include/llvm/Support/Endian.h

   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>
  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>
  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>
  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 {
  75   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