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
  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 template<typename value_type, endianness endian>
  38 inline value_type byte_swap(value_type value) {
  39   if (endian != native && sys::IsBigEndianHost != (endian == big))
  40     return sys::SwapByteOrder(value);
  41   return value;
  42 }
  43
  44 template<typename value_type,
  45          endianness endian,
  46          std::size_t alignment>
  47 inline value_type read(const void *memory) {
  48   value_type ret;
  49
  50   memcpy(&ret,
  51          LLVM_ASSUME_ALIGNED(memory,
  52            (detail::PickAlignment<value_type, alignment>::value)),
  53          sizeof(value_type));
  54   return byte_swap<value_type, endian>(ret);
  55 }
  56
  57 template<typename value_type,
  58          endianness endian,
  59          std::size_t alignment>
  60 inline void write(void *memory, value_type value) {
  61   value = byte_swap<value_type, endian>(value);
  62   memcpy(LLVM_ASSUME_ALIGNED(memory,
  63            (detail::PickAlignment<value_type, alignment>::value)),
  64          &value,
  65          sizeof(value_type));
  66 }
  67 } // end namespace endian
  68
  69 namespace detail {
  70 template<typename value_type,
  71          endianness endian,
  72          std::size_t alignment>
  73 struct packed_endian_specific_integral {
  74   operator value_type() const {
  75     return endian::read<value_type, endian, alignment>(
  76       (const void*)Value.buffer);
  77   }
  78
  79   void operator=(value_type newValue) {
  80     endian::write<value_type, endian, alignment>(
  81       (void*)Value.buffer, newValue);
  82   }
  83
  84 private:
  85   AlignedCharArray<PickAlignment<value_type, alignment>::value,
  86                    sizeof(value_type)> Value;
  87 };
  88 } // end namespace detail
  89
  90 typedef detail::packed_endian_specific_integral
  91                   <uint8_t, little, unaligned>  ulittle8_t;
  92 typedef detail::packed_endian_specific_integral
  93                   <uint16_t, little, unaligned> ulittle16_t;
  94 typedef detail::packed_endian_specific_integral
  95                   <uint32_t, little, unaligned> ulittle32_t;
  96 typedef detail::packed_endian_specific_integral
  97                   <uint64_t, little, unaligned> ulittle64_t;
  98
  99 typedef detail::packed_endian_specific_integral
 100                    <int8_t, little, unaligned>  little8_t;
 101 typedef detail::packed_endian_specific_integral
 102                    <int16_t, little, unaligned> little16_t;
 103 typedef detail::packed_endian_specific_integral
 104                    <int32_t, little, unaligned> little32_t;
 105 typedef detail::packed_endian_specific_integral
 106                    <int64_t, little, unaligned> little64_t;
 107
 108 typedef detail::packed_endian_specific_integral
 109                     <uint8_t, little, aligned>  aligned_ulittle8_t;
 110 typedef detail::packed_endian_specific_integral
 111                     <uint16_t, little, aligned> aligned_ulittle16_t;
 112 typedef detail::packed_endian_specific_integral
 113                     <uint32_t, little, aligned> aligned_ulittle32_t;
 114 typedef detail::packed_endian_specific_integral
 115                     <uint64_t, little, aligned> aligned_ulittle64_t;
 116
 117 typedef detail::packed_endian_specific_integral
 118                      <int8_t, little, aligned>  aligned_little8_t;
 119 typedef detail::packed_endian_specific_integral
 120                      <int16_t, little, aligned> aligned_little16_t;
 121 typedef detail::packed_endian_specific_integral
 122                      <int32_t, little, aligned> aligned_little32_t;
 123 typedef detail::packed_endian_specific_integral
 124                      <int64_t, little, aligned> aligned_little64_t;
 125
 126 typedef detail::packed_endian_specific_integral
 127                   <uint8_t, big, unaligned>     ubig8_t;
 128 typedef detail::packed_endian_specific_integral
 129                   <uint16_t, big, unaligned>    ubig16_t;
 130 typedef detail::packed_endian_specific_integral
 131                   <uint32_t, big, unaligned>    ubig32_t;
 132 typedef detail::packed_endian_specific_integral
 133                   <uint64_t, big, unaligned>    ubig64_t;
 134
 135 typedef detail::packed_endian_specific_integral
 136                    <int8_t, big, unaligned>     big8_t;
 137 typedef detail::packed_endian_specific_integral
 138                    <int16_t, big, unaligned>    big16_t;
 139 typedef detail::packed_endian_specific_integral
 140                    <int32_t, big, unaligned>    big32_t;
 141 typedef detail::packed_endian_specific_integral
 142                    <int64_t, big, unaligned>    big64_t;
 143
 144 typedef detail::packed_endian_specific_integral
 145                     <uint8_t, big, aligned>     aligned_ubig8_t;
 146 typedef detail::packed_endian_specific_integral
 147                     <uint16_t, big, aligned>    aligned_ubig16_t;
 148 typedef detail::packed_endian_specific_integral
 149                     <uint32_t, big, aligned>    aligned_ubig32_t;
 150 typedef detail::packed_endian_specific_integral
 151                     <uint64_t, big, aligned>    aligned_ubig64_t;
 152
 153 typedef detail::packed_endian_specific_integral
 154                      <int8_t, big, aligned>     aligned_big8_t;
 155 typedef detail::packed_endian_specific_integral
 156                      <int16_t, big, aligned>    aligned_big16_t;
 157 typedef detail::packed_endian_specific_integral
 158                      <int32_t, big, aligned>    aligned_big32_t;
 159 typedef detail::packed_endian_specific_integral
 160                      <int64_t, big, aligned>    aligned_big64_t;
 161
 162 typedef detail::packed_endian_specific_integral
 163                   <uint16_t, native, unaligned> unaligned_uint16_t;
 164 typedef detail::packed_endian_specific_integral
 165                   <uint32_t, native, unaligned> unaligned_uint32_t;
 166 typedef detail::packed_endian_specific_integral
 167                   <uint64_t, native, unaligned> unaligned_uint64_t;
 168
 169 typedef detail::packed_endian_specific_integral
 170                    <int16_t, native, unaligned> unaligned_int16_t;
 171 typedef detail::packed_endian_specific_integral
 172                    <int32_t, native, unaligned> unaligned_int32_t;
 173 typedef detail::packed_endian_specific_integral
 174                    <int64_t, native, unaligned> unaligned_int64_t;
 175 } // end namespace llvm
 176 } // end namespace support
 177
 178 #endif