1 /*
2  *  Copyright (c) 2020, The OpenThread Authors.
3  *  All rights reserved.
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8  *     notice, this list of conditions and the following disclaimer.
9  *  2. Redistributions in binary form must reproduce the above copyright
10  *     notice, this list of conditions and the following disclaimer in the
11  *     documentation and/or other materials provided with the distribution.
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14  *     derived from this software without specific prior written permission.
15  *
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27  */
28 
29 /**
30  * @file
31  *   This file includes definitions for numeric limits.
32  */
33 
34 #ifndef NUMERIC_LIMITS_HPP_
35 #define NUMERIC_LIMITS_HPP_
36 
37 #include <stdint.h>
38 
39 namespace ot {
40 
41 static constexpr uint8_t kBitsPerByte = 8; ///< Number of bits in a byte.
42 
43 /**
44  * Returns the bit-size (number of bits) of a given type or variable.
45  *
46  * @param[in] aItem   The item (type or variable or expression) to get the bit-size of.
47  *
48  * @returns Number of bits of @p aItem.
49  *
50  */
51 #define BitSizeOf(aItem) (sizeof(aItem) * kBitsPerByte)
52 
53 /**
54  * Determines number of byes to represent a given number of bits.
55  *
56  * @param[in] aBitSize    The bit-size (number of bits).
57  *
58  * @returns Number of bytes to represent @p aBitSize.
59  *
60  */
61 #define BytesForBitSize(aBitSize) static_cast<uint8_t>(((aBitSize) + (kBitsPerByte - 1)) / kBitsPerByte)
62 
63 /**
64  * Provides a way to query properties of arithmetic types.
65  *
66  * There are no members if `Type` is not a supported arithmetic type.
67  *
68  */
69 template <typename Type> struct NumericLimits
70 {
71 };
72 
73 // Specialization for different integral types.
74 
75 template <> struct NumericLimits<int8_t>
76 {
77     static constexpr int8_t kMin = INT8_MIN;
78     static constexpr int8_t kMax = INT8_MAX;
79 };
80 
81 template <> struct NumericLimits<int16_t>
82 {
83     static constexpr int16_t kMin = INT16_MIN;
84     static constexpr int16_t kMax = INT16_MAX;
85 };
86 
87 template <> struct NumericLimits<int32_t>
88 {
89     static constexpr int32_t kMin = INT32_MIN;
90     static constexpr int32_t kMax = INT32_MAX;
91 };
92 
93 template <> struct NumericLimits<int64_t>
94 {
95     static constexpr int64_t kMin = INT64_MIN;
96     static constexpr int64_t kMax = INT64_MAX;
97 };
98 
99 template <> struct NumericLimits<uint8_t>
100 {
101     static constexpr uint8_t kMin = 0;
102     static constexpr uint8_t kMax = UINT8_MAX;
103 };
104 
105 template <> struct NumericLimits<uint16_t>
106 {
107     static constexpr uint16_t kMin = 0;
108     static constexpr uint16_t kMax = UINT16_MAX;
109 };
110 
111 template <> struct NumericLimits<uint32_t>
112 {
113     static constexpr uint32_t kMin = 0;
114     static constexpr uint32_t kMax = UINT32_MAX;
115 };
116 
117 template <> struct NumericLimits<uint64_t>
118 {
119     static constexpr uint64_t kMin = 0;
120     static constexpr uint64_t kMax = UINT64_MAX;
121 };
122 
123 } // namespace ot
124 
125 #endif // NUMERIC_LIMITS_HPP_
126