// sparksandflames.com

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>



int main(int argc, char *argv[]);
void *UNIXThreadFunction( void *argPointer );

pthread_mutex_t mutexObject = PTHREAD_MUTEX_INITIALIZER; 
int threadsStarted=0; 
int tcnt=4;
double f[100];


int main(int argc, char *argv[])
{   
   int  rc;
   int count = 0;
   
   time_t wallstart,wallend;

   double timework;
  
   pthread_t threads[100];

   // PARAMETER 1 OVER RIDES DEFAULT

   if (argc == 2)
   {
      tcnt = atoi(argv[1]);
      if (tcnt < 1 || tcnt > 100 )
      {
         printf("unixthread('%d'): Thread count must be between 1 - 100\n",tcnt);
         return 0;
      }
   }

   printf("%d threads\n",tcnt);

   // START TIMER
    
   wallstart = time(NULL);

    
   // START TCNT THREADS

   while(count < tcnt)
   {
      rc = pthread_create(&threads[count], NULL, &UNIXThreadFunction,(void *) count); 
      if(rc) 
      {  
         printf("thread creation failed\n");
         exit(1);
      }
      count++;
  }

   // WAIT FOR TCNT THREADS TO FINISH
   
   while( count >= 0)
   { 
      pthread_join( threads[count], NULL);
      count--;
   }
    
  
   // STOP TIMER. 
 
   wallend   = time(NULL);

   timework = wallend - wallstart;

   // DISPLAY STATS

   printf("Elapsed time: %.0f seconds\n", timework);
 
   exit(0);
  
}


void *UNIXThreadFunction( void *argPointer )
{

   int w;
   int i,j;
   int tot;
   int x = 100000;
   int savestarted;             
  
   // GET THREAD INDEX
   
   w =  (int ) argPointer;
   f[w] = 0 ;

   // INCREASE THREAD COUNT
   
   pthread_mutex_lock( &mutexObject );
   threadsStarted++;
   savestarted = threadsStarted;
   pthread_mutex_unlock( &mutexObject );

   // DISPLAY TRACE
   
   printf("Start Thread = %d Count = %d\n",w,savestarted);
   fflush(stdout);


   // DO SOME BUSY WORK THE COMPILER WON'T OPTIMIZE AWAY

   tot = 0;
   for(i=0;i<x;i++)
   {
     for(j=0;j<x;j++)
     {
         f[w] = f[w] + 1.00;
         tot++;
     }
   }


   // ACCURACY TEST

   if (tot != x*x)
   {
      printf("Thread #%d: i<>x*x %d %d\n",w,i,x*x);  
      fflush(stdout);
   }


   // DECREASE THREAD COUNT
   
   pthread_mutex_lock( &mutexObject );
   threadsStarted--;
   savestarted = threadsStarted;
   pthread_mutex_unlock( &mutexObject );
   
   printf("End   Thread = %d Count = %d\n",w,savestarted);


   // SEE HOW EVEN THE WORKLOAD IS
  
   for(i=0;i<tcnt;i++)
      printf("%12.0f",f[i]);
   printf("\n"); 
   fflush(stdout);


   return UNIXThreadFunction ;
   
}