#define _GNU_SOURCE
#include <time.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <fcntl.h>


void A();

double calculateAverage(double *arr, int len)
{
  double average=0.00;
	//first sum up all entries
	for(int i=0;i<len;i++)
	{
		average+=arr[i];
	}
	return average;
}

static inline long long timespec_to_ns(const struct timespec *tv)
{
return ((long long) tv->tv_sec * 1000000000) +
tv->tv_nsec;
}

 double timespec_to_ms(struct timespec *ts)
 {
 	return ts->tv_sec*1000.0 + ts->tv_nsec/1000000.0;
 }

 int main(int argc, char **argv)
 {
	struct timespec start_time, end_time;

	if(argc <2)
	{
		printf("You entered less than two arguements\n");
		exit(-2);
	}
	if(argv[1] <0)
	{
		printf("you entered a negative argument\n");
		exit(-1);
	}
	//double *TestArray=malloc(sizeof(double)*atoi(argv[1]));
	//double *TestArray2=malloc(sizeof(double)*atoi(argv[1]));
	//double *TestArray3=malloc(sizeof(double)*atoi(argv[1]));
	//double *TestArray4=malloc(sizeof(double)*atoi(argv[1]));

	int n=(atoi(argv[1]));
	// Do empty 1
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_time);
	for(int i=0;i<n;i++)
	{

	 /* begin timing */
		/*for(int i=0;i<1000000;i++)
		{
			//getpid();
			syscall(SYS_getpid);
		}*/
		/*int errorCount=0;
		for(int i=0;i<1000;i++)
		{
			int pid = fork();
		 	if (pid == 0) {
		 	return 0;
			}
		 	if (pid < 0) {
		 		printf("ERROR: Fork failed.\n");
		 	errorCount++;
		 	}
		 	wait(0);

		}*/
		A();

	 /* end timing */

	 //TestArray[i]=(timespec_to_ms(&end_time)-timespec_to_ms(&start_time));
	}
	 clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_time);
 printf("%f ms\n", (timespec_to_ms(&end_time)
- timespec_to_ms(&start_time))/n);


// Do system getpid() call test
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_time);
	for(int i=0;i<n;i++)
	{

	 /* begin timing */

		//A();
		getpid();
		//syscall(SYS_getpid);

	 /* end timing */

	 //TestArray[i]=(timespec_to_ms(&end_time)-timespec_to_ms(&start_time));
	}
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_time);
	// Print average of pid test
	 printf("%f ms\n", (timespec_to_ms(&end_time)
- timespec_to_ms(&start_time))/n);
	int status;
	int p[2];
	int p1[2];
	if(pipe(p)<0) exit(1);// 0 for read 1 for writing
	//pipe(p);
	if(pipe(p1)<0) exit(1);
	//pipe(p1[1]);
	char arr[1];
	//char arr2[1];
	int pid=fork();
// Do process spawn context switching overhead  test
	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start_time);
	if(pid==0)
	{
		while(1)
		{
			if(read(p[0],&arr,1)<=0) exit(1);
			if(write(p1[1],&arr,1)<=0) exit(1);

		}
		_exit(status);
	}
	for(int i=0;i<n;i++){
		if(write(p[1],&arr,1)<=0) exit(1);
		if(read(p1[0],&arr,1)<=0) exit(1);
	}


	clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end_time);
	printf("%f ms\n", (timespec_to_ms(&end_time)
- timespec_to_ms(&start_time))/n);

/*printf("%lld ns\n", (timespec_to_ns(&end_time)
- timespec_to_ns(&start_time))/n);
*/
 }