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> 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> 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> 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> 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 { 86 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
