compiler-rt/lib/orc/endianness.h

   1 //===- endian.h - Endianness support ----------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file declares generic and optimized functions to swap the byte order of
  10 // an integral type.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef ORC_RT_ENDIAN_H
  15 #define ORC_RT_ENDIAN_H
  16
  17 #include <cstddef>
  18 #include <cstdint>
  19 #include <type_traits>
  20 #if defined(_MSC_VER) && !defined(_DEBUG)
  21 #include <stdlib.h>
  22 #endif
  23
  24 #if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__) ||            \
  25     defined(__Fuchsia__) || defined(__EMSCRIPTEN__)
  26 #include <endian.h>
  27 #elif defined(_AIX)
  28 #include <sys/machine.h>
  29 #elif defined(__sun)
  30 /* Solaris provides _BIG_ENDIAN/_LITTLE_ENDIAN selector in sys/types.h */
  31 #include <sys/types.h>
  32 #define BIG_ENDIAN 4321
  33 #define LITTLE_ENDIAN 1234
  34 #if defined(_BIG_ENDIAN)
  35 #define BYTE_ORDER BIG_ENDIAN
  36 #else
  37 #define BYTE_ORDER LITTLE_ENDIAN
  38 #endif
  39 #elif defined(__MVS__)
  40 #define BIG_ENDIAN 4321
  41 #define LITTLE_ENDIAN 1234
  42 #define BYTE_ORDER BIG_ENDIAN
  43 #else
  44 #if !defined(BYTE_ORDER) && !defined(_WIN32)
  45 #include <machine/endian.h>
  46 #endif
  47 #endif
  48
  49 namespace __orc_rt {
  50
  51 /// ByteSwap_16 - This function returns a byte-swapped representation of
  52 /// the 16-bit argument.
  53 inline uint16_t ByteSwap_16(uint16_t value) {
  54 #if defined(_MSC_VER) && !defined(_DEBUG)
  55   // The DLL version of the runtime lacks these functions (bug!?), but in a
  56   // release build they're replaced with BSWAP instructions anyway.
  57   return _byteswap_ushort(value);
  58 #else
  59   uint16_t Hi = value << 8;
  60   uint16_t Lo = value >> 8;
  61   return Hi | Lo;
  62 #endif
  63 }
  64
  65 /// This function returns a byte-swapped representation of the 32-bit argument.
  66 inline uint32_t ByteSwap_32(uint32_t value) {
  67 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
  68   return __builtin_bswap32(value);
  69 #elif defined(_MSC_VER) && !defined(_DEBUG)
  70   return _byteswap_ulong(value);
  71 #else
  72   uint32_t Byte0 = value & 0x000000FF;
  73   uint32_t Byte1 = value & 0x0000FF00;
  74   uint32_t Byte2 = value & 0x00FF0000;
  75   uint32_t Byte3 = value & 0xFF000000;
  76   return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
  77 #endif
  78 }
  79
  80 /// This function returns a byte-swapped representation of the 64-bit argument.
  81 inline uint64_t ByteSwap_64(uint64_t value) {
  82 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
  83   return __builtin_bswap64(value);
  84 #elif defined(_MSC_VER) && !defined(_DEBUG)
  85   return _byteswap_uint64(value);
  86 #else
  87   uint64_t Hi = ByteSwap_32(uint32_t(value));
  88   uint32_t Lo = ByteSwap_32(uint32_t(value >> 32));
  89   return (Hi << 32) | Lo;
  90 #endif
  91 }
  92
  93 #if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN
  94 constexpr bool IsBigEndianHost = true;
  95 #else
  96 constexpr bool IsBigEndianHost = false;
  97 #endif
  98
  99 static const bool IsLittleEndianHost = !IsBigEndianHost;
 100
 101 inline unsigned char getSwappedBytes(unsigned char C) { return C; }
 102 inline signed char getSwappedBytes(signed char C) { return C; }
 103 inline char getSwappedBytes(char C) { return C; }
 104
 105 inline unsigned short getSwappedBytes(unsigned short C) {
 106   return ByteSwap_16(C);
 107 }
 108 inline signed short getSwappedBytes(signed short C) { return ByteSwap_16(C); }
 109
 110 inline unsigned int getSwappedBytes(unsigned int C) { return ByteSwap_32(C); }
 111 inline signed int getSwappedBytes(signed int C) { return ByteSwap_32(C); }
 112
 113 inline unsigned long getSwappedBytes(unsigned long C) {
 114   // Handle LLP64 and LP64 platforms.
 115   return sizeof(long) == sizeof(int) ? ByteSwap_32((uint32_t)C)
 116                                      : ByteSwap_64((uint64_t)C);
 117 }
 118 inline signed long getSwappedBytes(signed long C) {
 119   // Handle LLP64 and LP64 platforms.
 120   return sizeof(long) == sizeof(int) ? ByteSwap_32((uint32_t)C)
 121                                      : ByteSwap_64((uint64_t)C);
 122 }
 123
 124 inline unsigned long long getSwappedBytes(unsigned long long C) {
 125   return ByteSwap_64(C);
 126 }
 127 inline signed long long getSwappedBytes(signed long long C) {
 128   return ByteSwap_64(C);
 129 }
 130
 131 template <typename T>
 132 inline std::enable_if_t<std::is_enum<T>::value, T> getSwappedBytes(T C) {
 133   return static_cast<T>(
 134       getSwappedBytes(static_cast<std::underlying_type_t<T>>(C)));
 135 }
 136
 137 template <typename T> inline void swapByteOrder(T &Value) {
 138   Value = getSwappedBytes(Value);
 139 }
 140
 141 } // end namespace __orc_rt
 142
 143 #endif // ORC_RT_ENDIAN_H