//========================================================================== // // philo.cxx // // A test of the dining philosophers problem // //========================================================================== //####ECOSGPLCOPYRIGHTBEGIN#### // ------------------------------------------- // This file is part of eCos, the Embedded Configurable Operating System. // Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc. // // eCos is free software; you can redistribute it and/or modify it under // the terms of the GNU General Public License as published by the Free // Software Foundation; either version 2 or (at your option) any later version. // // eCos is distributed in the hope that it will be useful, but WITHOUT ANY // WARRANTY; without even the implied warranty of MERCHANTABILITY or // FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License // for more details. // // You should have received a copy of the GNU General Public License along // with eCos; if not, write to the Free Software Foundation, Inc., // 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. // // As a special exception, if other files instantiate templates or use macros // or inline functions from this file, or you compile this file and link it // with other works to produce a work based on this file, this file does not // by itself cause the resulting work to be covered by the GNU General Public // License. However the source code for this file must still be made available // in accordance with section (3) of the GNU General Public License. // // This exception does not invalidate any other reasons why a work based on // this file might be covered by the GNU General Public License. // // Alternative licenses for eCos may be arranged by contacting Red Hat, Inc. // at http://sources.redhat.com/ecos/ecos-license/ // ------------------------------------------- //####ECOSGPLCOPYRIGHTEND#### //========================================================================== //#####DESCRIPTIONBEGIN#### // // Author(s): dsm // Contributors: dsm // Date: 1998-02-24 // Description: A test of the dining philosophers problem //####DESCRIPTIONEND#### // #include #include // ------------------------------------------------------------------------- // 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