/*
 * Copyright (c) 2005, Swedish Institute of Computer Science
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the Contiki operating system.
 *
 * @(#)$Id: rand.c,v 1.4 2007/06/01 15:28:02 bg- Exp $
 */

#include <stdlib.h>

#include "rand.h"

/*
 * Minimal standard random number generator.
 *
 * Simple crappy ANSI C compatible random number generator that is
 * good enough for us!
 *
 * Park, S.K. and K.W. Miller, 1988;
 * Random Number Generators: Good Ones are Hard to Find,
 * Comm. of the ACM, V. 31. No. 10, pp 1192-1201
 */

/*
 * When possible, keep rand_state across reboots.
 */
#ifdef __GNUC__
unsigned long rand_state __attribute__((section(".noinit")));
#else
unsigned long rand_state = 123459876ul;
#endif

int
rand()
{
  rand_state = (16807*rand_state) % 2147483647ul;
  return (rand_state ^ (rand_state >> 16)) & RAND_MAX;
}

void
srand(unsigned int seed)
{
  rand_state = seed;
}