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87 lines
2.7 KiB
C++
87 lines
2.7 KiB
C++
// vim: set noet ts=4 sw=4:
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/*! \file
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* \brief \ref Thread abstraction required for multithreading
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*/
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/*! \defgroup thread Multithreading
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* \brief The Multithreading Subsystem
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*
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* The group Multithreading contains all elements that form the foundation
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* of CPU multiplexing. This module's objective is to provide the abstraction
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* thread that provides a virtualised CPU for the user's applications.
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*/
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#pragma once
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#include "../arch/context.h"
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#include "../object/queue.h"
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#include "../types.h"
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#include "../interrupt/guard.h"
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/*! \brief The Thread is an object used by the scheduler.
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* \ingroup thread
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*/
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class Thread {
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public:
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/*! \brief The thread's entry point.
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*
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* For the first activation of a thread, we need a "return address"
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* pointing to a function that will take care of calling C++ virtual
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* methods (e.g. \ref action()), based on the thread object pointer.
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* For this purpose, we use this `kickoff()` function.
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*
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* \note As this function is never actually called, but only executed by
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* returning from the co-routine's initial stack, it may never return.
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* Otherwise garbage values from the stack will be interpreted as
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* return address and the system might crash.
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*
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* \param object Thread to be started
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*/
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/// \todo(14) Implement Method
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static void kickoff(Thread* object);
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public:
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/*! \brief Marker for a dying thread
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*/
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volatile bool kill_flag;
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/*! \brief Constructor
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* Initializes the context using \ref prepareContext with the given stack
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* space.
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*
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* \param tos the top of stack, highest address of some memory block that
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* should be used as stack (remember stacks grow to the lower addresses on
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* x86).
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*
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* \todo(14) Implement constructor
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*/
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explicit Thread(void* tos);
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/*! \brief Activates the first thread on this CPU.
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*
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* Calling the method starts the first thread on the calling CPU.
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* From then on, \ref Thread::resume() must be used for all subsequent
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* context switches.
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*
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* \todo(14) Implement Method
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*/
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void go();
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/*! \brief Switches from the currently running thread to the `next` one.
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*
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* The values currently present in the callee-saved registers will be
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* stored in this threads context-structure, the corresponding values
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* belonging to `next` thread will be loaded.
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* \param next Pointer to the next thread.
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*
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* \todo(14) Implement Method
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*/
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void resume(Thread* next);
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/*! \brief Method that contains the thread's program code.
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*
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* Derived classes are meant to override this method to provide
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* meaningful code to be run in this thread.
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*/
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virtual void action();
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};
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