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
21 namespace llvm {
22 namespace support {
23 enum endianness {big, little, native};
24
25 // These are named values for common alignments.
26 enum {aligned = 0, unaligned = 1};
27
28 namespace detail {
29 /// \brief ::value is either alignment, or alignof(T) if alignment is 0.
30 template<class T, int alignment>
31 struct PickAlignment {
32 enum {value = alignment == 0 ? AlignOf<T>::Alignment : alignment};
33 };
34 } // end namespace detail
35
36 namespace endian {
37 /// Swap the bytes of value to match the given endianness.
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 sys::swapByteOrder(value);
42 return value;
43 }
44
45 /// Read a value of a particular endianness from memory.
46 template<typename value_type,
47 endianness endian,
48 std::size_t alignment>
read(const void * memory)49 inline value_type read(const void *memory) {
50 value_type ret;
51
52 memcpy(&ret,
53 LLVM_ASSUME_ALIGNED(memory,
54 (detail::PickAlignment<value_type, alignment>::value)),
55 sizeof(value_type));
56 return byte_swap<value_type, endian>(ret);
57 }
58
59 /// Read a value of a particular endianness from a buffer, and increment the
60 /// buffer past that value.
61 template<typename value_type, endianness endian, std::size_t alignment>
readNext(const unsigned char * & memory)62 inline value_type readNext(const unsigned char *&memory) {
63 value_type ret = read<value_type, endian, alignment>(memory);
64 memory += sizeof(value_type);
65 return ret;
66 }
67
68 /// Write a value to memory with a particular endianness.
69 template<typename value_type,
70 endianness endian,
71 std::size_t alignment>
write(void * memory,value_type value)72 inline void write(void *memory, value_type value) {
73 value = byte_swap<value_type, endian>(value);
74 memcpy(LLVM_ASSUME_ALIGNED(memory,
75 (detail::PickAlignment<value_type, alignment>::value)),
76 &value,
77 sizeof(value_type));
78 }
79 } // end namespace endian
80
81 namespace detail {
82 template<typename value_type,
83 endianness endian,
84 std::size_t alignment>
85 struct packed_endian_specific_integral {
value_typepacked_endian_specific_integral86 operator value_type() const {
87 return endian::read<value_type, endian, alignment>(
88 (const void*)Value.buffer);
89 }
90
91 void operator=(value_type newValue) {
92 endian::write<value_type, endian, alignment>(
93 (void*)Value.buffer, newValue);
94 }
95
96 private:
97 AlignedCharArray<PickAlignment<value_type, alignment>::value,
98 sizeof(value_type)> Value;
99 };
100 } // end namespace detail
101
102 typedef detail::packed_endian_specific_integral
103 <uint8_t, little, unaligned> ulittle8_t;
104 typedef detail::packed_endian_specific_integral
105 <uint16_t, little, unaligned> ulittle16_t;
106 typedef detail::packed_endian_specific_integral
107 <uint32_t, little, unaligned> ulittle32_t;
108 typedef detail::packed_endian_specific_integral
109 <uint64_t, little, unaligned> ulittle64_t;
110
111 typedef detail::packed_endian_specific_integral
112 <int8_t, little, unaligned> little8_t;
113 typedef detail::packed_endian_specific_integral
114 <int16_t, little, unaligned> little16_t;
115 typedef detail::packed_endian_specific_integral
116 <int32_t, little, unaligned> little32_t;
117 typedef detail::packed_endian_specific_integral
118 <int64_t, little, unaligned> little64_t;
119
120 typedef detail::packed_endian_specific_integral
121 <uint8_t, little, aligned> aligned_ulittle8_t;
122 typedef detail::packed_endian_specific_integral
123 <uint16_t, little, aligned> aligned_ulittle16_t;
124 typedef detail::packed_endian_specific_integral
125 <uint32_t, little, aligned> aligned_ulittle32_t;
126 typedef detail::packed_endian_specific_integral
127 <uint64_t, little, aligned> aligned_ulittle64_t;
128
129 typedef detail::packed_endian_specific_integral
130 <int8_t, little, aligned> aligned_little8_t;
131 typedef detail::packed_endian_specific_integral
132 <int16_t, little, aligned> aligned_little16_t;
133 typedef detail::packed_endian_specific_integral
134 <int32_t, little, aligned> aligned_little32_t;
135 typedef detail::packed_endian_specific_integral
136 <int64_t, little, aligned> aligned_little64_t;
137
138 typedef detail::packed_endian_specific_integral
139 <uint8_t, big, unaligned> ubig8_t;
140 typedef detail::packed_endian_specific_integral
141 <uint16_t, big, unaligned> ubig16_t;
142 typedef detail::packed_endian_specific_integral
143 <uint32_t, big, unaligned> ubig32_t;
144 typedef detail::packed_endian_specific_integral
145 <uint64_t, big, unaligned> ubig64_t;
146
147 typedef detail::packed_endian_specific_integral
148 <int8_t, big, unaligned> big8_t;
149 typedef detail::packed_endian_specific_integral
150 <int16_t, big, unaligned> big16_t;
151 typedef detail::packed_endian_specific_integral
152 <int32_t, big, unaligned> big32_t;
153 typedef detail::packed_endian_specific_integral
154 <int64_t, big, unaligned> big64_t;
155
156 typedef detail::packed_endian_specific_integral
157 <uint8_t, big, aligned> aligned_ubig8_t;
158 typedef detail::packed_endian_specific_integral
159 <uint16_t, big, aligned> aligned_ubig16_t;
160 typedef detail::packed_endian_specific_integral
161 <uint32_t, big, aligned> aligned_ubig32_t;
162 typedef detail::packed_endian_specific_integral
163 <uint64_t, big, aligned> aligned_ubig64_t;
164
165 typedef detail::packed_endian_specific_integral
166 <int8_t, big, aligned> aligned_big8_t;
167 typedef detail::packed_endian_specific_integral
168 <int16_t, big, aligned> aligned_big16_t;
169 typedef detail::packed_endian_specific_integral
170 <int32_t, big, aligned> aligned_big32_t;
171 typedef detail::packed_endian_specific_integral
172 <int64_t, big, aligned> aligned_big64_t;
173
174 typedef detail::packed_endian_specific_integral
175 <uint16_t, native, unaligned> unaligned_uint16_t;
176 typedef detail::packed_endian_specific_integral
177 <uint32_t, native, unaligned> unaligned_uint32_t;
178 typedef detail::packed_endian_specific_integral
179 <uint64_t, native, unaligned> unaligned_uint64_t;
180
181 typedef detail::packed_endian_specific_integral
182 <int16_t, native, unaligned> unaligned_int16_t;
183 typedef detail::packed_endian_specific_integral
184 <int32_t, native, unaligned> unaligned_int32_t;
185 typedef detail::packed_endian_specific_integral
186 <int64_t, native, unaligned> unaligned_int64_t;
187 } // end namespace llvm
188 } // end namespace support
189
190 #endif
191