ivory.core.compression

Class BitInputStream

java.lang.Object

ivory.core.compression.BitInputStream

public class BitInputStream
extends Object

This class reads from a file or an InputStream integers that can be coded with different encoding algorithms. It does not use any internal buffering, and operates with bytes.

Author:

Roi Blanco

Constructor Summary

Constructors

Constructor and Description
BitInputStream(InputStream is) Constructs an instance of the class for a given stream

Method Summary

Methods

Modifier and Type	Method and Description
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 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 =
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

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

Constructor Detail

BitInputStream

public BitInputStream(InputStream is)
               throws IOException

Constructs an instance of the class for a given stream

Parameters:

is - java.io.InputStream the underlying input stream

Throws:

IOException - if an I/O error occurs

Method Detail

align

public void align()
           throws IOException

Aligns the stream to the next byte

Throws:

IOException - if an I/O error occurs

close

public void close()
           throws IOException

Closes the stream.

Throws:

IOException - if an I/O error occurs

getBitOffset

public byte getBitOffset()

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

Returns:

the bit offset in the stream.

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.

Returns:

the byte offset in the stream.

readBinary

public int readBinary(int len)
               throws IOException

Reads a binary integer from the already read buffer.

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

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

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

Parameters:

b - the golomb modulus

Returns:

the int read

Throws:

IOException - if and I/O error occurs

readInterpolativeCoding

public void readInterpolativeCoding(int[] data,
                           int offset,
                           int len,
                           int lo,
                           int hi)
                             throws 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:

IOException - if an I/O error occurs

readMinimalBinary

public int readMinimalBinary(int b)
                      throws IOException

Reads a binary encoded integer, given an upper bound

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

Parameters:

b - the upper bound

Returns:

the int 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 = The sum of the elements in the vector goes b, 3b, 7b, 2^(i-1)*b

Returns:

the number read

Throws:

IOException - if an I/O error occurs

readUnary

public int readUnary()
              throws IOException

Reads a unary encoded integer from the underlying stream

Returns:

the number read

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

Parameters:

len - The number of bits to skip

Throws:

IOException - if an I/O error occurs