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236
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1 // -*- C++ -*-
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2 //===----------------------------------------------------------------------===//
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3 //
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4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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5 // See https://llvm.org/LICENSE.txt for license information.
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6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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7 //
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8 //===----------------------------------------------------------------------===//
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9
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10 #ifndef _LIBCPP___BIT_BYTESWAP_H
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11 #define _LIBCPP___BIT_BYTESWAP_H
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12
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13 #include <__concepts/arithmetic.h>
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14 #include <__config>
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15 #include <cstdint>
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16
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17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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18 # pragma GCC system_header
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19 #endif
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20
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21 _LIBCPP_BEGIN_NAMESPACE_STD
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22
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252
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23 #if _LIBCPP_STD_VER >= 23
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236
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24
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25 template <integral _Tp>
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252
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26 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _Tp byteswap(_Tp __val) noexcept {
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236
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27
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28 if constexpr (sizeof(_Tp) == 1) {
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29 return __val;
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30 } else if constexpr (sizeof(_Tp) == 2) {
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31 return __builtin_bswap16(__val);
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32 } else if constexpr (sizeof(_Tp) == 4) {
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33 return __builtin_bswap32(__val);
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34 } else if constexpr (sizeof(_Tp) == 8) {
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35 return __builtin_bswap64(__val);
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36 #ifndef _LIBCPP_HAS_NO_INT128
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37 } else if constexpr (sizeof(_Tp) == 16) {
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38 #if __has_builtin(__builtin_bswap128)
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39 return __builtin_bswap128(__val);
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40 #else
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41 return static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val))) << 64 |
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42 static_cast<_Tp>(byteswap(static_cast<uint64_t>(__val >> 64)));
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43 #endif // __has_builtin(__builtin_bswap128)
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44 #endif // _LIBCPP_HAS_NO_INT128
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45 } else {
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46 static_assert(sizeof(_Tp) == 0, "byteswap is unimplemented for integral types of this size");
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47 }
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48 }
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49
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252
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50 #endif // _LIBCPP_STD_VER >= 23
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236
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51
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52 _LIBCPP_END_NAMESPACE_STD
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53
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54 #endif // _LIBCPP___BIT_BYTESWAP_H
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