STL/stl/inc/limits

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33 KiB
C++

// limits standard header (core)
// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#pragma once
#ifndef _LIMITS_
#define _LIMITS_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR
#include <cfloat>
#include <climits>
#include <cwchar>
#include <intrin0.h>
#include <isa_availability.h>
#include <xstddef>
#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
_STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new
_STD_BEGIN
// ENUM float_denorm_style
enum float_denorm_style { // constants for different IEEE float denormalization styles
denorm_indeterminate = -1,
denorm_absent = 0,
denorm_present = 1
};
// ENUM float_round_style
enum float_round_style { // constants for different IEEE rounding styles
round_indeterminate = -1,
round_toward_zero = 0,
round_to_nearest = 1,
round_toward_infinity = 2,
round_toward_neg_infinity = 3
};
// STRUCT _Num_base
struct _Num_base { // base for all types, with common defaults
static constexpr float_denorm_style has_denorm = denorm_absent;
static constexpr bool has_denorm_loss = false;
static constexpr bool has_infinity = false;
static constexpr bool has_quiet_NaN = false;
static constexpr bool has_signaling_NaN = false;
static constexpr bool is_bounded = false;
static constexpr bool is_exact = false;
static constexpr bool is_iec559 = false;
static constexpr bool is_integer = false;
static constexpr bool is_modulo = false;
static constexpr bool is_signed = false;
static constexpr bool is_specialized = false;
static constexpr bool tinyness_before = false;
static constexpr bool traps = false;
static constexpr float_round_style round_style = round_toward_zero;
static constexpr int digits = 0;
static constexpr int digits10 = 0;
static constexpr int max_digits10 = 0;
static constexpr int max_exponent = 0;
static constexpr int max_exponent10 = 0;
static constexpr int min_exponent = 0;
static constexpr int min_exponent10 = 0;
static constexpr int radix = 0;
};
// CLASS TEMPLATE numeric_limits
template <class _Ty>
class numeric_limits : public _Num_base { // numeric limits for arbitrary type _Ty (say little or nothing)
public:
_NODISCARD static constexpr _Ty(min)() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty(max)() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty lowest() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty epsilon() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty round_error() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty denorm_min() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty infinity() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty quiet_NaN() noexcept {
return _Ty();
}
_NODISCARD static constexpr _Ty signaling_NaN() noexcept {
return _Ty();
}
};
template <class _Ty>
class numeric_limits<const _Ty> : public numeric_limits<_Ty> {}; // numeric limits for const types
template <class _Ty>
class numeric_limits<volatile _Ty> : public numeric_limits<_Ty> {}; // numeric limits for volatile types
template <class _Ty>
class numeric_limits<const volatile _Ty> : public numeric_limits<_Ty> {}; // numeric limits for const volatile types
// STRUCT _Num_int_base
struct _Num_int_base : _Num_base { // base for integer types
static constexpr bool is_bounded = true;
static constexpr bool is_exact = true;
static constexpr bool is_integer = true;
static constexpr bool is_specialized = true;
static constexpr int radix = 2;
};
// STRUCT _Num_float_base
struct _Num_float_base : _Num_base { // base for floating-point types
static constexpr float_denorm_style has_denorm = denorm_present;
static constexpr bool has_infinity = true;
static constexpr bool has_quiet_NaN = true;
static constexpr bool has_signaling_NaN = true;
static constexpr bool is_bounded = true;
static constexpr bool is_iec559 = true;
static constexpr bool is_signed = true;
static constexpr bool is_specialized = true;
static constexpr float_round_style round_style = round_to_nearest;
static constexpr int radix = FLT_RADIX;
};
// CLASS numeric_limits<bool>
template <>
class numeric_limits<bool> : public _Num_int_base {
public:
_NODISCARD static constexpr bool(min)() noexcept {
return false;
}
_NODISCARD static constexpr bool(max)() noexcept {
return true;
}
_NODISCARD static constexpr bool lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr bool epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr bool round_error() noexcept {
return 0;
}
_NODISCARD static constexpr bool denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr bool infinity() noexcept {
return 0;
}
_NODISCARD static constexpr bool quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr bool signaling_NaN() noexcept {
return 0;
}
static constexpr int digits = 1;
};
// CLASS numeric_limits<char>
template <>
class numeric_limits<char> : public _Num_int_base {
public:
_NODISCARD static constexpr char(min)() noexcept {
return CHAR_MIN;
}
_NODISCARD static constexpr char(max)() noexcept {
return CHAR_MAX;
}
