orcasim::base::Engine Class Reference

This class implements an event queue to schedule and execute hardware modules. More...

#include <Engine.hpp>

Public Member Functions
	Engine ()
	Default constructor, takes no parameters. More...
SimulationTime	Run (SimulationTime time=100000)
	Executes the simulator until the internal clock reaches <time> cycles. More...
SimulationTime	GetGlobalTime ()
	Gets the current global time. More...
SimulationTime	GetEpochs ()
	Gets the number of cycles to simulate before reseting the simulation clock. More...
SimulationTime	NextEpoch ()
	Resets the simulation clock and advance simulation to the next epoch. More...
void	Schedule (const Event &e)
	Adds an event to the simulation queue. More...
	~Engine ()
	Destructor. More...

Private Member Functions
void	executeNext ()
	execute event at top of event queue More...

Private Attributes
SimulationTime	_epochs
	number of cycles to simulate before reseting the queue More...
std::priority_queue< Event >	_queue
	queue that stores all events More...
SimulationTime	_globalTime
	The global clock, stores current simulation time. More...
SimulationTime	_timeout
	max time the simulation can reach More...

Detailed Description

This class implements an event queue to schedule and execute hardware modules.

The <priority_queue> from the std lib is used to sort elements by time.

Definition at line 46 of file Engine.hpp.

Constructor & Destructor Documentation

Engine()

Engine::Engine

(

)

Default constructor, takes no parameters.

Defaul constructor.

Definition at line 34 of file Engine.cpp.

               {
    _queue = std::priority_queue<Event>();
    _globalTime = 0;
    _epochs = 0;
    _timeout = 1;
}

~Engine()

Engine::~Engine

(

)

Destructor.

Dtor.

Definition at line 135 of file Engine.cpp.

                {
    // nothing to do
}

Member Function Documentation

executeNext()

void orcasim::base::Engine::executeNext ( )

private

execute event at top of event queue

GetEpochs()

SimulationTime Engine::GetEpochs

(

)

Gets the number of cycles to simulate before reseting the simulation clock.

Returns

value of __epochs

Definition at line 115 of file Engine.cpp.

                                 {
    return _epochs;
}

GetGlobalTime()

SimulationTime Engine::GetGlobalTime

(

)

Gets the current global time.

Returns

value of _globalTime

Definition at line 110 of file Engine.cpp.

                                     {
    return _globalTime;
}

NextEpoch()

SimulationTime Engine::NextEpoch

(

)

Resets the simulation clock and advance simulation to the next epoch.

Generate the next epoch for a simulation session.

Returns

The time in which the simulation clock was before advancing to the next epoch.

?

Definition at line 81 of file Engine.cpp.

                                 {
    // get the number of elements scheduled
    int queue_size = static_cast<int>(_queue.size());

    // time that amount of time
    SimulationTime discount = _globalTime - 1;

    // create a new queue and reschedule events
    Event tmp_queue[queue_size];

    // store events in an array so that we can update
    // them without messing up with the priority queue
    for (int i = 0; i < queue_size; i++) {
        tmp_queue[i] = _queue.top();
        tmp_queue[i].time -= discount;

        _queue.pop();
    }

    // put update events back in simulator's queue
    for (int i = 0; i < queue_size; i++)
        _queue.push(tmp_queue[i]);

    // update epochs counters
    _epochs++;

    return _globalTime;
}

Run()

SimulationTime Engine::Run

(

SimulationTime

time = 100000

)

Executes the simulator until the internal clock reaches <time> cycles.

Runs an epoch of simulation.

Parameters

time	Maximum cycles to simulate

Returns

the time in which the clock ended the simulation.

Parameters

time	Number of cycles to run

Returns

the time in which the last event was executed. Should roughly correspond to <time>.

Definition at line 46 of file Engine.cpp.

                                              {
    _globalTime = 0;
    _timeout = time;

    while (_globalTime <= _timeout) {
        #ifdef ORCA_BASE_CHECK_FOR_EMPTY_QUEUE
        if (_queue.size() <= 0) {
            throw std::runtime_error("Simulation queue is empty");
        }
        #endif

        // get next event to be processed. Since we use a priority
        // queue to store events, the event nealy in time will be
        // popped first
        Event e = _queue.top();
        _queue.pop();

        // update global time
        _globalTime = e.time;

        // schedule current event to be executed after a certain number
        // cycles, defined in the correspondent Run method
        e.time += e.timedModel->Run();

        // push event back to the queue
        _queue.push(e);
    }

    // return point in time in which the last event was executed
    return _globalTime;
}

Schedule()

void Engine::Schedule

(

const Event &

e

)

Adds an event to the simulation queue.

Schedule an event to run in a certain period of time.

Parameters

e	Event to be added
e	Event to run.

Definition at line 122 of file Engine.cpp.

                                    {
    #ifdef URSA_ZERO_TIME_CHECKING
    if (e.time == 0) {
        throw std::runtime_error("Simulator: unable to schedule "
            + e.timedModel->GetName() + " to run in the past. " +
            "Events must be scheduled to run with time > 0.");
    }
    #endif
    _queue.push(e);
}

Member Data Documentation

_epochs

SimulationTime orcasim::base::Engine::_epochs

private

number of cycles to simulate before reseting the queue

Definition at line 49 of file Engine.hpp.

_globalTime

SimulationTime orcasim::base::Engine::_globalTime

private

The global clock, stores current simulation time.

Definition at line 55 of file Engine.hpp.

_queue

std::priority_queue<Event> orcasim::base::Engine::_queue

private

queue that stores all events

Definition at line 52 of file Engine.hpp.

_timeout

SimulationTime orcasim::base::Engine::_timeout

private

max time the simulation can reach

Definition at line 58 of file Engine.hpp.

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

• orcasim-base/include/Engine.hpp
• orcasim-base/src/Engine.cpp