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//========================================================================== // // bin_sem2.cxx // // Binary semaphore test 2 // //========================================================================== //####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): nickg,dsm // Contributors: dsm // Date: 1998-03-10 // Description: // Dining philosophers test. Based on philo.cxx //####DESCRIPTIONEND#### #include <pkgconf/kernel.h> #include <cyg/kernel/sched.hxx> #include <cyg/kernel/thread.hxx> #include <cyg/kernel/thread.inl> #include <cyg/kernel/mutex.hxx> #include <cyg/kernel/sema.hxx> #include <cyg/infra/testcase.h> #include <cyg/kernel/sched.inl> static cyg_ucount16 PHILO_LOOPS = 1000; #define PHILOSOPHERS 15 #define NTHREADS PHILOSOPHERS #include "testaux.hxx" static Cyg_Binary_Semaphore chopstick[PHILOSOPHERS]; static char pstate[PHILOSOPHERS+1]; // state of each philosopher static cyg_ucount16 state_changes = 0; // state_changes keep track of number of changes to pstate so // we can exit after we've seen enough. static Cyg_Mutex pstate_mutex; static Cyg_Mutex cycle_mutex; static inline int left(cyg_count8 i) { return (0 == i) ? PHILOSOPHERS-1 : i-1 ; } static inline int right(cyg_count8 i) { return (PHILOSOPHERS == i+1) ? 0 : i+1 ; } void change_state(int id, char newstate) { if (PHILO_LOOPS == state_changes++) CYG_TEST_PASS_FINISH("Binary Semaphore 2 OK"); pstate_mutex.lock(); { pstate[id] = newstate; bool all_hungry = true; // until proved otherwise for(cyg_ucount8 i=0; i < PHILOSOPHERS; i++) { if('E' == pstate[i]) { CHECK('E' != pstate[left(i)]); CHECK('E' != pstate[right(i)]); } if('H' != pstate[i]) { all_hungry = false; } } // Theoretically it is possible for all the philosophers to be // hungry but not waiting on semaphores. But in practice this // means something is wrong. CHECK(false == all_hungry); } pstate_mutex.unlock(); } char get_state(int id) { pstate_mutex.lock(); char s = pstate[id]; pstate_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]; CHECK( id >= 0 && id < PHILOSOPHERS); // 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 sticks first_stick->wait(); second_stick->wait(); // Got them, now eat change_state(id,'E'); // Check that the world is as I think it is... CYG_TEST_CHECK( !first_stick->posted(), "Not got first stick"); CYG_TEST_CHECK( !second_stick->posted(), "Not got second stick"); CYG_TEST_CHECK( get_state(left(id)) != 'E', "Left neighbour also eating!!"); CYG_TEST_CHECK( get_state(right(id)) != 'E', "Right neighbour also eating!!"); self->delay((id+cycle++)%6); // munch munch // Finished eating, put down sticks. change_state(id,'T'); // put sticks back on table first_stick->post(); second_stick->post(); } } // ------------------------------------------------------------------------- void bin_sem2_main( void ) { CYG_TEST_INIT(); if (cyg_test_is_simulator) PHILO_LOOPS = 100; for( int i = 0; i < PHILOSOPHERS; i++ ) { pstate[i] = 'T'; // starting state new_thread(Philosopher, i); // make the matching chopstick present chopstick[i].post(); } Cyg_Scheduler::scheduler.start(); } externC void cyg_start( void ) { #ifdef CYGSEM_HAL_STOP_CONSTRUCTORS_ON_FLAG cyg_hal_invoke_constructors(); #endif bin_sem2_main(); } // EOF bin_sem2.cxx
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