/******************************************************************************
* FILE: loop02.c
* DESCRIPTION:
*   Demonstrates loop fusion
******************************************************************************/

#include <stdio.h>
#include <sys/time.h>
#include <time.h>
#define ARRAY_SIZE	16384
#define	SEED		1995

float a[ARRAY_SIZE], aa[ARRAY_SIZE];
float b[ARRAY_SIZE], bb[ARRAY_SIZE];
float c[ARRAY_SIZE], cc[ARRAY_SIZE];
float d[ARRAY_SIZE], dd[ARRAY_SIZE];
float e[ARRAY_SIZE], ee[ARRAY_SIZE];
float x, y, z, xx, yy, zz;
struct timeval start_time, end_time;

main()
{
   int i;
   initialize_data();

/*****************************************************************************/
/*				Unfused Loop				     */
/*****************************************************************************/
   gettimeofday(&start_time, (struct timeval*)0);

   for(i=0;i<ARRAY_SIZE;i++)
      x = x * a[i] + b[i];
   for(i=0;i<ARRAY_SIZE;i++)
      y = y * c[i] + d[i];
   for(i=0;i<ARRAY_SIZE;i++)
      z = z * e[i];

   gettimeofday(&end_time, (struct timeval*)0);  /* after time */
   printf("Untuned results:\n");
   print_execution_times();

/*****************************************************************************/
/*				Fused Loop				     */
/*****************************************************************************/
   gettimeofday(&start_time, (struct timeval*)0);

   for(i=0;i<ARRAY_SIZE;i++)
   {
      xx = xx * aa[i] + bb[i];
      yy = yy * cc[i] + dd[i];
      zz = zz * ee[i];
   }

   gettimeofday(&end_time, (struct timeval*)0);  /* after time */
   printf("Tuned results:\n");
   print_execution_times();
   finalize_data();
}

initialize_data()
{
   int i;
   srandom(SEED);
   for(i=0;i<ARRAY_SIZE;i++)
   {
      aa[i] = a[i] = (float) (random() % 100000);
      bb[i] = b[i] = (float) (random() % 100000);
      cc[i] = c[i] = (float) (random() % 100000);
      dd[i] = d[i] = (float) (random() % 100000);
      ee[i] = e[i] = (float) (random() % 100000);
   }
   x = xx = 0.0;
   y = yy = 0.0;
   z = zz = 0.0;
}

finalize_data()
{
   FILE *fp, *fopen();

   fp = fopen("/dev/null", "w");
   fprintf(fp, "%f %f %f\n", x, y, z);
   fprintf(fp, "%f %f %f\n", xx, yy, zz);
   fclose(fp);
}

print_execution_times()
{
   int total_usecs;
   float total_time;
   total_usecs = (end_time.tv_sec-start_time.tv_sec) * 1000000 +
         (end_time.tv_usec-start_time.tv_usec);
   printf("Total time was %.2f mSec\n", ((float) total_usecs) / 1000.0);
   total_time = ((float) total_usecs) / 1000000.0;
}