72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
/*
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* Copyright (c) 2005, Swedish Institute of Computer Science
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* @(#)$Id: random.c,v 1.2 2008/02/10 12:30:57 oliverschmidt Exp $
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*/
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/*
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From:
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D. Seetharam and S. Rhee, ``An Efficient Random Number Generator
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for Low-Power Sensor Networks'' First IEEE Workshop on Embedded
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Networked Sensors (EmNets-I), November 2004.
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http://www.dseetharam.org/papers/emnets.pdf
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*/
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#include "lib/random.h"
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#include "sys/clock.h"
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static clock_time_t time;
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static unsigned short key;
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void
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random_init(unsigned short seed)
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{
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key = seed;
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}
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unsigned short
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random_rand(void)
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{
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unsigned short rv, tv;
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rv = tv = 0;
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tv = (unsigned short)(time + clock_time());
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rv = tv ^ key;
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key = ~tv + 4711;
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tv = ~rv;
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time = tv;
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return rv;
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}
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