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1 #ifndef MINORI_CORE_ENDIAN_H_
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2 #define MINORI_CORE_ENDIAN_H_
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3
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4 /* definition of endian-related stuff. primarily used for*/
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5
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6 #include <cstdint>
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7 #include <type_traits>
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8
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9 class Endian {
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10 private:
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11 static constexpr uint32_t uint32_ = 0x01020304;
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12 static constexpr uint8_t magic_ = static_cast<const uint8_t&>(uint32_);
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13
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14 /* check for compiler builtins for byteswapping */
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15 #ifdef __has_builtin
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16 # if __has_builtin(__builtin_bswap16)
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17 # define COMPILER_BUILTIN_BSWAP16(x) __builtin_bswap16(x)
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18 # endif
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19 # if __has_builtin(__builtin_bswap32)
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20 # define COMPILER_BUILTIN_BSWAP32(x) __builtin_bswap32(x)
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21 # endif
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22 # if __has_builtin(__builtin_bswap64)
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23 # define COMPILER_BUILTIN_BSWAP64(x) __builtin_bswap64(x)
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24 # endif
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25 #endif
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26
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27 static constexpr uint16_t byteswap_16(uint16_t x) {
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28 #ifdef COMPILER_BUILTIN_BSWAP16
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29 return COMPILER_BUILTIN_BSWAP16(x);
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30 #else
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31 return (
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32 ((x & UINT16_C(0x00FF)) << 8)
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33 | ((x & UINT16_C(0xFF00)) >> 8)
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34 );
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35 #endif
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36 }
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37
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38 static constexpr uint32_t byteswap_32(uint32_t x) {
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39 #ifdef COMPILER_BUILTIN_BSWAP32
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40 return COMPILER_BUILTIN_BSWAP32(x);
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41 #else
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42 return (
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43 ((x & UINT32_C(0x000000FF)) << 24)
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44 | ((x & UINT32_C(0x0000FF00)) << 8)
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45 | ((x & UINT32_C(0x00FF0000)) >> 8)
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46 | ((x & UINT32_C(0xFF000000)) >> 24)
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47 );
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48 #endif
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49 }
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50
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51 static constexpr uint64_t byteswap_64(uint64_t x) {
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52 #ifdef COMPILER_BUILTIN_BSWAP64
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53 return COMPILER_BUILTIN_BSWAP64(x);
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54 #else
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55 return (
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56 ((x & UINT64_C(0x00000000000000FF)) << 56)
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57 | ((x & UINT64_C(0x000000000000FF00)) << 40)
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58 | ((x & UINT64_C(0x0000000000FF0000)) << 24)
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59 | ((x & UINT64_C(0x00000000FF000000)) << 8)
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60 | ((x & UINT64_C(0x000000FF00000000)) >> 8)
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61 | ((x & UINT64_C(0x0000FF0000000000)) >> 24)
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62 | ((x & UINT64_C(0x00FF000000000000)) >> 40)
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63 | ((x & UINT64_C(0xFF00000000000000)) >> 56)
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64 );
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65 #endif
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66 }
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67
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68 #ifdef COMPILER_BUILTIN_BSWAP16
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69 # undef COMPILER_BUILTIN_BSWAP16
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70 #endif
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71 #ifdef COMPILER_BUILTIN_BSWAP32
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72 # undef COMPILER_BUILTIN_BSWAP32
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73 #endif
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74 #ifdef COMPILER_BUILTIN_BSWAP64
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75 # undef COMPILER_BUILTIN_BSWAP64
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76 #endif
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77 public:
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78 static constexpr bool little = magic_ == 0x04;
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79 static constexpr bool big = magic_ == 0x01;
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80 static_assert(little || big, "unsupported endianness");
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81
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82 template<typename T>
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83 static constexpr T byteswap(T x) {
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84 static_assert(std::is_integral<T>::value);
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85 static_assert(std::is_unsigned<T>::value);
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86
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87 if constexpr (std::is_same<T, uint8_t>::value) {
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88 return x;
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89 } else if constexpr (std::is_same<T, uint16_t>::value) {
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90 return byteswap_16(x);
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91 } else if constexpr (std::is_same<T, uint32_t>::value) {
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92 return byteswap_32(x);
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93 } else if constexpr (std::is_same<T, uint64_t>::value) {
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94 return byteswap_64(x);
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95 } else {
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96 static_assert(false, "byteswapping with unknown integer type");
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97 }
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98 }
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99
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100 template<typename T>
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101 static constexpr T byteswap_little_to_host(T x) {
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102 if constexpr (little) {
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103 return x;
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104 } else if constexpr (big) {
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105 return byteswap(x);
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106 }
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107 }
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108
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109 template<typename T>
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110 static constexpr T byteswap_big_to_host(T x) {
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111 if constexpr (big) {
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112 return x;
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113 } else if constexpr (little) {
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114 return byteswap(x);
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115 }
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116 }
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117 private:
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118 Endian() = delete;
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119 };
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120
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121 #endif /* MINORI_CORE_ENDIAN_H_ */
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