Category : Files from Magazines
Archive   : SCBENCH.ZIP
Filename : SIEVE.C

/*
** BYTE Sieve Benchmark
** Version 1 for 8088/8086/80286/80386
** March 1988
** Written in BYTE Small-C
** Based on Small-C by J.E. Hendrix
**
** This program executes the infamous Eratosthenes Sieve Prime
** Number Program from BYTE, Jan. 1983.
**
** Operation:
** 1. Turn on stopwatch
** 2. Execute SIEVE for LOOP iterations
** 3. Turn off stopwatch
** 4. Report time and number of primes found
** 5. Exit
**
*/

#include stdio.h

#define size 8190
#define LOOP 100
#define TRUE YES
#define FALSE NO

int tblock[4]; /* Timer holding array */
char flags [size + 1];

main()

{
int i, prime, k, count, iter;

/* Announce yourself */
printf("BYTE Sieve Benchmark\n");

printf("%d iterations\n",LOOP);

/* Start timer and execute loop */
gtime(tblock);
for (iter = 1; iter <= LOOP; iter++)
{
count = 0; /* prime counter */
for (i = 0; i <= size; i++) /* set all flags true */
flags [i] = TRUE;
for (i = 0; i <= size; i++)
{
if (flags [i]) /* found a prime */
{
prime = i + i + 3; /* twice index + 3 */
/* printf ("\n%d", prime); */
for (k = i + prime; k <= size; k+= prime)
flags [k] = FALSE; /* kill all multiple */
count++; /* primes found */
}
}
}
calctim(tblock);

/* Report results */
printf("Results: (HH:MM:SS:1/100ths)\n");
printf("Elapsed time: %d:%d:%d:%d\n\n",tblock[0],tblock[1],
tblock[2],tblock[3]);

printf ("%d primes.\n\n", count); /* primes found on 100th pass */

/* Exit */
printf("Press RETURN to exit:");
fgetc(stdin);
exit(0);
}