputStream	_out Underlying output stream.

Constructor Summary

BitOutput(java.io.OutputStream out)
Construct a bit output from the specified output stream.

Method Summary

void	close() Closes underlying output stream after filling to a byte boundary with 0 bits.
void	flush() Flushes the underlying output stream.
private void	reset() Resets the bit buffer.
void	writeBit(boolean bit) Writes the single specified bit to the underlying output stream, 1 for true and 0 for false.
void	writeBitFalse() Writes a single false (0) bit.
void	writeBitTrue() Writes a single true (1) bit.

Methods inherited from class java.lang.Object

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

Field Detail

_nextByte

private int _nextByte

Buffering for output. Bytes are represented as integers, primarily for efficiency of bit fiddling and for compatibility with underlying output stream.

_nextBitIndex

private int _nextBitIndex

The indexof the next bit to write into the next byte.

_out

private final java.io.OutputStream _out

Underlying output stream.

Constructor Detail

BitOutput

public BitOutput(java.io.OutputStream out)

Construct a bit output from the specified output stream.

Parameters:

out - Underlying output stream.

Method Detail

close

public void close()
           throws java.io.IOException

Closes underlying output stream after filling to a byte boundary with 0 bits.

Throws:

java.io.IOException - If there is an I/O exception writing the next byte or closing the underlying output stream.

flush

public void flush()
           throws java.io.IOException

Flushes the underlying output stream.

Throws:

java.io.IOException - If there is an exception flushing the underlying output stream.

writeBit

public void writeBit(boolean bit)
              throws java.io.IOException

Writes the single specified bit to the underlying output stream, 1 for true and 0 for false.

Parameters:

bit - Value to write.

Throws:

java.io.IOException - If there is an exception in the underlying output stream.

writeBitTrue

public void writeBitTrue()
                  throws java.io.IOException

Writes a single true (1) bit.

Throws:

java.io.IOException - If there is an exception in the underlying output stream.

writeBitFalse

public void writeBitFalse()
                   throws java.io.IOException

Writes a single false (0) bit.

Throws:

java.io.IOException - If there is an exception in the underlying output stream.

reset

private void reset()

Resets the bit buffer.