#define OFFSETOF(s, i) ((unsigned int) PTR_TO(s, i))
#define SKIP_BACK(s, i, p) ((s *)((char *)p - OFFSETOF(s, i)))
#define ALIGN_TO(s, a) (((s)+a-1)&~(a-1))
#define OFFSETOF(s, i) ((unsigned int) PTR_TO(s, i))
#define SKIP_BACK(s, i, p) ((s *)((char *)p - OFFSETOF(s, i)))
#define ALIGN_TO(s, a) (((s)+a-1)&~(a-1))