struct display { char pad[0x90]; void *screens; };
struct screen { char pad[0x8]; unsigned int root; };

/* The 1987 compiler's &-of-member is a bit address, so these return the
   ROM's bit offsets 0x480/0x40 directly. */
int layout_screens() { return (int)&((struct display *)0)->screens; }
int layout_root() { return (int)&((struct screen *)0)->root; }