/*
 * ISA 563, Spring 2011
 * Copyleft by Muhammad Abdulla
 */

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <unistd.h>
#include <sys/time.h>

/*
 * large_args.c -- Demonstrates the speed-up when using call by reference for large data types 
 */

#define MAX (100 * 1000)
#define DATSIZE 10000

typedef enum { false, true } bool ;

struct data {
   bool cleared;
   char dat[DATSIZE];
};

struct data clear_data_by_val(struct data d)
{
   memset ( d.dat, 0, DATSIZE );
   d.cleared = true;

   return d;
}

void clear_data_by_ref(struct data *d)
{
   memset ( d->dat, 0, DATSIZE );
   d->cleared = true;

   return;
}

// return time passed in milli-seconds
double tp (struct timeval start, struct timeval end)
{
   double t;
   t = 1000 * (end.tv_sec - start.tv_sec) + (end.tv_usec - start.tv_usec) / 1000.0;
   return t;
}


int main (int argc, char *argv[] )
{
   struct timeval tv1;
   struct timeval tv2;
   int i;

   struct data d;

   gettimeofday(&tv1, NULL);
   for ( i = 0; i < MAX ; i++ ) {
      d = clear_data_by_val(d);
   } 
   gettimeofday(&tv2, NULL);

   printf ( "time to clear data by val: %g (ms)\n", tp(tv1, tv2) );

   gettimeofday(&tv1, NULL);
   for ( i = 0; i < MAX ; i++ ) {
      clear_data_by_ref(&d);
   } 
   gettimeofday(&tv2, NULL);

   printf ( "time to clear data by ref: %g (ms)\n", tp(tv1, tv2) );

   return 0;
}