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57 lines
2.0 KiB
57 lines
2.0 KiB
5 months ago
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#ifndef INCLUDE_ADD_WITH_SATURATE_H_
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#define INCLUDE_ADD_WITH_SATURATE_H_
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/*
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Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/**
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@file include/add_with_saturate.h
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Some utilities for saturating add.
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*/
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#include <limits>
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#include <type_traits>
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// Returns a + b, saturated to the range of a.
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template <class T, class U>
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inline T AddWithSaturate(T a, U b) {
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static_assert(!std::is_signed<T>::value, "values must be unsigned");
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static_assert(!std::is_signed<U>::value, "values must be unsigned");
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auto result = a + b;
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if (result < a || result > std::numeric_limits<T>::max()) {
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// Value wrapped around or was promoted to a larger type; saturate to the
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// maximum value.
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return std::numeric_limits<T>::max();
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}
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return result;
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}
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// Effectively does b += a; with saturation.
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template <class T, class U>
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inline void AddWithSaturate(T a, U *b) {
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*b = AddWithSaturate(*b, a);
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}
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#endif // INCLUDE_ADD_WITH_SATURATE_H_
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