Class BitUtil

A variety of high efficiency bit twiddling routines.

Note

This API is for internal purposes only and might change in incompatible ways in the next release.

Inheritance
object
BitUtil
Inherited Members
Namespace: Lucene.Net.Util
Assembly: Lucene.Net.dll
Syntax
public static class BitUtil

Methods

BitCount(byte)

Return the number of bits sets in b.

Declaration
public static int BitCount(byte b)
Parameters
Type Name Description
byte b
Returns
Type Description
int

BitList(byte)

Return the list of bits which are set in b encoded as followed:

(i >>> (4 * n)) & 0x0F
is the offset of the n-th set bit of

the given byte plus one, or 0 if there are n or less bits set in the given byte. For example 

bitList(12)
returns 0x43: 
  • 0x43 & 0x0F
    is 3, meaning the the first bit set is at offset 3-1 = 2,
  • (0x43 >>> 4) & 0x0F
    is 4, meaning there is a second bit set at offset 4-1=3,
  • (0x43 >>> 8) & 0x0F
    is 0, meaning there is no more bit set in this byte.
Declaration
public static int BitList(byte b)
Parameters
Type Name Description
byte b
Returns
Type Description
int

NextHighestPowerOfTwo(int)

Returns the next highest power of two, or the current value if it's already a power of two or zero

Declaration
public static int NextHighestPowerOfTwo(int v)
Parameters
Type Name Description
int v
Returns
Type Description
int

NextHighestPowerOfTwo(long)

Returns the next highest power of two, or the current value if it's already a power of two or zero

Declaration
public static long NextHighestPowerOfTwo(long v)
Parameters
Type Name Description
long v
Returns
Type Description
long

Pop_AndNot(long[], long[], int, int)

Returns the popcount or cardinality of A & ~B. Neither array is modified.

Declaration
public static long Pop_AndNot(long[] arr1, long[] arr2, int wordOffset, int numWords)
Parameters
Type Name Description
long[] arr1
long[] arr2
int wordOffset
int numWords
Returns
Type Description
long

Pop_Array(long[], int, int)

Returns the number of set bits in an array of longs.

Declaration
public static long Pop_Array(long[] arr, int wordOffset, int numWords)
Parameters
Type Name Description
long[] arr
int wordOffset
int numWords
Returns
Type Description
long

Pop_Intersect(long[], long[], int, int)

Returns the popcount or cardinality of the two sets after an intersection. Neither array is modified.

Declaration
public static long Pop_Intersect(long[] arr1, long[] arr2, int wordOffset, int numWords)
Parameters
Type Name Description
long[] arr1
long[] arr2
int wordOffset
int numWords
Returns
Type Description
long

Pop_Union(long[], long[], int, int)

Returns the popcount or cardinality of the union of two sets. Neither array is modified.

Declaration
public static long Pop_Union(long[] arr1, long[] arr2, int wordOffset, int numWords)
Parameters
Type Name Description
long[] arr1
long[] arr2
int wordOffset
int numWords
Returns
Type Description
long

Pop_Xor(long[], long[], int, int)

Returns the popcount or cardinality of A ^ B Neither array is modified.

Declaration
public static long Pop_Xor(long[] arr1, long[] arr2, int wordOffset, int numWords)
Parameters
Type Name Description
long[] arr1
long[] arr2
int wordOffset
int numWords
Returns
Type Description
long