libstdc++
stdckdint.h
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1 // C compatibility header <stdckdint.h> -*- C++ -*-
2 
3 // Copyright The GNU Toolchain Authors.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file include/stdckdint.h
26  * This is a Standard C++ Library header.
27  */
28 
29 #ifndef _GLIBCXX_STDCKDINT_H
30 #define _GLIBCXX_STDCKDINT_H
31 
32 #if __cplusplus > 202302L
33 #include <type_traits>
34 #include <concepts>
35 
36 #define __STDC_VERSION_STDCKDINT_H__ 202311L
37 
38 #ifndef _GLIBCXX_DOXYGEN
39 // We define these in our own namespace, but let Doxygen think otherwise.
40 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
41 {
42 #endif
43 /// @cond undocumented
44 namespace __detail
45 {
46  template<typename _Tp>
47  concept __cv_unqual_signed_or_unsigned_integer_type
48  = std::same_as<_Tp, std::remove_cv_t<_Tp>>
49  && std::__is_standard_integer<_Tp>::value;
50 }
51 /// @endcond
52 
53 /** Checked integer arithmetic
54  *
55  * Performs arithmetic on `__a` and `__b` and stores the result in `*__result`,
56  * with overflow detection.
57  * The arithmetic is performed in infinite signed precision, without overflow,
58  * then converted to the result type, `_Tp1`. If the converted result is not
59  * equal to the infinite precision result, the stored result is wrapped to the
60  * width of `_Tp1` and `true` is returned. Otherwise, the stored result is
61  * correct and `false` is returned.
62  *
63  * @param __result A pointer to a signed or unsigned integer type.
64  * @param __a A signed or unsigned integer type.
65  * @param __b A signed or unsigned integer type.
66  * @return True if overflow occurred, false otherwise.
67  * @since C++26
68  * @{
69  */
70 template<typename _Tp1, typename _Tp2, typename _Tp3>
71  inline bool
72  ckd_add(_Tp1* __result, _Tp2 __a, _Tp3 __b)
73  {
74  using __gnu_cxx::__detail::__cv_unqual_signed_or_unsigned_integer_type;
75  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp1>);
76  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp2>);
77  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp3>);
78  return __builtin_add_overflow(__a, __b, __result);
79  }
80 
81 template<typename _Tp1, typename _Tp2, typename _Tp3>
82  inline bool
83  ckd_sub(_Tp1* __result, _Tp2 __a, _Tp3 __b)
84  {
85  using __gnu_cxx::__detail::__cv_unqual_signed_or_unsigned_integer_type;
86  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp1>);
87  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp2>);
88  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp3>);
89  return __builtin_sub_overflow(__a, __b, __result);
90  }
91 
92 template<typename _Tp1, typename _Tp2, typename _Tp3>
93  inline bool
94  ckd_mul(_Tp1* __result, _Tp2 __a, _Tp3 __b)
95  {
96  using __gnu_cxx::__detail::__cv_unqual_signed_or_unsigned_integer_type;
97  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp1>);
98  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp2>);
99  static_assert(__cv_unqual_signed_or_unsigned_integer_type<_Tp3>);
100  return __builtin_mul_overflow(__a, __b, __result);
101  }
102 /// @}
103 #ifndef _GLIBCXX_DOXYGEN
104 }
105 
106 using __gnu_cxx::ckd_add;
107 using __gnu_cxx::ckd_sub;
108 using __gnu_cxx::ckd_mul;
109 #endif
110 
111 #endif // C++26
112 
113 #endif // _GLIBCXX_STDCKDINT_H
GNU extensions for public use.