org.terrier.compression.bit

Class BitInBase

java.lang.Object

org.terrier.compression.bit.BitInBase

All Implemented Interfaces:

Closeable, AutoCloseable, BitIn

Direct Known Subclasses:

BitFileBuffered.BitInBuffered, BitInCodec, BitInputStream

public abstract class BitInBase
extends Object
implements BitIn

Base class for various BitIn implementations

Since:

3.6

Author:

Craig Macdonald

Field Summary

Fields

Modifier and Type	Field and Description
protected int	bitOffset bit offset in this byte, and in the larger file
protected byte	byteRead current byte
protected long	offset offset in the larger file

Fields inherited from interface org.terrier.compression.bit.BitIn

USUAL_EXTENSION

Constructor Summary

Constructors

Constructor and Description
BitInBase()

Method Summary

Modifier and Type	Method and Description
void	align() Aligns the stream to the next byte
byte	getBitOffset() Returns the bit offset in the last byte.
long	getByteOffset() Returns the byte offset of the stream.
protected abstract void	incrByte() Move forward one byte.
protected abstract void	incrByte(int i) Move forward i bytes.
int	readBinary(int len) Reads a binary integer from the already read buffer.
int	readDelta() Reads a delta encoded integer from the underlying stream
int	readGamma() Reads a gamma encoded integer from the underlying stream
int	readGolomb(int b) Reads a Golomb encoded integer
protected void	readIn() Reads a new byte from the InputStream if we have finished with the current one.
void	readInterpolativeCoding(int[] data, int localoffset, int len, int lo, int hi) Reads a sequence of numbers from the stream interpolative coded.
int	readMinimalBinary(int b) Reads a binary encoded integer, given an upper bound
int	readMinimalBinaryZero(int b) Reads a minimal binary encoded number, when the upper bound can b zero.
int	readSkewedGolomb(int b) Reads a skewed-golomb encoded integer from the underlying stream Consider a bucket-vector v = <0, 2b, 4b, ...
int	readUnary() Reads a unary encoded integer from the underlying stream
void	skipBits(int len) Skip a number of bits in the current input stream

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.terrier.compression.bit.BitIn

skipBytes

Methods inherited from interface java.io.Closeable

close

Field Detail

bitOffset

protected int bitOffset

bit offset in this byte, and in the larger file

offset

protected long offset

offset in the larger file

byteRead

protected byte byteRead

current byte

Constructor Detail

BitInBase

public BitInBase()

Method Detail

getByteOffset

public long getByteOffset()

Returns the byte offset of the stream. It corresponds to the position of the byte in which the next bit will be written. Use only when writting

Specified by:

getByteOffset in interface BitIn

Returns:

the byte offset in the stream.

getBitOffset

public byte getBitOffset()

Returns the bit offset in the last byte. It corresponds to the position in which the next bit will be written. Use only when writting.

Specified by:

getBitOffset in interface BitIn

Returns:

the bit offset in the stream.

readUnary

public int readUnary()
              throws IOException

Reads a unary encoded integer from the underlying stream

Specified by:

readUnary in interface BitIn

Returns:

the number read

Throws:

IOException - if an I/O error occurs

readBinary

public int readBinary(int len)
               throws IOException

Reads a binary integer from the already read buffer.

Specified by:

readBinary in interface BitIn

Parameters:

len - the number of binary bits to read

Returns:

the decoded integer

Throws:

IOException - if an I/O error occurs

readDelta

public int readDelta()
              throws IOException

Reads a delta encoded integer from the underlying stream

Specified by:

readDelta in interface BitIn

Returns:

the number read

Throws:

IOException - if an I/O error occurs

readGamma

public int readGamma()
              throws IOException

Reads a gamma encoded integer from the underlying stream

Specified by:

readGamma in interface BitIn

Returns:

the number read

Throws:

IOException - if an I/O error occurs

readSkewedGolomb

public int readSkewedGolomb(int b)
                     throws IOException

Reads a skewed-golomb encoded integer from the underlying stream Consider a bucket-vector v = <0, 2b, 4b, ... , 2^i b, ...> The sum of the elements in the vector goes b, 3b, 7b, 2^(i-1)*b

Specified by:

readSkewedGolomb in interface BitIn

Returns:

the number read

Throws:

IOException - if an I/O error occurs

readGolomb

public int readGolomb(int b)
               throws IOException

Reads a Golomb encoded integer

Specified by:

readGolomb in interface BitIn

Parameters:

b - the golomb modulus

Returns:

the int read

Throws:

IOException - if and I/O error occurs

readMinimalBinary

public int readMinimalBinary(int b)
                      throws IOException

Reads a binary encoded integer, given an upper bound

Specified by:

readMinimalBinary in interface BitIn

Parameters:

b - the upper bound

Returns:

the int read

Throws:

IOException - if an I/O error occurs

readMinimalBinaryZero

public int readMinimalBinaryZero(int b)
                          throws IOException

Reads a minimal binary encoded number, when the upper bound can b zero. Used to interpolative code

Specified by:

readMinimalBinaryZero in interface BitIn

Parameters:

b - the upper bound

Returns:

the int read

Throws:

IOException - if an I/O error occurs

readInterpolativeCoding

public void readInterpolativeCoding(int[] data,
                                    int localoffset,
                                    int len,
                                    int lo,
                                    int hi)
                             throws IOException

Reads a sequence of numbers from the stream interpolative coded.

Specified by:

readInterpolativeCoding in interface BitIn

Parameters:

data - the result vector

localoffset - offset where to write in the vector

len - the number of integers to decode.

lo - a lower bound (the same one passed to writeInterpolativeCoding)

hi - an upper bound (the same one passed to writeInterpolativeCoding)

Throws:

IOException - if an I/O error occurs

skipBits

public void skipBits(int len)
              throws IOException

Skip a number of bits in the current input stream

Specified by:

skipBits in interface BitIn

Parameters:

len - The number of bits to skip

Throws:

IOException - if an I/O error occurs

align

public void align()
           throws IOException

Aligns the stream to the next byte

Specified by:

align in interface BitIn

Throws:

IOException - if an I/O error occurs

incrByte

protected abstract void incrByte()
                          throws IOException

Move forward one byte. The newly read byte should appear in the byteRead variable.

Throws:

IOException

incrByte

protected abstract void incrByte(int i)
                          throws IOException

Move forward i bytes. The newly read byte should appear in byteRead variable.

Throws:

IOException

readIn

protected void readIn()
               throws IOException

Reads a new byte from the InputStream if we have finished with the current one.

Throws:

IOException