PopCnt Benchmark

PopCntBenchmark.java

public class PopCntBenchmark extends SimpleBenchmark
{
    public int timeIntegerBitCount(int iterations)
    {
        int result = 0;
        for (int i = 0; i < iterations; i++)
        {
            result += Integer.bitCount(i);
        }
        return result;
    }
    
    public int timeMyBitCount(int iterations)
    {
        int result = 0;
        for (int i = 0; i < iterations; i++)
        {
            result += myBitCount(i);
        }
        return result;
    }
    
    private static int myBitCount(int i)
    {
        // HD, Figure 5-2
        i = i - ((i >>> 1) & 0x55555555);
        i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
        i = (i + (i >>> 4)) & 0x0f0f0f0f;
        i = i + (i >>> 8);
        i = i + (i >>> 16);
        return i & 0x3f;        
    }
}