_NODISCARD static constexpr char lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr char epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr char round_error() noexcept {
return 0;
}
_NODISCARD static constexpr char denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr char infinity() noexcept {
return 0;
}
_NODISCARD static constexpr char quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr char signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_signed = CHAR_MIN != 0;
static constexpr bool is_modulo = CHAR_MIN == 0;
static constexpr int digits = 8 - (CHAR_MIN != 0);
static constexpr int digits10 = 2;
};
// CLASS numeric_limits<signed char>
template <>
class numeric_limits<signed char> : public _Num_int_base {
public:
_NODISCARD static constexpr signed char(min)() noexcept {
return SCHAR_MIN;
}
_NODISCARD static constexpr signed char(max)() noexcept {
return SCHAR_MAX;
}
_NODISCARD static constexpr signed char lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr signed char epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr signed char round_error() noexcept {
return 0;
}
_NODISCARD static constexpr signed char denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr signed char infinity() noexcept {
return 0;
}
_NODISCARD static constexpr signed char quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr signed char signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_signed = true;
static constexpr int digits = 7;
static constexpr int digits10 = 2;
};
// CLASS numeric_limits<unsigned char>
template <>
class numeric_limits<unsigned char> : public _Num_int_base {
public:
_NODISCARD static constexpr unsigned char(min)() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char(max)() noexcept {
return UCHAR_MAX;
}
_NODISCARD static constexpr unsigned char lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr unsigned char epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char round_error() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char infinity() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned char signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 8;
static constexpr int digits10 = 2;
};
#ifdef __cpp_char8_t
// CLASS numeric_limits<char8_t>
template <>
class numeric_limits<char8_t> : public _Num_int_base {
public:
_NODISCARD static constexpr char8_t(min)() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t(max)() noexcept {
return UCHAR_MAX;
}
_NODISCARD static constexpr char8_t lowest() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t round_error() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t infinity() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr char8_t signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 8;
static constexpr int digits10 = 2;
};
#endif // __cpp_char8_t
// CLASS numeric_limits<char16_t>
template <>
class numeric_limits<char16_t> : public _Num_int_base {
public:
_NODISCARD static constexpr char16_t(min)() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t(max)() noexcept {
return USHRT_MAX;
}
_NODISCARD static constexpr char16_t lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr char16_t epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t round_error() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t infinity() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr char16_t signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 16;
static constexpr int digits10 = 4;
};
// CLASS numeric_limits<char32_t>
template <>
class numeric_limits<char32_t> : public _Num_int_base {
public:
_NODISCARD static constexpr char32_t(min)() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t(max)() noexcept {
return UINT_MAX;
}
_NODISCARD static constexpr char32_t lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr char32_t epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t round_error() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t infinity() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr char32_t signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 32;
static constexpr int digits10 = 9;
};
// CLASS numeric_limits<wchar_t>
template <>
class numeric_limits<wchar_t> : public _Num_int_base {
public:
_NODISCARD static constexpr wchar_t(min)() noexcept {
return WCHAR_MIN;
}
_NODISCARD static constexpr wchar_t(max)() noexcept {
return WCHAR_MAX;
}
_NODISCARD static constexpr wchar_t lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr wchar_t epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr wchar_t round_error() noexcept {
return 0;
}
_NODISCARD static constexpr wchar_t denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr wchar_t infinity() noexcept {
return 0;
}
_NODISCARD static constexpr wchar_t quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr wchar_t signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 16;
static constexpr int digits10 = 4;
};
// CLASS numeric_limits<short>
template <>
class numeric_limits<short> : public _Num_int_base {
