com.google.zxing.common

Class BitArray

java.lang.Object

com.google.zxing.common.BitArray

public final class BitArray
extends Object

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

Author:

Sean Owen

Field Summary

Fields

Modifier and Type	Field and Description
int[]	bits
int	size

Constructor Summary

Constructors

Constructor and Description
BitArray()
BitArray(int size)

Method Summary

Modifier and Type	Method and 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).
void	flip(int i) Flips bit i.
boolean	get(int i)
int[]	getBitArray()
int	getSize()
int	getSizeInBytes()
boolean	isRange(int start, int end, boolean value) Efficient method to check if a range of bits is set, or not set.
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	toBytes(int bitOffset, byte[] array, int offset, int numBytes)
String	toString()
void	xor(BitArray other)

Methods inherited from class java.lang.Object

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

Field Detail

bits

public int[] bits

size

public int size

Constructor Detail

BitArray

public BitArray()

BitArray

public BitArray(int size)

Method Detail

getSize

public int getSize()

getSizeInBytes

public int getSizeInBytes()

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

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.

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:

IllegalArgumentException - if end is less than or equal to start

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.

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.

toString

public String toString()

Overrides:

toString in class Object