io.lacuna.bifurcan.utils

Class BitVector

java.lang.Object

io.lacuna.bifurcan.utils.BitVector

public final class BitVector
extends Object

Static methods which implement bit-range operations over a bit-vector stored within a long[].

Constructor Summary

Constructors

Constructor and Description
BitVector()

Method Summary

Modifier and Type	Method and Description
static int	branchingBit(long[] a, long[] b, int aIdx, int bIdx, int bitOffset, int bitLen)
static long[]	clone(long[] vector)
static void	copy(long[] src, int srcOffset, long[] dst, int dstOffset, int len) Copies a bit range from one vector to another.
static long[]	create(int length)
static long	get(long[] vector, int offset, int len) Reads a bit range from the vector, which cannot be longer than 64 bits.
static long[]	insert(long[] vector, int vectorLen, long val, int offset, int len)
static long[]	interleave(int bitLen, long[] vectors)
static long[]	interpose(long[] vector, int vectorLen, int offset, int len) Returns a copy of the vector, with an empty bit range inserted at the specified location.
static void	overwrite(long[] vector, int bitIdx, boolean flag)
static void	overwrite(long[] vector, long val, int offset, int len) Overwrites a bit range within the vector.
static long[]	remove(long[] vector, int vectorLen, int offset, int len) Returns a copy of the vector, with a bit range excised from the specified location.
static boolean	test(long[] vector, int bitIndex)

Methods inherited from class java.lang.Object

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

Constructor Detail

BitVector

public BitVector()

Method Detail

create

public static long[] create(int length)

Parameters:

length - the bit length of the vector

Returns:

a bit vector which can hold the specified number of bits

clone

public static long[] clone(long[] vector)

test

public static boolean test(long[] vector,
                           int bitIndex)

Parameters:

vector - the bit vector

bitIndex - the bit to be tested

Returns:

true if the bit is 1, false otherwise

interleave

public static long[] interleave(int bitLen,
                                long[] vectors)

Parameters:

bitLen - the number of significant bits in each vector

vectors - a list of bit-vectors

Returns:

the bit-wise interleaving of the values, starting with the topmost bit of the 0th vector, followed by the topmost bit of the 1st vector, and downward from there

branchingBit

public static int branchingBit(long[] a,
                               long[] b,
                               int aIdx,
                               int bIdx,
                               int bitOffset,
                               int bitLen)

get

public static long get(long[] vector,
                       int offset,
                       int len)

Reads a bit range from the vector, which cannot be longer than 64 bits.

Parameters:

vector - the bit vector

offset - the bit offset

len - the bit length

Returns:

a number representing the bit range

overwrite

public static void overwrite(long[] vector,
                             long val,
                             int offset,
                             int len)

Overwrites a bit range within the vector.

Parameters:

vector - the bit vector

val - the rowValue to set

offset - the offset of the write

len - the bit length of the rowValue

overwrite

public static void overwrite(long[] vector,
                             int bitIdx,
                             boolean flag)

copy

public static void copy(long[] src,
                        int srcOffset,
                        long[] dst,
                        int dstOffset,
                        int len)

Copies a bit range from one vector to another.

Parameters:

src - the source vector

srcOffset - the bit offset within src

dst - the destination vector

dstOffset - the bit offset within dst

len - the length of the bit range

interpose

public static long[] interpose(long[] vector,
                               int vectorLen,
                               int offset,
                               int len)

Returns a copy of the vector, with an empty bit range inserted at the specified location.

Parameters:

vector - the bit vector

vectorLen - the length of the bit vector

offset - the offset within the bit vector

len - the length of the empty bit range

Returns:

an updated copy of the vector

insert

public static long[] insert(long[] vector,
                            int vectorLen,
                            long val,
                            int offset,
                            int len)

Parameters:

vector - the bit vector

vectorLen - the length of the bit vector

val - the rowValue to be inserted

offset - the offset within the bit vector

len - the bit length of the rowValue

Returns:

an updated copy of the vector

remove

public static long[] remove(long[] vector,
                            int vectorLen,
                            int offset,
                            int len)

Returns a copy of the vector, with a bit range excised from the specified location.

Parameters:

vector - the bit vector

vectorLen - the length of the bit vector

offset - the offset within the bit vector

len - the length of the excised bit range

Returns:

an updated copy of the vector