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// $Id: RandomLfsrC.nc,v 1.5 2010-06-29 22:07:56 scipio Exp $
/*
* Copyright (c) 2000-2003 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - Neither the name of the University of California 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
*
* Copyright (c) 2002-2005 Intel Corporation
* All rights reserved.
*
* This file is distributed under the terms in the attached INTEL-LICENSE
* file. If you do not find these files, copies can be found by writing to
* Intel Research Berkeley, 2150 Shattuck Avenue, Suite 1300, Berkeley, CA,
* 94704. Attention: Intel License Inquiry.
*/
/*
*
* Authors: Alec Woo, David Gay, Philip Levis
* Date last modified: 8/8/05
*
*/
/**
* This is a 16 bit Linear Feedback Shift Register pseudo random number
generator. It is faster than the MLCG generator, but the numbers generated
* have less randomness.
*
* @author Alec Woo
* @author David Gay
* @author Philip Levis
* @date August 8 2005
*/
module RandomLfsrC
{
provides interface Init;
provides interface Random;
}
implementation
{
uint16_t shiftReg;
uint16_t initSeed;
uint16_t mask;
/**
* Initialize the pseudorandom generator with a specific seed.
* @return void.
*/
async command void Random.setSeed(uint16_t seed)
{
atomic
{
if (seed == 0)
{
// Use TOS_NODE_ID
shiftReg = 119 * 119 * (TOS_NODE_ID + 1);
initSeed = shiftReg;
mask = 137 * 29 * (TOS_NODE_ID + 1);
}
else
{
// Use seed
shiftReg = 119 * 119 * (seed + 1);
initSeed = shiftReg;
mask = 137 * 29 * (seed + 1);
}
}
}
/* Initialize the seed from the ID of the node */
command error_t Init.init() {
atomic {
shiftReg = 119 * 119 * (TOS_NODE_ID + 1);
initSeed = shiftReg;
mask = 137 * 29 * (TOS_NODE_ID + 1);
}
return SUCCESS;
}
/* Return the next 16 bit random number */
async command uint16_t Random.rand16() {
bool endbit;
uint16_t tmpShiftReg;
atomic {
tmpShiftReg = shiftReg;
endbit = ((tmpShiftReg & 0x8000) != 0);
tmpShiftReg <<= 1;
if (endbit)
tmpShiftReg ^= 0x100b;
tmpShiftReg++;
shiftReg = tmpShiftReg;
tmpShiftReg = tmpShiftReg ^ mask;
}
return tmpShiftReg;
}
async command uint32_t Random.rand32() {
return (uint32_t)call Random.rand16() << 16 | call Random.rand16();
}
}
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