#include<stdio.h> /*a program to find out p^p,ptimes,that is if the input is 2,output gives,2^2^2.if
                   input is 3,output is 3^3^3,and so on */
#include<stdlib.h>
#include<math.h>
#include<unistd.h>
#include  <sys/types.h>
#include  <signal.h>
#include  <sys/ipc.h>
#include  <sys/shm.h>

/* ---------------------------------------------------------------- */
/*                 signal handler function prototypes               */
/* ---------------------------------------------------------------- */

void  SIGINT_handler(int);         /* for SIGINT                    */
     

/* ---------------------------------------------------------------- */
/*                         global variable                          */
/* ---------------------------------------------------------------- */

int   ShmID;                       /* shared memory ID              */
pid_t *ShmPTR;                     /* shared memory pointer         */
main()
{double load[3];
  if (getloadavg(load, 3) != -1) /*getloadavg is the function used to calculate and obtain the load a
verage*/
 {
 printf("load average : %f , %f , %f\n", load[0],load[1],load[2]);
  }
 float m;
 int n=2;
 long double g,h,i,pid,j,p,x=1,a=1;
 printf("enter the number whose exponential's is to be found\n");
 scanf("%Lf",&p);
 printf("enter the load average to be generated for the 1st minute\n");
 scanf("%f",&m);                               /*reading the input*/
 printf("finding (p^p^p^p....ptimes)\n");
 h=p;
 while(h>0)                 /*calculating the final exponent value*/
 {x=x*p;
   h--;
 }
 for(i=x;i>0;i--)           /*calculating the actual answer*/
 {a=a*p;
 }
 printf("the value is:%Lf\n",a);
 getloadavg(load,3);

 while(load[0]<m)
 {
   n=n*2;      /*increasing the number of child process*/
  goto x;
 }

/*
 printf("enter the number of child processes to be spwaned\n");
 scanf("%Lf",&n);
*/
x:
 while(load[0]<=m)
  {
   for(j=n;j>0;j--)
    {
      pid=fork();  /*creating the child process*/
      if(pid>0)
      wait();                 /*making the parent process wait*/
      if(pid <0)
      {printf("error:cannot fork!!");
       exit(1);
      }
   if (pid==0)                          /*child process*/
     {   long double f=1;
        MyKey   = ftok(".", 's');     /* create a shared memory segment*/
     ShmID   = shmget(MyKey, sizeof(pid_t), IPC_CREAT | 0666);
     ShmPTR  = (pid_t *) shmat(ShmID, NULL, 0);
     *ShmPTR = pid;                /* save my pid there             */
         break;
     
         printf("finding (p^p^p^p....ptimes)\n");
         h=p;
         while(h>0)
         {x=x*p;
          h--;
         }
         for(i=x;i>0;i--)
         {f=f*p;
         }
         printf("the value is:%Lf\n",a);
         if (getloadavg(load, 3) != -1)
         {
          printf("load average: %f, %f,%f\n",load[0],load[1],load[2]);
          printf("The number of child processes created:%d\n",n);
         }
         pid_t pid = getpid();
     key_t MyKey;

     if (signal(SIGINT, SIGINT_handler) == SIG_ERR) {
          printf("SIGINT install error\n");
          exit(1);
      } 
      MyKey   = ftok(".", 's');     /* create a shared memory segment*/
     ShmID   = shmget(MyKey, sizeof(pid_t), IPC_CREAT | 0666);
     ShmPTR  = (pid_t *) shmat(ShmID, NULL, 0);
     *ShmPTR = pid;                /* save my pid there             */
         break;
     }

    }
    getloadavg(load,3);
    if(load[0]<m)
    n=n*2;               /*increasing the forked processes*/
    continue;
  }


}
void  SIGINT_handler(int sig)
{
     signal(sig, SIG_IGN);
     printf("From SIGINT: just got a %d (SIGINT ^C) signal\n", sig);
      signal(sig, SIGINT_handler);
}