text: // Copyright 2015 The Emscripten Authors.  All rights reserved.
  // Emscripten is available under two separate licenses, the MIT license and the
  // University of Illinois/NCSA Open Source License.  Both these licenses can be
  // found in the LICENSE file.
  
  #include <pthread.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <emscripten/emscripten.h>
  #include <emscripten/threading.h>
  
  #define NUM_THREADS  3
  #define TCOUNT 10
  #define COUNT_LIMIT 12
  
  int     count = 0;
  int     thread_ids[3] = {0,1,2};
  pthread_mutex_t count_mutex;
  pthread_cond_t count_threshold_cv;
  
  void *inc_count(void *t) 
  {
    int i;
    long my_id = (long)t;
  
    for (i=0; i<TCOUNT; i++) {
      pthread_mutex_lock(&count_mutex);
      count++;
  
      /* 
      Check the value of count and signal waiting thread when condition is
      reached.  Note that this occurs while mutex is locked. 
      */
      if (count == COUNT_LIMIT) {
        pthread_cond_signal(&count_threshold_cv);
   //     printf("inc_count(): thread %ld, count = %d  Threshold reached.\n", 
   //            my_id, count);
        EM_ASM(out('inc_count(): thread ' + $0 + ', count = ' + $1 + ', Threshold reached.'), my_id, count);
        }
  //    printf("inc_count(): thread %ld, count = %d, unlocking mutex\n", 
  //	   my_id, count);
      EM_ASM(out('inc_count(): thread ' + $0 + ', count = ' + $1 + ', unlocking mutex.'), my_id, count);
      pthread_mutex_unlock(&count_mutex);
  
      /* Do some "work" so threads can alternate on mutex lock */
      //sleep(1);
      }
    pthread_exit(NULL);
  }
  
  void *watch_count(void *t) 
  {
    long my_id = (long)t;
  
  //  printf("Starting watch_count(): thread %ld\n", my_id);
    EM_ASM(out('Starting watch_count(): thread ' + $0), my_id);
  
    /*
    Lock mutex and wait for signal.  Note that the pthread_cond_wait 
    routine will automatically and atomically unlock mutex while it waits. 
    Also, note that if COUNT_LIMIT is reached before this routine is run by
    the waiting thread, the loop will be skipped to prevent pthread_cond_wait
    from never returning. 
    */
    pthread_mutex_lock(&count_mutex);
    while (count<COUNT_LIMIT) {
      pthread_cond_wait(&count_threshold_cv, &count_mutex);
  //    printf("watch_count(): thread %ld Condition signal received.\n", my_id);
      EM_ASM(out('watch_count(): thread ' + $0 + ' Condition signal received.'), my_id);
      count += 125;
  //    printf("watch_count(): thread %ld count now = %d.\n", my_id, count);
      EM_ASM(out('watch_count(): thread ' + $0 + ', count now = ' + $1), my_id, count);
      }
    pthread_mutex_unlock(&count_mutex);
    pthread_exit(NULL);
  }
  
  int main (int argc, char *argv[])
  {
    int i, rc;
    long t1=1, t2=2, t3=3;
    pthread_t threads[3];
    pthread_attr_t attr;
  
    /* Initialize mutex and condition variable objects */
    pthread_mutex_init(&count_mutex, NULL);
    pthread_cond_init (&count_threshold_cv, NULL);
  
    /* For portability, explicitly create threads in a joinable state */
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    pthread_create(&threads[0], &attr, watch_count, (void *)t1);
    pthread_create(&threads[1], &attr, inc_count, (void *)t2);
    pthread_create(&threads[2], &attr, inc_count, (void *)t3);
  
    if (emscripten_has_threading_support())
    {
      /* Wait for all threads to complete */
      for (i=0; i<NUM_THREADS; i++) {
        pthread_join(threads[i], NULL);
      }
      printf ("Main(): Waited on %d  threads. Done.\n", NUM_THREADS);
    }
  
    /* Clean up and exit */
    pthread_attr_destroy(&attr);
    pthread_mutex_destroy(&count_mutex);
    pthread_cond_destroy(&count_threshold_cv);
  #ifdef REPORT_RESULT
    REPORT_RESULT(0);
  #endif
    pthread_exit(NULL);
  }
  