/*
 Programming with pthread: pthread1.c++   
    one thread computes factorial and 
    the other thread computes fibonacci
 $ g++ -Wall pthread1.c++ -lpthread
 $ ./a.out 5          
*/
#include <iostream>
using namespace std;
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#define loop(X) {for(int i=0; i<=(X); ++i);}

void * thread1(void *) ;
void * thread2(void *) ;
int eS1, eS2;

int fact(int n){
     if(n == 0) return 1 ;
     return n*fact(n-1) ;
}

int fib(int n) {
     int f0 = 0, f1 = 1, i ;

     if(n == 0) return f0 ;
     if(n == 1) return f1 ;
     for(i=2; i<=n; ++i) {
          int temp = f0 ;

          f0 = f1 ;
          f1 = f0 + temp ;     
     }
     return f1 ;
}

int main(int count, char *vect[]) {  
     pthread_t thID1, thID2; // thread ID
     int n ; // pthread1.c++
     int err, *esP1, *esP2;

     if(count < 2) {
        cerr << "No argument for function\n" ;
        exit(1) ;
     }
     
     n = atoi(vect[1]) ;
     cout << "main thread: n = " 
          << n << "\n" ;

     err = pthread_create(&thID1, NULL, thread1, (void *) &n); 
                           // 1st child thread1
     if(err != 0){
       cerr << "Thread 1 creation problem\n";
       exit(1);
     }
     err = pthread_create(&thID2, NULL, thread2, (void *) &n); 
                           // 2nd child thread2
     if(err != 0){
       cerr << "Thread 2 creation problem\n";
       exit(1);
     }
     
     pthread_join(thID2, (void **)&esP2);// 2nd thread joins
     pthread_join(thID1, (void **)&esP1);// 1st thread joins    
     cout << "Thread 1: " << *esP1 << endl;
     cout << "Thread 2: " << *esP2 << endl;

     return 0 ;
}
void *thread1(void *vp) {// Address of parameter
     int i, *p ;         // to pass

     p = (int *) vp ;
     for(i=0; i<=*p; ++i) {
        cout << "Th1: fib(" << i  
             << ") = " << fib(i) << endl ; 
        loop(5000000);
     }
     eS1 = 1;
     pthread_exit((void *)&eS1) ;
}
void *thread2(void *vp) {// Address of parameter
     int i, *p;         // to pass

     p = (int *) vp ;
     for(i=0; i<=*p; ++i) {
        cout << "Th2:" << i 
             << "! = " << fact(i) << endl ; 
        loop(5000000);
     }
     eS2 = 2;
     pthread_exit((void *)&eS2) ;
}