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//==========================================================================

//

//        philo.cxx

//

//        A test of the dining philosophers problem

//

//==========================================================================

//####ECOSGPLCOPYRIGHTBEGIN####

// -------------------------------------------

// This file is part of eCos, the Embedded Configurable Operating System.

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//####ECOSGPLCOPYRIGHTEND####

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):     dsm

// Contributors:    dsm

// Date:          1998-02-24

// Description:   A test of the dining philosophers problem

//####DESCRIPTIONEND####

// 

#include <cyg/kernel/kernel.hxx>

#include <cyg/hal/hal_io.h>

// -------------------------------------------------------------------------

// Data for the philosophers problem

#define PHILOSOPHERS    15              // number of philosophers

#define STACKSIZE       (2*1024)        // size of thread stack

#define NTHREADS PHILOSOPHERS

#include "testaux.hxx"

// array of chopsticks

Cyg_Binary_Semaphore chopstick[PHILOSOPHERS];

//cyg_thread_entry Philosopher;

// -------------------------------------------------------------------------

// State recording and display

static char pstate[PHILOSOPHERS+1];     // state vector showing what each

                                        // philosopher is doing

Cyg_Mutex state_mutex;

#ifdef CYG_HAL_MN10300_MN103002

static cyg_count8 eaters = 0;

#endif

void change_state(int id, char newstate)

{

    CYG_INSTRUMENT_USER( 1, 0, 0);

    state_mutex.lock();

    CYG_INSTRUMENT_USER( 2, 0, 0);

#ifdef CYG_HAL_MN10300_MN103002

    if( pstate[id] == 'E' ) eaters--;

    if( newstate == 'E' ) eaters++;

//    led(eaters);

#endif

    pstate[id] = newstate;

    diag_write_string(pstate);

#if 0

    diag_write_char(' ');

    diag_write_dec(Cyg_Scheduler::get_thread_switches());

#endif    

    diag_write_char('\n');

    CYG_INSTRUMENT_USER( 3, 0, 0);

    state_mutex.unlock();

    CYG_INSTRUMENT_USER( 4, 0, 0);

}

char get_state( int id)

{

    state_mutex.lock();

    char s = pstate[id];

    state_mutex.unlock();

    return s;

}

// -------------------------------------------------------------------------

// Thread to behave like a philosopher

void Philosopher( CYG_ADDRESS id )

{

    Cyg_Thread *self = Cyg_Thread::self();

    Cyg_Binary_Semaphore *first_stick = &chopstick[id];

    Cyg_Binary_Semaphore *second_stick = &chopstick[(id+1)%PHILOSOPHERS];

#ifdef CYGPKG_INFRA_DEBUG

    int left_philo = ((id==0)?PHILOSOPHERS:id)-1;

    int right_philo = (id==PHILOSOPHERS-1)?0:(id+1);

#endif

    CYG_ASSERT( id >= 0 && id < PHILOSOPHERS, "Bad id");

    // Deadlock avoidance. The easiest way to make the philosophers

    // behave is to make each pick up the lowest numbered stick

    // first. This is how it works out anyway for all the philosophers

    // except the last, who must have his sticks swapped.

    if( id == PHILOSOPHERS-1 )

    {

        Cyg_Binary_Semaphore *t = first_stick;

        first_stick = second_stick;

        second_stick = t;

    }

    // The following variable is shared by all philosophers.

    // It is incremented unprotected, but this does not matter

    // since it is only present to introduce a little variability

    // into the think and eat times.

    static int cycle = 0;

    for(;;)

    {

        // Think for a bit

        self->delay((id+cycle++)%12);    // Cogito ergo sum...

        // I am now hungry, try to get the chopsticks

        change_state(id,'H');

        // Get the first stick

    CYG_INSTRUMENT_USER( 5, 0, 0);

        first_stick->wait();

    CYG_INSTRUMENT_USER( 6, 0, 0);

        // Get the second stick

    CYG_INSTRUMENT_USER( 7, 0, 0);

        second_stick->wait();

    CYG_INSTRUMENT_USER( 8, 0, 0);

        // Got them, now eat

        change_state(id,'E');

        // Check that the world is as I think it is...

        CYG_ASSERT( !first_stick->posted(), "Not got first stick");

        CYG_ASSERT( !second_stick->posted(), "Not got second stick");

        CYG_ASSERT( get_state(left_philo) != 'E', "Left neighbour also eating!!");

        CYG_ASSERT( get_state(right_philo) != 'E', "Right neighbour also eating!!");

        self->delay((id+cycle++)%6);    // munch munch

        // Finished eating, put down sticks.

        change_state(id,'T');

    CYG_INSTRUMENT_USER( 9, 0, 0);

        first_stick->post();

    CYG_INSTRUMENT_USER( 10, 0, 0);

        second_stick->post();

    CYG_INSTRUMENT_USER( 11, 0, 0);

//    Cyg_Scheduler::lock();

//    Cyg_Scheduler::unlock();

    CYG_INSTRUMENT_USER( 12, 0, 0);

    }

}

// -------------------------------------------------------------------------

externC void

cyg_start( void )

{

#ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG

    cyg_hal_invoke_constructors();

#endif

    diag_init();

    diag_write_string("Philosophers\n");

    diag_write_string("Started\n");

    // Zero last element in state so it acts like

    // a string.

    pstate[PHILOSOPHERS] = 0;

#if 1

    for( int i = 0; i < PHILOSOPHERS; i++ )

    {

        change_state(i,'T');            // starting state

        // Start the philosopher

        Cyg_Thread *t = new_thread( Philosopher, i );

        // resume it

        t->resume();

        // and make the matching chopstick present

        chopstick[i].post();

    }

#endif

    // Get the world going

    Cyg_Scheduler::scheduler.start();

}

// -------------------------------------------------------------------------

// EOF philo.cxx