int al_get_font_ranges(ALLEGRO_FONT *f, int ranges_count, int *ranges)
Gets information about all glyphs contained in a font, as a list of ranges. Ranges have the same format as with al_grab_font_from_bitmap(3alleg5).
ranges_count is the maximum number of ranges that will be returned.
ranges should be an array with room for ranges_count * 2 elements. The even integers are the first unicode point in a range, the odd integers the last unicode point in a range.
Returns the number of ranges contained in the font (even if it is bigger than ranges_count).