public:
_NODISCARD static constexpr short(min)() noexcept {
return SHRT_MIN;
}
_NODISCARD static constexpr short(max)() noexcept {
return SHRT_MAX;
}
_NODISCARD static constexpr short lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr short epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr short round_error() noexcept {
return 0;
}
_NODISCARD static constexpr short denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr short infinity() noexcept {
return 0;
}
_NODISCARD static constexpr short quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr short signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_signed = true;
static constexpr int digits = 15;
static constexpr int digits10 = 4;
};
// CLASS numeric_limits<int>
template <>
class numeric_limits<int> : public _Num_int_base {
public:
_NODISCARD static constexpr int(min)() noexcept {
return INT_MIN;
}
_NODISCARD static constexpr int(max)() noexcept {
return INT_MAX;
}
_NODISCARD static constexpr int lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr int epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr int round_error() noexcept {
return 0;
}
_NODISCARD static constexpr int denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr int infinity() noexcept {
return 0;
}
_NODISCARD static constexpr int quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr int signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_signed = true;
static constexpr int digits = 31;
static constexpr int digits10 = 9;
};
// CLASS numeric_limits<long>
template <>
class numeric_limits<long> : public _Num_int_base {
public:
_NODISCARD static constexpr long(min)() noexcept {
return LONG_MIN;
}
_NODISCARD static constexpr long(max)() noexcept {
return LONG_MAX;
}
_NODISCARD static constexpr long lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr long epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr long round_error() noexcept {
return 0;
}
_NODISCARD static constexpr long denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr long infinity() noexcept {
return 0;
}
_NODISCARD static constexpr long quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr long signaling_NaN() noexcept {
return 0;
}
static_assert(sizeof(int) == sizeof(long), "LLP64 assumption");
static constexpr bool is_signed = true;
static constexpr int digits = 31;
static constexpr int digits10 = 9;
};
// CLASS numeric_limits<long long>
template <>
class numeric_limits<long long> : public _Num_int_base {
public:
_NODISCARD static constexpr long long(min)() noexcept {
return LLONG_MIN;
}
_NODISCARD static constexpr long long(max)() noexcept {
return LLONG_MAX;
}
_NODISCARD static constexpr long long lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr long long epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr long long round_error() noexcept {
return 0;
}
_NODISCARD static constexpr long long denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr long long infinity() noexcept {
return 0;
}
_NODISCARD static constexpr long long quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr long long signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_signed = true;
static constexpr int digits = 63;
static constexpr int digits10 = 18;
};
#ifdef _NATIVE_WCHAR_T_DEFINED
// CLASS numeric_limits<unsigned short>
template <>
class numeric_limits<unsigned short> : public _Num_int_base {
public:
_NODISCARD static constexpr unsigned short(min)() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short(max)() noexcept {
return USHRT_MAX;
}
_NODISCARD static constexpr unsigned short lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr unsigned short epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short round_error() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short infinity() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned short signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 16;
static constexpr int digits10 = 4;
};
#endif // _NATIVE_WCHAR_T_DEFINED
// CLASS numeric_limits<unsigned int>
template <>
class numeric_limits<unsigned int> : public _Num_int_base {
public:
_NODISCARD static constexpr unsigned int(min)() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int(max)() noexcept {
return UINT_MAX;
}
_NODISCARD static constexpr unsigned int lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr unsigned int epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int round_error() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int infinity() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned int signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 32;
static constexpr int digits10 = 9;
};
// CLASS numeric_limits<unsigned long>
template <>
class numeric_limits<unsigned long> : public _Num_int_base {
public:
_NODISCARD static constexpr unsigned long(min)() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long(max)() noexcept {
return ULONG_MAX;
}
