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/* Bytes swap functions, reverse order of bytes:
- _Py_bswap16(uint16_t)
- _Py_bswap32(uint32_t)
- _Py_bswap64(uint64_t)
*/
#ifndef Py_INTERNAL_BSWAP_H
#define Py_INTERNAL_BSWAP_H
#ifdef __cplusplus
extern "C" {
#endif
#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif
#if ((defined(__GNUC__) \
&& ((__GNUC__ >= 5) || (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8))) \
|| (defined(__clang__) \
&& (__clang_major__ >= 4 \
|| (__clang_major__ == 3 && __clang_minor__ >= 2))))
/* __builtin_bswap16() is available since GCC 4.8 and clang 3.2,
__builtin_bswap32() is available since GCC 4.3,
__builtin_bswap64() is available since GCC 4.3. */
# define _PY_HAVE_BUILTIN_BSWAP
#endif
#ifdef _MSC_VER
/* Get _byteswap_ushort(), _byteswap_ulong(), _byteswap_uint64() */
# include <intrin.h>
#endif
static inline uint16_t
_Py_bswap16(uint16_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap16(word);
#elif defined(_MSC_VER)
Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned short));
return _byteswap_ushort(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT16_C(0x00FF)) << 8)
| ((word & UINT16_C(0xFF00)) >> 8));
#endif
}
static inline uint32_t
_Py_bswap32(uint32_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap32(word);
#elif defined(_MSC_VER)
Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned long));
return _byteswap_ulong(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT32_C(0x000000FF)) << 24)
| ((word & UINT32_C(0x0000FF00)) << 8)
| ((word & UINT32_C(0x00FF0000)) >> 8)
| ((word & UINT32_C(0xFF000000)) >> 24));
#endif
}
static inline uint64_t
_Py_bswap64(uint64_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap64(word);
#elif defined(_MSC_VER)
return _byteswap_uint64(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT64_C(0x00000000000000FF)) << 56)
| ((word & UINT64_C(0x000000000000FF00)) << 40)
| ((word & UINT64_C(0x0000000000FF0000)) << 24)
| ((word & UINT64_C(0x00000000FF000000)) << 8)
| ((word & UINT64_C(0x000000FF00000000)) >> 8)
| ((word & UINT64_C(0x0000FF0000000000)) >> 24)
| ((word & UINT64_C(0x00FF000000000000)) >> 40)
| ((word & UINT64_C(0xFF00000000000000)) >> 56));
#endif
}
#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_BSWAP_H */
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