How to get a window Lisp_Object from struct window *w?

[Keith David Bershatsky]

I am chiseling away at feature requests #17684 (crosshairs) and #22873 
(multiple fake cursors).

In this particular example, redisplay gives us the w (struct window *w) as it 
goes through each window.  I am recording the window Lisp_Object in a cache 
(also a Lisp_Object) and am later checking that cache to see if w == XWINDOW 
(window).  There is no guarantee that the window that I am interested in is the 
selected_window, and the functions giving me the w do not provide the window as 
an incoming argument.  I see that I can use:

Lisp_Object window = window_from_coordinates (f, opoint_x, opoint_y, &part, 
true);

get-buffer-window/w->contents is not helpful because there may be more than one 
window on the frame displaying the same buffer.

I was wondering if there is a more efficient way to derive window from a struct 
window *w?

Thanks,

Keith