_NODISCARD static constexpr unsigned long lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr unsigned long epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long round_error() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long infinity() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long signaling_NaN() noexcept {
return 0;
}
static_assert(sizeof(unsigned int) == sizeof(unsigned long), "LLP64 assumption");
static constexpr bool is_modulo = true;
static constexpr int digits = 32;
static constexpr int digits10 = 9;
};
// CLASS numeric_limits<unsigned long long>
template <>
class numeric_limits<unsigned long long> : public _Num_int_base {
public:
_NODISCARD static constexpr unsigned long long(min)() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long(max)() noexcept {
return ULLONG_MAX;
}
_NODISCARD static constexpr unsigned long long lowest() noexcept {
return (min) ();
}
_NODISCARD static constexpr unsigned long long epsilon() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long round_error() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long denorm_min() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long infinity() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long quiet_NaN() noexcept {
return 0;
}
_NODISCARD static constexpr unsigned long long signaling_NaN() noexcept {
return 0;
}
static constexpr bool is_modulo = true;
static constexpr int digits = 64;
static constexpr int digits10 = 19;
};
// CLASS numeric_limits<float>
template <>
class numeric_limits<float> : public _Num_float_base {
public:
_NODISCARD static constexpr float(min)() noexcept {
return FLT_MIN;
}
_NODISCARD static constexpr float(max)() noexcept {
return FLT_MAX;
}
_NODISCARD static constexpr float lowest() noexcept {
return -(max) ();
}
_NODISCARD static constexpr float epsilon() noexcept {
return FLT_EPSILON;
}
_NODISCARD static constexpr float round_error() noexcept {
return 0.5F;
}
_NODISCARD static constexpr float denorm_min() noexcept {
return FLT_TRUE_MIN;
}
_NODISCARD static constexpr float infinity() noexcept {
return __builtin_huge_valf();
}
_NODISCARD static constexpr float quiet_NaN() noexcept {
return __builtin_nanf("0");
}
_NODISCARD static constexpr float signaling_NaN() noexcept {
return __builtin_nansf("1");
}
static constexpr int digits = FLT_MANT_DIG;
static constexpr int digits10 = FLT_DIG;
static constexpr int max_digits10 = 9;
static constexpr int max_exponent = FLT_MAX_EXP;
static constexpr int max_exponent10 = FLT_MAX_10_EXP;
static constexpr int min_exponent = FLT_MIN_EXP;
static constexpr int min_exponent10 = FLT_MIN_10_EXP;
};
// CLASS numeric_limits<double>
template <>
class numeric_limits<double> : public _Num_float_base {
public:
_NODISCARD static constexpr double(min)() noexcept {
return DBL_MIN;
}
_NODISCARD static constexpr double(max)() noexcept {
return DBL_MAX;
}
_NODISCARD static constexpr double lowest() noexcept {
return -(max) ();
}
_NODISCARD static constexpr double epsilon() noexcept {
return DBL_EPSILON;
}
_NODISCARD static constexpr double round_error() noexcept {
return 0.5;
}
_NODISCARD static constexpr double denorm_min() noexcept {
return DBL_TRUE_MIN;
}
_NODISCARD static constexpr double infinity() noexcept {
return __builtin_huge_val();
}
_NODISCARD static constexpr double quiet_NaN() noexcept {
return __builtin_nan("0");
}
_NODISCARD static constexpr double signaling_NaN() noexcept {
return __builtin_nans("1");
}
static constexpr int digits = DBL_MANT_DIG;
static constexpr int digits10 = DBL_DIG;
static constexpr int max_digits10 = 17;
static constexpr int max_exponent = DBL_MAX_EXP;
static constexpr int max_exponent10 = DBL_MAX_10_EXP;
static constexpr int min_exponent = DBL_MIN_EXP;
static constexpr int min_exponent10 = DBL_MIN_10_EXP;
};
// CLASS numeric_limits<long double>
template <>
class numeric_limits<long double> : public _Num_float_base {
public:
_NODISCARD static constexpr long double(min)() noexcept {
return LDBL_MIN;
}
_NODISCARD static constexpr long double(max)() noexcept {
return LDBL_MAX;
}
_NODISCARD static constexpr long double lowest() noexcept {
return -(max) ();
}
_NODISCARD static constexpr long double epsilon() noexcept {
return LDBL_EPSILON;
}
_NODISCARD static constexpr long double round_error() noexcept {
return 0.5L;
}
_NODISCARD static constexpr long double denorm_min() noexcept {
return LDBL_TRUE_MIN;
}
_NODISCARD static constexpr long double infinity() noexcept {
return __builtin_huge_val();
}
_NODISCARD static constexpr long double quiet_NaN() noexcept {
return __builtin_nan("0");
}
_NODISCARD static constexpr long double signaling_NaN() noexcept {
return __builtin_nans("1");
}
static constexpr int digits = LDBL_MANT_DIG;
static constexpr int digits10 = LDBL_DIG;
static constexpr int max_digits10 = 17;
static constexpr int max_exponent = LDBL_MAX_EXP;
static constexpr int max_exponent10 = LDBL_MAX_10_EXP;
static constexpr int min_exponent = LDBL_MIN_EXP;
static constexpr int min_exponent10 = LDBL_MIN_10_EXP;
};
// Implementation of countl_zero without using specialized CPU instructions.
