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//========================================================================
//
// GooCheckedOps.h
//
// This file is licensed under the GPLv2 or later
//
// Copyright (C) 2018 Adam Reichold <adam.reichold@t-online.de>
// Copyright (C) 2019 LE GARREC Vincent <legarrec.vincent@gmail.com>
//
//========================================================================
#ifndef GOO_CHECKED_OPS_H
#define GOO_CHECKED_OPS_H
#include <climits>
#include <limits>
inline bool checkedAssign(long long lz, int *z) {
static_assert(LLONG_MAX > INT_MAX, "Need type larger than int to perform overflow checks.");
if (lz > INT_MAX || lz < INT_MIN) {
return true;
}
*z = static_cast<int>(lz);
return false;
}
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
inline bool checkedAdd(int x, int y, int *z) {
#if __GNUC__ >= 5 || __has_builtin(__builtin_sadd_overflow)
return __builtin_sadd_overflow(x, y, z);
#else
const auto lz = static_cast<long long>(x) + static_cast<long long>(y);
return checkedAssign(lz, z);
#endif
}
inline bool checkedMultiply(int x, int y, int *z) {
#if __GNUC__ >= 5 || __has_builtin(__builtin_smul_overflow)
return __builtin_smul_overflow(x, y, z);
#else
const auto lz = static_cast<long long>(x) * static_cast<long long>(y);
return checkedAssign(lz, z);
#endif
}
template<typename T> inline T safeAverage(T a, T b) {
static_assert(std::numeric_limits<long long>::max() > std::numeric_limits<T>::max(),
"The max of long long type must be larger to perform overflow checks.");
static_assert(std::numeric_limits<long long>::min() < std::numeric_limits<T>::min(),
"The min of long long type must be smaller to perform overflow checks.");
return static_cast<T>((static_cast<long long>(a) + static_cast<long long>(b)) / 2);
}
#endif // GOO_CHECKED_OPS_H
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