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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-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___CHARCONV_TRAITS
11#define _LIBCPP___CHARCONV_TRAITS
12
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_header
26#endif
27
28_LIBCPP_PUSH_MACROS
29#include <__undef_macros>
30
31_LIBCPP_BEGIN_NAMESPACE_STD
32
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 on
45 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
46 /// 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 on
68 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
69 /// 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_INT128
85template <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 on
92 /// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
93 /// 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# endif
115
116template <typename _Tp>
117inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool
118__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 bool
126__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 available
150 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 _Up
169 __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 __itoa
177
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_STD
185
186_LIBCPP_POP_MACROS
187
188#endif // _LIBCPP___CHARCONV_TRAITS