sieve.java

/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
class sieve {
  static final int size = 8190*2;
  static boolean[] flags = new boolean[size+1];
  public static void main(String[] args) {
    go();
  }
  static boolean run() {
    int i = go();
    System.out.println("Sieve returned: " + i);
    return true;
  }

  public static int go() {
    int i, prime, k, count = 0, iter;
    //    System.out.print("3000 iterations --> ");
    for (iter = 1; iter <= 100; iter++) { /* do program 100 times*/
      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 */
          for (k = i + prime; k <= size; k += prime)
            flags[k] = false;             /* kill all multiple */
          count++;
        }
      }
    }
    // System.out.println(count + " primes."); /* primes found on 100th pass */

    return count;
  }
}