Aufgabe 6: Synchronisation

Windup / initialize.

Assigns itself to the Plugbox and initializes the LAPIC::Timer in such a way that regular interrupts are triggered approx. every us microseconds when Watch::activate() is called. For this purpose, a suitable timer divisor is determined based on the timer frequency determined with LAPIC::Timer::ticks(). This timer divisor has to be as small as possible, but large enough to prevent the 32bit counter from overflowing.

Parameters

us	Desired interrupt interval in microseconds.

Returns

Indicates if the interval could be set.

Prologue of timer interrupts.

Returns

true if the Watch::epilogue should be executed.

Implements Gate.

Epilogue of timer interrupts.

Triggers the thread switch and checks the Bellringer.

Todo:

Extend method (add Bellringer)

Reimplemented from Gate.

Retrieve the interrupt interval.

Returns

Interval in microseconds

Activate the timer on this core.

The core local timer starts with the interval previously configured in windup(). To get timer interrupts on all cores, this method must be called once per core (however, it is sufficient to call windup only once since the APIC-Bus frequency is the same on each core).

Blocks the timer interrupts on this core.

The LAPIC Timer can be masked with LAPIC::Timer::setMasked as soon as no thread is ready and no Bell is waiting to be counted down. block() and unblock() must be called from the idle loop.

Optional:

Implement for tickless kernel

Allow the previously blocked timer interrupts on this core.

Logical counterpart to Watch::block(). Allows the delivery of core local timer interrupts again.

Optional:

Implement for tickless kernel