| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | //====================================================================================================================== | ||
| 2 | /* | ||
| 3 | POLYFLOAT - Extended precision floating points | ||
| 4 | Copyright : POLYFLOAT Contributors & Maintainers | ||
| 5 | SPDX-License-Identifier: BSL-1.0 | ||
| 6 | */ | ||
| 7 | //====================================================================================================================== | ||
| 8 | #pragma once | ||
| 9 | |||
| 10 | #include <polyfloat/details/callable.hpp> | ||
| 11 | #include <polyfloat/types/concepts.hpp> | ||
| 12 | #include <polyfloat/types/traits.hpp> | ||
| 13 | #include <type_traits> | ||
| 14 | #include <polyfloat/module/core/constants/nbmantissabits.hpp> | ||
| 15 | #include <polyfloat/module/core/ldexp.hpp> | ||
| 16 | namespace plf | ||
| 17 | { | ||
| 18 | |||
| 19 | template<typename Options> struct two_split_t : eve::callable<two_split_t, Options> | ||
| 20 | { | ||
| 21 | template<auto N, concepts::polyfloat_like T> | ||
| 22 | POLYFLOAT_ABI eve::zipped<T, T> constexpr operator()(T t, std::integral_constant<int, N> s) const noexcept | ||
| 23 | { | ||
| 24 | return POLYFLOAT_CALL(t, s); | ||
| 25 | } | ||
| 26 | |||
| 27 | 30452 | template<concepts::polyfloat_like T> POLYFLOAT_ABI eve::zipped<T, T> constexpr operator()(T t) const noexcept | |
| 28 | { | ||
| 29 | 30452 | return POLYFLOAT_CALL(t); | |
| 30 | } | ||
| 31 | |||
| 32 | 30452 | POLYFLOAT_CALLABLE_OBJECT(two_split_t, two_split_); | |
| 33 | }; | ||
| 34 | //================================================================================================ | ||
| 35 | //! @addtogroup core_accuracy | ||
| 36 | //! @{ | ||
| 37 | //! @var two_split | ||
| 38 | //! @brief Computes the pair from Veltkamp's splitting algorithm | ||
| 39 | //! | ||
| 40 | //! @groupheader{Header file} | ||
| 41 | //! | ||
| 42 | //! @code | ||
| 43 | //! #include <eve/module/core.hpp> | ||
| 44 | //! @endcode | ||
| 45 | //! | ||
| 46 | //! @groupheader{Callable Signatures} | ||
| 47 | //! | ||
| 48 | //! @code | ||
| 49 | //! namespace eve | ||
| 50 | //! { | ||
| 51 | //! // Regular overload | ||
| 52 | //! template <auto N> constexpr auto two_split(auto x, std::integral_constant<N> s) noexcept; // 1 | ||
| 53 | //! constexpr auto two_split( auto x) noexcept; // 2 | ||
| 54 | //! } | ||
| 55 | //! @endcode | ||
| 56 | //! | ||
| 57 | //! **Parameters** | ||
| 58 | //! | ||
| 59 | //! * `x`: polyfloat argument](@ref eve::floating_value) of same dimension. | ||
| 60 | //! | ||
| 61 | //! | ||
| 62 | //! **Return value** | ||
| 63 | //! | ||
| 64 | //! 1. Returns a pair \f$(x_h, x_l)\f$ such that the significand of \f$x_h\f$ fits in p $B!](B s bits, | ||
| 65 | //! the significand of \f$x_l\f$ fits in s$B!](B1 bits, and \f$x_h \oplus x_l = x\f$. | ||
| 66 | //! p is the number of mantissa bits of x, With 2 $(C!B(B s $(C!B(B p $B!](B 2 | ||
| 67 | //! 2. s is taken as \f$\lceil p/2 \rceil\f$ | ||
| 68 | //! | ||
| 69 | //! | ||
| 70 | //! @groupheader{External references} | ||
| 71 | //! * [On the Computation of Correctly-Rounded Sums](https://www.vinc17.net/research/papers/rr_ccrsums2.pdf) | ||
| 72 | //! | ||
| 73 | //! @groupheader{Example} | ||
| 74 | //! @godbolt_todo{doc/core/core/two_split.cpp} | ||
| 75 | //================================================================================================ | ||
| 76 | inline constexpr auto two_split = eve::functor<two_split_t>; | ||
| 77 | //================================================================================================ | ||
| 78 | //! @} | ||
| 79 | //================================================================================================ | ||
| 80 | |||
| 81 | namespace _ | ||
| 82 | { | ||
| 83 | template<auto N, typename T, eve::callable_options O> | ||
| 84 | constexpr auto two_split_(POLYFLOAT_DELAY(), O const&, T x, std::integral_constant<int, N>) | ||
| 85 | { | ||
| 86 | auto K = plf::ldexp(T(1), N); | ||
| 87 | auto g = K * x; | ||
| 88 | auto d = x - g; | ||
| 89 | auto xh = g + d; | ||
| 90 | return eve::zip(xh, x - xh); | ||
| 91 | } | ||
| 92 | |||
| 93 | 30452 | template<typename T, eve::callable_options O> constexpr auto two_split_(POLYFLOAT_DELAY(), O const&, T x) | |
| 94 | { | ||
| 95 | using u_t = eve::underlying_type_t<T>; | ||
| 96 |
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30452 | auto N = (plf::nbmantissabits(eve::as<u_t>()) + 1) / 2; |
| 97 | 30452 | auto K = plf::ldexp(T(1), N); | |
| 98 | 30452 | auto g = K * x; | |
| 99 | 30452 | auto d = x - g; | |
| 100 | 30452 | auto xh = g + d; | |
| 101 | 60900 | return eve::zip(xh, x - xh); | |
| 102 | } | ||
| 103 | } | ||
| 104 | } | ||
| 105 |