//--------------------------------------------------------------------------------------------------
static inline void lwb_estimate_skew() {
uint16_t t_diff = CURRENT_SCHEDULE_INFO().time - OLD_SCHEDULE_INFO().time;
// The maximum time that can be measured with rtimer (32 kHz) is 2.048 seconds before integer wrap-round.
// This is due to 16-bit counters are used in Glossy.
// Therefore, if t_diff is a multiple of 2, then we do not need to use it for skew calculation.
int16_t skew_tmp = lwb_context.t_sync_ref - (lwb_context.t_last_sync_ref + (uint16_t)RTIMER_SECOND * (t_diff % 2));
if (skew_tmp < 500 && t_diff != 0) {
/// @todo Why 64 is used in here.
/// I think 64 is used to make skew_tmp large. The skew_tmp is calculated in rtimer
/// clock ticks. If it is smaller than t_diff, clock skew per unit time becomes zero.
/// Therefore, skew_tmp is multiplied by 64 to make it larger.
lwb_context.skew = (int32_t)(64 * (int32_t)skew_tmp) / (int32_t)t_diff;
/// @todo "dirty hack" to temporary fix a Glossy bug that rarely occurs in disconnected networks
OLD_SCHEDULE_INFO().time = CURRENT_SCHEDULE_INFO().time;
lwb_context.t_last_sync_ref = GLOSSY_T_REF;
} else {
lwb_context.sync_state = LWB_SYNC_STATE_BOOTSTRAP;
set_t_ref_l_updated(0);
}
}
char glossy_scheduler(struct rtimer *t, void *ptr) {
PT_BEGIN(&pt);
if (IS_INITIATOR()) { // Glossy initiator.
while (1) {
printf("[SCHEDULER]: Get Data from queue\n");
// Increment sequence number.
glossy_data.seq_no++;
// Glossy phase.
leds_on(LEDS_GREEN);
rtimer_clock_t t_stop = RTIMER_TIME(t) + GLOSSY_DURATION;
// Start Glossy.
glossy_start((uint8_t *)&glossy_data, DATA_LEN, GLOSSY_INITIATOR, GLOSSY_SYNC, N_TX,
APPLICATION_HEADER, t_stop, (rtimer_callback_t)glossy_scheduler, t, ptr);
// Store time at which Glossy has started.
t_start = RTIMER_TIME(t);
// Yield the protothread. It will be resumed when Glossy terminates.
PT_YIELD(&pt);
// Off phase.
leds_off(LEDS_GREEN);
// Stop Glossy.
glossy_stop();
if (!GLOSSY_IS_BOOTSTRAPPING()) {
// Glossy has already successfully bootstrapped.
if (!GLOSSY_IS_SYNCED()) {
// The reference time was not updated: increment reference time by GLOSSY_PERIOD.
set_t_ref_l(GLOSSY_REFERENCE_TIME + GLOSSY_PERIOD);
set_t_ref_l_updated(1);
}
}
// Schedule begin of next Glossy phase based on GLOSSY_PERIOD.
rtimer_set(t, t_start + GLOSSY_PERIOD, 1, (rtimer_callback_t)glossy_scheduler, ptr);
// Estimate the clock skew over the last period.
estimate_period_skew();
// Poll the process that prints statistics (will be activated later by Contiki).
process_poll(&glossy_print_stats_process);
// Yield the protothread.
PT_YIELD(&pt);
}
} else { // Glossy receiver.
while (1) {
// Glossy phase.
leds_on(LEDS_GREEN);
rtimer_clock_t t_stop;
if (GLOSSY_IS_BOOTSTRAPPING()) {
// Glossy is still bootstrapping:
// Schedule end of Glossy phase based on GLOSSY_INIT_DURATION.
t_stop = RTIMER_TIME(t) + GLOSSY_INIT_DURATION;
} else {
// Glossy has already successfully bootstrapped:
// Schedule end of Glossy phase based on GLOSSY_DURATION.
t_stop = RTIMER_TIME(t) + GLOSSY_DURATION;
}
// Start Glossy.
glossy_start((uint8_t *)&glossy_data, DATA_LEN, GLOSSY_RECEIVER, GLOSSY_SYNC, N_TX,
APPLICATION_HEADER, t_stop, (rtimer_callback_t)glossy_scheduler, t, ptr);
// Yield the protothread. It will be resumed when Glossy terminates.
PT_YIELD(&pt);
// Off phase.
leds_off(LEDS_GREEN);
// Stop Glossy.
glossy_stop();
if (GLOSSY_IS_BOOTSTRAPPING()) {
// Glossy is still bootstrapping.
if (!GLOSSY_IS_SYNCED()) {
// The reference time was not updated: reset skew_estimated to zero.
skew_estimated = 0;
}
} else {
// Glossy has already successfully bootstrapped.
if (!GLOSSY_IS_SYNCED()) {
// The reference time was not updated:
// increment reference time by GLOSSY_PERIOD + period_skew.
set_t_ref_l(GLOSSY_REFERENCE_TIME + GLOSSY_PERIOD + period_skew);
set_t_ref_l_updated(1);
// Increment sync_missed.
sync_missed++;
} else {
// The reference time was not updated: reset sync_missed to zero.
sync_missed = 0;
}
}
// Estimate the clock skew over the last period.
estimate_period_skew();
if (GLOSSY_IS_BOOTSTRAPPING()) {
// Glossy is still bootstrapping.
if (skew_estimated == 0) {
// The reference time was not updated:
// Schedule begin of next Glossy phase based on last begin and GLOSSY_INIT_PERIOD.
rtimer_set(t, RTIMER_TIME(t) + GLOSSY_INIT_PERIOD, 1,
(rtimer_callback_t)glossy_scheduler, ptr);
} else {
// The reference time was updated:
// Schedule begin of next Glossy phase based on reference time and GLOSSY_INIT_PERIOD.
rtimer_set(t, GLOSSY_REFERENCE_TIME + GLOSSY_PERIOD - GLOSSY_INIT_GUARD_TIME, 1,
(rtimer_callback_t)glossy_scheduler, ptr);
}
} else {
// Glossy has already successfully bootstrapped:
// Schedule begin of next Glossy phase based on reference time and GLOSSY_PERIOD.
rtimer_set(t, GLOSSY_REFERENCE_TIME + GLOSSY_PERIOD +
period_skew - GLOSSY_GUARD_TIME * (1 + sync_missed), 1,
(rtimer_callback_t)glossy_scheduler, ptr);
}
// Poll the process that prints statistics (will be activated later by Contiki).
process_poll(&glossy_print_stats_process);
// Yield the protothread.
PT_YIELD(&pt);
}
}
PT_END(&pt);
}
