mirror of
https://github.com/zerotier/ZeroTierOne.git
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92 lines
2.3 KiB
C++
92 lines
2.3 KiB
C++
/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2015 ZeroTier, Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* --
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*
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* ZeroTier may be used and distributed under the terms of the GPLv3, which
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* are available at: http://www.gnu.org/licenses/gpl-3.0.html
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*
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* If you would like to embed ZeroTier into a commercial application or
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* redistribute it in a modified binary form, please contact ZeroTier Networks
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* LLC. Start here: http://www.zerotier.com/
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*/
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#ifndef ZT_CMWC4096_HPP
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#define ZT_CMWC4096_HPP
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#include <stdint.h>
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#include "Utils.hpp"
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namespace ZeroTier {
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/**
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* Complement Multiply With Carry random number generator
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*
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* Based on original code posted to Usenet in the public domain by
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* George Marsaglia. Period is approximately 2^131086.
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*
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* This is not used for cryptographic purposes but for a very fast
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* and high-quality PRNG elsewhere in the code.
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*/
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class CMWC4096
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{
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public:
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/**
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* Construct and initialize from secure random source
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*/
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CMWC4096()
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throw()
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{
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Utils::getSecureRandom(Q,sizeof(Q));
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Utils::getSecureRandom(&c,sizeof(c));
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c %= 809430660;
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i = 4095;
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}
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inline uint32_t next32()
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throw()
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{
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uint32_t __i = ++i & 4095;
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const uint64_t t = (18782ULL * (uint64_t)Q[__i]) + (uint64_t)c;
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c = (uint32_t)(t >> 32);
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uint32_t x = c + (uint32_t)t;
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const uint32_t p = (uint32_t)(x < c); x += p; c += p;
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return (Q[__i] = 0xfffffffe - x);
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}
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inline uint64_t next64()
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throw()
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{
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return ((((uint64_t)next32()) << 32) ^ (uint64_t)next32());
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}
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inline double nextDouble()
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throw()
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{
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return ((double)(next32()) / 4294967296.0);
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}
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private:
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uint32_t Q[4096];
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uint32_t c;
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uint32_t i;
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};
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} // namespace ZeroTier
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#endif
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