master
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_TO_CHARS_INTEGRAL_H
11#define _LIBCPP___CHARCONV_TO_CHARS_INTEGRAL_H
12
13#include <__algorithm/copy_n.h>
14#include <__assert>
15#include <__bit/countl.h>
16#include <__charconv/tables.h>
17#include <__charconv/to_chars_base_10.h>
18#include <__charconv/to_chars_result.h>
19#include <__charconv/traits.h>
20#include <__config>
21#include <__cstddef/ptrdiff_t.h>
22#include <__system_error/errc.h>
23#include <__type_traits/enable_if.h>
24#include <__type_traits/integral_constant.h>
25#include <__type_traits/is_integral.h>
26#include <__type_traits/is_same.h>
27#include <__type_traits/make_32_64_or_128_bit.h>
28#include <__type_traits/make_unsigned.h>
29#include <__utility/unreachable.h>
30#include <cstdint>
31#include <limits>
32
33#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
34# pragma GCC system_header
35#endif
36
37_LIBCPP_PUSH_MACROS
38#include <__undef_macros>
39
40_LIBCPP_BEGIN_NAMESPACE_STD
41
42template <typename _Tp>
43inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
44__to_chars_itoa(char* __first, char* __last, _Tp __value, false_type);
45
46template <typename _Tp>
47inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
48__to_chars_itoa(char* __first, char* __last, _Tp __value, true_type) {
49 auto __x = std::__to_unsigned_like(__value);
50 if (__value < 0 && __first != __last) {
51 *__first++ = '-';
52 __x = std::__complement(__x);
53 }
54
55 return std::__to_chars_itoa(__first, __last, __x, false_type());
56}
57
58template <typename _Tp>
59inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
60__to_chars_itoa(char* __first, char* __last, _Tp __value, false_type) {
61 using __tx = __itoa::__traits<_Tp>;
62 auto __diff = __last - __first;
63
64 if (__tx::digits <= __diff || __tx::__width(__value) <= __diff)
65 return {__tx::__convert(__first, __value), errc(0)};
66 else
67 return {__last, errc::value_too_large};
68}
69
70# if _LIBCPP_HAS_INT128
71template <>
72inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
73__to_chars_itoa(char* __first, char* __last, __uint128_t __value, false_type) {
74 // When the value fits in 64-bits use the 64-bit code path. This reduces
75 // the number of expensive calculations on 128-bit values.
76 //
77 // NOTE the 128-bit code path requires this optimization.
78 if (__value <= numeric_limits<uint64_t>::max())
79 return __to_chars_itoa(__first, __last, static_cast<uint64_t>(__value), false_type());
80
81 using __tx = __itoa::__traits<__uint128_t>;
82 auto __diff = __last - __first;
83
84 if (__tx::digits <= __diff || __tx::__width(__value) <= __diff)
85 return {__tx::__convert(__first, __value), errc(0)};
86 else
87 return {__last, errc::value_too_large};
88}
89# endif
90
91template <class _Tp, __enable_if_t<!is_signed<_Tp>::value, int> = 0>
92inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
93__to_chars_integral(char* __first, char* __last, _Tp __value, int __base);
94
95template <class _Tp, __enable_if_t<is_signed<_Tp>::value, int> = 0>
96inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
97__to_chars_integral(char* __first, char* __last, _Tp __value, int __base) {
98 auto __x = std::__to_unsigned_like(__value);
99 if (__value < 0 && __first != __last) {
100 *__first++ = '-';
101 __x = std::__complement(__x);
102 }
103
104 return std::__to_chars_integral(__first, __last, __x, __base);
105}
106
107namespace __itoa {
108
109template <unsigned _Base>
110struct _LIBCPP_HIDDEN __integral;
111
112template <>
113struct _LIBCPP_HIDDEN __integral<2> {
114 template <typename _Tp>
115 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR int __width(_Tp __value) _NOEXCEPT {
116 // If value == 0 still need one digit. If the value != this has no
117 // effect since the code scans for the most significant bit set.
