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 #if defined(_MSC_VER) && !defined(_DEBUG)
  21 #include <stdlib.h>
  22 #endif
  23
  24 namespace llvm {
  25 namespace sys {
  26
  27 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
  28 /// the 16-bit argument.
  29 inline uint16_t SwapByteOrder_16(uint16_t value) {
  30 #if defined(_MSC_VER) && !defined(_DEBUG)
  31   // The DLL version of the runtime lacks these functions (bug!?), but in a
  32   // release build they're replaced with BSWAP instructions anyway.
  33   return _byteswap_ushort(value);
  34 #else
  35   uint16_t Hi = value << 8;
  36   uint16_t Lo = value >> 8;
  37   return Hi | Lo;
  38 #endif
  39 }
  40
  41 /// SwapByteOrder_32 - This function returns a byte-swapped representation of
  42 /// the 32-bit argument.
  43 inline uint32_t SwapByteOrder_32(uint32_t value) {
  44 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !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 /// SwapByteOrder_64 - This function returns a byte-swapped representation of
  58 /// the 64-bit argument.
  59 inline uint64_t SwapByteOrder_64(uint64_t value) {
  60 #if defined(__llvm__) || (LLVM_GNUC_PREREQ(4, 3, 0) && !defined(__ICC))
  61   return __builtin_bswap64(value);
  62 #elif defined(_MSC_VER) && !defined(_DEBUG)
  63   return _byteswap_uint64(value);
  64 #else
  65   uint64_t Hi = SwapByteOrder_32(uint32_t(value));
  66   uint32_t Lo = SwapByteOrder_32(uint32_t(value >> 32));
  67   return (Hi << 32) | Lo;
  68 #endif
  69 }
  70
  71 inline unsigned char  getSwappedBytes(unsigned char C) { return C; }
  72 inline   signed char  getSwappedBytes(signed char C) { return C; }
  73 inline          char  getSwappedBytes(char C) { return C; }
  74
  75 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
  76 inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
  77
  78 inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
  79 inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
  80
  81 #if __LONG_MAX__ == __INT_MAX__
  82 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
  83 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
  84 #elif __LONG_MAX__ == __LONG_LONG_MAX__
  85 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
  86 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
  87 #else
  88 #error "Unknown long size!"
  89 #endif
  90
  91 inline unsigned long long getSwappedBytes(unsigned long long C) {
  92   return SwapByteOrder_64(C);
  93 }
  94 inline signed long long getSwappedBytes(signed long long C) {
  95   return SwapByteOrder_64(C);
  96 }
  97
  98 inline float getSwappedBytes(float C) {
  99   union {
 100     uint32_t i;
 101     float f;
 102   } in, out;
 103   in.f = C;
 104   out.i = SwapByteOrder_32(in.i);
 105   return out.f;
 106 }
 107
 108 inline double getSwappedBytes(double C) {
 109   union {
 110     uint64_t i;
 111     double d;
 112   } in, out;
 113   in.d = C;
 114   out.i = SwapByteOrder_64(in.i);
 115   return out.d;
 116 }
 117
 118 template<typename T>
 119 inline void swapByteOrder(T &Value) {
 120   Value = getSwappedBytes(Value);
 121 }
 122
 123 } // end namespace sys
 124 } // end namespace llvm
 125
 126 #endif