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BAN: Implement will_{addition,multiplication}_overflow

This commit is contained in:
Bananymous 2024-06-14 11:04:29 +03:00
parent ea7fc7f6c4
commit 05e9d76c77
2 changed files with 25 additions and 24 deletions
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22
BAN/include/BAN/Math.h
View File

@ -1,5 +1,6 @@
#pragma once #pragma once
#include <BAN/Limits.h>
#include <BAN/Traits.h> #include <BAN/Traits.h>
#include <stddef.h> #include <stddef.h>
@ -65,6 +66,27 @@ namespace BAN::Math
return (value & (value - 1)) == 0; return (value & (value - 1)) == 0;
} }
template<BAN::integral T>
static constexpr bool will_multiplication_overflow(T a, T b)
{
if (a == 0 || b == 0)
return false;
if ((a > 0) == (b > 0))
return a > BAN::numeric_limits<T>::max() / b;
else
return a < BAN::numeric_limits<T>::min() / b;
}
template<BAN::integral T>
static constexpr bool will_addition_overflow(T a, T b)
{
if (a > 0 && b > 0)
return a > BAN::numeric_limits<T>::max() - b;
if (a < 0 && b < 0)
return a < BAN::numeric_limits<T>::min() - b;
return false;
}
template<typename T> template<typename T>
requires is_same_v<T, unsigned int> || is_same_v<T, unsigned long> || is_same_v<T, unsigned long long> requires is_same_v<T, unsigned int> || is_same_v<T, unsigned long> || is_same_v<T, unsigned long long>
inline constexpr T ilog2(T value) inline constexpr T ilog2(T value)

27
libc/stdlib.cpp
View File

@ -64,35 +64,14 @@ static constexpr int get_base_digit(char c, int base)
return -1; return -1;
} }
template<BAN::integral T>
static constexpr bool will_multiplication_overflow(T a, T b)
{
if (a == 0 || b == 0)
return false;
if ((a > 0) == (b > 0))
return a > BAN::numeric_limits<T>::max() / b;
else
return a < BAN::numeric_limits<T>::min() / b;
}
template<BAN::integral T>
static constexpr bool will_addition_overflow(T a, T b)
{
if (a > 0 && b > 0)
return a > BAN::numeric_limits<T>::max() - b;
if (a < 0 && b < 0)
return a < BAN::numeric_limits<T>::min() - b;
return false;
}
template<BAN::integral T> template<BAN::integral T>
static constexpr bool will_digit_append_overflow(bool negative, T current, int digit, int base) static constexpr bool will_digit_append_overflow(bool negative, T current, int digit, int base)
{ {
if (BAN::is_unsigned_v<T> && negative && digit) if (BAN::is_unsigned_v<T> && negative && digit)
return true; return true;
if (will_multiplication_overflow<T>(current, base)) if (BAN::Math::will_multiplication_overflow<T>(current, base))
return true; return true;
if (will_addition_overflow<T>(current * base, current < 0 ? -digit : digit)) if (BAN::Math::will_addition_overflow<T>(current * base, current < 0 ? -digit : digit))
return true; return true;
return false; return false;
} }
@ -286,7 +265,7 @@ static T strtoT(const char* str, char** endp, int& error)
int extra_exponent = strtoT<int>(str + 1, &maybe_end, 10, exp_error); int extra_exponent = strtoT<int>(str + 1, &maybe_end, 10, exp_error);
if (exp_error != EINVAL) if (exp_error != EINVAL)
{ {
if (exp_error == ERANGE || will_addition_overflow(exponent, extra_exponent)) if (exp_error == ERANGE || BAN::Math::will_addition_overflow(exponent, extra_exponent))
exponent = negative ? BAN::numeric_limits<int>::min() : BAN::numeric_limits<int>::max(); exponent = negative ? BAN::numeric_limits<int>::min() : BAN::numeric_limits<int>::max();
else else
exponent += extra_exponent; exponent += extra_exponent;