Interrupt Class Reference

Public Member Functions
	Interrupt ()
	Interrupt::Interrupt Initialize the simulation of hardware device interrupts. More...
	~Interrupt ()
	Interrupt::~Interrupt De-allocate the data structures needed by the interrupt simulation.
IntStatus	SetLevel (IntStatus level)
	Interrupt::SetLevel Change interrupts to be enabled or disabled, and if interrupts are being enabled, advance simulated time by calling OneTick(). More...
void	Enable ()
	Interrupt::Enable Turn interrupts on. Who cares what they used to be? Used in ThreadRoot, to turn interrupts on when first starting up a thread.
IntStatus	getLevel ()
void	Idle ()
	Interrupt::Idle Routine called when there is nothing in the ready queue. More...
void	Halt ()
	Interrupt::Halt Shut down Nachos cleanly, printing out performance statistics.
void	YieldOnReturn ()
	Interrupt::YieldOnReturn Called from within an interrupt handler, to cause a context switch (for example, on a time slice) in the interrupted thread, when the handler returns. More...
MachineStatus	getStatus ()
void	setStatus (MachineStatus st)
void	DumpState ()
	DumpState Print the complete interrupt state - the status, and all interrupts that are scheduled to occur in the future.
void	Schedule (VoidFunctionPtr handler, int arg, long long when, IntType type)
	Interrupt::Schedule Arrange for the CPU to be interrupted when simulated time reaches "now + when". More...
void	OneTick ()
	Interrupt::OneTick Advance simulated time and check if there are any pending interrupts to be called. More...

Constructor & Destructor Documentation

Interrupt::Interrupt

(

)

Interrupt::Interrupt Initialize the simulation of hardware device interrupts.

Interrupts start disabled, with no interrupts pending, etc.

Member Function Documentation

void Interrupt::Idle

(

)

Interrupt::Idle Routine called when there is nothing in the ready queue.

Since something has to be running in order to put a thread on the ready queue, the only thing to do is to advance simulated time until the next scheduled hardware interrupt.

If there are no pending interrupts, stop. There's nothing more for us to do.

void Interrupt::OneTick

(

)

Interrupt::OneTick Advance simulated time and check if there are any pending interrupts to be called.

Two things can cause OneTick to be called: interrupts are re-enabled a user instruction is executed

void Interrupt::Schedule	(	VoidFunctionPtr	handler,
		int	arg,
		long long	fromNow,
		IntType	type
	)

Interrupt::Schedule Arrange for the CPU to be interrupted when simulated time reaches "now + when".

Implementation: just put it on a sorted list.

NOTE: the Nachos kernel should not call this routine directly. Instead, it is only called by the hardware device simulators.

Parameters

handler	is the procedure to call when the interrupt occurs
arg	is the argument to pass to the procedure
fromNow	is how far in the future (in simulated time) the interrupt is to occur
type	is the hardware device that generated the interrupt

IntStatus Interrupt::SetLevel

(

IntStatus

now

)

Interrupt::SetLevel Change interrupts to be enabled or disabled, and if interrupts are being enabled, advance simulated time by calling OneTick().

Returns:

Returns

The old interrupt status. Parameters:

Parameters

now	– the new interrupt status

void Interrupt::YieldOnReturn

(

)

Interrupt::YieldOnReturn Called from within an interrupt handler, to cause a context switch (for example, on a time slice) in the interrupted thread, when the handler returns.

We can't do the context switch here, because that would switch out the interrupt handler, and we want to switch out the interrupted thread.

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

• code/machine/interrupt.h
• code/machine/interrupt.cc