+#include "base/trace.hh"
+#include "config/the_isa.hh"
+#include "debug/TimeSync.hh"
+#include "sim/full_system.hh"
+#include "sim/root.hh"
+
+Root *Root::_root = NULL;
+
+/*
+ * This function is called periodically by an event in M5 and ensures that
+ * at least as much real time has passed between invocations as simulated time.
+ * If not, the function either sleeps, or if the difference is small enough
+ * spin waits.
+ */
+void
+Root::timeSync()
+{
+ Time cur_time, diff, period = timeSyncPeriod();
+
+ do {
+ cur_time.setTimer();
+ diff = cur_time - lastTime;
+ Time remainder = period - diff;
+ if (diff < period && remainder > _spinThreshold) {
+ DPRINTF(TimeSync, "Sleeping to sync with real time.\n");
+ // Sleep until the end of the period, or until a signal.
+ sleep(remainder);
+ // Refresh the current time.
+ cur_time.setTimer();
+ }
+ } while (diff < period);
+ lastTime = cur_time;
+ schedule(&syncEvent, curTick() + _periodTick);
+}
+
+void
+Root::timeSyncEnable(bool en)
+{
+ if (en == _enabled)
+ return;
+ _enabled = en;
+ if (_enabled) {
+ // Get event going.
+ Tick periods = ((curTick() + _periodTick - 1) / _periodTick);
+ Tick nextPeriod = periods * _periodTick;
+ schedule(&syncEvent, nextPeriod);
+ } else {
+ // Stop event.
+ deschedule(&syncEvent);
+ }
+}
+
+/// Configure the period for time sync events.
+void
+Root::timeSyncPeriod(Time newPeriod)
+{
+ bool en = timeSyncEnabled();
+ _period = newPeriod;
+ _periodTick = _period.getTick();
+ timeSyncEnable(en);
+}
+
+/// Set the threshold for time remaining to spin wait.
+void
+Root::timeSyncSpinThreshold(Time newThreshold)
+{
+ bool en = timeSyncEnabled();
+ _spinThreshold = newThreshold;
+ timeSyncEnable(en);
+}