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66 lines
2.5 KiB
66 lines
2.5 KiB
4 months ago
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/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_INTERPRETER_SAFE_MATH_H_
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#define ART_RUNTIME_INTERPRETER_SAFE_MATH_H_
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#include <functional>
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#include <type_traits>
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namespace art {
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namespace interpreter {
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// Declares a type which is the larger in bit size of the two template parameters.
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template <typename T1, typename T2>
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struct select_bigger {
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typedef typename std::conditional<sizeof(T1) >= sizeof(T2), T1, T2>::type type;
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};
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// Perform signed arithmetic Op on 'a' and 'b' with defined wrapping behavior.
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template<template <typename OpT> class Op, typename T1, typename T2>
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static inline typename select_bigger<T1, T2>::type SafeMath(T1 a, T2 b) {
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typedef typename select_bigger<T1, T2>::type biggest_T;
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typedef typename std::make_unsigned<biggest_T>::type unsigned_biggest_T;
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static_assert(std::is_signed<T1>::value, "Expected T1 to be signed");
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static_assert(std::is_signed<T2>::value, "Expected T2 to be signed");
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unsigned_biggest_T val1 = static_cast<unsigned_biggest_T>(static_cast<biggest_T>(a));
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unsigned_biggest_T val2 = static_cast<unsigned_biggest_T>(b);
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return static_cast<biggest_T>(Op<unsigned_biggest_T>()(val1, val2));
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}
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// Perform a signed add on 'a' and 'b' with defined wrapping behavior.
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template<typename T1, typename T2>
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static inline typename select_bigger<T1, T2>::type SafeAdd(T1 a, T2 b) {
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return SafeMath<std::plus>(a, b);
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}
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// Perform a signed substract on 'a' and 'b' with defined wrapping behavior.
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template<typename T1, typename T2>
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static inline typename select_bigger<T1, T2>::type SafeSub(T1 a, T2 b) {
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return SafeMath<std::minus>(a, b);
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}
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// Perform a signed multiply on 'a' and 'b' with defined wrapping behavior.
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template<typename T1, typename T2>
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static inline typename select_bigger<T1, T2>::type SafeMul(T1 a, T2 b) {
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return SafeMath<std::multiplies>(a, b);
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}
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} // namespace interpreter
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} // namespace art
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#endif // ART_RUNTIME_INTERPRETER_SAFE_MATH_H_
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