sym_reg
#define REGJ(p,r) (offsetof(struct sym_reg, p ## r))
o = offsetof(struct sym_reg, nc_scrx[0]);
assert (((offsetof(struct sym_reg, nc_sxfer) ^
assert (((offsetof(struct sym_reg, nc_scntl3) ^
#define INB(np, r) INB_OFF(np, offsetof(struct sym_reg, r))
#define INW(np, r) INW_OFF(np, offsetof(struct sym_reg, r))
#define INL(np, r) INL_OFF(np, offsetof(struct sym_reg, r))
#define OUTB(np, r, v) OUTB_OFF(np, offsetof(struct sym_reg, r), (v))
#define OUTW(np, r, v) OUTW_OFF(np, offsetof(struct sym_reg, r), (v))
#define OUTL(np, r, v) OUTL_OFF(np, offsetof(struct sym_reg, r), (v))