codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * pg_bswap.h4 *	  Byte swapping.5 *6 * Macros for reversing the byte order of 16, 32 and 64-bit unsigned integers.7 * For example, 0xAABBCCDD becomes 0xDDCCBBAA.  These are just wrappers for8 * built-in functions provided by the compiler where support exists.9 *10 * Note that all of these functions accept unsigned integers as arguments and11 * return the same.  Use caution when using these wrapper macros with signed12 * integers.13 *14 * Copyright (c) 2015-2023, PostgreSQL Global Development Group15 *16 * src/include/port/pg_bswap.h17 *18 *-------------------------------------------------------------------------19 */20#ifndef PG_BSWAP_H21#define PG_BSWAP_H22 23 24/*25 * In all supported versions msvc provides _byteswap_* functions in stdlib.h,26 * already included by c.h.27 */28 29 30/* implementation of uint16 pg_bswap16(uint16) */31#if defined(HAVE__BUILTIN_BSWAP16)32 33#define pg_bswap16(x) __builtin_bswap16(x)34 35#elif defined(_MSC_VER)36 37#define pg_bswap16(x) _byteswap_ushort(x)38 39#else40 41static inline uint1642pg_bswap16(uint16 x)43{44	return45		((x << 8) & 0xff00) |46		((x >> 8) & 0x00ff);47}48 49#endif							/* HAVE__BUILTIN_BSWAP16 */50 51 52/* implementation of uint32 pg_bswap32(uint32) */53#if defined(HAVE__BUILTIN_BSWAP32)54 55#define pg_bswap32(x) __builtin_bswap32(x)56 57#elif defined(_MSC_VER)58 59#define pg_bswap32(x) _byteswap_ulong(x)60 61#else62 63static inline uint3264pg_bswap32(uint32 x)65{66	return67		((x << 24) & 0xff000000) |68		((x << 8) & 0x00ff0000) |69		((x >> 8) & 0x0000ff00) |70		((x >> 24) & 0x000000ff);71}72 73#endif							/* HAVE__BUILTIN_BSWAP32 */74 75 76/* implementation of uint64 pg_bswap64(uint64) */77#if defined(HAVE__BUILTIN_BSWAP64)78 79#define pg_bswap64(x) __builtin_bswap64(x)80 81 82#elif defined(_MSC_VER)83 84#define pg_bswap64(x) _byteswap_uint64(x)85 86#else87 88static inline uint6489pg_bswap64(uint64 x)90{91	return92		((x << 56) & UINT64CONST(0xff00000000000000)) |93		((x << 40) & UINT64CONST(0x00ff000000000000)) |94		((x << 24) & UINT64CONST(0x0000ff0000000000)) |95		((x << 8) & UINT64CONST(0x000000ff00000000)) |96		((x >> 8) & UINT64CONST(0x00000000ff000000)) |97		((x >> 24) & UINT64CONST(0x0000000000ff0000)) |98		((x >> 40) & UINT64CONST(0x000000000000ff00)) |99		((x >> 56) & UINT64CONST(0x00000000000000ff));100}101#endif							/* HAVE__BUILTIN_BSWAP64 */102 103 104/*105 * Portable and fast equivalents for ntohs, ntohl, htons, htonl,106 * additionally extended to 64 bits.107 */108#ifdef WORDS_BIGENDIAN109 110#define pg_hton16(x)		(x)111#define pg_hton32(x)		(x)112#define pg_hton64(x)		(x)113 114#define pg_ntoh16(x)		(x)115#define pg_ntoh32(x)		(x)116#define pg_ntoh64(x)		(x)117 118#else119 120#define pg_hton16(x)		pg_bswap16(x)121#define pg_hton32(x)		pg_bswap32(x)122#define pg_hton64(x)		pg_bswap64(x)123 124#define pg_ntoh16(x)		pg_bswap16(x)125#define pg_ntoh32(x)		pg_bswap32(x)126#define pg_ntoh64(x)		pg_bswap64(x)127 128#endif							/* WORDS_BIGENDIAN */129 130 131/*132 * Rearrange the bytes of a Datum from big-endian order into the native byte133 * order.  On big-endian machines, this does nothing at all.  Note that the C134 * type Datum is an unsigned integer type on all platforms.135 *136 * One possible application of the DatumBigEndianToNative() macro is to make137 * bitwise comparisons cheaper.  A simple 3-way comparison of Datums138 * transformed by the macro (based on native, unsigned comparisons) will return139 * the same result as a memcmp() of the corresponding original Datums, but can140 * be much cheaper.  It's generally safe to do this on big-endian systems141 * without any special transformation occurring first.142 *143 * If SIZEOF_DATUM is not defined, then postgres.h wasn't included and these144 * macros probably shouldn't be used, so we define nothing.  Note that145 * SIZEOF_DATUM == 8 would evaluate as 0 == 8 in that case, potentially146 * leading to the wrong implementation being selected and confusing errors, so147 * defining nothing is safest.148 */149#ifdef SIZEOF_DATUM150#ifdef WORDS_BIGENDIAN151#define		DatumBigEndianToNative(x)	(x)152#else							/* !WORDS_BIGENDIAN */153#if SIZEOF_DATUM == 8154#define		DatumBigEndianToNative(x)	pg_bswap64(x)155#else							/* SIZEOF_DATUM != 8 */156#define		DatumBigEndianToNative(x)	pg_bswap32(x)157#endif							/* SIZEOF_DATUM == 8 */158#endif							/* WORDS_BIGENDIAN */159#endif							/* SIZEOF_DATUM */160 161#endif							/* PG_BSWAP_H */162