internal static extern Result FMOD_System_AttachFileSystem(IntPtr systemHandle, FileOpenCallback userOpen, FileCloseCallback userClose, FileReadCallback userRead, FileSeekCallback userSeek);
internal static extern Result FMOD_System_SetFileSystem(IntPtr systemHandle, FileOpenCallback userOpen, FileCloseCallback userClose, FileReadCallback userRead, FileSeekCallback userSeek, int bufferSize);
private static extern Result FMOD_System_AttachFileSystem(IntPtr system, FileOpenCallback useropen, FileCloseCallback userclose, FileReadCallback userread, FileSeekCallback userseek);
private static extern Result FMOD_System_SetFileSystem(IntPtr system, FileOpenCallback useropen, FileCloseCallback userclose, FileReadCallback userread, FileSeekCallback userseek, FileAsyncReadCallback userasyncread, FileAsyncCancelCallback userasynccancel, int blockalign);