The Watch device deals with timer interrupts. More...

#include <device/watch.h>

Inheritance diagram for Watch:

Collaboration diagram for Watch:

Public Member Functions
bool	windup (uint32_t us)
	Windup / initialize. More...

bool	prologue () override
	Prologue of timer interrupts. More...

void	epilogue () override
	Epilogue of timer interrupts. More...

uint32_t	interval () const
	Retrieve the interrupt interval. More...

void	activate () const
	Activate the timer on this core. More...

Public Member Functions inherited from Gate
	Gate ()
	Constructor.

virtual	~Gate ()
	Destructor. More...

virtual bool	prologue ()=0
	Device-specific interrupt handling routine that is executed immediately after the interrupt occurs (asynchronously). More...

virtual void	epilogue ()
	Possibly delayed, synchronously executed Device-specific interrupt handling routine. More...

Detailed Description

The Watch device deals with timer interrupts.

Handles LAPIC::Timer interrupts, therefore managing the time slices and triggering a thread switch if necessary.

Member Function Documentation

◆ windup()

bool Watch::windup ( uint32_t us )

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. However, the LAPIC::Timer is not armed until Watch::activate() is called. Hence, Watch::windup() just sets up all the values. 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()

bool Watch::prologue ( )

overridevirtual

Prologue of timer interrupts.

Returns: true if the Watch::epilogue should be executed.

Implements Gate.

◆ epilogue()

void Watch::epilogue ( )

overridevirtual

Epilogue of timer interrupts.

Triggers the thread switch and checks the Bellringer.

Todo:: Extend method (add Bellringer)

Reimplemented from Gate.

◆ interval()

uint32_t Watch::interval ( ) const

Retrieve the interrupt interval.

Returns: Interval in microseconds

◆ activate()

void Watch::activate ( ) const

Activate the timer on this core.

Activate the LAPIC::Timer using LAPIC::Timer::set(). 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).

The documentation for this class was generated from the following files:

device/watch.h
device/watch.cc