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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___CHARCONV_TRAITS11#define _LIBCPP___CHARCONV_TRAITS12 13#include <__assert>14#include <__bit/countl.h>15#include <__charconv/tables.h>16#include <__charconv/to_chars_base_10.h>17#include <__config>18#include <__memory/addressof.h>19#include <__type_traits/enable_if.h>20#include <__type_traits/is_unsigned.h>21#include <cstdint>22#include <limits>23 24#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)25# pragma GCC system_header26#endif27 28_LIBCPP_PUSH_MACROS29#include <__undef_macros>30 31_LIBCPP_BEGIN_NAMESPACE_STD32 33namespace __itoa {34 35template <typename _Tp, typename = void>36struct _LIBCPP_HIDDEN __traits_base;37 38template <typename _Tp>39struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) <= sizeof(uint32_t)> > {40 using type = uint32_t;41 42 /// The width estimation using a log10 algorithm.43 ///44 /// The algorithm is based on45 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog1046 /// Instead of using IntegerLogBase2 it uses __countl_zero.47 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {48 auto __t = (32 - std::__countl_zero(static_cast<type>(__v | 1))) * 1233 >> 12;49 return __t - (__v < __itoa::__pow10_32[__t]) + 1;50 }51 52 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) {53 return __itoa::__base_10_u32(__p, __v);54 }55 56 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_32)& __pow() {57 return __itoa::__pow10_32;58 }59};60 61template <typename _Tp>62struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(uint64_t)> > {63 using type = uint64_t;64 65 /// The width estimation using a log10 algorithm.66 ///67 /// The algorithm is based on68 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog1069 /// Instead of using IntegerLogBase2 it uses __countl_zero.70 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {71 auto __t = (64 - std::__countl_zero(static_cast<type>(__v | 1))) * 1233 >> 12;72 return __t - (__v < __itoa::__pow10_64[__t]) + 1;73 }74 75 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) {76 return __itoa::__base_10_u64(__p, __v);77 }78 79 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_64)& __pow() {80 return __itoa::__pow10_64;81 }82};83 84# if _LIBCPP_HAS_INT12885template <typename _Tp>86struct _LIBCPP_HIDDEN __traits_base<_Tp, __enable_if_t<sizeof(_Tp) == sizeof(__uint128_t)> > {87 using type = __uint128_t;88 89 /// The width estimation using a log10 algorithm.90 ///91 /// The algorithm is based on92 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog1093 /// Instead of using IntegerLogBase2 it uses __countl_zero.94 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __width(_Tp __v) {95 _LIBCPP_ASSERT_INTERNAL(96 __v > numeric_limits<uint64_t>::max(), "The optimizations for this algorithm fail when this isn't true.");97 // There's always a bit set in the upper 64-bits.98 auto __t = (128 - std::__countl_zero(static_cast<uint64_t>(__v >> 64))) * 1233 >> 12;99 _LIBCPP_ASSERT_INTERNAL(__t >= __itoa::__pow10_128_offset, "Index out of bounds");100 // __t is adjusted since the lookup table misses the lower entries.101 return __t - (__v < __itoa::__pow10_128[__t - __itoa::__pow10_128_offset]) + 1;102 }103 104 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char* __convert(char* __p, _Tp __v) {105 return __itoa::__base_10_u128(__p, __v);106 }107 108 // TODO FMT This pow function should get an index.109 // By moving this to its own header it can be reused by the pow function in to_chars_base_10.110 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI decltype(__pow10_128)& __pow() {111 return __itoa::__pow10_128;112 }113};114# endif115 116template <typename _Tp>117inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool118__mul_overflowed(unsigned char __a, _Tp __b, unsigned char& __r) {119 auto __c = __a * __b;120 __r = __c;121 return __c > numeric_limits<unsigned char>::max();122}123 124template <typename _Tp>125inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool126__mul_overflowed(unsigned short __a, _Tp __b, unsigned short& __r) {127 auto __c = __a * __b;128 __r = __c;129 return __c > numeric_limits<unsigned short>::max();130}131 132template <typename _Tp>133inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool __mul_overflowed(_Tp __a, _Tp __b, _Tp& __r) {134 static_assert(is_unsigned<_Tp>::value, "");135 return __builtin_mul_overflow(__a, __b, std::addressof(__r));136}137 138template <typename _Tp, typename _Up>139inline _LIBCPP_HIDE_FROM_ABI bool _LIBCPP_CONSTEXPR_SINCE_CXX23 __mul_overflowed(_Tp __a, _Up __b, _Tp& __r) {140 return __itoa::__mul_overflowed(__a, static_cast<_Tp>(__b), __r);141}142 143template <typename _Tp>144struct _LIBCPP_HIDDEN __traits : __traits_base<_Tp> {145 static _LIBCPP_CONSTEXPR const int digits = numeric_limits<_Tp>::digits10 + 1;146 using __traits_base<_Tp>::__pow;147 using typename __traits_base<_Tp>::type;148 149 // precondition: at least one non-zero character available150 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI char const*151 __read(char const* __p, char const* __ep, type& __a, type& __b) {152 type __cprod[digits];153 int __j = digits - 1;154 int __i = digits;155 do {156 if (*__p < '0' || *__p > '9')157 break;158 __cprod[--__i] = *__p++ - '0';159 } while (__p != __ep && __i != 0);160 161 __a = __inner_product(__cprod + __i + 1, __cprod + __j, __pow() + 1, __cprod[__i]);162 if (__itoa::__mul_overflowed(__cprod[__j], __pow()[__j - __i], __b))163 --__p;164 return __p;165 }166 167 template <typename _It1, typename _It2, class _Up>168 static _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Up169 __inner_product(_It1 __first1, _It1 __last1, _It2 __first2, _Up __init) {170 for (; __first1 < __last1; ++__first1, ++__first2)171 __init = __init + *__first1 * *__first2;172 return __init;173 }174};175 176} // namespace __itoa177 178template <typename _Tp>179inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI _Tp __complement(_Tp __x) {180 static_assert(is_unsigned<_Tp>::value, "cast to unsigned first");181 return _Tp(~__x + 1);182}183 184_LIBCPP_END_NAMESPACE_STD185 186_LIBCPP_POP_MACROS187 188#endif // _LIBCPP___CHARCONV_TRAITS189