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      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 <stdint.h>
     15 
     16 #include "build/build_config.h"
     17 
     18 #if defined(COMPILER_MSVC)
     19 #include <stdlib.h>
     20 #endif
     21 
     22 namespace base {
     23 
     24 // Returns a value with all bytes in |x| swapped, i.e. reverses the endianness.
     25 inline uint16_t ByteSwap(uint16_t x) {
     26 #if defined(COMPILER_MSVC)
     27   return _byteswap_ushort(x);
     28 #else
     29   return __builtin_bswap16(x);
     30 #endif
     31 }
     32 
     33 inline uint32_t ByteSwap(uint32_t x) {
     34 #if defined(COMPILER_MSVC)
     35   return _byteswap_ulong(x);
     36 #else
     37   return __builtin_bswap32(x);
     38 #endif
     39 }
     40 
     41 inline uint64_t ByteSwap(uint64_t x) {
     42 #if defined(COMPILER_MSVC)
     43   return _byteswap_uint64(x);
     44 #else
     45   return __builtin_bswap64(x);
     46 #endif
     47 }
     48 
     49 // Converts the bytes in |x| from host order (endianness) to little endian, and
     50 // returns the result.
     51 inline uint16_t ByteSwapToLE16(uint16_t x) {
     52 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     53   return x;
     54 #else
     55   return ByteSwap(x);
     56 #endif
     57 }
     58 inline uint32_t ByteSwapToLE32(uint32_t x) {
     59 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     60   return x;
     61 #else
     62   return ByteSwap(x);
     63 #endif
     64 }
     65 inline uint64_t ByteSwapToLE64(uint64_t x) {
     66 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     67   return x;
     68 #else
     69   return ByteSwap(x);
     70 #endif
     71 }
     72 
     73 // Converts the bytes in |x| from network to host order (endianness), and
     74 // returns the result.
     75 inline uint16_t NetToHost16(uint16_t x) {
     76 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     77   return ByteSwap(x);
     78 #else
     79   return x;
     80 #endif
     81 }
     82 inline uint32_t NetToHost32(uint32_t x) {
     83 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     84   return ByteSwap(x);
     85 #else
     86   return x;
     87 #endif
     88 }
     89 inline uint64_t NetToHost64(uint64_t x) {
     90 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     91   return ByteSwap(x);
     92 #else
     93   return x;
     94 #endif
     95 }
     96 
     97 // Converts the bytes in |x| from host to network order (endianness), and
     98 // returns the result.
     99 inline uint16_t HostToNet16(uint16_t x) {
    100 #if defined(ARCH_CPU_LITTLE_ENDIAN)
    101   return ByteSwap(x);
    102 #else
    103   return x;
    104 #endif
    105 }
    106 inline uint32_t HostToNet32(uint32_t x) {
    107 #if defined(ARCH_CPU_LITTLE_ENDIAN)
    108   return ByteSwap(x);
    109 #else
    110   return x;
    111 #endif
    112 }
    113 inline uint64_t HostToNet64(uint64_t x) {
    114 #if defined(ARCH_CPU_LITTLE_ENDIAN)
    115   return ByteSwap(x);
    116 #else
    117   return x;
    118 #endif
    119 }
    120 
    121 }  // namespace base
    122 
    123 #endif  // BASE_SYS_BYTEORDER_H_
    124