GiciStream
Class BitStream

java.lang.Object
  GiciStream.BitStream

public class BitStream
extends java.lang.Object

This class is a bit buffer, useful to store a bit stream.
ATTENTION: this class should be optimized like ByteStream. Now it has a very poor performance!!!

Version:

1.2

Author:

Group on Interactive Coding of Images (GICI)

Field Summary

(package private) long	actualPosition Actual position in the bitstream (useful to scan bytestream from begin to end)..
(package private) byte[]	bitBuffer Byte array used to store bits.
(package private) int	buffAllocation Number of bytes used in each step of buffer allocation (when the buffer is full, another one es reserved with buffAllocation bytes more and the contents are copied).
(package private) long	numBits Number of bits saved in bitBuffer.

Constructor Summary

BitStream()
Class constructor (performs needed initializations).

BitStream(byte[] bitBuffer)
Class constructor that initilizaes the BitStream with a bitBuffer.

BitStream(int initialSizeBuffer)
Class constructor with a specified amount of bits to allocate initially in the buffer.

Method Summary

void	addBit(boolean bit) Inserts a bit in the bitstream.
void	addBit(int bit) Inserts a bit in the bitstream.
void	addBits(int bits, int length) Inserts the bits of an int to the bitstream starting at length MSB position of the int passed.
void	addBitStream(BitStream bs) Inserts a BitStream in the current object.
void	addByte(int byt) Inserts the bits of a byte into the bitstream.
void	deleteBeginBit() Deletes a bit of the bitstream (starting at the begining of bitstream).
void	deleteBeginBits(long num) Deletes a number of bits of the bitstream (starting at the begining of bitstream).
void	deleteEndBit() Deletes a bit of the bitstream (starting at the end of bitstream).
void	deleteEndBits(long num) Deletes a number of bits of the bitstream (starting at the end of bitstream).
long	getActualPosition() Return the position of the bit which is pointed by the bitstream
boolean	getBit() Return the actual bit and increments actual bit plus 1.
boolean	getBit(long numBit) Return the bit value indicated.
int	getBits(int length) Return length bits like an integer.
byte[]	getBitStream() Return the bit stream in an array of bytes (the length of array byte returned is equal or greater than the real bytes used in bitStream -it can be known using getNumBits function-).
byte	getByte(int numByte) Return the byte indicated.
long	getNumBits() Return the number of bits in the bit stream.
long	getNumBytes() Return the number of bytes in the bit stream.
void	reset() Reset the bit stream
void	rewindBits(long numBits) Rewind the index in the bit stream

Methods inherited from class java.lang.Object

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

Field Detail

bitBuffer

byte[] bitBuffer

Byte array used to store bits.

All values allowed.

numBits

long numBits

Number of bits saved in bitBuffer.

Negative values are not allowed for this field.

actualPosition

long actualPosition

Actual position in the bitstream (useful to scan bytestream from begin to end)..

Only positive values allowed.

buffAllocation

int buffAllocation

Number of bytes used in each step of buffer allocation (when the buffer is full, another one es reserved with buffAllocation bytes more and the contents are copied).

Negative values are not allowed for this field.

Constructor Detail

BitStream

public BitStream()

Class constructor (performs needed initializations).

BitStream

public BitStream(int initialSizeBuffer)

Class constructor with a specified amount of bits to allocate initially in the buffer.

Parameters:

initialSizeBuffer - number of bits that initially the buffer will contain

BitStream

public BitStream(byte[] bitBuffer)

Class constructor that initilizaes the BitStream with a bitBuffer.

Parameters:

bitBuffer - a byte array from which the BitStream initializes his bitBuffer

Method Detail

addBit

public void addBit(boolean bit)

Inserts a bit in the bitstream.

Parameters:

bit - a boolean that indicates the bit (1=true, 0=false) to insert

addBit

public void addBit(int bit)

Inserts a bit in the bitstream.

Parameters:

bit - a integer that indicates the bit (1=true, 0=false) to insert

addByte

public void addByte(int byt)

Inserts the bits of a byte into the bitstream.

Parameters:

byt - the byte to be inserted

addBits

public void addBits(int bits,
                    int length)

Inserts the bits of an int to the bitstream starting at length MSB position of the int passed.

Parameters:

bits - a integer that contains the sequence of values to be inserted

length - a integer that indicates the number of bits to take into account

addBitStream

public void addBitStream(BitStream bs)

Inserts a BitStream in the current object.

Parameters:

bs - BitStream object to append.

deleteEndBit

public void deleteEndBit()

Deletes a bit of the bitstream (starting at the end of bitstream).

deleteEndBits

public void deleteEndBits(long num)

Deletes a number of bits of the bitstream (starting at the end of bitstream). If number of bits to delete is greater than bitstream, bitstream length will be 0.

Parameters:

num - the number of bits to delete

deleteBeginBit

public void deleteBeginBit()
                    throws WarningException

Deletes a bit of the bitstream (starting at the begining of bitstream).

Throws:

WarningException - because it uses addBit functions

deleteBeginBits

public void deleteBeginBits(long num)
                     throws WarningException

Deletes a number of bits of the bitstream (starting at the begining of bitstream). If number of bits to delete is greater than bitstream, bitstream length will be 0.

Parameters:

num - the number of bits to delete

Throws:

WarningException - because it uses addBit functions

getBit

public boolean getBit(long numBit)
               throws WarningException

Return the bit value indicated.

Parameters:

numBit - the number of bit in bitstream (starting at 0)

Returns:

a boolean that represents the bit value indicated (true - 1, false - 0)

Throws:

WarningException - when numBit is greater than the buffer length

getBit

public boolean getBit()
               throws WarningException

Return the actual bit and increments actual bit plus 1.

Returns:

a boolean that represents the bit value indicated (true - 1, false - 0)

Throws:

WarningException - when max buffer length is reached

getBits

public int getBits(int length)
            throws WarningException

Return length bits like an integer.

Parameters:

length - indicated the number of bits that must be given

Returns:

an integer that represents the bits value

Throws:

WarningException - when max buffer length is reached

getBitStream

public byte[] getBitStream()

Return the bit stream in an array of bytes (the length of array byte returned is equal or greater than the real bytes used in bitStream -it can be known using getNumBits function-).

Returns:

a byte array that contains the bit stream

getNumBits

public long getNumBits()

Return the number of bits in the bit stream.

Returns:

a long indicating number of bits in the bit stream

getByte

public byte getByte(int numByte)
             throws WarningException

Return the byte indicated.

Parameters:

numByte - the number of byte in bytestream (starting at 0)

Returns:

the byte asked for

Throws:

WarningException - when numByte is greater than the buffer length

getNumBytes

public long getNumBytes()

Return the number of bytes in the bit stream.

Returns:

a long indicating number of bytes in the bit stream

getActualPosition

public long getActualPosition()

Return the position of the bit which is pointed by the bitstream

Returns:

a long indicating number of the bit which is pointed by the bitstream

reset

public void reset()

Reset the bit stream

rewindBits

public void rewindBits(long numBits)
                throws WarningException

Rewind the index in the bit stream

Parameters:

numBits - indicates the number of bits to be rewinded

Throws:

WarningException - when the number of bits to be rewinded is greater than the available.