118 return numeric_limits<_Tp>::digits - std::__countl_zero(__value | 1);
119 }
120
121 template <typename _Tp>
122 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static __to_chars_result
123 __to_chars(char* __first, char* __last, _Tp __value) {
124 ptrdiff_t __cap = __last - __first;
125 int __n = __width(__value);
126 if (__n > __cap)
127 return {__last, errc::value_too_large};
128
129 __last = __first + __n;
130 char* __p = __last;
131 const unsigned __divisor = 16;
132 while (__value > __divisor) {
133 unsigned __c = __value % __divisor;
134 __value /= __divisor;
135 __p -= 4;
136 std::copy_n(&__base_2_lut[4 * __c], 4, __p);
137 }
138 do {
139 unsigned __c = __value % 2;
140 __value /= 2;
141 *--__p = "01"[__c];
142 } while (__value != 0);
143 return {__last, errc(0)};
144 }
145};
146
147template <>
148struct _LIBCPP_HIDDEN __integral<8> {
149 template <typename _Tp>
150 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR int __width(_Tp __value) _NOEXCEPT {
151 // If value == 0 still need one digit. If the value != this has no
152 // effect since the code scans for the most significat bit set.
153 return ((numeric_limits<_Tp>::digits - std::__countl_zero(__value | 1)) + 2) / 3;
154 }
155
156 template <typename _Tp>
157 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static __to_chars_result
158 __to_chars(char* __first, char* __last, _Tp __value) {
159 ptrdiff_t __cap = __last - __first;
160 int __n = __width(__value);
161 if (__n > __cap)
162 return {__last, errc::value_too_large};
163
164 __last = __first + __n;
165 char* __p = __last;
166 unsigned __divisor = 64;
167 while (__value > __divisor) {
168 unsigned __c = __value % __divisor;
169 __value /= __divisor;
170 __p -= 2;
171 std::copy_n(&__base_8_lut[2 * __c], 2, __p);
172 }
173 do {
174 unsigned __c = __value % 8;
175 __value /= 8;
176 *--__p = "01234567"[__c];
177 } while (__value != 0);
178 return {__last, errc(0)};
179 }
180};
181
182template <>
183struct _LIBCPP_HIDDEN __integral<16> {
184 template <typename _Tp>
185 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR int __width(_Tp __value) _NOEXCEPT {
186 // If value == 0 still need one digit. If the value != this has no
187 // effect since the code scans for the most significat bit set.
188 return (numeric_limits<_Tp>::digits - std::__countl_zero(__value | 1) + 3) / 4;
189 }
190
191 template <typename _Tp>
192 _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI static __to_chars_result
193 __to_chars(char* __first, char* __last, _Tp __value) {
194 ptrdiff_t __cap = __last - __first;
195 int __n = __width(__value);
196 if (__n > __cap)
197 return {__last, errc::value_too_large};
198
199 __last = __first + __n;
200 char* __p = __last;
201 unsigned __divisor = 256;
202 while (__value > __divisor) {
203 unsigned __c = __value % __divisor;
204 __value /= __divisor;
205 __p -= 2;
206 std::copy_n(&__base_16_lut[2 * __c], 2, __p);
207 }
208 if (__first != __last)
209 do {
210 unsigned __c = __value % 16;
211 __value /= 16;
212 *--__p = "0123456789abcdef"[__c];
213 } while (__value != 0);
214 return {__last, errc(0)};
215 }
216};
217
218} // namespace __itoa
219
220template <unsigned _Base, typename _Tp, __enable_if_t<(sizeof(_Tp) >= sizeof(unsigned)), int> = 0>
221_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __to_chars_integral_width(_Tp __value) {
222 return __itoa::__integral<_Base>::__width(__value);
223}
224
225template <unsigned _Base, typename _Tp, __enable_if_t<(sizeof(_Tp) < sizeof(unsigned)), int> = 0>
226_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __to_chars_integral_width(_Tp __value) {
227 return std::__to_chars_integral_width<_Base>(static_cast<unsigned>(__value));
228}
229
230template <unsigned _Base, typename _Tp, __enable_if_t<(sizeof(_Tp) >= sizeof(unsigned)), int> = 0>
