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ec306a2fd9
Fix building pycore_bitutils.h internal header on old clang version
without __builtin_bswap16() (ex: Xcode 4.6.3 on Mac OS X 10.7).
Add a new private _Py__has_builtin() macro to check for availability
of a preprocessor builtin function.
Co-Authored-By: Joshua Root <jmr@macports.org>
Co-authored-by: Joshua Root <jmr@macports.org>
(cherry picked from commit b3b98082c5)
88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/* Bytes swap functions, reverse order of bytes:
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- _Py_bswap16(uint16_t)
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- _Py_bswap32(uint32_t)
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- _Py_bswap64(uint64_t)
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*/
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#ifndef Py_INTERNAL_BSWAP_H
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#define Py_INTERNAL_BSWAP_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#if defined(__GNUC__) \
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&& ((__GNUC__ >= 5) || (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8))
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/* __builtin_bswap16() is available since GCC 4.8,
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__builtin_bswap32() is available since GCC 4.3,
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__builtin_bswap64() is available since GCC 4.3. */
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# define _PY_HAVE_BUILTIN_BSWAP
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#endif
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#ifdef _MSC_VER
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/* Get _byteswap_ushort(), _byteswap_ulong(), _byteswap_uint64() */
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# include <intrin.h>
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#endif
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static inline uint16_t
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_Py_bswap16(uint16_t word)
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{
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#if defined(_PY_HAVE_BUILTIN_BSWAP) || _Py__has_builtin(__builtin_bswap16)
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return __builtin_bswap16(word);
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#elif defined(_MSC_VER)
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Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned short));
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return _byteswap_ushort(word);
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#else
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// Portable implementation which doesn't rely on circular bit shift
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return ( ((word & UINT16_C(0x00FF)) << 8)
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| ((word & UINT16_C(0xFF00)) >> 8));
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#endif
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}
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static inline uint32_t
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_Py_bswap32(uint32_t word)
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{
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#if defined(_PY_HAVE_BUILTIN_BSWAP) || _Py__has_builtin(__builtin_bswap32)
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return __builtin_bswap32(word);
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#elif defined(_MSC_VER)
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Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned long));
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return _byteswap_ulong(word);
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#else
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// Portable implementation which doesn't rely on circular bit shift
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return ( ((word & UINT32_C(0x000000FF)) << 24)
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| ((word & UINT32_C(0x0000FF00)) << 8)
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| ((word & UINT32_C(0x00FF0000)) >> 8)
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| ((word & UINT32_C(0xFF000000)) >> 24));
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#endif
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}
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static inline uint64_t
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_Py_bswap64(uint64_t word)
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{
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#if defined(_PY_HAVE_BUILTIN_BSWAP) || _Py__has_builtin(__builtin_bswap64)
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return __builtin_bswap64(word);
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#elif defined(_MSC_VER)
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return _byteswap_uint64(word);
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#else
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// Portable implementation which doesn't rely on circular bit shift
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return ( ((word & UINT64_C(0x00000000000000FF)) << 56)
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| ((word & UINT64_C(0x000000000000FF00)) << 40)
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| ((word & UINT64_C(0x0000000000FF0000)) << 24)
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| ((word & UINT64_C(0x00000000FF000000)) << 8)
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| ((word & UINT64_C(0x000000FF00000000)) >> 8)
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| ((word & UINT64_C(0x0000FF0000000000)) >> 24)
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| ((word & UINT64_C(0x00FF000000000000)) >> 40)
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| ((word & UINT64_C(0xFF00000000000000)) >> 56));
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#endif
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}
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_BSWAP_H */
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