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/*
* ZeroTier One - Global Peer to Peer Ethernet
* Copyright (C) 2011-2014 ZeroTier Networks LLC
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* --
*
* ZeroTier may be used and distributed under the terms of the GPLv3, which
* are available at: http://www.gnu.org/licenses/gpl-3.0.html
*
* If you would like to embed ZeroTier into a commercial application or
* redistribute it in a modified binary form, please contact ZeroTier Networks
* LLC. Start here: http://www.zerotier.com/
*/
#ifndef ZT_CMWC4096_HPP
#define ZT_CMWC4096_HPP
#include <stdint.h>
#include "Utils.hpp"
namespace ZeroTier {
/**
* Complement Multiply With Carry random number generator
*
* Based on original code posted to Usenet in the public domain by
* George Marsaglia. Period is approximately 2^131086.
*
* This is not used for cryptographic purposes but for a very fast
* and high-quality PRNG elsewhere in the code.
*/
class CMWC4096
{
public:
/**
* Construct and initialize from secure random source
*/
CMWC4096()
throw()
{
Utils::getSecureRandom(Q,sizeof(Q));
Utils::getSecureRandom(&c,sizeof(c));
c %= 809430660;
i = 4095;
}
inline uint32_t next32()
throw()
{
uint32_t __i = ++i & 4095;
const uint64_t t = (18782ULL * (uint64_t)Q[__i]) + (uint64_t)c;
c = (uint32_t)(t >> 32);
uint32_t x = c + (uint32_t)t;
const uint32_t p = (uint32_t)(x < c); x += p; c += p;
return (Q[__i] = 0xfffffffe - x);
}
inline uint64_t next64()
throw()
{
return ((((uint64_t)next32()) << 32) ^ (uint64_t)next32());
}
inline double nextDouble()
throw()
{
return ((double)(next32()) / 4294967296.0);
}
private:
uint32_t Q[4096];
uint32_t c;
uint32_t i;
};
} // namespace ZeroTier
#endif
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