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<random>: Improvements around static constexpr member variables #3006

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 5 commits into from
Aug 12, 2022
Merged

<random>: Improvements around static constexpr member variables #3006

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0995077
Improve static constexpr members in <random>
frederick-vs-ja Aug 8, 2022
b99b483
Why didn't this get clang-formatted...
frederick-vs-ja Aug 8, 2022
546bed7
A severe typo
frederick-vs-ja Aug 8, 2022
8be848c
Drop the out-of-class definition of static constexpr members
frederick-vs-ja Aug 9, 2022
048d49b
Change _Cx_ldexp_one to _Cx_exp2
frederick-vs-ja Aug 9, 2022
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52 changes: 16 additions & 36 deletions stl/inc/random
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Original file line number Diff line number Diff line change
Expand Up @@ -790,12 +790,6 @@ protected:
typename _Swc_Traits::_Cy_t _Carry;
};

template <class _Ty, size_t _Sx, size_t _Rx, class _Swc_Traits>
const size_t _Swc_base<_Ty, _Sx, _Rx, _Swc_Traits>::short_lag;

template <class _Ty, size_t _Sx, size_t _Rx, class _Swc_Traits>
const size_t _Swc_base<_Ty, _Sx, _Rx, _Swc_Traits>::long_lag;

template <class _Ty, _Ty _Mx, size_t _Nw>
struct _Swc_traits { // traits for subtract_with_carry generator
using _Cy_t = int;
Expand Down Expand Up @@ -1005,16 +999,28 @@ public:
};

#if _HAS_TR1_NAMESPACE
_CONSTEVAL double _Cx_exp2(const int _Exp) noexcept {
double _Ret = 1.0;
for (int _Count = _Exp; _Count > 0; --_Count) {
_Ret *= 2.0;
}
for (int _Count = _Exp; _Count < 0; ++_Count) {
_Ret *= 0.5;
}

return _Ret;
}

template <class _Ty, size_t _Wx, size_t _Rx>
struct _Swc_01_traits { // traits for subtract_with_carry_01 generator
using _Cy_t = _Ty;
using _UCy_t = _Ty;
using _Mod_t = _Ty;
using _Seed_t = unsigned int;

static const _Cy_t _Cy;
static const _Mod_t _Mod;
static const _Ty _Max;
static constexpr _Cy_t _Cy = static_cast<_Cy_t>(_Cx_exp2(static_cast<int>(-static_cast<ptrdiff_t>(_Wx))));
static constexpr _Mod_t _Mod = 1;
static constexpr _Ty _Max = 1;
static constexpr int _Nwords = (_Wx + 31) / 32;

template <class _Gen>
Expand Down Expand Up @@ -1058,24 +1064,10 @@ struct _Swc_01_traits { // traits for subtract_with_carry_01 generator
}

private:
static const _Ty _Scale1;
static constexpr _Ty _Scale1 = static_cast<_Ty>(_Cx_exp2(_Wx % 32));
static constexpr unsigned long _Mask = ~((~0UL) << (_Wx % 32));
};

template <class _Ty, size_t _Wx, size_t _Rx>
const typename _Swc_01_traits<_Ty, _Wx, _Rx>::_Cy_t
_Swc_01_traits<_Ty, _Wx, _Rx>::_Cy = static_cast<typename _Swc_01_traits<_Ty, _Wx, _Rx>::_Cy_t>(
_CSTD ldexp(1.0, static_cast<int>(-static_cast<ptrdiff_t>(_Wx))));

template <class _Ty, size_t _Wx, size_t _Rx>
const typename _Swc_01_traits<_Ty, _Wx, _Rx>::_Mod_t _Swc_01_traits<_Ty, _Wx, _Rx>::_Mod = 1;

template <class _Ty, size_t _Wx, size_t _Rx>
const _Ty _Swc_01_traits<_Ty, _Wx, _Rx>::_Max = 1;

template <class _Ty, size_t _Wx, size_t _Rx>
const _Ty _Swc_01_traits<_Ty, _Wx, _Rx>::_Scale1 = static_cast<_Ty>(_CSTD ldexp(1.0, _Wx % 32));

template <class _Ty, size_t _Wx, size_t _Sx, size_t _Rx>
class _DEPRECATE_TR1_NAMESPACE subtract_with_carry_01
: public _Swc_base<_Ty, _Sx, _Rx, _Swc_01_traits<_Ty, _Wx, _Rx>> { // subtract_with_carry_01 generator
Expand All @@ -1091,12 +1083,6 @@ public:
template <class _Gen, _Enable_if_seed_seq_t<_Gen, subtract_with_carry_01> = 0>
subtract_with_carry_01(_Gen& _Gx) : _Mybase(_Gx) {}
};

_STL_DISABLE_DEPRECATED_WARNING
template <class _Ty, size_t _Wx, size_t _Sx, size_t _Rx>
const size_t subtract_with_carry_01<_Ty, _Wx, _Sx, _Rx>::word_size;
_STL_RESTORE_DEPRECATED_WARNING

#endif // _HAS_TR1_NAMESPACE

template <class _Ty, int _Wx, int _Nx, int _Mx, int _Rx, _Ty _Px, int _Ux, int _Sx, _Ty _Bx, int _Tx, _Ty _Cx, int _Lx>
Expand Down Expand Up @@ -1443,12 +1429,6 @@ private:
int _Nx;
};

template <class _Engine, int _Px, int _Rx>
const int discard_block<_Engine, _Px, _Rx>::block_size;

template <class _Engine, int _Px, int _Rx>
const int discard_block<_Engine, _Px, _Rx>::used_block;

template <class _Engine, size_t _Px, size_t _Rx>
class discard_block_engine : public discard_block<_Engine, _Px, _Rx> { // discard_block_engine compound engine
public:
Expand Down