org.apache.lucene.util
Class BitUtil

java.lang.Object
  org.apache.lucene.util.BitUtil

public final class BitUtil
extends Object

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.

Method Summary

static int	nextHighestPowerOfTwo(int v) returns the next highest power of two, or the current value if it's already a power of two or zero
static long	nextHighestPowerOfTwo(long v) returns the next highest power of two, or the current value if it's already a power of two or zero
static long	pop_andnot(long[] arr1, long[] arr2, int wordOffset, int numWords) Returns the popcount or cardinality of A & ~B.
static long	pop_array(long[] arr, int wordOffset, int numWords) Returns the number of set bits in an array of longs.
static long	pop_intersect(long[] arr1, long[] arr2, int wordOffset, int numWords) Returns the popcount or cardinality of the two sets after an intersection.
static long	pop_union(long[] arr1, long[] arr2, int wordOffset, int numWords) Returns the popcount or cardinality of the union of two sets.
static long	pop_xor(long[] arr1, long[] arr2, int wordOffset, int numWords) Returns the popcount or cardinality of A ^ B Neither array is modified.

Methods inherited from class java.lang.Object

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

Method Detail

pop_array

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

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

pop_intersect

public static long pop_intersect(long[] arr1,
                                 long[] arr2,
                                 int wordOffset,
                                 int numWords)

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

pop_union

public static long pop_union(long[] arr1,
                             long[] arr2,
                             int wordOffset,
                             int numWords)

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

pop_andnot

public static long pop_andnot(long[] arr1,
                              long[] arr2,
                              int wordOffset,
                              int numWords)

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

pop_xor

public static long pop_xor(long[] arr1,
                           long[] arr2,
                           int wordOffset,
                           int numWords)

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

nextHighestPowerOfTwo

public static int nextHighestPowerOfTwo(int v)

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

nextHighestPowerOfTwo

public static long nextHighestPowerOfTwo(long v)

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