contrib/llvm/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/Host.h"
  18 #include "llvm/Support/SwapByteOrder.h"
  19 #include "llvm/Support/type_traits.h"
  20
  21 namespace llvm {
  22 namespace support {
  23
  24 enum endianness {big, little};
  25 enum alignment {unaligned, aligned};
  26
  27 namespace detail {
  28
  29 template<typename value_type, alignment align>
  30 struct alignment_access_helper;
  31
  32 template<typename value_type>
  33 struct alignment_access_helper<value_type, aligned>
  34 {
  35   value_type val;
  36 };
  37
  38 // Provides unaligned loads and stores.
  39 #pragma pack(push)
  40 #pragma pack(1)
  41 template<typename value_type>
  42 struct alignment_access_helper<value_type, unaligned>
  43 {
  44   value_type val;
  45 };
  46 #pragma pack(pop)
  47
  48 } // end namespace detail
  49
  50 namespace endian {
  51   template<typename value_type, alignment align>
  52   static value_type read_le(const void *memory) {
  53     value_type t =
  54       reinterpret_cast<const detail::alignment_access_helper
  55         <value_type, align> *>(memory)->val;
  56     if (sys::isBigEndianHost())
  57       return sys::SwapByteOrder(t);
  58     return t;
  59   }
  60
  61   template<typename value_type, alignment align>
  62   static void write_le(void *memory, value_type value) {
  63     if (sys::isBigEndianHost())
  64       value = sys::SwapByteOrder(value);
  65     reinterpret_cast<detail::alignment_access_helper<value_type, align> *>
  66       (memory)->val = value;
  67   }
  68
  69   template<typename value_type, alignment align>
  70   static value_type read_be(const void *memory) {
  71     value_type t =
  72       reinterpret_cast<const detail::alignment_access_helper
  73         <value_type, align> *>(memory)->val;
  74     if (sys::isLittleEndianHost())
  75       return sys::SwapByteOrder(t);
  76     return t;
  77   }
  78
  79   template<typename value_type, alignment align>
  80   static void write_be(void *memory, value_type value) {
  81     if (sys::isLittleEndianHost())
  82       value = sys::SwapByteOrder(value);
  83     reinterpret_cast<detail::alignment_access_helper<value_type, align> *>
  84       (memory)->val = value;
  85   }
  86 }
  87
  88 namespace detail {
  89
  90 template<typename value_type,
  91          endianness endian,
  92          alignment  align>
  93 class packed_endian_specific_integral;
  94
  95 template<typename value_type>
  96 class packed_endian_specific_integral<value_type, little, unaligned> {
  97 public:
  98   operator value_type() const {
  99     return endian::read_le<value_type, unaligned>(Value);
 100   }
 101 private:
 102   uint8_t Value[sizeof(value_type)];
 103 };
 104
 105 template<typename value_type>
 106 class packed_endian_specific_integral<value_type, big, unaligned> {
 107 public:
 108   operator value_type() const {
 109     return endian::read_be<value_type, unaligned>(Value);
 110   }
 111 private:
 112   uint8_t Value[sizeof(value_type)];
 113 };
 114
 115 template<typename value_type>
 116 class packed_endian_specific_integral<value_type, little, aligned> {
 117 public:
 118   operator value_type() const {
 119     return endian::read_le<value_type, aligned>(&Value);
 120   }
 121 private:
 122   value_type Value;
 123 };
 124
 125 template<typename value_type>
 126 class packed_endian_specific_integral<value_type, big, aligned> {
 127 public:
 128   operator value_type() const {
 129     return endian::read_be<value_type, aligned>(&Value);
 130   }
 131 private:
 132   value_type Value;
 133 };
 134
 135 } // end namespace detail
 136
 137 typedef detail::packed_endian_specific_integral
 138                   <uint8_t, little, unaligned>  ulittle8_t;
 139 typedef detail::packed_endian_specific_integral
 140                   <uint16_t, little, unaligned> ulittle16_t;
 141 typedef detail::packed_endian_specific_integral
 142                   <uint32_t, little, unaligned> ulittle32_t;
 143 typedef detail::packed_endian_specific_integral
 144                   <uint64_t, little, unaligned> ulittle64_t;
 145
 146 typedef detail::packed_endian_specific_integral
 147                    <int8_t, little, unaligned>  little8_t;
 148 typedef detail::packed_endian_specific_integral
 149                    <int16_t, little, unaligned> little16_t;
 150 typedef detail::packed_endian_specific_integral
 151                    <int32_t, little, unaligned> little32_t;
 152 typedef detail::packed_endian_specific_integral
 153                    <int64_t, little, unaligned> little64_t;
 154
 155 typedef detail::packed_endian_specific_integral
 156                     <uint8_t, little, aligned>  aligned_ulittle8_t;
 157 typedef detail::packed_endian_specific_integral
 158                     <uint16_t, little, aligned> aligned_ulittle16_t;
 159 typedef detail::packed_endian_specific_integral
 160                     <uint32_t, little, aligned> aligned_ulittle32_t;
 161 typedef detail::packed_endian_specific_integral
 162                     <uint64_t, little, aligned> aligned_ulittle64_t;
 163
 164 typedef detail::packed_endian_specific_integral
 165                      <int8_t, little, aligned>  aligned_little8_t;
 166 typedef detail::packed_endian_specific_integral
 167                      <int16_t, little, aligned> aligned_little16_t;
 168 typedef detail::packed_endian_specific_integral
 169                      <int32_t, little, aligned> aligned_little32_t;
 170 typedef detail::packed_endian_specific_integral
 171                      <int64_t, little, aligned> aligned_little64_t;
 172
 173 typedef detail::packed_endian_specific_integral
 174                   <uint8_t, big, unaligned>     ubig8_t;
 175 typedef detail::packed_endian_specific_integral
 176                   <uint16_t, big, unaligned>    ubig16_t;
 177 typedef detail::packed_endian_specific_integral
 178                   <uint32_t, big, unaligned>    ubig32_t;
 179 typedef detail::packed_endian_specific_integral
 180                   <uint64_t, big, unaligned>    ubig64_t;
 181
 182 typedef detail::packed_endian_specific_integral
 183                    <int8_t, big, unaligned>     big8_t;
 184 typedef detail::packed_endian_specific_integral
 185                    <int16_t, big, unaligned>    big16_t;
 186 typedef detail::packed_endian_specific_integral
 187                    <int32_t, big, unaligned>    big32_t;
 188 typedef detail::packed_endian_specific_integral
 189                    <int64_t, big, unaligned>    big64_t;
 190
 191 typedef detail::packed_endian_specific_integral
 192                     <uint8_t, big, aligned>     aligned_ubig8_t;
 193 typedef detail::packed_endian_specific_integral
 194                     <uint16_t, big, aligned>    aligned_ubig16_t;
 195 typedef detail::packed_endian_specific_integral
 196                     <uint32_t, big, aligned>    aligned_ubig32_t;
 197 typedef detail::packed_endian_specific_integral
 198                     <uint64_t, big, aligned>    aligned_ubig64_t;
 199
 200 typedef detail::packed_endian_specific_integral
 201                      <int8_t, big, aligned>     aligned_big8_t;
 202 typedef detail::packed_endian_specific_integral
 203                      <int16_t, big, aligned>    aligned_big16_t;
 204 typedef detail::packed_endian_specific_integral
 205                      <int32_t, big, aligned>    aligned_big32_t;
 206 typedef detail::packed_endian_specific_integral
 207                      <int64_t, big, aligned>    aligned_big64_t;
 208
 209 } // end namespace llvm
 210 } // end namespace support
 211
 212 #endif