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 /// 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          typename CharT>
  63 inline value_type readNext(const CharT *&memory) {
  64   value_type ret = read<value_type, endian, alignment>(memory);
  65   memory += sizeof(value_type);
  66   return ret;
  67 }
  68
  69 /// Write a value to memory with a particular endianness.
  70 template<typename value_type,
  71          endianness endian,
  72          std::size_t alignment>
  73 inline void write(void *memory, value_type value) {
  74   value = byte_swap<value_type, endian>(value);
  75   memcpy(LLVM_ASSUME_ALIGNED(memory,
  76            (detail::PickAlignment<value_type, alignment>::value)),
  77          &value,
  78          sizeof(value_type));
  79 }
  80 } // end namespace endian
  81
  82 namespace detail {
  83 template<typename value_type,
  84          endianness endian,
  85          std::size_t alignment>
  86 struct packed_endian_specific_integral {
  87   operator value_type() const {
  88     return endian::read<value_type, endian, alignment>(
  89       (const void*)Value.buffer);
  90   }
  91
  92   void operator=(value_type newValue) {
  93     endian::write<value_type, endian, alignment>(
  94       (void*)Value.buffer, newValue);
  95   }
  96
  97   packed_endian_specific_integral &operator+=(value_type newValue) {
  98     *this = *this + newValue;
  99     return *this;
 100   }
 101
 102   packed_endian_specific_integral &operator-=(value_type newValue) {
 103     *this = *this - newValue;
 104     return *this;
 105   }
 106
 107 private:
 108   AlignedCharArray<PickAlignment<value_type, alignment>::value,
 109                    sizeof(value_type)> Value;
 110
 111 public:
 112   struct ref {
 113     explicit ref(void *Ptr) : Ptr(Ptr) {}
 114
 115     operator value_type() const {
 116       return endian::read<value_type, endian, alignment>(Ptr);
 117     }
 118
 119     void operator=(value_type NewValue) {
 120       endian::write<value_type, endian, alignment>(Ptr, NewValue);
 121     }
 122
 123   private:
 124     void *Ptr;
 125   };
 126 };
 127
 128 } // end namespace detail
 129
 130 typedef detail::packed_endian_specific_integral
 131                   <uint16_t, little, unaligned> ulittle16_t;
 132 typedef detail::packed_endian_specific_integral
 133                   <uint32_t, little, unaligned> ulittle32_t;
 134 typedef detail::packed_endian_specific_integral
 135                   <uint64_t, little, unaligned> ulittle64_t;
 136
 137 typedef detail::packed_endian_specific_integral
 138                    <int16_t, little, unaligned> little16_t;
 139 typedef detail::packed_endian_specific_integral
 140                    <int32_t, little, unaligned> little32_t;
 141 typedef detail::packed_endian_specific_integral
 142                    <int64_t, little, unaligned> little64_t;
 143
 144 typedef detail::packed_endian_specific_integral
 145                     <uint16_t, little, aligned> aligned_ulittle16_t;
 146 typedef detail::packed_endian_specific_integral
 147                     <uint32_t, little, aligned> aligned_ulittle32_t;
 148 typedef detail::packed_endian_specific_integral
 149                     <uint64_t, little, aligned> aligned_ulittle64_t;
 150
 151 typedef detail::packed_endian_specific_integral
 152                      <int16_t, little, aligned> aligned_little16_t;
 153 typedef detail::packed_endian_specific_integral
 154                      <int32_t, little, aligned> aligned_little32_t;
 155 typedef detail::packed_endian_specific_integral
 156                      <int64_t, little, aligned> aligned_little64_t;
 157
 158 typedef detail::packed_endian_specific_integral
 159                   <uint16_t, big, unaligned>    ubig16_t;
 160 typedef detail::packed_endian_specific_integral
 161                   <uint32_t, big, unaligned>    ubig32_t;
 162 typedef detail::packed_endian_specific_integral
 163                   <uint64_t, big, unaligned>    ubig64_t;
 164
 165 typedef detail::packed_endian_specific_integral
 166                    <int16_t, big, unaligned>    big16_t;
 167 typedef detail::packed_endian_specific_integral
 168                    <int32_t, big, unaligned>    big32_t;
 169 typedef detail::packed_endian_specific_integral
 170                    <int64_t, big, unaligned>    big64_t;
 171
 172 typedef detail::packed_endian_specific_integral
 173                     <uint16_t, big, aligned>    aligned_ubig16_t;
 174 typedef detail::packed_endian_specific_integral
 175                     <uint32_t, big, aligned>    aligned_ubig32_t;
 176 typedef detail::packed_endian_specific_integral
 177                     <uint64_t, big, aligned>    aligned_ubig64_t;
 178
 179 typedef detail::packed_endian_specific_integral
 180                      <int16_t, big, aligned>    aligned_big16_t;
 181 typedef detail::packed_endian_specific_integral
 182                      <int32_t, big, aligned>    aligned_big32_t;
 183 typedef detail::packed_endian_specific_integral
 184                      <int64_t, big, aligned>    aligned_big64_t;
 185
 186 typedef detail::packed_endian_specific_integral
 187                   <uint16_t, native, unaligned> unaligned_uint16_t;
 188 typedef detail::packed_endian_specific_integral
 189                   <uint32_t, native, unaligned> unaligned_uint32_t;
 190 typedef detail::packed_endian_specific_integral
 191                   <uint64_t, native, unaligned> unaligned_uint64_t;
 192
 193 typedef detail::packed_endian_specific_integral
 194                    <int16_t, native, unaligned> unaligned_int16_t;
 195 typedef detail::packed_endian_specific_integral
 196                    <int32_t, native, unaligned> unaligned_int32_t;
 197 typedef detail::packed_endian_specific_integral
 198                    <int64_t, native, unaligned> unaligned_int64_t;
 199
 200 namespace endian {
 201 inline uint16_t read16le(const void *p) { return *(const ulittle16_t *)p; }
 202 inline uint32_t read32le(const void *p) { return *(const ulittle32_t *)p; }
 203 inline uint64_t read64le(const void *p) { return *(const ulittle64_t *)p; }
 204 inline uint16_t read16be(const void *p) { return *(const ubig16_t *)p; }
 205 inline uint32_t read32be(const void *p) { return *(const ubig32_t *)p; }
 206 inline uint64_t read64be(const void *p) { return *(const ubig64_t *)p; }
 207
 208 inline void write16le(void *p, uint16_t v) { *(ulittle16_t *)p = v; }
 209 inline void write32le(void *p, uint32_t v) { *(ulittle32_t *)p = v; }
 210 inline void write64le(void *p, uint64_t v) { *(ulittle64_t *)p = v; }
 211 inline void write16be(void *p, uint16_t v) { *(ubig16_t *)p = v; }
 212 inline void write32be(void *p, uint32_t v) { *(ubig32_t *)p = v; }
 213 inline void write64be(void *p, uint64_t v) { *(ubig64_t *)p = v; }
 214 } // end namespace endian
 215 } // end namespace support
 216 } // end namespace llvm
 217
 218 #endif