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

System.Object

BitUtil

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.ToString()

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
System.Byte	b

Returns

Type	Description
System.Int32

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
System.Byte	b

Returns

Type	Description
System.Int32

NextHighestPowerOfTwo(Int32)

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
System.Int32	v

Returns

Type	Description
System.Int32

NextHighestPowerOfTwo(Int64)

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
System.Int64	v

Returns

Type	Description
System.Int64

Pop_AndNot(Int64[], Int64[], Int32, Int32)

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
System.Int64[]	arr1
System.Int64[]	arr2
System.Int32	wordOffset
System.Int32	numWords

Returns

Type	Description
System.Int64

Pop_Array(Int64[], Int32, Int32)

Returns the number of set bits in an array of System.Int64s.

Declaration

public static long Pop_Array(long[] arr, int wordOffset, int numWords)

Parameters

Type	Name	Description
System.Int64[]	arr
System.Int32	wordOffset
System.Int32	numWords

Returns

Type	Description
System.Int64

Pop_Intersect(Int64[], Int64[], Int32, Int32)

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
System.Int64[]	arr1
System.Int64[]	arr2
System.Int32	wordOffset
System.Int32	numWords

Returns

Type	Description
System.Int64

Pop_Union(Int64[], Int64[], Int32, Int32)

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
System.Int64[]	arr1
System.Int64[]	arr2
System.Int32	wordOffset
System.Int32	numWords

Returns

Type	Description
System.Int64

Pop_Xor(Int64[], Int64[], Int32, Int32)

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
System.Int64[]	arr1
System.Int64[]	arr2
System.Int32	wordOffset
System.Int32	numWords

Returns

Type	Description
System.Int64