protozero  1.7.1
Minimalistic protocol buffer decoder and encoder in C++.
byteswap.hpp
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1 #ifndef PROTOZERO_BYTESWAP_HPP
2 #define PROTOZERO_BYTESWAP_HPP
3 
4 /*****************************************************************************
5 
6 protozero - Minimalistic protocol buffer decoder and encoder in C++.
7 
8 This file is from https://github.com/mapbox/protozero where you can find more
9 documentation.
10 
11 *****************************************************************************/
12 
19 #include "config.hpp"
20 
21 #include <cstdint>
22 #include <cstring>
23 
24 namespace protozero {
25 namespace detail {
26 
27 inline uint32_t byteswap_impl(uint32_t value) noexcept {
28 #ifdef PROTOZERO_USE_BUILTIN_BSWAP
29  return __builtin_bswap32(value);
30 #else
31  return ((value & 0xff000000U) >> 24U) |
32  ((value & 0x00ff0000U) >> 8U) |
33  ((value & 0x0000ff00U) << 8U) |
34  ((value & 0x000000ffU) << 24U);
35 #endif
36 }
37 
38 inline uint64_t byteswap_impl(uint64_t value) noexcept {
39 #ifdef PROTOZERO_USE_BUILTIN_BSWAP
40  return __builtin_bswap64(value);
41 #else
42  return ((value & 0xff00000000000000ULL) >> 56U) |
43  ((value & 0x00ff000000000000ULL) >> 40U) |
44  ((value & 0x0000ff0000000000ULL) >> 24U) |
45  ((value & 0x000000ff00000000ULL) >> 8U) |
46  ((value & 0x00000000ff000000ULL) << 8U) |
47  ((value & 0x0000000000ff0000ULL) << 24U) |
48  ((value & 0x000000000000ff00ULL) << 40U) |
49  ((value & 0x00000000000000ffULL) << 56U);
50 #endif
51 }
52 
53 } // end namespace detail
54 
56 inline void byteswap_inplace(uint32_t* ptr) noexcept {
57  *ptr = detail::byteswap_impl(*ptr);
58 }
59 
61 inline void byteswap_inplace(uint64_t* ptr) noexcept {
62  *ptr = detail::byteswap_impl(*ptr);
63 }
64 
66 inline void byteswap_inplace(int32_t* ptr) noexcept {
67  auto* bptr = reinterpret_cast<uint32_t*>(ptr);
68  *bptr = detail::byteswap_impl(*bptr);
69 }
70 
72 inline void byteswap_inplace(int64_t* ptr) noexcept {
73  auto* bptr = reinterpret_cast<uint64_t*>(ptr);
74  *bptr = detail::byteswap_impl(*bptr);
75 }
76 
78 inline void byteswap_inplace(float* ptr) noexcept {
79  static_assert(sizeof(float) == 4, "Expecting four byte float");
80 
81  uint32_t tmp = 0;
82  std::memcpy(&tmp, ptr, 4);
83  tmp = detail::byteswap_impl(tmp); // uint32 overload
84  std::memcpy(ptr, &tmp, 4);
85 }
86 
88 inline void byteswap_inplace(double* ptr) noexcept {
89  static_assert(sizeof(double) == 8, "Expecting eight byte double");
90 
91  uint64_t tmp = 0;
92  std::memcpy(&tmp, ptr, 8);
93  tmp = detail::byteswap_impl(tmp); // uint64 overload
94  std::memcpy(ptr, &tmp, 8);
95 }
96 
97 namespace detail {
98 
99  // Added for backwards compatibility with any code that might use this
100  // function (even if it shouldn't have). Will be removed in a later
101  // version of protozero.
103 
104 } // end namespace detail
105 
106 } // end namespace protozero
107 
108 #endif // PROTOZERO_BYTESWAP_HPP
Contains macro checks for different configurations.
All parts of the protozero header-only library are in this namespace.
Definition: basic_pbf_builder.hpp:24
void byteswap_inplace(uint32_t *ptr) noexcept
byteswap the data pointed to by ptr in-place.
Definition: byteswap.hpp:56
void byteswap_inplace(double *ptr) noexcept
byteswap the data pointed to by ptr in-place.
Definition: byteswap.hpp:88