/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */ /* * This file is part of the LibreOffice project. * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
namespace o3tl
{ // Return true iff `value` of floating-point type `F` converts to a value of integral type `I` no // smaller than `min`: template <floating_point F, integral I> constexpr bool convertsToAtLeast(F value, I min)
{ // If `F(min)`, `F(min) - F(1)` are too large in magnitude for `F`'s precision, then they either // fall into the same bucket, in which case we should return false if `value` represents that // bucket, or they are on the boundary of two adjacent buckets, in which case we should return // true if `value`represents the higher bucket containing `F(min)`: return value > F(min) - F(1);
}
// Return true iff `value` of floating-point type `F` converts to a value of integral type `I` no // larger than `max`: template <floating_point F, integral I> constexpr bool convertsToAtMost(F value, I max)
{ // If `F(max)`, `F(max) + F(1)` are too large in magnitude for `F`'s precision, then they either // fall into the same bucket, in which case we should return false if `value` represents that // bucket, or they are on the boundary of two adjacent buckets, in which case we should return // true if `value`represents the lower bucket containing `F(max)`: return value < F(max) + F(1);
}
// Casts a floating-point to an integer, avoiding overflow. Used like: // sal_Int64 n = o3tl::saturating_cast<sal_Int64>(f); template <integral I, floating_point F> constexpr I saturating_cast(F f)
{ if constexpr (std::is_signed_v<I>) if (!convertsToAtLeast(f, std::numeric_limits<I>::min())) return std::numeric_limits<I>::min(); if (!convertsToAtMost(f, std::numeric_limits<I>::max())) return std::numeric_limits<I>::max(); return f;
}
// Return `value` of floating-point type `F` rounded to the nearest integer away from zero (which // can be useful in calls to convertsToAtLeast/Most(roundAway(x), n), to reject x that are // smaller/larger than n because they have a fractional part): template <floating_point F> F roundAway(F value)
{ return value >= 0 ? std::ceil(value) : std::floor(value);
}
}
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