Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

refactor generate_canonical #2452

Closed
wants to merge 2 commits into from
Closed

refactor generate_canonical #2452

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
8ac4869
refactor generate_canonical
CaseyCarter Jan 1, 2022
0d6916c
Merge branch 'main' into canon
CaseyCarter Jan 20, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
60 changes: 44 additions & 16 deletions stl/inc/random
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -238,32 +238,60 @@ private:
vector<result_type> _Myvec;
};

template <class _Real, size_t _Minbits, class _Result, _Result _Ix>
CaseyCarter marked this conversation as resolved.
Show resolved Hide resolved
_NODISCARD constexpr int _Generate_canonical_helper() {
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

"Helper" names aren't actually helpful. Maybe _Generate_canonical_times_ceil() ?

if constexpr ((_Ix & (_Ix - 1)) == 0) {
constexpr auto _Log2 = _STD _Countr_zero(_Ix);
return static_cast<int>((_Minbits + _Log2 - 1) / _Log2);
CaseyCarter marked this conversation as resolved.
Show resolved Hide resolved
} else {
return static_cast<int>(_STD ceil(_Minbits / _STD log2(_Ix)));
}
}

template <class _Real, size_t _Bits, class _Gen>
_NODISCARD _Real generate_canonical(_Gen& _Gx) { // build a floating-point value from random sequence
_NODISCARD _Real generate_canonical(_Gen& _Gx) {
_RNG_REQUIRE_REALTYPE(generate_canonical, _Real);

const size_t _Digits = static_cast<size_t>(numeric_limits<_Real>::digits);
const size_t _Minbits = _Digits < _Bits ? _Digits : _Bits;
constexpr auto _Digits = static_cast<size_t>(numeric_limits<_Real>::digits);
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

(Pre existing) convert with {} as you changed _NRAND to do so.

constexpr size_t _Minbits = _Digits < _Bits ? _Digits : _Bits;

if constexpr (is_integral_v<typename _Gen::result_type>) {
constexpr auto _Ix = (_Gen::max)() - (_Gen::min)() + 1;
const int _Ceil = _Generate_canonical_helper<_Real, _Minbits, typename _Gen::result_type, _Ix>();
#pragma warning(suppress : 6326) // Potential comparison of a constant with another constant
const int _Kx = _Ceil < 1 ? 1 : _Ceil;

const _Real _Gxmin = static_cast<_Real>((_Gx.min)());
const _Real _Gxmax = static_cast<_Real>((_Gx.max)());
const _Real _Rx = (_Gxmax - _Gxmin) + _Real{1};
_Real _Ans{0};
_Real _Factor{1};
constexpr auto _Gxmin = (_Gen::min)();
constexpr auto _Rx = static_cast<_Real>((_Gen::max)() - _Gxmin) + 1;

const int _Ceil = static_cast<int>(_STD ceil(static_cast<_Real>(_Minbits) / _STD log2(_Rx)));
const int _Kx = _Ceil < 1 ? 1 : _Ceil;
for (int _Idx = 0; _Idx < _Kx; ++_Idx) { // add in another set of bits
_Ans += static_cast<_Real>(_Gx() - _Gxmin) * _Factor;
_Factor *= _Rx;
}

_Real _Ans{0};
_Real _Factor{1};
return _Ans / _Factor;
} else { // We still need to tolerate TR1-era engines
const auto _Gxmin = static_cast<_Real>((_Gx.min)());
const auto _Gxmax = static_cast<_Real>((_Gx.max)());
const auto _Rx = (_Gxmax - _Gxmin) + _Real{1};

for (int _Idx = 0; _Idx < _Kx; ++_Idx) { // add in another set of bits
_Ans += (static_cast<_Real>(_Gx()) - _Gxmin) * _Factor;
_Factor *= _Rx;
}
const auto _Ceil = static_cast<int>(_STD ceil(_Minbits / _STD log2(_Rx)));
const int _Kx = _Ceil < 1 ? 1 : _Ceil;

return _Ans / _Factor;
_Real _Ans{0};
_Real _Factor{1};
for (int _Idx = 0; _Idx < _Kx; ++_Idx) { // add in another set of bits
_Ans += (static_cast<_Real>(_Gx()) - _Gxmin) * _Factor;
_Factor *= _Rx;
}

return _Ans / _Factor;
Comment on lines +283 to +290
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This repeats the above block, can it be fused?

}
}

#define _NRAND(eng, resty) (_STD generate_canonical<resty, static_cast<size_t>(-1)>(eng))
#define _NRAND(eng, resty) (_STD generate_canonical<resty, ~size_t{0}>(eng))

_INLINE_VAR constexpr int _MP_len = 5;
using _MP_arr = uint64_t[_MP_len];
Expand Down