1 //===- Endian.h - Utilities for IO with endian specific data ----*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file declares generic functions to read and write endian specific data.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #ifndef LLVM_SUPPORT_ENDIAN_H
15 #define LLVM_SUPPORT_ENDIAN_H
16
17 #include "llvm/Support/AlignOf.h"
18 #include "llvm/Support/Host.h"
19 #include "llvm/Support/SwapByteOrder.h"
20 #include "llvm/Support/type_traits.h"
21
22 namespace llvm {
23 namespace support {
24 enum endianness {big, little, native};
25
26 // These are named values for common alignments.
27 enum {aligned = 0, unaligned = 1};
28
29 namespace detail {
30 /// \brief ::value is either alignment, or alignof(T) if alignment is 0.
31 template<class T, int alignment>
32 struct PickAlignment {
33 enum {value = alignment == 0 ? AlignOf<T>::Alignment : alignment};
34 };
35 } // end namespace detail
36
37 namespace endian {
38 template<typename value_type, endianness endian>
byte_swap(value_type value)39 inline value_type byte_swap(value_type value) {
40 if (endian != native && sys::isBigEndianHost() != (endian == big))
41 return sys::SwapByteOrder(value);
42 return value;
43 }
44
45 template<typename value_type,
46 endianness endian,
47 std::size_t alignment>
read(const void * memory)48 inline value_type read(const void *memory) {
49 value_type ret;
50
51 memcpy(&ret,
52 LLVM_ASSUME_ALIGNED(memory,
53 (detail::PickAlignment<value_type, alignment>::value)),
54 sizeof(value_type));
55 return byte_swap<value_type, endian>(ret);
56 }
57
58 template<typename value_type,
59 endianness endian,
60 std::size_t alignment>
write(void * memory,value_type value)61 inline void write(void *memory, value_type value) {
62 value = byte_swap<value_type, endian>(value);
63 memcpy(LLVM_ASSUME_ALIGNED(memory,
64 (detail::PickAlignment<value_type, alignment>::value)),
65 &value,
66 sizeof(value_type));
67 }
68 } // end namespace endian
69
70 namespace detail {
71 template<typename value_type,
72 endianness endian,
73 std::size_t alignment>
74 struct packed_endian_specific_integral {
value_typepacked_endian_specific_integral75 operator value_type() const {
76 return endian::read<value_type, endian, alignment>(
77 (const void*)Value.buffer);
78 }
79
80 void operator=(value_type newValue) {
81 endian::write<value_type, endian, alignment>(
82 (void*)Value.buffer, newValue);
83 }
84
85 private:
86 AlignedCharArray<PickAlignment<value_type, alignment>::value,
87 sizeof(value_type)> Value;
88 };
89 } // end namespace detail
90
91 typedef detail::packed_endian_specific_integral
92 <uint8_t, little, unaligned> ulittle8_t;
93 typedef detail::packed_endian_specific_integral
94 <uint16_t, little, unaligned> ulittle16_t;
95 typedef detail::packed_endian_specific_integral
96 <uint32_t, little, unaligned> ulittle32_t;
97 typedef detail::packed_endian_specific_integral
98 <uint64_t, little, unaligned> ulittle64_t;
99
100 typedef detail::packed_endian_specific_integral
101 <int8_t, little, unaligned> little8_t;
102 typedef detail::packed_endian_specific_integral
103 <int16_t, little, unaligned> little16_t;
104 typedef detail::packed_endian_specific_integral
105 <int32_t, little, unaligned> little32_t;
106 typedef detail::packed_endian_specific_integral
107 <int64_t, little, unaligned> little64_t;
108
109 typedef detail::packed_endian_specific_integral
110 <uint8_t, little, aligned> aligned_ulittle8_t;
111 typedef detail::packed_endian_specific_integral
112 <uint16_t, little, aligned> aligned_ulittle16_t;
113 typedef detail::packed_endian_specific_integral
114 <uint32_t, little, aligned> aligned_ulittle32_t;
115 typedef detail::packed_endian_specific_integral
116 <uint64_t, little, aligned> aligned_ulittle64_t;
117
118 typedef detail::packed_endian_specific_integral
119 <int8_t, little, aligned> aligned_little8_t;
120 typedef detail::packed_endian_specific_integral
121 <int16_t, little, aligned> aligned_little16_t;
122 typedef detail::packed_endian_specific_integral
123 <int32_t, little, aligned> aligned_little32_t;
124 typedef detail::packed_endian_specific_integral
125 <int64_t, little, aligned> aligned_little64_t;
126
127 typedef detail::packed_endian_specific_integral
128 <uint8_t, big, unaligned> ubig8_t;
129 typedef detail::packed_endian_specific_integral
130 <uint16_t, big, unaligned> ubig16_t;
131 typedef detail::packed_endian_specific_integral
132 <uint32_t, big, unaligned> ubig32_t;
133 typedef detail::packed_endian_specific_integral
134 <uint64_t, big, unaligned> ubig64_t;
135
136 typedef detail::packed_endian_specific_integral
137 <int8_t, big, unaligned> big8_t;
138 typedef detail::packed_endian_specific_integral
139 <int16_t, big, unaligned> big16_t;
140 typedef detail::packed_endian_specific_integral
141 <int32_t, big, unaligned> big32_t;
142 typedef detail::packed_endian_specific_integral
143 <int64_t, big, unaligned> big64_t;
144
145 typedef detail::packed_endian_specific_integral
146 <uint8_t, big, aligned> aligned_ubig8_t;
147 typedef detail::packed_endian_specific_integral
148 <uint16_t, big, aligned> aligned_ubig16_t;
149 typedef detail::packed_endian_specific_integral
150 <uint32_t, big, aligned> aligned_ubig32_t;
151 typedef detail::packed_endian_specific_integral
152 <uint64_t, big, aligned> aligned_ubig64_t;
153
154 typedef detail::packed_endian_specific_integral
155 <int8_t, big, aligned> aligned_big8_t;
156 typedef detail::packed_endian_specific_integral
157 <int16_t, big, aligned> aligned_big16_t;
158 typedef detail::packed_endian_specific_integral
159 <int32_t, big, aligned> aligned_big32_t;
160 typedef detail::packed_endian_specific_integral
161 <int64_t, big, aligned> aligned_big64_t;
162
163 typedef detail::packed_endian_specific_integral
164 <uint16_t, native, unaligned> unaligned_uint16_t;
165 typedef detail::packed_endian_specific_integral
166 <uint32_t, native, unaligned> unaligned_uint32_t;
167 typedef detail::packed_endian_specific_integral
168 <uint64_t, native, unaligned> unaligned_uint64_t;
169
170 typedef detail::packed_endian_specific_integral
171 <int16_t, native, unaligned> unaligned_int16_t;
172 typedef detail::packed_endian_specific_integral
173 <int32_t, native, unaligned> unaligned_int32_t;
174 typedef detail::packed_endian_specific_integral
175 <int64_t, native, unaligned> unaligned_int64_t;
176 } // end namespace llvm
177 } // end namespace support
178
179 #endif
180