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      1 /* This testcase is part of GDB, the GNU debugger.
      2 
      3    Copyright 2018-2024 Free Software Foundation, Inc.
      4 
      5    This program is free software; you can redistribute it and/or modify
      6    it under the terms of the GNU General Public License as published by
      7    the Free Software Foundation; either version 3 of the License, or
      8    (at your option) any later version.
      9 
     10    This program is distributed in the hope that it will be useful,
     11    but WITHOUT ANY WARRANTY; without even the implied warranty of
     12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     13    GNU General Public License for more details.
     14 
     15    You should have received a copy of the GNU General Public License
     16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
     17 
     18 #include <stdio.h>
     19 #include <stdlib.h>
     20 #include <pthread.h>
     21 
     22 /* This defines the number of threads to spawn.  */
     23 #define THREADCOUNT 4
     24 
     25 /* Global barrier type to control synchronization between threads.  */
     26 static pthread_barrier_t print_barrier;
     27 
     28 /* Define global thread identifiers.  */
     29 static pthread_t threads[THREADCOUNT];
     30 
     31 /* Hold values for each thread at the index supplied to the thread
     32    on creation.  */
     33 static int thread_ids[THREADCOUNT];
     34 
     35 /* Find the value associated with the calling thread.  */
     36 static int
     37 get_value ()
     38 {
     39   for (int tid = 0; tid < THREADCOUNT; ++tid)
     40     {
     41       if (pthread_equal (threads[tid], pthread_self ()))
     42 	return thread_ids[tid];
     43     }
     44   /* Value for the main thread.  */
     45   return 1;
     46 }
     47 
     48 /* Return the nth Fibonacci number.  */
     49 static unsigned long
     50 fast_fib (unsigned int n)
     51 {
     52   int a = 0;
     53   int b = 1;
     54   int t;
     55   for (unsigned int i = 0; i < n; ++i)
     56     {
     57       t = b;
     58       b = a + b;
     59       a = t;
     60     }
     61   return a;
     62 }
     63 
     64 /* Encapsulate the synchronization of the threads. Perform a barrier before
     65    and after the computation.  */
     66 static void *
     67 thread_function (void *args)
     68 {
     69   int tid = *((int *) args);
     70   int status = pthread_barrier_wait (&print_barrier);
     71   if (status == PTHREAD_BARRIER_SERIAL_THREAD)
     72     printf ("All threads entering compute region\n");
     73 
     74   unsigned long result = fast_fib (100); /* testmarker01 */
     75   status = pthread_barrier_wait (&print_barrier);
     76   if (status == PTHREAD_BARRIER_SERIAL_THREAD)
     77     printf ("All threads outputting results\n");
     78 
     79   pthread_barrier_wait (&print_barrier);
     80   printf ("Thread %d Result: %lu\n", tid, result);
     81 }
     82 
     83 int
     84 main (void)
     85 {
     86   int err = pthread_barrier_init (&print_barrier, NULL, THREADCOUNT);
     87   if (err != 0)
     88     {
     89       fprintf (stderr, "Barrier creation failed\n");
     90       return EXIT_FAILURE;
     91     }
     92   /* Create the worker threads (main).  */
     93   printf ("Spawning worker threads\n");
     94   for (int tid = 0; tid < THREADCOUNT; ++tid)
     95     {
     96       /* Add 2 so the value maps to the debugger's thread identifiers.  */
     97       thread_ids[tid] = tid + 2; /* prethreadcreationmarker */
     98       err = pthread_create (&threads[tid], NULL, thread_function,
     99 			    (void *) &thread_ids[tid]);
    100       if (err != 0)
    101 	{
    102 	  fprintf (stderr, "Thread creation failed\n");
    103 	  return EXIT_FAILURE;
    104 	}
    105     }
    106   /* Wait for the threads to complete then exit.  */
    107   for (int tid = 0; tid < THREADCOUNT; ++tid)
    108     pthread_join (threads[tid], NULL);
    109 
    110   return EXIT_SUCCESS;
    111 }
    112