org.terrier.compression
Interface BitIn

All Superinterfaces:

java.io.Closeable

All Known Implementing Classes:

BitFile, BitFileBuffered.BitInBuffered, BitInputStream, DebuggingBitIn

public interface BitIn
extends java.io.Closeable

Interface describing the read compression methods supported by the BitFileBuffered and BitInputStream classes. Integers read by the BitIn interface are always greater than 0.

Since:

2.0

Author:

Craig Macdonald

Field Summary

static java.lang.String

USUAL_EXTENSION file extension

Method Summary

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.
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
void	readInterpolativeCoding(int[] data, int offset, 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 while reading the bit file.
void	skipBytes(long len) Skip a number of bytes while reading the bit file.

Methods inherited from interface java.io.Closeable

close

Field Detail

USUAL_EXTENSION

static final java.lang.String USUAL_EXTENSION

file extension

See Also:

Constant Field Values

Method Detail

getByteOffset

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

Returns:

the byte offset in the stream.

getBitOffset

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.

Returns:

the bit offset in the stream.

readUnary

int readUnary()
              throws java.io.IOException

Reads a unary encoded integer from the underlying stream

Returns:

the number read

Throws:

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

readGamma

int readGamma()
              throws java.io.IOException

Reads a gamma encoded integer from the underlying stream

Returns:

the number read

Throws:

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

readBinary

int readBinary(int len)
               throws java.io.IOException

Reads a binary integer from the already read buffer.

Parameters:

len - the number of binary bits to read

Returns:

the decoded integer

Throws:

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

readMinimalBinary

int readMinimalBinary(int b)
                      throws java.io.IOException

Reads a binary encoded integer, given an upper bound

Parameters:

b - the upper bound

Returns:

the int read

Throws:

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

readMinimalBinaryZero

int readMinimalBinaryZero(int b)
                          throws java.io.IOException

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

Parameters:

b - the upper bound

Returns:

the int read

Throws:

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

readGolomb

int readGolomb(int b)
               throws java.io.IOException

Reads a Golomb encoded integer

Parameters:

b - the golomb modulus

Returns:

the int read

Throws:

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

readSkewedGolomb

int readSkewedGolomb(int b)
                     throws java.io.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

Returns:

the number read

Throws:

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

readDelta

int readDelta()
              throws java.io.IOException

Reads a delta encoded integer from the underlying stream

Returns:

the number read

Throws:

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

readInterpolativeCoding

void readInterpolativeCoding(int[] data,
                             int offset,
                             int len,
                             int lo,
                             int hi)
                             throws java.io.IOException

Reads a sequence of numbers from the stream interpolative coded.

Parameters:

data - the result vector

offset - 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:

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

skipBits

void skipBits(int len)
              throws java.io.IOException

Skip a number of bits while reading the bit file.

Parameters:

len - The number of bits to skip

Throws:

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

skipBytes

void skipBytes(long len)
               throws java.io.IOException

Skip a number of bytes while reading the bit file. After this opteration, getBitOffset() == 0, so use skipBits to get getBitOffset() to desired value.

Parameters:

len - The number of bytes to skip

Throws:

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

align

void align()
           throws java.io.IOException

Aligns the stream to the next byte

Throws:

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