1//===-- A self contained equivalent of std::limits --------------*- C++ -*-===//
 2//
 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 4// See https://llvm.org/LICENSE.txt for license information.
 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 6//
 7//===----------------------------------------------------------------------===//
 8
 9#ifndef LLVM_LIBC_SRC___SUPPORT_CPP_LIMITS_H
10#define LLVM_LIBC_SRC___SUPPORT_CPP_LIMITS_H
11
12#include "hdr/limits_macros.h" // CHAR_BIT
13#include "src/__support/CPP/type_traits/is_integral.h"
14#include "src/__support/CPP/type_traits/is_signed.h"
15#include "src/__support/macros/attributes.h" // LIBC_INLINE
16#include "src/__support/macros/config.h"
17#include "src/__support/macros/properties/types.h" // LIBC_TYPES_HAS_INT128
18
19namespace LIBC_NAMESPACE_DECL {
20namespace cpp {
21
22namespace internal {
23
24template <typename T, T min_value, T max_value> struct integer_impl {
25  static_assert(cpp::is_integral_v<T>);
26  LIBC_INLINE static constexpr T max() { return max_value; }
27  LIBC_INLINE static constexpr T min() { return min_value; }
28  LIBC_INLINE_VAR static constexpr int digits =
29      CHAR_BIT * sizeof(T) - cpp::is_signed_v<T>;
30};
31
32} // namespace internal
33
34template <class T> struct numeric_limits {};
35
36// TODO: Add numeric_limits specializations as needed for new types.
37template <>
38struct numeric_limits<short>
39    : public internal::integer_impl<short, SHRT_MIN, SHRT_MAX> {};
40
41template <>
42struct numeric_limits<unsigned short>
43    : public internal::integer_impl<unsigned short, 0, USHRT_MAX> {};
44
45template <>
46struct numeric_limits<int>
47    : public internal::integer_impl<int, INT_MIN, INT_MAX> {};
48
49template <>
50struct numeric_limits<unsigned int>
51    : public internal::integer_impl<unsigned int, 0, UINT_MAX> {};
52
53template <>
54struct numeric_limits<long>
55    : public internal::integer_impl<long, LONG_MIN, LONG_MAX> {};
56
57template <>
58struct numeric_limits<unsigned long>
59    : public internal::integer_impl<unsigned long, 0, ULONG_MAX> {};
60
61template <>
62struct numeric_limits<long long>
63    : public internal::integer_impl<long long, LLONG_MIN, LLONG_MAX> {};
64
65template <>
66struct numeric_limits<unsigned long long>
67    : public internal::integer_impl<unsigned long long, 0, ULLONG_MAX> {};
68
69template <>
70struct numeric_limits<char>
71    : public internal::integer_impl<char, CHAR_MIN, CHAR_MAX> {};
72
73template <>
74struct numeric_limits<signed char>
75    : public internal::integer_impl<signed char, SCHAR_MIN, SCHAR_MAX> {};
76
77template <>
78struct numeric_limits<unsigned char>
79    : public internal::integer_impl<unsigned char, 0, UCHAR_MAX> {};
80
81#ifdef LIBC_TYPES_HAS_INT128
82// On platform where UInt128 resolves to __uint128_t, this specialization
83// provides the limits of UInt128.
84template <>
85struct numeric_limits<__uint128_t>
86    : public internal::integer_impl<__uint128_t, 0, ~__uint128_t(0)> {};
87#endif
88
89} // namespace cpp
90} // namespace LIBC_NAMESPACE_DECL
91
92#endif // LLVM_LIBC_SRC___SUPPORT_CPP_LIMITS_H