com.ghgande.j2mod.modbus.util

Class BitVector

java.lang.Object

com.ghgande.j2mod.modbus.util.BitVector

public class BitVector
extends Object

Class that implements a collection for bits, storing them packed into bytes. Per default the access operations will index from the LSB (rightmost) bit.

Version:

2.0 (March 2016)

Author:

Dieter Wimberger, Steve O'Hara (4NG)

Constructor Summary

Constructors

Constructor and Description
BitVector(int size) Constructs a new BitVector instance with a given size.

Method Summary

Modifier and Type	Method and Description
int	byteSize() Returns the number of bytes used to store the collection of bits as int.
static BitVector	createBitVector(byte[] data) Factory method for creating a BitVector instance wrapping the given byte data.
static BitVector	createBitVector(byte[] data, int size) Factory method for creating a BitVector instance wrapping the given byte data.
void	forceSize(int size) Forces the number of bits in this BitVector.
boolean	getBit(int index) Returns the state of the bit at the given index of this BitVector.
byte[]	getBytes() Returns the byte[] which is used to store the bits of this BitVector.
boolean	isLSBAccess() Tests if this BitVector has the LSB (rightmost) as the first bit (i.e.
boolean	isMSBAccess() Tests if this BitVector has the MSB (leftmost) as the first bit (i.e.
void	setBit(int index, boolean b) Sets the state of the bit at the given index of this BitVector.
void	setBytes(byte[] data) Sets the byte[] which stores the bits of this BitVector.
void	setBytes(byte[] data, int size) Sets the byte[] which stores the bits of this BitVector.
int	size() Returns the number of bits in this BitVector as int.
void	toggleAccess(boolean b) Toggles the flag deciding whether the LSB or the MSB of the byte corresponds to the first bit (index=0).
String	toString() Returns a String representing the contents of the bit collection in a way that can be printed to a screen or log.

Methods inherited from class java.lang.Object

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

Constructor Detail

BitVector

public BitVector(int size)

Constructs a new BitVector instance with a given size.

Parameters:

size - the number of bits the BitVector should be able to hold.

Method Detail

createBitVector

public static BitVector createBitVector(byte[] data,
                                        int size)

Factory method for creating a BitVector instance wrapping the given byte data.

Parameters:

data - a byte[] containing packed bits.

size - Size to set the bit vector to

Returns:

the newly created BitVector instance.

createBitVector

public static BitVector createBitVector(byte[] data)

Factory method for creating a BitVector instance wrapping the given byte data.

Parameters:

data - a byte[] containing packed bits.

Returns:

the newly created BitVector instance.

toggleAccess

public void toggleAccess(boolean b)

Toggles the flag deciding whether the LSB or the MSB of the byte corresponds to the first bit (index=0).

Parameters:

b - true if LSB=0 up to MSB=7, false otherwise.

isLSBAccess

public boolean isLSBAccess()

Tests if this BitVector has the LSB (rightmost) as the first bit (i.e. at index 0).

Returns:

true if LSB=0 up to MSB=7, false otherwise.

isMSBAccess

public boolean isMSBAccess()

Tests if this BitVector has the MSB (leftmost) as the first bit (i.e. at index 0).

Returns:

true if LSB=0 up to MSB=7, false otherwise.

getBytes

public final byte[] getBytes()

Returns the byte[] which is used to store the bits of this BitVector.

Returns:

the byte[] used to store the bits.

setBytes

public void setBytes(byte[] data)

Sets the byte[] which stores the bits of this BitVector.

Parameters:

data - a byte[].

setBytes

public void setBytes(byte[] data,
                     int size)

Sets the byte[] which stores the bits of this BitVector.

Parameters:

data - a byte[].

size - Size to set the bit vector to

getBit

public boolean getBit(int index)
               throws IndexOutOfBoundsException

Returns the state of the bit at the given index of this BitVector.

Parameters:

index - the index of the bit to be returned.

Returns:

true if the bit at the specified index is set, false otherwise.

Throws:

IndexOutOfBoundsException - if the index is out of bounds.

setBit

public void setBit(int index,
                   boolean b)
            throws IndexOutOfBoundsException

Sets the state of the bit at the given index of this BitVector.

Parameters:

index - the index of the bit to be set.

b - true if the bit should be set, false if it should be reset.

Throws:

IndexOutOfBoundsException - if the index is out of bounds.

size

public int size()

Returns the number of bits in this BitVector as int.

Returns:

the number of bits in this BitVector.

forceSize

public void forceSize(int size)

Forces the number of bits in this BitVector.

Parameters:

size - Size to set the bit vector to

Throws:

IllegalArgumentException - if the size exceeds the byte[] store size multiplied by 8.

byteSize

public int byteSize()

Returns the number of bytes used to store the collection of bits as int.

Returns:

the number of bits in this BitVector.

toString

public String toString()

Returns a String representing the contents of the bit collection in a way that can be printed to a screen or log.

Note that this representation will ALLWAYS show the MSB to the left and the LSB to the right in each byte.

Overrides:

toString in class Object

Returns:

a String representing this BitVector.