Example #1
0
        internal static Func <uint, uint> GetRandomHashMethod1(uint size)
        {
            uint a     = (uint)random.Next();
            uint b     = (uint)(random.Next(65536) << 16);
            int  shift = 31 - (int)BitHacks.Log2Ceiling(size);

            return((x) => ((a * x + b) >> shift) >> 1);
        }
Example #2
0
        static void Main(string[] args)
        {
            uint m       = BitHacks.RoundToPower((uint)random.Next(1000, int.MaxValue / 2));
            int  width   = (int)BitHacks.Log2Ceiling(m);
            var  fks     = GetRandomHashMethodFKS(m);
            var  nomod1  = GetRandomHashMethod1(m);
            var  nomod2  = GetRandomHashMethod2(width);
            var  randoms = Enumerable.Range(0, 100000000).Select((i) => (uint)random.Next((int)m)).ToArray();
            uint a       = (uint)random.Next();
            uint b       = (uint)(random.Next(65536) << 16);
            var  watch   = new Stopwatch();

            watch.Start();
            for (int i = 0; i < randoms.Length; i++)
            {
                fks(randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("fks: {0}", watch.ElapsedMilliseconds);
            watch.Restart();
            for (int i = 0; i < randoms.Length; i++)
            {
                nomod1(randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("nomod by size: {0}", watch.ElapsedMilliseconds);
            watch.Restart();
            for (int i = 0; i < randoms.Length; i++)
            {
                nomod2(randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("nomod by width: {0}", watch.ElapsedMilliseconds);
            watch.Restart();
            for (int i = 0; i < randoms.Length; i++)
            {
                UnrolledHash1(a, b, width, randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("unrolled conditional: {0}", watch.ElapsedMilliseconds);
            watch.Restart();
            for (int i = 0; i < randoms.Length; i++)
            {
                UnrolledHash2(a, b, width, randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("unrolled shift by width: {0}", watch.ElapsedMilliseconds);
            watch.Restart();
            for (int i = 0; i < randoms.Length; i++)
            {
                UnrolledHash3(a, b, m, randoms[i]);
            }
            watch.Stop();
            Console.WriteLine("unrolled shift by size: {0}", watch.ElapsedMilliseconds);
        }
Example #3
0
 internal static uint UnrolledHash3(uint a, uint b, uint size, uint x)
 {
     return(((a * x + b) >> (31 - (int)BitHacks.Log2Ceiling(size))) >> 1);
 }