47 lines
1.6 KiB
C
47 lines
1.6 KiB
C
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/*-------------------------------------------------------------------------
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*
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* pg_bswap.h
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* Byte swapping.
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*
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* Macros for reversing the byte order of 32-bit and 64-bit unsigned integers.
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* For example, 0xAABBCCDD becomes 0xDDCCBBAA. These are just wrappers for
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* built-in functions provided by the compiler where support exists.
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*
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* Note that the GCC built-in functions __builtin_bswap32() and
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* __builtin_bswap64() are documented as accepting single arguments of type
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* uint32_t and uint64_t respectively (these are also the respective return
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* types). Use caution when using these wrapper macros with signed integers.
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*
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* Copyright (c) 2015, PostgreSQL Global Development Group
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*
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* src/include/port/pg_bswap.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_BSWAP_H
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#define PG_BSWAP_H
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#ifdef HAVE__BUILTIN_BSWAP32
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#define BSWAP32(x) __builtin_bswap32(x)
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#else
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#define BSWAP32(x) (((x << 24) & 0xff000000) | \
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((x << 8) & 0x00ff0000) | \
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((x >> 8) & 0x0000ff00) | \
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((x >> 24) & 0x000000ff))
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#endif /* HAVE__BUILTIN_BSWAP32 */
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#ifdef HAVE__BUILTIN_BSWAP64
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#define BSWAP64(x) __builtin_bswap64(x)
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#else
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#define BSWAP64(x) (((x << 56) & 0xff00000000000000UL) | \
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((x << 40) & 0x00ff000000000000UL) | \
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((x << 24) & 0x0000ff0000000000UL) | \
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((x << 8) & 0x000000ff00000000UL) | \
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((x >> 8) & 0x00000000ff000000UL) | \
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((x >> 24) & 0x0000000000ff0000UL) | \
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((x >> 40) & 0x000000000000ff00UL) | \
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((x >> 56) & 0x00000000000000ffUL))
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#endif /* HAVE__BUILTIN_BSWAP64 */
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#endif /* PG_BSWAP_H */
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