1// Copyright 2020 The Pigweed Authors
2//
3// Licensed under the Apache License, Version 2.0 (the "License"); you may not
4// use this file except in compliance with the License. You may obtain a copy of
5// the License at
6//
7//     https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12// License for the specific language governing permissions and limitations under
13// the License.
14#pragma once
15
16#include <limits.h>
17
18#include "pw_polyfill/standard_library/namespace.h"
19
20_PW_POLYFILL_BEGIN_NAMESPACE_STD
21
22template <typename T>
23struct numeric_limits {
24  static constexpr bool is_specialized = false;
25  static constexpr int digits = 0;
26};
27
28// Only a few of the numeric_limits methods are implemented.
29#define _PW_LIMITS_SPECIALIZATION(                                 \
30    type, val_signed, val_int, min_value, max_value, digits_value) \
31  template <>                                                      \
32  struct numeric_limits<type> {                                    \
33    static constexpr bool is_specialized = true;                   \
34                                                                   \
35    static constexpr bool is_signed = (val_signed);                \
36    static constexpr bool is_integer = (val_int);                  \
37                                                                   \
38    static constexpr int digits = (digits_value);                  \
39                                                                   \
40    static constexpr type min() noexcept { return (min_value); }   \
41    static constexpr type max() noexcept { return (max_value); }   \
42  }
43
44#define _PW_INTEGRAL_LIMIT(type, sname, uname)        \
45  _PW_LIMITS_SPECIALIZATION(signed type,              \
46                            true,                     \
47                            true,                     \
48                            sname##_MIN,              \
49                            sname##_MAX,              \
50                            CHAR_BIT * sizeof(type)); \
51  _PW_LIMITS_SPECIALIZATION(unsigned type,            \
52                            false,                    \
53                            true,                     \
54                            0u,                       \
55                            uname##_MAX,              \
56                            CHAR_BIT * sizeof(type) - 1)
57
58_PW_LIMITS_SPECIALIZATION(bool, false, true, false, true, 1);
59_PW_LIMITS_SPECIALIZATION(
60    char, char(-1) < char(0), true, CHAR_MIN, CHAR_MAX, 1);
61
62_PW_INTEGRAL_LIMIT(char, SCHAR, UCHAR);
63_PW_INTEGRAL_LIMIT(short, SHRT, USHRT);
64_PW_INTEGRAL_LIMIT(int, INT, UINT);
65_PW_INTEGRAL_LIMIT(long, LONG, ULONG);
66
67#ifndef LLONG_MIN
68#define LLONG_MIN ((long long)(~0ull ^ (~0ull >> 1)))
69#define LLONG_MAX ((long long)(~0ull >> 1))
70
71#define ULLONG_MIN (0ull)
72#define ULLONG_MAX (~0ull)
73#endif  // LLONG_MIN
74
75_PW_INTEGRAL_LIMIT(long long, LLONG, ULLONG);
76
77#undef _PW_LIMITS_SPECIALIZATION
78#undef _PW_INTEGRAL_LIMIT
79
80_PW_POLYFILL_END_NAMESPACE_STD
81