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construct/include/ircd/rand.h

115 lines
2.3 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_RAND_H
/// Some character set dictionaries
namespace ircd::rand::dict
{
extern const std::string alnum;
extern const std::string alpha;
extern const std::string upper;
extern const std::string lower;
extern const std::string numeric;
}
/// Tools for randomization
namespace ircd::rand
{
struct xoshiro256p;
// Interface state.
extern std::random_device device;
extern std::mt19937_64 mt;
// Random integer
uint64_t integer();
uint64_t integer(const uint64_t &min, const uint64_t &max); // inclusive
// Random vector
template<class T> T vector() = delete;
template<> u128x1 vector();
template<> u256x1 vector();
template<> u512x1 vector();
// Random character from dictionary
char character(const std::string &dict = dict::alnum);
// Random string from dictionary, fills buffer
string_view string(const mutable_buffer &out, const std::string &dict);
// Random fill of buffer
const_buffer fill(const mutable_buffer &out);
}
struct ircd::rand::xoshiro256p
{
u64x4 s
{
-1UL, -1UL, -1UL, -1UL
};
uint64_t operator()();
};
inline uint64_t
ircd::rand::xoshiro256p::operator()()
{
const u64
ret(s[0] + s[3]),
t(s[1] << 17);
s[2] ^= s[0];
s[3] ^= s[1];
s[1] ^= s[2];
s[0] ^= s[3];
s[2] ^= t;
#if __has_builtin(__builtin_rotateleft64)
s[3] = __builtin_rotateleft64(s[3], 45);
#else
s[3] = (s[3] << 45) | (s[3] >> (64 - 45));
#endif
return ret;
};
/// Random character from dictionary
inline char
ircd::rand::character(const std::string &dict)
{
assert(!dict.empty());
const auto pos
{
integer(0, dict.size() - 1)
};
return dict.at(pos);
}
/// Random integer in range (inclusive)
inline uint64_t
ircd::rand::integer(const uint64_t &min,
const uint64_t &max)
{
std::uniform_int_distribution<uint64_t> dist
{
min, max
};
return dist(mt);
}
/// Random 64-bits
inline uint64_t
ircd::rand::integer()
{
return mt();
}