// Used at compile time and when said instructions are not supported.
// see "Hacker's Delight" section 5-3
template <class _Ty>
_NODISCARD constexpr int _Countl_zero_fallback(_Ty _Val) noexcept {
_Ty _Yy = 0;
unsigned int _Nn = numeric_limits<_Ty>::digits;
unsigned int _Cc = numeric_limits<_Ty>::digits / 2;
do {
_Yy = static_cast<_Ty>(_Val >> _Cc);
if (_Yy != 0) {
_Nn -= _Cc;
_Val = _Yy;
}
_Cc >>= 1;
} while (_Cc != 0);
return static_cast<int>(_Nn) - static_cast<int>(_Val);
}
// Implementation of countr_zero without using specialized CPU instructions.
// Used at compile time and when said instructions are not supported.
// see "Hacker's Delight" section 5-4
template <class _Ty>
_NODISCARD constexpr int _Countr_zero_fallback(const _Ty _Val) noexcept {
constexpr int _Digits = std::numeric_limits<_Ty>::digits;
return _Digits - _Countl_zero_fallback(static_cast<_Ty>(static_cast<_Ty>(~_Val) & static_cast<_Ty>(_Val - 1)));
}
// Implementation of popcount without using specialized CPU instructions.
// Used at compile time and when said instructions are not supported.
template <class _Ty>
_NODISCARD constexpr int _Popcount_fallback(_Ty _Val) noexcept {
constexpr int _Digits = numeric_limits<_Ty>::digits;
// we static_cast these bit patterns in order to truncate them to the correct size
_Val = static_cast<_Ty>(_Val - ((_Val >> 1) & static_cast<_Ty>(0x5555'5555'5555'5555ull)));
_Val = static_cast<_Ty>((_Val & static_cast<_Ty>(0x3333'3333'3333'3333ull))
+ ((_Val >> 2) & static_cast<_Ty>(0x3333'3333'3333'3333ull)));
_Val = static_cast<_Ty>((_Val + (_Val >> 4)) & static_cast<_Ty>(0x0F0F'0F0F'0F0F'0F0Full));
for (int _Shift_digits = 8; _Shift_digits < _Digits; _Shift_digits <<= 1) {
_Val = static_cast<_Ty>(_Val + static_cast<_Ty>(_Val >> _Shift_digits));
}
// we want the bottom "slot" that's big enough to store _Digits
return static_cast<int>(_Val & static_cast<_Ty>(_Digits + _Digits - 1));
}
#if defined(_M_IX86) || defined(_M_X64)
extern "C" {
extern int __isa_available;
#ifdef __clang__
#define _TZCNT_U32 __builtin_ia32_tzcnt_u32
#define _TZCNT_U64 __builtin_ia32_tzcnt_u64
#else // ^^^ __clang__ / !__clang__ vvv
#define _TZCNT_U32 _tzcnt_u32
#define _TZCNT_U64 _tzcnt_u64
#endif // __clang__
}
template <class _Ty>
_NODISCARD int _Checked_x86_x64_countr_zero(const _Ty _Val) noexcept {
constexpr int _Digits = numeric_limits<_Ty>::digits;
constexpr _Ty _Max = (numeric_limits<_Ty>::max) ();
#ifndef __AVX2__
// Because the widening done below will always give a non-0 value, checking for tzcnt
// is not required for 8-bit and 16-bit since the only difference in behavior between
// bsf and tzcnt is when the value is 0.
