c3a7edad85
Change-Id: Idc533f1849c8be44ed04d3ed823c7f69c12c2d79 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/120988 Tested-by: Jenkins Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
72 lines
2.9 KiB
C++
72 lines
2.9 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#ifndef INCLUDED_O3TL_FLOAT_INT_CONVERSION_HXX
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#define INCLUDED_O3TL_FLOAT_INT_CONVERSION_HXX
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#include <sal/config.h>
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#include <cmath>
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#include <limits>
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#include <type_traits>
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namespace o3tl
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{
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// Return true iff `value` of floating-point type `F` converts to a value of integral type `I` no
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// smaller than `min`:
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template <typename F, typename I>
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constexpr std::enable_if_t<std::is_floating_point_v<F> && std::is_integral_v<I>, bool>
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convertsToAtLeast(F value, I min)
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{
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// If `F(min)`, `F(min) - F(1)` are too large in magnitude for `F`'s precision, then they either
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// fall into the same bucket, in which case we should return false if `value` represents that
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// bucket, or they are on the boundary of two adjacent buckets, in which case we should return
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// true if `value`represents the higher bucket containing `F(min)`:
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return value > F(min) - F(1);
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}
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// Return true iff `value` of floating-point type `F` converts to a value of integral type `I` no
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// larger than `max`:
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template <typename F, typename I>
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constexpr std::enable_if_t<std::is_floating_point_v<F> && std::is_integral_v<I>, bool>
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convertsToAtMost(F value, I max)
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{
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// If `F(max)`, `F(max) + F(1)` are too large in magnitude for `F`'s precision, then they either
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// fall into the same bucket, in which case we should return false if `value` represents that
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// bucket, or they are on the boundary of two adjacent buckets, in which case we should return
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// true if `value`represents the lower bucket containing `F(max)`:
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return value < F(max) + F(1);
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}
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// Casts a floating-point to an integer, avoiding overflow. Used like:
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// sal_Int64 n = o3tl::saturating_cast<sal_Int64>(f);
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template <typename I, typename F>
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constexpr std::enable_if_t<std::is_floating_point_v<F> && std::is_integral_v<I>, I>
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saturating_cast(F f)
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{
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if constexpr (std::is_signed_v<I>)
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if (!convertsToAtLeast(f, std::numeric_limits<I>::min()))
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return std::numeric_limits<I>::min();
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if (!convertsToAtMost(f, std::numeric_limits<I>::max()))
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return std::numeric_limits<I>::max();
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return f;
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}
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// Return `value` of floating-point type `F` rounded to the nearest integer away from zero (which
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// can be useful in calls to convertsToAtLeast/Most(roundAway(x), n), to reject x that are
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// smaller/larger than n because they have a fractional part):
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template <typename F> std::enable_if_t<std::is_floating_point_v<F>, F> roundAway(F value)
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{
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return value >= 0 ? std::ceil(value) : std::floor(value);
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}
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}
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#endif
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/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
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