Subversion Repositories programming

/*******************************************************************************

 * elevator.cpp

 *

 * Implementation for the Elevator class.

 *

 * Copyright 2006, Ira W. Snyder (devel@irasnyder.com)

 ******************************************************************************/

#include "elevator.h"

Elevator::Elevator (int num_floors) : num_floors(num_floors)

{

    int i;

    this->terminate = false;

    this->pause = false;

    this->direction = IDLE;

    this->current_floor = 0.0;

    this->controller = NULL;

    this->stop_at_floors.reserve (num_floors);

    for (i=0; i<num_floors; i++)

        this->stop_at_floors.push_back(bool(false));

    printf ("created elevator 0x%x-- numfloors=%d\n", this, this->num_floors);

}

Elevator::~Elevator ()

{

    this->pause = false;

    this->terminate = true;

}

int Elevator::get_direction ()

{

    return this->direction;

}

/**

 * Return the number of floors above the current one that

 * are queued to be stopped at.

 */

int Elevator::floors_above_current ()

{

    int i = ((int)current_floor) + 1;

    int count = 0;

    for (/* see above */; i<num_floors; i++)

        if (stop_at_floors.at(i))

            count++;

    return count;

}

/**

 * Return the number of floors below the current one that

 * are queued to be stopped at.

 */

int Elevator::floors_below_current ()

{

    int i;

    int count = 0;

    if (near_a_floor ())

        i = (int)current_floor - 1;

    else

        i = (int)current_floor;

    for (/* see above */; i>=0; i--)

        if (stop_at_floors.at(i))

            count++;

    return count;

}

void Elevator::push_button (int floor)

{

    assert (floor < num_floors);

    assert (floor >= 0);

    this->stop_at_floors.at(floor) = true;

}

/**

 * This function is the entry point for a thread.

 *

 * You must pass the object in, since this is a static function

 * and we aren't allowed to access the this pointer.

 */

void Elevator::thread_entry (const Elevator *me)

{

    assert (me != NULL);

    Elevator *pthis = (Elevator*)me;

    while (!pthis->terminate)

    {

        /* Implement "pausing" */

        while (pthis->pause)

        {

            usleep (ELEVATOR_TIME_PAUSE_USEC);

        }

        pthis->run_elevator_logic ();

#ifndef QUIET

        std::cout << pthis << " Position: " << pthis->current_floor << std::endl;

#endif

        usleep (ELEVATOR_TIME_DELAY_USEC);

    }

}

void Elevator::thread_start ()

{

    boost::thread the_thread (boost::bind (this->thread_entry, this));

}

void Elevator::run_elevator_logic ()

{

    int i;

    /* Decide what to do */

    switch (direction)

    {

        case IDLE:

            /* Move towards the direction that has more floors to stop at.

             * Prefer DOWN if there is a tie. */

            if (has_floors_to_stop_at ())

            {

                direction = (floors_above_current () > floors_below_current ()) ? MOVE_UP : MOVE_DOWN;

#ifndef QUIET

                printf ("changed direction to: %s\n", (direction == MOVE_UP) ? "MOVE_UP" : "MOVE_DOWN");

#endif

            }

            break;

        case MOVE_UP:

            /* Decide if we should stop at the floor we're at */

            if (should_stop_at_current_floor ())

            {

#ifndef QUIET

                printf ("stop at floor %d -- while going up\n", (int)(current_floor+0.5));

#endif

                stop_at_floors.at((int)(current_floor+0.5)) = false;

                have_user_enter_buttons ();

            }

            /* Decide to sit idle if we have no more floors to stop at */

            if (!has_floors_to_stop_at ())

            {

#ifndef QUIET

                puts ("decides to sit idle");

#endif

                direction = IDLE;

            }

            /* Decide to switch directions if we have no more floors to stop

             * at in the current direction, but we have floors in the

             * opposite direction to stop at. */

            else if (floors_below_current () && !floors_above_current ())

