include/llvm/Support/SwapByteOrder.h

   1 //===- SwapByteOrder.h - Generic and optimized byte swaps -------*- 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 LLVM_SUPPORT_SWAPBYTEORDER_H
  15 #define LLVM_SUPPORT_SWAPBYTEORDER_H
  16
  17 #include "llvm/Support/Compiler.h"
  18 #include "llvm/Support/DataTypes.h"
  19 #include <cstddef>
  20 #include <type_traits>
  21 #if defined(_MSC_VER) && !defined(_DEBUG)
  22 #include <stdlib.h>
  23 #endif
  24
  25 namespace llvm {
  26 namespace sys {
  27
  28 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
  29 /// the 16-bit argument.
  30 inline uint16_t SwapByteOrder_16(uint16_t value) {
  31 #if defined(_MSC_VER) && !defined(_DEBUG)
  32   // The DLL version of the runtime lacks these functions (bug!?), but in a
  33   // release build they're replaced with BSWAP instructions anyway.
  34   return _byteswap_ushort(value);
  35 #else
  36   uint16_t Hi = value << 8;
  37   uint16_t Lo = value >> 8;
  38   return Hi | Lo;
  39 #endif
  40 }
  41
  42 /// This function returns a byte-swapped representation of the 32-bit argument.
  43 inline uint32_t SwapByteOrder_32(uint32_t value) {
  44 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
  45   return __builtin_bswap32(value);
  46 #elif defined(_MSC_VER) && !defined(_DEBUG)
  47   return _byteswap_ulong(value);
  48 #else
  49   uint32_t Byte0 = value & 0x000000FF;
  50   uint32_t Byte1 = value & 0x0000FF00;
  51   uint32_t Byte2 = value & 0x00FF0000;
  52   uint32_t Byte3 = value & 0xFF000000;
  53   return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
  54 #endif
  55 }
  56
  57 /// This function returns a byte-swapped representation of the 64-bit argument.
  58 inline uint64_t SwapByteOrder_64(uint64_t value) {
  59 #if defined(__llvm__) || (defined(__GNUC__) && !defined(__ICC))
  60   return __builtin_bswap64(value);
  61 #elif defined(_MSC_VER) && !defined(_DEBUG)
  62   return _byteswap_uint64(value);
  63 #else
  64   uint64_t Hi = SwapByteOrder_32(uint32_t(value));
  65   uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
  66   return (Hi << 32) | Lo;
  67 #endif
  68 }
  69
  70 inline unsigned char  getSwappedBytes(unsigned char C) { return C; }
  71 inline   signed char  getSwappedBytes(signed char C) { return C; }
  72 inline          char  getSwappedBytes(char C) { return C; }
  73
  74 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
  75 inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
  76
  77 inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
  78 inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
  79
  80 #if __LONG_MAX__ == __INT_MAX__
  81 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
  82 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
  83 #elif __LONG_MAX__ == __LONG_LONG_MAX__
  84 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
  85 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
  86 #else
  87 #error "Unknown long size!"
  88 #endif
  89
  90 inline unsigned long long getSwappedBytes(unsigned long long C) {
  91   return SwapByteOrder_64(C);
  92 }
  93 inline signed long long getSwappedBytes(signed long long C) {
  94   return SwapByteOrder_64(C);
  95 }
  96
  97 inline float getSwappedBytes(float C) {
  98   union {
  99     uint32_t i;
 100     float f;
 101   } in, out;
 102   in.f = C;
 103   out.i = SwapByteOrder_32(in.i);
 104   return out.f;
 105 }
 106
 107 inline double getSwappedBytes(double C) {
 108   union {
 109     uint64_t i;
 110     double d;
 111   } in, out;
 112   in.d = C;
 113   out.i = SwapByteOrder_64(in.i);
 114   return out.d;
 115 }
 116
 117 template <typename T>
 118 inline typename std::enable_if<std::is_enum<T>::value, T>::type
 119 getSwappedBytes(T C) {
 120   return static_cast<T>(
 121       getSwappedBytes(static_cast<typename std::underlying_type<T>::type>(C)));
 122 }
 123
 124 template<typename T>
 125 inline void swapByteOrder(T &Value) {
 126   Value = getSwappedBytes(Value);
 127 }
 128
 129 } // end namespace sys
 130 } // end namespace llvm
 131
 132 #endif