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comparison include/core/endian.h @ 351:c844f8bb87ce

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gui/theme: add xsettings backend this also adds newly-necessary endianness methods in core/endian.h which just so happen to be constexpr as well
author Paper <paper@paper.us.eu.org>
date Sun, 14 Jul 2024 23:23:56 -0400
parents
children 9aaf1e788896
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equal deleted inserted replaced
350:daa03aa2262d 351:c844f8bb87ce
1 #ifndef MINORI_CORE_ENDIAN_H_
2 #define MINORI_CORE_ENDIAN_H_
3
4 /* definition of endian-related stuff. primarily used for*/
5
6 #include <cstdint>
7 #include <type_traits>
8
9 class Endian {
10 private:
11 static constexpr uint32_t uint32_ = 0x01020304;
12 static constexpr uint8_t magic_ = static_cast<const uint8_t&>(uint32_);
13
14 /* check for compiler builtins for byteswapping */
15 #ifdef __has_builtin
16 # if __has_builtin(__builtin_bswap16)
17 # define COMPILER_BUILTIN_BSWAP16(x) __builtin_bswap16(x)
18 # endif
19 # if __has_builtin(__builtin_bswap32)
20 # define COMPILER_BUILTIN_BSWAP32(x) __builtin_bswap32(x)
21 # endif
22 # if __has_builtin(__builtin_bswap64)
23 # define COMPILER_BUILTIN_BSWAP64(x) __builtin_bswap64(x)
24 # endif
25 #endif
26
27 static constexpr uint16_t byteswap_16(uint16_t x) {
28 #ifdef COMPILER_BUILTIN_BSWAP16
29 return COMPILER_BUILTIN_BSWAP16(x);
30 #else
31 return (
32 ((x & UINT16_C(0x00FF)) << 8)
33 | ((x & UINT16_C(0xFF00)) >> 8)
34 );
35 #endif
36 }
37
38 static constexpr uint32_t byteswap_32(uint32_t x) {
39 #ifdef COMPILER_BUILTIN_BSWAP32
40 return COMPILER_BUILTIN_BSWAP32(x);
41 #else
42 return (
43 ((x & UINT32_C(0x000000FF)) << 24)
44 | ((x & UINT32_C(0x0000FF00)) << 8)
45 | ((x & UINT32_C(0x00FF0000)) >> 8)
46 | ((x & UINT32_C(0xFF000000)) >> 24)
47 );
48 #endif
49 }
50
51 static constexpr uint64_t byteswap_64(uint64_t x) {
52 #ifdef COMPILER_BUILTIN_BSWAP64
53 return COMPILER_BUILTIN_BSWAP64(x);
54 #else
55 return (
56 ((x & UINT64_C(0x00000000000000FF)) << 56)
57 | ((x & UINT64_C(0x000000000000FF00)) << 40)
58 | ((x & UINT64_C(0x0000000000FF0000)) << 24)
59 | ((x & UINT64_C(0x00000000FF000000)) << 8)
60 | ((x & UINT64_C(0x000000FF00000000)) >> 8)
61 | ((x & UINT64_C(0x0000FF0000000000)) >> 24)
62 | ((x & UINT64_C(0x00FF000000000000)) >> 40)
63 | ((x & UINT64_C(0xFF00000000000000)) >> 56)
64 );
65 #endif
66 }
67
68 #ifdef COMPILER_BUILTIN_BSWAP16
69 # undef COMPILER_BUILTIN_BSWAP16
70 #endif
71 #ifdef COMPILER_BUILTIN_BSWAP32
72 # undef COMPILER_BUILTIN_BSWAP32
73 #endif
74 #ifdef COMPILER_BUILTIN_BSWAP64
75 # undef COMPILER_BUILTIN_BSWAP64
76 #endif
77 public:
78 static constexpr bool little = magic_ == 0x04;
79 static constexpr bool big = magic_ == 0x01;
80 static_assert(little || big, "unsupported endianness");
81
82 template<typename T>
83 static constexpr T byteswap(T x) {
84 static_assert(std::is_integral<T>::value);
85 static_assert(std::is_unsigned<T>::value);
86
87 if constexpr (std::is_same<T, uint8_t>::value) {
88 return x;
89 } else if constexpr (std::is_same<T, uint16_t>::value) {
90 return byteswap_16(x);
91 } else if constexpr (std::is_same<T, uint32_t>::value) {
92 return byteswap_32(x);
93 } else if constexpr (std::is_same<T, uint64_t>::value) {
94 return byteswap_64(x);
95 } else {
96 static_assert(false, "byteswapping with unknown integer type");
97 }
98 }
99
100 template<typename T>
101 static constexpr T byteswap_little_to_host(T x) {
102 if constexpr (little) {
103 return x;
104 } else if constexpr (big) {
105 return byteswap(x);
106 }
107 }
108
109 template<typename T>
110 static constexpr T byteswap_big_to_host(T x) {
111 if constexpr (big) {
112 return x;
113 } else if constexpr (little) {
114 return byteswap(x);
115 }
116 }
117 private:
118 Endian() = delete;
119 };
120
121 #endif /* MINORI_CORE_ENDIAN_H_ */