base/sys_byteorder.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // This header defines cross-platform ByteSwap() implementations for 16, 32 and
   6 // 64-bit values, and NetToHostXX() / HostToNextXX() functions equivalent to
   7 // the traditional ntohX() and htonX() functions.
   8 // Use the functions defined here rather than using the platform-specific
   9 // functions directly.
  10
  11 #ifndef BASE_SYS_BYTEORDER_H_
  12 #define BASE_SYS_BYTEORDER_H_
  13
  14 #include "base/basictypes.h"
  15 #include "build/build_config.h"
  16
  17 #if defined(OS_WIN)
  18 #include <winsock2.h>
  19 #else
  20 #include <arpa/inet.h>
  21 #endif
  22
  23 namespace base {
  24
  25 // Returns a value with all bytes in |x| swapped, i.e. reverses the endianness.
  26 inline uint16 ByteSwap(uint16 x) {
  27   return ((x & 0x00ff) << 8) | ((x & 0xff00) >> 8);
  28 }
  29
  30 inline uint32 ByteSwap(uint32 x) {
  31   return ((x & 0x000000fful) << 24) | ((x & 0x0000ff00ul) << 8) |
  32       ((x & 0x00ff0000ul) >> 8) | ((x & 0xff000000ul) >> 24);
  33 }
  34
  35 inline uint64 ByteSwap(uint64 x) {
  36   return ((x & 0x00000000000000ffull) << 56) |
  37       ((x & 0x000000000000ff00ull) << 40) |
  38       ((x & 0x0000000000ff0000ull) << 24) |
  39       ((x & 0x00000000ff000000ull) << 8) |
  40       ((x & 0x000000ff00000000ull) >> 8) |
  41       ((x & 0x0000ff0000000000ull) >> 24) |
  42       ((x & 0x00ff000000000000ull) >> 40) |
  43       ((x & 0xff00000000000000ull) >> 56);
  44 }
  45
  46 // Converts the bytes in |x| from host order (endianness) to little endian, and
  47 // returns the result.
  48 inline uint16 ByteSwapToLE16(uint16 x) {
  49 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  50   return x;
  51 #else
  52   return ByteSwap(x);
  53 #endif
  54 }
  55 inline uint32 ByteSwapToLE32(uint32 x) {
  56 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  57   return x;
  58 #else
  59   return ByteSwap(x);
  60 #endif
  61 }
  62 inline uint64 ByteSwapToLE64(uint64 x) {
  63 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  64   return x;
  65 #else
  66   return ByteSwap(x);
  67 #endif
  68 }
  69
  70 // Converts the bytes in |x| from network to host order (endianness), and
  71 // returns the result.
  72 inline uint16 NetToHost16(uint16 x) {
  73 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  74   return ByteSwap(x);
  75 #else
  76   return x;
  77 #endif
  78 }
  79 inline uint32 NetToHost32(uint32 x) {
  80 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  81   return ByteSwap(x);
  82 #else
  83   return x;
  84 #endif
  85 }
  86 inline uint64 NetToHost64(uint64 x) {
  87 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  88   return ByteSwap(x);
  89 #else
  90   return x;
  91 #endif
  92 }
  93
  94 // Converts the bytes in |x| from host to network order (endianness), and
  95 // returns the result.
  96 inline uint16 HostToNet16(uint16 x) {
  97 #if defined(ARCH_CPU_LITTLE_ENDIAN)
  98   return ByteSwap(x);
  99 #else
 100   return x;
 101 #endif
 102 }
 103 inline uint32 HostToNet32(uint32 x) {
 104 #if defined(ARCH_CPU_LITTLE_ENDIAN)
 105   return ByteSwap(x);
 106 #else
 107   return x;
 108 #endif
 109 }
 110 inline uint64 HostToNet64(uint64 x) {
 111 #if defined(ARCH_CPU_LITTLE_ENDIAN)
 112   return ByteSwap(x);
 113 #else
 114   return x;
 115 #endif
 116 }
 117
 118 }  // namespace base
 119
 120 #endif  // BASE_SYS_BYTEORDER_H_