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/*
* Copyright (c) 2002-2005 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.
*/
/** This code is a fast implementation of the Park-Miller Minimal Standard
* Generator for pseudo-random numbers. It uses the 32 bit multiplicative
* linear congruential generator,
*
* S' = (A x S) mod (2^31 - 1)
*
* for A = 16807.
*
*
* @author Barbara Hohlt
* @date March 1 2005
*/
module RandomMlcgC @safe() {
provides interface Init;
provides interface ParameterInit<uint16_t> as SeedInit;
provides interface Random;
}
implementation
{
uint32_t seed ;
/**
* Initialize the pseudorandom generator with a specific seed.
* @return void.
*/
async command void Random.setSeed(uint16_t sseed)
{
}
/* Initialize the seed from the ID of the node */
command error_t Init.init() {
atomic seed = (uint32_t)(TOS_NODE_ID + 1);
return SUCCESS;
}
/* Initialize with 16-bit seed */
command error_t SeedInit.init(uint16_t s) {
atomic seed = (uint32_t)(s + 1);
return SUCCESS;
}
/* Return the next 32 bit random number */
async command uint32_t Random.rand32() {
uint32_t mlcg,p,q;
uint64_t tmpseed;
atomic
{
tmpseed = (uint64_t)33614U * (uint64_t)seed;
q = tmpseed; /* low */
q = q >> 1;
p = tmpseed >> 32 ; /* hi */
mlcg = p + q;
if (mlcg & 0x80000000) {
mlcg = mlcg & 0x7FFFFFFF;
mlcg++;
}
seed = mlcg;
}
return mlcg;
}
/* Return low 16 bits of next 32 bit random number */
async command uint16_t Random.rand16() {
return (uint16_t)call Random.rand32();
}
#if 0
/* Return high 16 bits of 32 bit number */
inline uint16_t getHigh16(uint32_t num) {
return num >> 16;
}
#endif
}
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