/// <summary>Returns the popcount or cardinality of the intersection of the two sets.
/// Neither set is modified.
/// </summary>
public static long IntersectionCount(OpenBitSet a, OpenBitSet b)
{
return(BitUtil.Pop_intersect(a.internalbits, b.internalbits, 0, System.Math.Min(a.wlen, b.wlen)));
}
/*
* public static int pop(long v0, long v1, long v2, long v3) {
* // derived from pop_array by setting last four elems to 0.
* // exchanges one pop() call for 10 elementary operations
* // saving about 7 instructions... is there a better way?
* long twosA=v0 & v1;
* long ones=v0^v1;
*
* long u2=ones^v2;
* long twosB =(ones&v2)|(u2&v3);
* ones=u2^v3;
*
* long fours=(twosA&twosB);
* long twos=twosA^twosB;
*
* return (pop(fours)<<2)
+ (pop(twos)<<1)
+ pop(ones);
+
+ }
*/
/// <returns> the number of set bits
/// </returns>
public virtual long Cardinality()
{
return(BitUtil.Pop_array(internalbits, 0, wlen));
}