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/*
* Copyright (C) 2007-2012 Xagasoft, All rights reserved.
*
* This file is part of the libbu++ library and is released under the
* terms of the license contained in the file LICENSE.
*/
#include "bu/randomcmwc.h"
#define PHI 0x9e3779b9
RandomCmwc::RandomCmwc() :
q( NULL ),
c( 362436 )
{
q = new uint32_t[4096];
}
RandomCmwc::~RandomCmwc()
{
delete[] q;
}
void RandomCmwc::seed( int32_t iSeed )
{
int i;
Q[0] = iSeed;
Q[1] = iSeed + PHI;
Q[2] = iSeed + PHI + PHI;
for (i = 3; i < 4096; i++)
Q[i] = Q[i - 3] ^ Q[i - 2] ^ PHI ^ i;
}
int32_t RandomCmwc::rand()
{
uint64_t t, a = 18782LL;
static uint32_t i = 4095;
uint32_t x, r = 0xfffffffe;
i = (i + 1) & 4095;
t = a * Q[i] + c;
c = (t >> 32);
x = t + c;
if( x < c )
{
x++;
c++;
}
return (Q[i] = r - x);
}
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