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//==========================================================================
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//
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//        philo.cxx
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//
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//        A test of the dining philosophers problem
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//
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//==========================================================================
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//####ECOSGPLCOPYRIGHTBEGIN####
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// -------------------------------------------
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// This file is part of eCos, the Embedded Configurable Operating System.
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// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
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//
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// eCos is free software; you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free
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// Software Foundation; either version 2 or (at your option) any later version.
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//
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// eCos is distributed in the hope that it will be useful, but WITHOUT ANY
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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// for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with eCos; if not, write to the Free Software Foundation, Inc.,
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// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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//
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// As a special exception, if other files instantiate templates or use macros
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// or inline functions from this file, or you compile this file and link it
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// with other works to produce a work based on this file, this file does not
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// by itself cause the resulting work to be covered by the GNU General Public
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// License. However the source code for this file must still be made available
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// in accordance with section (3) of the GNU General Public License.
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//
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// This exception does not invalidate any other reasons why a work based on
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// this file might be covered by the GNU General Public License.
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//
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// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
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// at http://sources.redhat.com/ecos/ecos-license/
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// -------------------------------------------
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//####ECOSGPLCOPYRIGHTEND####
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//==========================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s):     dsm
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// Contributors:    dsm
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// Date:          1998-02-24
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// Description:   A test of the dining philosophers problem
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//####DESCRIPTIONEND####
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// 
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#include <cyg/kernel/kernel.hxx>
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#include <cyg/hal/hal_io.h>
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// -------------------------------------------------------------------------
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// Data for the philosophers problem
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#define PHILOSOPHERS    15              // number of philosophers
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#define STACKSIZE       (2*1024)        // size of thread stack
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#define NTHREADS PHILOSOPHERS
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#include "testaux.hxx"
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// array of chopsticks
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Cyg_Binary_Semaphore chopstick[PHILOSOPHERS];
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//cyg_thread_entry Philosopher;
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// -------------------------------------------------------------------------
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// State recording and display
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static char pstate[PHILOSOPHERS+1];     // state vector showing what each
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                                        // philosopher is doing
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Cyg_Mutex state_mutex;
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#ifdef CYG_HAL_MN10300_MN103002
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static cyg_count8 eaters = 0;
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#endif
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void change_state(int id, char newstate)
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{
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    CYG_INSTRUMENT_USER( 1, 0, 0);
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    state_mutex.lock();
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    CYG_INSTRUMENT_USER( 2, 0, 0);
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#ifdef CYG_HAL_MN10300_MN103002
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    if( pstate[id] == 'E' ) eaters--;
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    if( newstate == 'E' ) eaters++;
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//    led(eaters);
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#endif
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    pstate[id] = newstate;
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    diag_write_string(pstate);
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#if 0
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    diag_write_char(' ');
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    diag_write_dec(Cyg_Scheduler::get_thread_switches());
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#endif    
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    diag_write_char('\n');
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    CYG_INSTRUMENT_USER( 3, 0, 0);
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    state_mutex.unlock();
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    CYG_INSTRUMENT_USER( 4, 0, 0);
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}
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char get_state( int id)
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{
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    state_mutex.lock();
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    char s = pstate[id];
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    state_mutex.unlock();
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    return s;
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}
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// -------------------------------------------------------------------------
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// Thread to behave like a philosopher
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void Philosopher( CYG_ADDRESS id )
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{
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    Cyg_Thread *self = Cyg_Thread::self();
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    Cyg_Binary_Semaphore *first_stick = &chopstick[id];
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    Cyg_Binary_Semaphore *second_stick = &chopstick[(id+1)%PHILOSOPHERS];
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#ifdef CYGPKG_INFRA_DEBUG
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    int left_philo = ((id==0)?PHILOSOPHERS:id)-1;
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    int right_philo = (id==PHILOSOPHERS-1)?0:(id+1);
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#endif
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    CYG_ASSERT( id >= 0 && id < PHILOSOPHERS, "Bad id");
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    // Deadlock avoidance. The easiest way to make the philosophers
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    // behave is to make each pick up the lowest numbered stick
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    // first. This is how it works out anyway for all the philosophers
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    // except the last, who must have his sticks swapped.
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    if( id == PHILOSOPHERS-1 )
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    {
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        Cyg_Binary_Semaphore *t = first_stick;
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        first_stick = second_stick;
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        second_stick = t;
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    }
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    // The following variable is shared by all philosophers.
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    // It is incremented unprotected, but this does not matter
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    // since it is only present to introduce a little variability
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    // into the think and eat times.
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    static int cycle = 0;
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    for(;;)
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    {
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        // Think for a bit
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        self->delay((id+cycle++)%12);    // Cogito ergo sum...
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        // I am now hungry, try to get the chopsticks
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        change_state(id,'H');
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        // Get the first stick
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    CYG_INSTRUMENT_USER( 5, 0, 0);
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        first_stick->wait();
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    CYG_INSTRUMENT_USER( 6, 0, 0);
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        // Get the second stick
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    CYG_INSTRUMENT_USER( 7, 0, 0);
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        second_stick->wait();
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    CYG_INSTRUMENT_USER( 8, 0, 0);
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        // Got them, now eat
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        change_state(id,'E');
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        // Check that the world is as I think it is...
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        CYG_ASSERT( !first_stick->posted(), "Not got first stick");
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        CYG_ASSERT( !second_stick->posted(), "Not got second stick");
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        CYG_ASSERT( get_state(left_philo) != 'E', "Left neighbour also eating!!");
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        CYG_ASSERT( get_state(right_philo) != 'E', "Right neighbour also eating!!");
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        self->delay((id+cycle++)%6);    // munch munch
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        // Finished eating, put down sticks.
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        change_state(id,'T');
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    CYG_INSTRUMENT_USER( 9, 0, 0);
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        first_stick->post();
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    CYG_INSTRUMENT_USER( 10, 0, 0);
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        second_stick->post();
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    CYG_INSTRUMENT_USER( 11, 0, 0);
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//    Cyg_Scheduler::lock();
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//    Cyg_Scheduler::unlock();
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    CYG_INSTRUMENT_USER( 12, 0, 0);
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    }
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}
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// -------------------------------------------------------------------------
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externC void
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cyg_start( void )
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{
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#ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG
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    cyg_hal_invoke_constructors();
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#endif
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    diag_init();
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    diag_write_string("Philosophers\n");
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    diag_write_string("Started\n");
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    // Zero last element in state so it acts like
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    // a string.
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    pstate[PHILOSOPHERS] = 0;
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#if 1
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    for( int i = 0; i < PHILOSOPHERS; i++ )
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    {
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        change_state(i,'T');            // starting state
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        // Start the philosopher
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        Cyg_Thread *t = new_thread( Philosopher, i );
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        // resume it
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        t->resume();
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        // and make the matching chopstick present
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        chopstick[i].post();
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    }
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#endif
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    // Get the world going
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    Cyg_Scheduler::scheduler.start();
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}
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// -------------------------------------------------------------------------
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// EOF philo.cxx

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