1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___BIT_BYTESWAP_H
#define _LIBCPP___BIT_BYTESWAP_H
#include <__concepts/arithmetic.h>
#include <__config>
#include <cstdint>
#include <cstdlib>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 20
template <integral _Tp>
_LIBCPP_HIDE_FROM_ABI constexpr _Tp byteswap(_Tp __val) noexcept {
if constexpr (sizeof(_Tp) == 1) {
return __val;
} else if constexpr (sizeof(_Tp) == 2) {
return __builtin_bswap16(__val);
} else if constexpr (sizeof(_Tp) == 4) {
return __builtin_bswap32(__val);
} else if constexpr (sizeof(_Tp) == 8) {
return __builtin_bswap64(__val);
#ifndef _LIBCPP_HAS_NO_INT128
} else if constexpr (sizeof(_Tp) == 16) {
#if __has_builtin(__builtin_bswap128)
return __builtin_bswap128(__val);
#else
return static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val))) << 64 |
static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val >> 64)));
#endif // __has_builtin(__builtin_bswap128)
#endif // _LIBCPP_HAS_NO_INT128
} else {
static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size");
}
}
#endif // _LIBCPP_STD_VER > 20
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___BIT_BYTESWAP_H
|
