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/*
* %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));
}
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