text: /*
   * %CopyrightBegin%
   * 
   * Copyright Ericsson AB 1998-2009. All Rights Reserved.
   * 
   * The contents of this file are subject to the Erlang Public License,
   * Version 1.1, (the "License"); you may not use this file except in
   * compliance with the License. You should have received a copy of the
   * Erlang Public License along with this software. If not, it can be
   * retrieved online at http://www.erlang.org/.
   * 
   * Software distributed under the License is distributed on an "AS IS"
   * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
   * the License for the specific language governing rights and limitations
   * under the License.
   * 
   * %CopyrightEnd%
   *
  
   */
  #include "hash.h"
  
  /* this is a general prime factoring function 
   * we get one prime factor each time we call it 
   * we only use it here to determine if n is prime, 
   * by checking if factor(n) == n .
   */
  static int factor(int n)
  {
    /* FIXME problem for threaded?! */
    static int a[] = { 0, 4, 1, 2, 0, 2 };
    static int m = 0;
    static int d = 0;
  
    if (n) {
      m = n;
      d = 2;
    }
  
    while ((d*d) <= m) {
      if (!(m%d)) {
        m /= d;
        return d;
      }
      d += a[d%6];
    }
    n = m; 
    m = 0;
  
    return n;
  }
  
  /* true if n prime */
  int ei_isprime(int n)
  {
    return (n == factor(n));
  }
  