Microsoft.Scripting.Math.BigInteger.Mantissa C# (CSharp) Method

    private static ulong Mantissa(byte[] v) {
      uint i1 = ((uint)v[0] | ((uint)v[1] << 8) | ((uint)v[2] << 16) | ((uint)v[3] << 24));
      uint i2 = ((uint)v[4] | ((uint)v[5] << 8) | ((uint)(v[6] & 0xF) << 16));

      return (ulong)((ulong)i1 | ((ulong)i2 << 32));
    }