unsafe byte[] ReadBytes(int offset, int num)
{
byte[] arr = new byte[num];
byte* ptr = (byte*)0;
Reader_accessor.SafeMemoryMappedViewHandle.AcquirePointer(ref ptr);
Marshal.Copy(IntPtr.Add(new IntPtr(ptr), offset), arr, 0, num);
Reader_accessor.SafeMemoryMappedViewHandle.ReleasePointer();
return arr;
}