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construct/ircd/rand.cc
Jason Volk b798192c15 ircd::rand: Improve xoshiro256p default values; improve interface consistency.
ircd::rand: Reorg iface; deinline mersenne twister so it's not emitted everywhere.
2020-12-11 22:50:57 -08:00

150 lines
2.6 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.
decltype(ircd::rand::device) ircd::rand::device
{
// on linux: uses RDRND or /dev/urandom
// on windows: TODO: verify construction source
};
decltype(ircd::rand::mt) ircd::rand::mt
{
device()
};
decltype(ircd::rand::dict::alnum) ircd::rand::dict::alnum
{
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
};
decltype(ircd::rand::dict::alpha) ircd::rand::dict::alpha
{
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
};
decltype(ircd::rand::dict::upper) ircd::rand::dict::upper
{
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
};
decltype(ircd::rand::dict::lower) ircd::rand::dict::lower
{
"abcdefghijklmnopqrstuvwxyz"
};
decltype(ircd::rand::dict::numeric) ircd::rand::dict::numeric
{
"0123456789"
};
ircd::string_view
ircd::rand::string(const mutable_buffer &out,
const std::string &dict)
noexcept
{
assert(!dict.empty());
std::uniform_int_distribution<size_t> dist
{
0, dict.size() - 1
};
std::generate(data(out), data(out) + size(out), [&dict, &dist]
() -> char
{
const auto &pos(dist(mt));
assert(pos < dict.size());
return dict[pos];
});
return out;
}
ircd::const_buffer
ircd::rand::fill(const mutable_buffer &out)
noexcept
{
uint64_t *const __restrict__ val
{
reinterpret_cast<uint64_t *>(data(out))
};
constexpr size_t word_size
{
sizeof(*val)
};
size_t i(0);
for(; i < size(out) / word_size; ++i)
val[i] = integer();
for(size_t j(i * word_size); j < size(out) % word_size; ++j)
out[j] = integer();
return out;
}
template<>
ircd::u512x1
ircd::rand::vector()
noexcept
{
return u64x8
{
integer(), integer(),
integer(), integer(),
integer(), integer(),
integer(), integer(),
};
}
template<>
ircd::u256x1
ircd::rand::vector()
noexcept
{
return u64x4
{
integer(), integer(),
integer(), integer(),
};
}
template<>
ircd::u128x1
ircd::rand::vector()
noexcept
{
return u64x2
{
integer(), integer()
};
}
/// Random integer in range (inclusive)
uint64_t
ircd::rand::integer(const uint64_t &min,
const uint64_t &max)
noexcept
{
std::uniform_int_distribution<uint64_t> dist
{
min, max
};
return dist(mt);
}
/// Random 64-bits
uint64_t
ircd::rand::integer()
noexcept
{
return mt();
}