231_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
232__to_chars_integral(char* __first, char* __last, _Tp __value) {
233 return __itoa::__integral<_Base>::__to_chars(__first, __last, __value);
234}
235
236template <unsigned _Base, typename _Tp, __enable_if_t<(sizeof(_Tp) < sizeof(unsigned)), int> = 0>
237_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
238__to_chars_integral(char* __first, char* __last, _Tp __value) {
239 return std::__to_chars_integral<_Base>(__first, __last, static_cast<unsigned>(__value));
240}
241
242template <typename _Tp>
243_LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI int __to_chars_integral_width(_Tp __value, unsigned __base) {
244 _LIBCPP_ASSERT_INTERNAL(__value >= 0, "The function requires a non-negative value.");
245
246 unsigned __base_2 = __base * __base;
247 unsigned __base_3 = __base_2 * __base;
248 unsigned __base_4 = __base_2 * __base_2;
249
250 int __r = 0;
251 while (true) {
252 if (__value < __base)
253 return __r + 1;
254 if (__value < __base_2)
255 return __r + 2;
256 if (__value < __base_3)
257 return __r + 3;
258 if (__value < __base_4)
259 return __r + 4;
260
261 __value /= __base_4;
262 __r += 4;
263 }
264
265 __libcpp_unreachable();
266}
267
268template <class _Tp, __enable_if_t<!is_signed<_Tp>::value, int> >
269inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI __to_chars_result
270__to_chars_integral(char* __first, char* __last, _Tp __value, int __base) {
271 if (__base == 10) [[likely]]
272 return std::__to_chars_itoa(__first, __last, __value, false_type());
273
274 switch (__base) {
275 case 2:
276 return std::__to_chars_integral<2>(__first, __last, __value);
277 case 8:
278 return std::__to_chars_integral<8>(__first, __last, __value);
279 case 16:
280 return std::__to_chars_integral<16>(__first, __last, __value);
281 }
282
283 ptrdiff_t __cap = __last - __first;
284 int __n = std::__to_chars_integral_width(__value, __base);
285 if (__n > __cap)
286 return {__last, errc::value_too_large};
287
288 __last = __first + __n;
289 char* __p = __last;
290 do {
291 unsigned __c = __value % __base;
292 __value /= __base;
293 *--__p = "0123456789abcdefghijklmnopqrstuvwxyz"[__c];
294 } while (__value != 0);
295 return {__last, errc(0)};
296}
297
298_LIBCPP_HIDE_FROM_ABI inline _LIBCPP_CONSTEXPR_SINCE_CXX14 char __hex_to_upper(char __c) {
299 switch (__c) {
300 case 'a':
301 return 'A';
302 case 'b':
303 return 'B';
304 case 'c':
305 return 'C';
306 case 'd':
307 return 'D';
308 case 'e':
309 return 'E';
310 case 'f':
311 return 'F';
312 }
313 return __c;
314}
315
316#if _LIBCPP_STD_VER >= 17
317
318to_chars_result to_chars(char*, char*, bool, int = 10) = delete;
319
320template <typename _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0>
321inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
322to_chars(char* __first, char* __last, _Tp __value) {
323 using _Type = __make_32_64_or_128_bit_t<_Tp>;
324 static_assert(!is_same<_Type, void>::value, "unsupported integral type used in to_chars");
325 return std::__to_chars_itoa(__first, __last, static_cast<_Type>(__value), is_signed<_Tp>());
326}
327
328template <typename _Tp, __enable_if_t<is_integral<_Tp>::value, int> = 0>
329inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI to_chars_result
330to_chars(char* __first, char* __last, _Tp __value, int __base) {
331 _LIBCPP_ASSERT_UNCATEGORIZED(2 <= __base && __base <= 36, "base not in [2, 36]");
332
333 using _Type = __make_32_64_or_128_bit_t<_Tp>;
334 return std::__to_chars_integral(__first, __last, static_cast<_Type>(__value), __base);
335}
336
337#endif // _LIBCPP_STD_VER >= 17
338
339_LIBCPP_END_NAMESPACE_STD
340
341_LIBCPP_POP_MACROS
342
343#endif // _LIBCPP___CHARCONV_TO_CHARS_INTEGRAL_H