npf_state_sample
npf_state_sample = func;
static void (*npf_state_sample)(npf_state_t *, bool) = NULL;
#define NPF_STATE_SAMPLE(n, r) if (npf_state_sample) (*npf_state_sample)(n, r);
static void npf_state_sample(npf_state_t *, bool);
npf_state_setsampler(npf_state_sample);