Package com.google.zxing.common

Class BitArray

java.lang.Object

com.google.zxing.common.BitArray

All Implemented Interfaces:

java.lang.Cloneable

public final class BitArray
extends java.lang.Object
implements java.lang.Cloneable

A simple, fast array of bits, represented compactly by an array of ints internally.

Field Summary

Fields

Modifier and Type	Field	Description
private int[]	bits
private static int[]	EMPTY_BITS
private static float	LOAD_FACTOR
private int	size

Constructor Summary

Constructors

Constructor	Description
BitArray()
BitArray(int size)
BitArray(int[] bits, int size)

Method Summary

Modifier and Type	Method	Description
void	appendBit(boolean bit)
void	appendBitArray(BitArray other)
void	appendBits(int value, int numBits)	Appends the least-significant bits, from value, in order from most-significant to least-significant.
void	clear()	Clears all bits (sets to false).
BitArray	clone()
private void	ensureCapacity(int newSize)
boolean	equals(java.lang.Object o)
void	flip(int i)	Flips bit i.
boolean	get(int i)
int[]	getBitArray()
int	getNextSet(int from)
int	getNextUnset(int from)
int	getSize()
int	getSizeInBytes()
int	hashCode()
boolean	isRange(int start, int end, boolean value)	Efficient method to check if a range of bits is set, or not set.
private static int[]	makeArray(int size)
void	reverse()	Reverses all bits in the array.
void	set(int i)	Sets bit i.
void	setBulk(int i, int newBits)	Sets a block of 32 bits, starting at bit i.
void	setRange(int start, int end)	Sets a range of bits.
void	toBytes(int bitOffset, byte[] array, int offset, int numBytes)
java.lang.String	toString()
void	xor(BitArray other)

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY_BITS

private static final int[] EMPTY_BITS

LOAD_FACTOR

private static final float LOAD_FACTOR

See Also:

Constant Field Values

bits

private int[] bits

size

private int size

Constructor Detail

BitArray

public BitArray()

BitArray

public BitArray(int size)

BitArray

BitArray(int[] bits,
         int size)

Method Detail

getSize

public int getSize()

getSizeInBytes

public int getSizeInBytes()

ensureCapacity

private void ensureCapacity(int newSize)

get

public boolean get(int i)

Parameters:

i - bit to get

Returns:

true iff bit i is set

set

public void set(int i)

Sets bit i.

Parameters:

i - bit to set

flip

public void flip(int i)

Flips bit i.

Parameters:

i - bit to set

getNextSet

public int getNextSet(int from)

Parameters:

from - first bit to check

Returns:

index of first bit that is set, starting from the given index, or size if none are set at or beyond this given index

See Also:

getNextUnset(int)

getNextUnset

public int getNextUnset(int from)

Parameters:

from - index to start looking for unset bit

Returns:

index of next unset bit, or size if none are unset until the end

See Also:

getNextSet(int)

setBulk

public void setBulk(int i,
                    int newBits)

Sets a block of 32 bits, starting at bit i.

Parameters:

i - first bit to set

newBits - the new value of the next 32 bits. Note again that the least-significant bit corresponds to bit i, the next-least-significant to i+1, and so on.

setRange

public void setRange(int start,
                     int end)

Sets a range of bits.

Parameters:

start - start of range, inclusive.

end - end of range, exclusive

clear

public void clear()

Clears all bits (sets to false).

isRange

public boolean isRange(int start,
                       int end,
                       boolean value)

Efficient method to check if a range of bits is set, or not set.

Parameters:

start - start of range, inclusive.

end - end of range, exclusive

value - if true, checks that bits in range are set, otherwise checks that they are not set

Returns:

true iff all bits are set or not set in range, according to value argument

Throws:

java.lang.IllegalArgumentException - if end is less than start or the range is not contained in the array

appendBit

public void appendBit(boolean bit)

appendBits

public void appendBits(int value,
                       int numBits)

Appends the least-significant bits, from value, in order from most-significant to least-significant. For example, appending 6 bits from 0x000001E will append the bits 0, 1, 1, 1, 1, 0 in that order.

Parameters:

value - int containing bits to append

numBits - bits from value to append

appendBitArray

public void appendBitArray(BitArray other)

xor

public void xor(BitArray other)

toBytes

public void toBytes(int bitOffset,
                    byte[] array,
                    int offset,
                    int numBytes)

Parameters:

bitOffset - first bit to start writing

array - array to write into. Bytes are written most-significant byte first. This is the opposite of the internal representation, which is exposed by getBitArray()

offset - position in array to start writing

numBytes - how many bytes to write

getBitArray

public int[] getBitArray()

Returns:

underlying array of ints. The first element holds the first 32 bits, and the least significant bit is bit 0.

reverse

public void reverse()

Reverses all bits in the array.

makeArray

private static int[] makeArray(int size)

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

clone

public BitArray clone()

Overrides:

clone in class java.lang.Object