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comparison packages/kernel/current/tests/kphilo.c @ 0:3111d98ba7b3 ecos-v1_1-release

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Initial commit of eCos version 1.1
author jlarmour
date Tue, 11 May 1999 11:16:07 +0000
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children 443894e2e912
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1 //==========================================================================
2 //
3 // kphilo.c
4 //
5 // A test of the dining philosophers problem
6 //
7 //==========================================================================
8 //####COPYRIGHTBEGIN####
9 //
10 // -------------------------------------------
11 // The contents of this file are subject to the Cygnus eCos Public License
12 // Version 1.0 (the "License"); you may not use this file except in
13 // compliance with the License. You may obtain a copy of the License at
14 // http://sourceware.cygnus.com/ecos
15 //
16 // Software distributed under the License is distributed on an "AS IS"
17 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
18 // License for the specific language governing rights and limitations under
19 // the License.
20 //
21 // The Original Code is eCos - Embedded Cygnus Operating System, released
22 // September 30, 1998.
23 //
24 // The Initial Developer of the Original Code is Cygnus. Portions created
25 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved.
26 // -------------------------------------------
27 //
28 //####COPYRIGHTEND####
29 //==========================================================================
30 //#####DESCRIPTIONBEGIN####
31 //
32 // Author(s): dsm
33 // Contributors: dsm
34 // Date: 1998-02-24
35 // Description: A test of the dining philosophers problem
36 //####DESCRIPTIONEND####
37 //
38
39 #include <cyg/kernel/kapi.h>
40
41 #include <cyg/infra/cyg_ass.h>
42 #include <cyg/kernel/diag.h>
43
44 // -------------------------------------------------------------------------
45 // Data for the philosophers problem
46
47 #define PHILOSOPHERS 15 // number of philosophers
48 #define STACKSIZE (2*1024) // size of thread stack
49
50 // array of stacks for philosopher threads
51 char thread_stack[PHILOSOPHERS][STACKSIZE];
52
53 // array of threads.
54 cyg_thread thread[PHILOSOPHERS];
55
56 cyg_handle_t thread_handle[PHILOSOPHERS];
57
58 // array of chopsticks
59 cyg_sem_t chopstick[PHILOSOPHERS];
60
61 cyg_ucount32 data_index;
62
63 // -------------------------------------------------------------------------
64 // State recording and display
65
66 static char pstate[PHILOSOPHERS+1]; // state vector showing what each
67 // philosopher is doing
68
69 cyg_mutex_t state_mutex;
70
71 #ifdef CYG_HAL_MN10300_MN103002
72 static cyg_count8 eaters = 0;
73 #endif
74
75 void change_state(int id, char newstate)
76 {
77 cyg_mutex_lock(&state_mutex);
78
79 #ifdef CYG_HAL_MN10300_MN103002
80 if( pstate[id] == 'E' ) eaters--;
81 if( newstate == 'E' ) eaters++;
82 // led(eaters);
83 #endif
84
85 pstate[id] = newstate;
86
87 diag_write_string(pstate);
88 #if 0
89 diag_write_char(' ');
90 diag_write_dec(Cyg_Scheduler::get_thread_switches());
91 #endif
92 diag_write_char('\n');
93
94 cyg_mutex_unlock(&state_mutex);
95
96 }
97
98 char get_state( int id)
99 {
100 char s;
101 cyg_mutex_lock(&state_mutex);
102
103 s = pstate[id];
104
105 cyg_mutex_unlock(&state_mutex);
106
107 return s;
108 }
109
110 // -------------------------------------------------------------------------
111 // Thread to behave like a philosopher
112
113 void Philosopher( cyg_addrword_t vid )
114 {
115 cyg_uint32 id = (cyg_uint32)vid;
116 cyg_sem_t *first_stick = &chopstick[id];
117 cyg_sem_t *second_stick = &chopstick[(id+1)%PHILOSOPHERS];
118 #ifdef CYGPKG_INFRA_DEBUG
119 int left_philo = ((id==0)?PHILOSOPHERS:id)-1;
120 int right_philo = (id==PHILOSOPHERS-1)?0:(id+1);
121 #endif
122
123 CYG_ASSERT( id >= 0 && id < PHILOSOPHERS, "Bad id");
124
125 // Deadlock avoidance. The easiest way to make the philosophers
126 // behave is to make each pick up the lowest numbered stick
127 // first. This is how it works out anyway for all the philosophers
128 // except the last, who must have his sticks swapped.
129
130 if( id == PHILOSOPHERS-1 )
131 {
132 cyg_sem_t *t = first_stick;
133 first_stick = second_stick;
134 second_stick = t;
135 }
136
137 for(;;)
138 {
139 cyg_ucount32 val;
140
141 // The following variable is shared by all philosophers.
142 // It is incremented unprotected, but this does not matter
143 // since it is only present to introduce a little variability
144 // into the think and eat times.
145
146 static volatile int cycle = 0;
147
148 // Think for a bit
149
150 cyg_thread_delay((id+cycle++)%12); // Cogito ergo sum...
151
152 // I am now hungry, try to get the chopsticks
153
154 change_state(id,'H');
155
156 // Get the first stick
157 cyg_semaphore_wait(first_stick);
158
159 // Get the second stick
160 cyg_semaphore_wait(second_stick);
161
162 // Got them, now eat
163
164 change_state(id,'E');
165
166 // Check that the world is as I think it is...
167 cyg_semaphore_peek( first_stick, &val);
168 CYG_ASSERT( val == 0, "Not got first stick");
169 cyg_semaphore_peek( second_stick, &val);
170 CYG_ASSERT( val == 0, "Not got second stick");
171 CYG_ASSERT( get_state(left_philo) != 'E', "Left neighbour also eating!!");
172 CYG_ASSERT( get_state(right_philo) != 'E', "Right neighbour also eating!!");
173
174 cyg_thread_delay((id+cycle++)%6); // munch munch
175
176 // Finished eating, put down sticks.
177
178 change_state(id,'T');
179
180 cyg_semaphore_post( first_stick );
181 cyg_semaphore_post( second_stick );
182
183 }
184 }
185
186 // -------------------------------------------------------------------------
187
188 externC void
189 cyg_start( void )
190 {
191 int i;
192
193 diag_init();
194
195 diag_write_string("Philosophers\n");
196 diag_write_string("Started\n");
197
198 // Zero last element in state so it acts like
199 // a string.
200 pstate[PHILOSOPHERS] = 0;
201
202 #if 1
203 for( i = 0; i < PHILOSOPHERS; i++ )
204 {
205 change_state(i,'T'); // starting state
206
207 cyg_thread_create(4, Philosopher, (cyg_addrword_t)i, "philosopher",
208 (void *)(&thread_stack[i]), STACKSIZE,
209 &thread_handle[i], &thread[i]);
210
211 // resume it
212 cyg_thread_resume(thread_handle[i]);
213
214 // and make the matching chopstick present
215 cyg_semaphore_init( &chopstick[i], 1);
216 }
217 #endif
218
219 // Get the world going
220 cyg_scheduler_start();
221
222 }
223
224 // -------------------------------------------------------------------------
225 // EOF kphilo.c