CH.SipHash.SipHash.SipHash_2_4_UlongCast C# (CSharp) Method

        public static unsafe ulong SipHash_2_4_UlongCast(byte[] inba, ulong k0, ulong k1)
        {
            var inlen = inba.Length;

            var v0 = 0x736f6d6570736575 ^ k0;
            var v1 = 0x646f72616e646f6d ^ k1;
            var v2 = 0x6c7967656e657261 ^ k0;
            var v3 = 0x7465646279746573 ^ k1;

            var b = ((ulong)inlen) << 56;

            if (inlen > 0)
                fixed (byte* finb = &inba[0])
                {
                    var inb = finb;
                    var left = inlen & 7;
                    var end = inb + inlen - left;
                    var linb = (ulong*) finb;
                    var lend = (ulong*) end;
                    for (; linb < lend; ++linb)
                    {
                        v3 ^= *linb;

                        SipRound(ref v0, ref v1, ref v2, ref v3);
                        SipRound(ref v0, ref v1, ref v2, ref v3);

                        v0 ^= *linb;
                    }
                    for (var i = 0; i < left; ++i)
                    {
                        b |= ((ulong)end[i]) << (8 * i);
                    }
                }

            v3 ^= b;
            SipRound(ref v0, ref v1, ref v2, ref v3);
            SipRound(ref v0, ref v1, ref v2, ref v3);
            v0 ^= b;
            v2 ^= 0xff;

            SipRound(ref v0, ref v1, ref v2, ref v3);
            SipRound(ref v0, ref v1, ref v2, ref v3);
            SipRound(ref v0, ref v1, ref v2, ref v3);
            SipRound(ref v0, ref v1, ref v2, ref v3);

            return v0 ^ v1 ^ v2 ^ v3;
        }