if constexpr (_Digits > 16) {
const bool _Definitely_have_tzcnt = __isa_available >= __ISA_AVAILABLE_AVX2;
if (!_Definitely_have_tzcnt && _Val == 0) {
return _Digits;
}
}
#endif // __AVX2__
if constexpr (_Digits <= 32) {
// Intended widening to int. This operation means that a narrow 0 will widen
// to 0xFFFF....FFFF0... instead of 0. We need this to avoid counting all the zeros
// of the wider type.
return static_cast<int>(_TZCNT_U32(static_cast<unsigned int>(~_Max | _Val)));
} else {
#ifdef _M_IX86
const unsigned int _High = _Val >> 32;
const unsigned int _Low = static_cast<unsigned int>(_Val);
if (_Low == 0) {
return 32 + _Checked_x86_x64_countr_zero(_High);
} else {
return _Checked_x86_x64_countr_zero(_Low);
}
#else // ^^^ _M_IX86 / !_M_IX86 vvv
return static_cast<int>(_TZCNT_U64(_Val));
#endif // _M_IX86
}
}
#undef _TZCNT_U32
#undef _TZCNT_U64
#endif // defined(_M_IX86) || defined(_M_X64)
#if (defined(_M_IX86) || (defined(_M_X64) && !defined(_M_ARM64EC))) && !defined(_M_CEE_PURE) && !defined(__CUDACC__) \
&& !defined(__INTEL_COMPILER)
#define _HAS_POPCNT_INTRINSICS 1
#else // ^^^ intrinsics available ^^^ / vvv intrinsics unavailable vvv
#define _HAS_POPCNT_INTRINSICS 0
#endif // ^^^ intrinsics unavailable ^^^
#if _HAS_POPCNT_INTRINSICS
template <class _Ty>
_NODISCARD int _Checked_x86_x64_popcount(const _Ty _Val) noexcept {
constexpr int _Digits = numeric_limits<_Ty>::digits;
#ifndef __AVX__
const bool _Definitely_have_popcnt = __isa_available >= __ISA_AVAILABLE_SSE42;
if (!_Definitely_have_popcnt) {
return _Popcount_fallback(_Val);
}
#endif // !defined(__AVX__)
if constexpr (_Digits <= 16) {
return static_cast<int>(__popcnt16(_Val));
} else if constexpr (_Digits == 32) {
return static_cast<int>(__popcnt(_Val));
} else {
#ifdef _M_IX86
return static_cast<int>(__popcnt(_Val >> 32) + __popcnt(static_cast<unsigned int>(_Val)));
#else // ^^^ _M_IX86 / !_M_IX86 vvv
return static_cast<int>(__popcnt64(_Val));
#endif // _M_IX86
}
}
#endif // _HAS_POPCNT_INTRINSICS
template <class _Ty>
constexpr bool _Is_standard_unsigned_integer =
_Is_any_of_v<remove_cv_t<_Ty>, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long>;
template <class _Ty, enable_if_t<_Is_standard_unsigned_integer<_Ty>, int> = 0>
_NODISCARD constexpr int _Countr_zero(const _Ty _Val) noexcept {
#if defined(_M_IX86) || defined(_M_X64)
#if _HAS_CXX20
if (!_STD is_constant_evaluated()) {
return _Checked_x86_x64_countr_zero(_Val);
}
#endif // _HAS_CXX20
#endif // defined(_M_IX86) || defined(_M_X64)
// C++17 constexpr gcd() calls this function, so it should be constexpr unless we detect runtime evaluation.
return _Countr_zero_fallback(_Val);
}
template <class _Ty, enable_if_t<_Is_standard_unsigned_integer<_Ty>, int> _Enabled = 0>
_NODISCARD _CONSTEXPR20 int _Popcount(const _Ty _Val) noexcept {
#if _HAS_POPCNT_INTRINSICS
#if _HAS_CXX20
if (!_STD is_constant_evaluated())
#endif // _HAS_CXX20
{
return _Checked_x86_x64_popcount(_Val);
}
#endif // _HAS_POPCNT_INTRINSICS
return _Popcount_fallback(_Val);
}
#undef _HAS_POPCNT_INTRINSICS
_STD_END
#pragma pop_macro("new")
_STL_RESTORE_CLANG_WARNINGS
#pragma warning(pop)
#pragma pack(pop)
#endif // _STL_COMPILER_PREPROCESSOR
#endif // _LIMITS_