Class BitUtil

A variety of high efficiency bit twiddling routines.

This is a Lucene.NET INTERNAL API, use at your own risk
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 sealed class BitUtil

Methods

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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
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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
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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
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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
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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
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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
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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
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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
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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