Thread Class Reference

The Thread is an object used by the scheduler. More...

#include <thread.h>

Inheritance diagram for Thread:

Collaboration diagram for Thread:

Public Member Functions
	Thread (void *tos)
	Constructor Initializes the context using prepareContext with the given stack space.
void	go ()
	Activates the first thread on this CPU.
void	resume (Thread *next)
	Switches from the currently running thread to the next one.
virtual void	action ()=0
	Method that contains the thread's program code.

Public Attributes
volatile bool	kill_flag
	Marker for a dying thread.

Static Protected Member Functions
static void	kickoff (Thread *object)
	The thread's entry point.

Protected Attributes
Context	context
	Context of the thread, used for saving and restoring the register values when context switching.

Private Attributes
Thread *	queue_link
	pointer to the next element of the readylist

Friends
class	Queue< Thread >
class	Semaphore

Detailed Description

The Thread is an object used by the scheduler.

Constructor & Destructor Documentation

Thread()

Thread::Thread ( void * tos )

explicit

Constructor Initializes the context using prepareContext with the given stack space.

Parameters

tos	the top of stack, highest address of some memory block that should be used as stack (remember stacks grow to the lower addresses on x86).

Member Function Documentation

action()

void Thread::action ( )

pure virtual

Method that contains the thread's program code.

Derived classes are meant to override this method to provide meaningful code to be run in this thread.

Implemented in Application, IdleThread, and KeyboardApplication.

go()

void Thread::go

(

)

Activates the first thread on this CPU.

Calling the method starts the first thread on the calling CPU. From then on, Thread::resume() must be used for all subsequent context switches.

kickoff()

void Thread::kickoff ( Thread * object )

staticprotected

The thread's entry point.

For the first activation of a thread, we need a "return address" pointing to a function that will take care of calling C++ virtual methods (e.g. action()), based on the thread object pointer. For this purpose, we use this kickoff() function.

Note

As this function is never actually called, but only executed by returning from the co-routine's initial stack, it may never return. Otherwise garbage values from the stack will be interpreted as return address and the system might crash.

Parameters

object

Thread to be started

resume()

void Thread::resume

(

Thread *

next

)

Switches from the currently running thread to the next one.

The values currently present in the callee-saved registers will be stored in this threads context-structure, the corresponding values belonging to next thread will be loaded.

Parameters

next	Pointer to the next thread.

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

• thread/thread.h
• thread/thread.cc