            {

#ifndef QUIET

                puts ("decides to switch direction to down");

#endif

                direction = MOVE_DOWN;

            }

            /* Since nothing else applies, we should keep moving in the

             * current direction, up. */

            else

            {

                current_floor += ELEVATOR_TIME_MOVE_AMOUNT;

                // Check to make sure we don't go too high

                assert (current_floor < (num_floors * 1.0));

            }

            break;

        case MOVE_DOWN:

            /* Decide if we should stop at the floor we're at */

            if (should_stop_at_current_floor ())

            {

#ifndef QUIET

                printf ("stop at floor %d -- while going down\n", (int)(current_floor+0.5));

#endif

                stop_at_floors.at((int)(current_floor+0.5)) = false;

                have_user_enter_buttons ();

            }

            /* Decide to sit idle if we have no more floors to stop at */

            if (!has_floors_to_stop_at ())

            {

#ifndef QUIET

                puts ("decides to sit idle");

#endif

                direction = IDLE;

            }

            /* Decide to switch directions if we have no more floors to stop

             * at in the current direction, but we have floors in the

             * opposite direction to stop at. */

            else if (floors_above_current () && !floors_below_current ())

            {

#ifndef QUIET

                puts ("decides to switch direction to up");

#endif

                direction = MOVE_UP;

            }

            /* Since nothing else applies, we should keep moving in the

             * current direction, down. */

            else

            {

                current_floor -= ELEVATOR_TIME_MOVE_AMOUNT;

                // Check to make sure we don't go too low

                assert (current_floor > -0.1);

            }

            break;

        default:

            assert (false); // bad value of direction

            break;

    }

}

/**

 * Call this to stop the thread from running.

 */

void Elevator::thread_stop ()

{

    this->terminate = true;

}

/**

 * Call this to pause the thread without exiting it.

 */

void Elevator::thread_pause ()

{

    this->pause = true;

}

/**

 * Call this to unpause the thread.

 */

void Elevator::thread_unpause ()

{

    this->pause = false;

}

bool Elevator::near_a_floor ()

{

    int i;

    for (i=0; i<num_floors; i++)

        if (near_floor (i))

            return true;

    return false;

}

bool Elevator::near_floor (int floor)

{

    assert (floor >= 0);

    assert (floor < num_floors);

    const float thresh  = ELEVATOR_TIME_MOVE_AMOUNT / 2.0;

    const float greater = floor + thresh;

    const float lower   = floor - thresh;

    if (current_floor > lower && current_floor < greater)

        return true;

    return false;

}

bool Elevator::has_floors_to_stop_at ()

{

    int i;

    for (i=0; i<num_floors; i++)

        if (stop_at_floors.at(i))

            return true;

    return false;

}

bool Elevator::should_stop_at_current_floor ()

{

    int i;

    for (i=0; i<num_floors; i++)

        if (near_floor (i) && stop_at_floors.at(i) == true)

            return true;

    return false;

}

bool Elevator::button_is_pushed (int floor)

{

    assert (floor < num_floors);

    assert (floor >= 0);

    return stop_at_floors.at(floor);

}

float Elevator::get_current_floor ()

{

    return current_floor;

}

void Elevator::set_controller (Controller *c)

{

    this->controller = c;

}

void Elevator::have_user_enter_buttons ()

{

    controller->pause_all_elevators ();

    usleep (10000);

    std::string s;

    std::cout << "Enter floors to stop at for elevator (space seperated): ";

    getline (std::cin, s);

    typedef std::vector<std::string> split_vector_type;

    split_vector_type SplitVec;

    boost::split (SplitVec, s, boost::is_any_of(" "));

    int i, val;

    for (i=0; i<SplitVec.size(); i++)

    {

        val = atoi (SplitVec[i].c_str());

        // Ignore values that are outside of range

        if (val >= 0 && val < num_floors)

            this->push_button (val);

    }

    controller->unpause_all_elevators ();

}