Watch Class Reference

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

#include <watch.h>

Inheritance diagram for Watch:

Collaboration diagram for Watch:

Public Member Functions
bool	windup (uint32_t us)
	Windup / initialize.
bool	prologue () override
	Prologue of timer interrupts.
void	epilogue () override
	Epilogue of timer interrupts.
uint32_t	interval () const
	Retrieve the interrupt interval.
void	activate () const
	Activate the timer on this core.
void	block_if_possible ()
	Blocks the timer interrupts on this core if no bells are pending.
void	unblock ()
	Allow the previously blocked timer interrupts on this core.
Public Member Functions inherited from Gate
	Gate ()
	Constructor.
virtual	~Gate ()
	Destructor.
virtual bool	prologue ()=0
	Device-specific interrupt handling routine that is executed immediately after the interrupt occurs (asynchronously).
virtual void	epilogue ()
	Possibly delayed, synchronously executed Device-specific interrupt handling routine.

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

activate()

void Watch::activate

(

)

const

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).

block_if_possible()

void Watch::block_if_possible

(

)

Blocks the timer interrupts on this core if no bells are pending.

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_if_possible() and unblock() must be called from the idle loop.

epilogue()

void Watch::epilogue ( )

overridevirtual

Epilogue of timer interrupts.

Triggers the thread switch and checks the Bellringer.

Todo:

Extend method (add Graphics)

Reimplemented from Gate.

interval()

uint32_t Watch::interval

(

)

const

Retrieve the interrupt interval.

Returns

Interval in microseconds

prologue()

bool Watch::prologue ( )

overridevirtual

Prologue of timer interrupts.

Returns

true if the Watch::epilogue should be executed.

Implements Gate.

unblock()

void Watch::unblock

(

)

Allow the previously blocked timer interrupts on this core.

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

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 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.

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

• device/watch.h
• device/watch.cc