M_KEEPALIVEINTVL
#define G_KEEPALIVEINTVL(x) (((x) >> S_KEEPALIVEINTVL) & M_KEEPALIVEINTVL)
#define G_KEEPALIVEINTVL(x) (((x) >> S_KEEPALIVEINTVL) & M_KEEPALIVEINTVL)
v &= M_KEEPALIVEINTVL;
V_KEEPALIVEINTVL(M_KEEPALIVEINTVL), V_KEEPALIVEINTVL(v));