73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/*
|
|
* 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: random.c,v 1.2 2008/02/10 12:30:57 oliverschmidt Exp $
|
|
*/
|
|
|
|
/*
|
|
From:
|
|
|
|
D. Seetharam and S. Rhee, ``An Efficient Random Number Generator
|
|
for Low-Power Sensor Networks'' First IEEE Workshop on Embedded
|
|
Networked Sensors (EmNets-I), November 2004.
|
|
|
|
http://www.dseetharam.org/papers/emnets.pdf
|
|
*/
|
|
|
|
#include "lib/random.h"
|
|
#include "sys/clock.h"
|
|
|
|
static clock_time_t time;
|
|
|
|
static unsigned short key;
|
|
|
|
void
|
|
random_init(unsigned short seed)
|
|
{
|
|
key = seed;
|
|
}
|
|
|
|
unsigned short
|
|
random_rand(void)
|
|
{
|
|
unsigned short rv, tv;
|
|
|
|
rv = tv = 0;
|
|
|
|
tv = (unsigned short)(time + clock_time());
|
|
rv = tv ^ key;
|
|
|
|
key = ~tv + 4711;
|
|
tv = ~rv;
|
|
time = tv;
|
|
|
|
return rv;
|
|
}
|