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