PTR_DIFF
#define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))
#define PTR_DIFF(a, b) ((u32)((unsigned long)(a) - (unsigned long)(b)))
#define PTR_DIFF(p1, p2) ((u8 *)(p1) - (u8 *)(p2))