Bits.cs

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namespace System.Xml;
 
internal static class Bits
{
    public static int Count(uint num)
    {
        num = (num & 0x55555555) + ((num >> 1) & 0x55555555);
        num = (num & 0x33333333) + ((num >> 2) & 0x33333333);
        num = (num & 0xF0F0F0F) + ((num >> 4) & 0xF0F0F0F);
        num = (num & 0xFF00FF) + ((num >> 8) & 0xFF00FF);
        num = (num & 0xFFFF) + (num >> 16);
        return (int)num;
    }
 
    public static bool ExactlyOne(uint num)
    {
        if (num != 0)
        {
            return (num & (num - 1)) == 0;
        }
        return false;
    }
 
    public static uint ClearLeast(uint num)
    {
        return num & (num - 1);
    }
 
    public static int LeastPosition(uint num)
    {
        if (num == 0)
        {
            return 0;
        }
        return Count(num ^ (num - 1));
    }
}