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/*
* Very simple prng to allow for randomized tests with reproducable
* results.
*
* Copyright (C) 2012 by Open Source Routing.
* Copyright (C) 2012 by Internet Systems Consortium, Inc. ("ISC")
*
* This file is part of Quagga
*
* Quagga 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 2, or (at your option) any
* later version.
*
* Quagga 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 Quagga; see the file COPYING. If not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <assert.h>
#include <stdlib.h>
#include "prng.h"
struct prng
{
unsigned long long state1;
unsigned long long state2;
};
static char
prng_bit(struct prng *prng)
{
prng->state1 *= 2416;
prng->state1 += 374441;
prng->state1 %= 1771875;
if (prng->state1 % 2)
{
prng->state2 *= 84589;
prng->state2 += 45989;
prng->state2 %= 217728;
}
return prng->state2 % 2;
}
struct prng*
prng_new(unsigned long long seed)
{
struct prng *rv = calloc(sizeof(*rv), 1);
assert(rv);
rv->state1 = rv->state2 = seed;
return rv;
}
unsigned int
prng_rand(struct prng *prng)
{
unsigned int i, rv = 0;
for (i = 0; i < 32; i++)
{
rv |= prng_bit(prng);
rv <<= 1;
}
return rv;
}
void
prng_free(struct prng *prng)
{
free(prng);
}
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