/* -*- tab-width: 4 -*-
*
* Electric(tm) VLSI Design System
*
* File: Primes.java
*
* Copyright (c) 2003 Sun Microsystems and Static Free Software
*
* Electric(tm) is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* Electric(tm) is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Electric(tm); see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, Mass 02111-1307, USA.
*/
package com.sun.electric.tool.ncc.basic;
import java.util.ArrayList;
/**
* Generate Prime numbers
*/
public class Primes {
private static int trial = 3;
private static ArrayList<Integer> primes = new ArrayList<Integer>();
static {
primes.add(new Integer(2));
}
private static void findNextPrime() {
while (true) {
for (int i=0; i<primes.size(); i++) {
int prime = ((Integer)primes.get(i)).intValue();
int r = trial % prime;
if (r==0) break; // trial not prime
int q = trial / prime;
// Knuth. Fundamental Algorithms. pp 142
if (q<=prime) {
primes.add(new Integer(trial));
trial += 2;
return;
}
}
trial += 2;
}
}
public static int get(int nth) {
while (primes.size()-1<nth) findNextPrime();
return ((Integer) primes.get(nth)).intValue();
}
}