net.wimpi.modbus.util
Class BitVector

java.lang.Object
  net.wimpi.modbus.util.BitVector

public final 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:

1.2 (@date@)

Author:

Dieter Wimberger

Field Summary

private byte[]	m_Data
private boolean	m_MSBAccess
private int	m_Size
private static int[]	ODD_OFFSETS
private static int[]	STRAIGHT_OFFSETS

Constructor Summary

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

Method Summary

private int	bitIndex(int index) Returns the index of the given bit in the byte where it it stored.
private int	byteIndex(int index) Returns the index of the byte in the the byte array that contains the given bit.
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.
static void	main(String[] args)
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() Toggles the flag deciding whether the LSB or the MSB of the byte corresponds to the first bit (index=0).
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.
private int	translateIndex(int idx)

Methods inherited from class java.lang.Object

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

Field Detail

m_Size

private int m_Size

m_Data

private byte[] m_Data

m_MSBAccess

private boolean m_MSBAccess

ODD_OFFSETS

private static final int[] ODD_OFFSETS

STRAIGHT_OFFSETS

private static final int[] STRAIGHT_OFFSETS

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

toggleAccess

public void toggleAccess()

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

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 final void setBytes(byte[] data)

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

Parameters:

data - a byte[].

setBytes

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

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

Parameters:

data - a byte[].

getBit

public final 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 final 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 final int size()

Returns the number of bits in this BitVector as int.

Returns:

the number of bits in this BitVector.

forceSize

public final void forceSize(int size)

Forces the number of bits in this BitVector.

Parameters:

size -

Throws:

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

byteSize

public final 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.

byteIndex

private final int byteIndex(int index)
                     throws IndexOutOfBoundsException

Returns the index of the byte in the the byte array that contains the given bit.

Parameters:

index - the index of the bit.

Returns:

the index of the byte where the given bit is stored.

Throws:

IndexOutOfBoundsException - if index is out of bounds.

bitIndex

private final int bitIndex(int index)
                    throws IndexOutOfBoundsException

Returns the index of the given bit in the byte where it it stored.

Parameters:

index - the index of the bit.

Returns:

the bit index relative to the position in the byte that stores the specified bit.

Throws:

IndexOutOfBoundsException - if index is out of bounds.

translateIndex

private final int translateIndex(int idx)

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.

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.

main

public static void main(String[] args)