ladybird/AK/NumericLimits.h
Daniel Bertalan 0cd85ab0fc AK+LibJS: Make Number.MIN_VALUE a denormal
ECMA-262 implies that `MIN_VALUE` should be a denormalized value if
denormal arithmetic is supported. This is the case on x86-64 and AArch64
using standard GCC/Clang compilation settings.

test262 checks whether `Number.MIN_VALUE / 2.0` is equal to 0, which
only holds if `MIN_VALUE` is the smallest denormalized value.

This commit renames the existing `NumericLimits<FloatingPoint>::min()`
to `min_normal()` and adds a `min_denormal()` method to force users to
explicitly think about which one is appropriate for their use case. We
shouldn't follow the STL's confusingly designed interface in this
regard.
2023-07-02 21:19:09 +01:00

153 lines
5.3 KiB
C++

/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Types.h>
namespace AK {
template<typename T>
struct NumericLimits {
};
template<>
struct NumericLimits<bool> {
static constexpr bool min() { return false; }
static constexpr bool max() { return true; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return 1; }
};
template<>
struct NumericLimits<signed char> {
static constexpr signed char min() { return -__SCHAR_MAX__ - 1; }
static constexpr signed char max() { return __SCHAR_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ - 1; }
};
template<>
struct NumericLimits<char> {
static constexpr char min() { return -__SCHAR_MAX__ - 1; }
static constexpr char max() { return __SCHAR_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ - 1; }
};
template<>
struct NumericLimits<short> {
static constexpr short min() { return -__SHRT_MAX__ - 1; }
static constexpr short max() { return __SHRT_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(short) - 1; }
};
template<>
struct NumericLimits<int> {
static constexpr int min() { return -__INT_MAX__ - 1; }
static constexpr int max() { return __INT_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(int) - 1; }
};
template<>
struct NumericLimits<long> {
static constexpr long min() { return -__LONG_MAX__ - 1; }
static constexpr long max() { return __LONG_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(long) - 1; }
};
template<>
struct NumericLimits<long long> {
static constexpr long long min() { return -__LONG_LONG_MAX__ - 1; }
static constexpr long long max() { return __LONG_LONG_MAX__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(long long) - 1; }
};
template<>
struct NumericLimits<unsigned char> {
static constexpr unsigned char min() { return 0; }
static constexpr unsigned char max() { return __SCHAR_MAX__ * 2u + 1; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return __CHAR_BIT__; }
};
template<>
struct NumericLimits<unsigned short> {
static constexpr unsigned short min() { return 0; }
static constexpr unsigned short max() { return __SHRT_MAX__ * 2u + 1; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(short); }
};
template<>
struct NumericLimits<unsigned> {
static constexpr unsigned min() { return 0; }
static constexpr unsigned max() { return __INT_MAX__ * 2u + 1; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(int); }
};
template<>
struct NumericLimits<unsigned long> {
static constexpr unsigned long min() { return 0; }
static constexpr unsigned long max() { return __LONG_MAX__ * 2ul + 1; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(long); }
};
template<>
struct NumericLimits<unsigned long long> {
static constexpr unsigned long long min() { return 0; }
static constexpr unsigned long long max() { return __LONG_LONG_MAX__ * 2ull + 1; }
static constexpr bool is_signed() { return false; }
static constexpr size_t digits() { return __CHAR_BIT__ * sizeof(long long); }
};
#ifndef KERNEL
template<>
struct NumericLimits<float> {
static constexpr float lowest() { return -__FLT_MAX__; }
static constexpr float min_normal() { return __FLT_MIN__; }
static constexpr float min_denormal() { return __FLT_DENORM_MIN__; }
static constexpr float max() { return __FLT_MAX__; }
static constexpr float epsilon() { return __FLT_EPSILON__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __FLT_MANT_DIG__; }
};
template<>
struct NumericLimits<double> {
static constexpr double lowest() { return -__DBL_MAX__; }
static constexpr double min_normal() { return __DBL_MIN__; }
static constexpr double min_denormal() { return __DBL_DENORM_MIN__; }
static constexpr double max() { return __DBL_MAX__; }
static constexpr double epsilon() { return __DBL_EPSILON__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __DBL_MANT_DIG__; }
};
template<>
struct NumericLimits<long double> {
static constexpr long double lowest() { return -__LDBL_MAX__; }
static constexpr long double min_normal() { return __LDBL_MIN__; }
static constexpr long double min_denormal() { return __LDBL_DENORM_MIN__; }
static constexpr long double max() { return __LDBL_MAX__; }
static constexpr long double epsilon() { return __LDBL_EPSILON__; }
static constexpr bool is_signed() { return true; }
static constexpr size_t digits() { return __LDBL_MANT_DIG__; }
};
#endif
}
#if USING_AK_GLOBALLY
using AK::NumericLimits;
#endif