uk.ac.gla.terrier.compression
Class OldBitInputStream

java.lang.Object
  uk.ac.gla.terrier.compression.BitInputStream
      uk.ac.gla.terrier.compression.OldBitInputStream

All Implemented Interfaces:

java.io.Closeable, BitIn

public class OldBitInputStream
extends BitInputStream

This class provides sequential stream access to a compressed BitFile file.

Version:

$Revision: 1.5 $

Author:

Gianni Amati, Vassilis Plachouras, Douglas Johnson

See Also:

BitFile

Constructor Summary

OldBitInputStream(java.io.File file)
Constructs an instance of the class for a given file

OldBitInputStream(java.io.InputStream is)
Constructs an instance of the class for a given stream.

OldBitInputStream(java.lang.String filename)
Constructs an instance of the class for a given filename

Method Summary

void	align() Aligns the stream to the next byte
void	close() Closes the stream.
byte	getBitOffset() Returns the bit offset in the last byte.
long	getByteOffset() Returns the byte offset of the stream.
int	readBinary(int noBits) Reads a binary integer from the already read buffer.
int	readGamma() Reads a gamma encoded integer from the stream
int	readUnary() Reads a unary encoded integer from the stream.
void	skipBits(int noBits) Skip a number of bits in the current input stream

Methods inherited from class uk.ac.gla.terrier.compression.BitInputStream

readDelta, readGolomb, readInterpolativeCoding, readMinimalBinary, readMinimalBinaryZero, readSkewedGolomb

Methods inherited from class java.lang.Object

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

Constructor Detail

OldBitInputStream

public OldBitInputStream(java.io.InputStream is)
                  throws java.io.IOException

Constructs an instance of the class for a given stream. We recommend that the inputstream passed to this class if buffered in some way - ie using java.io.BufferedInputStream

Parameters:

is - java.io.InputStream the underlying input stream

Throws:

java.io.IOException - if an I/O error occurs

OldBitInputStream

public OldBitInputStream(java.lang.String filename)
                  throws java.io.IOException

Constructs an instance of the class for a given filename

Parameters:

filename - java.lang.String the name of the undelying file

Throws:

java.io.IOException - if an I/O error occurs

OldBitInputStream

public OldBitInputStream(java.io.File file)
                  throws java.io.IOException

Constructs an instance of the class for a given file

Parameters:

file - java.io.File the underlying file

Throws:

java.io.IOException - if an I/O error occurs

Method Detail

readBinary

public int readBinary(int noBits)
               throws java.io.IOException

Reads a binary integer from the already read buffer. No IO is performed and 0 is returned if noBits == 0. NB: noBits > than 32 will give undefined results.

Specified by:

readBinary in interface BitIn

Overrides:

readBinary in class BitInputStream

Parameters:

noBits - the number of binary bits to read

Returns:

the decoded integer, -1 if eof was reached unexpectedly

Throws:

java.io.IOException - if an I/O error occurs

skipBits

public void skipBits(int noBits)
              throws java.io.IOException

Skip a number of bits in the current input stream

Specified by:

skipBits in interface BitIn

Overrides:

skipBits in class BitInputStream

Parameters:

noBits - The number of bits to skip

Throws:

java.io.IOException - if an I/O error occurs

close

public void close()
           throws java.io.IOException

Closes the stream.

Specified by:

close in interface java.io.Closeable

Overrides:

close in class BitInputStream

Throws:

java.io.IOException - if an I/O error occurs

readUnary

public int readUnary()
              throws java.io.IOException

Reads a unary encoded integer from the stream.

Specified by:

readUnary in interface BitIn

Overrides:

readUnary in class BitInputStream

Returns:

the decoded integer, or -1 if EOF is found

Throws:

java.io.IOException - if an I/O error occurs

readGamma

public int readGamma()
              throws java.io.IOException

Reads a gamma encoded integer from the stream

Specified by:

readGamma in interface BitIn

Overrides:

readGamma in class BitInputStream

Returns:

the decoded integer, or -1 if EOF is found

Throws:

java.io.IOException - if an I/O error occurs

getByteOffset

public long getByteOffset()

Returns the byte offset of the stream. It corresponds to the offset of the byte from which the next bit will be read.

Specified by:

getByteOffset in interface BitIn

Overrides:

getByteOffset in class BitInputStream

Returns:

the byte offset in the stream.

getBitOffset

public byte getBitOffset()

Returns the bit offset in the last byte. It corresponds to the next bit that it will be read.

Specified by:

getBitOffset in interface BitIn

Overrides:

getBitOffset in class BitInputStream

Returns:

the bit offset in the stream.

align

public void align()
           throws java.io.IOException

Aligns the stream to the next byte

Specified by:

align in interface BitIn

Overrides:

align in class BitInputStream

Throws:

java.io.IOException - if an I/O error occurs