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Diffstat (limited to 'src/include/port/pg_bswap.h')
| -rw-r--r-- | src/include/port/pg_bswap.h | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/src/include/port/pg_bswap.h b/src/include/port/pg_bswap.h new file mode 100644 index 00000000000..6555942c921 --- /dev/null +++ b/src/include/port/pg_bswap.h @@ -0,0 +1,46 @@ +/*------------------------------------------------------------------------- + * + * pg_bswap.h + * Byte swapping. + * + * Macros for reversing the byte order of 32-bit and 64-bit unsigned integers. + * For example, 0xAABBCCDD becomes 0xDDCCBBAA. These are just wrappers for + * built-in functions provided by the compiler where support exists. + * + * Note that the GCC built-in functions __builtin_bswap32() and + * __builtin_bswap64() are documented as accepting single arguments of type + * uint32_t and uint64_t respectively (these are also the respective return + * types). Use caution when using these wrapper macros with signed integers. + * + * Copyright (c) 2015, PostgreSQL Global Development Group + * + * src/include/port/pg_bswap.h + * + *------------------------------------------------------------------------- + */ +#ifndef PG_BSWAP_H +#define PG_BSWAP_H + +#ifdef HAVE__BUILTIN_BSWAP32 +#define BSWAP32(x) __builtin_bswap32(x) +#else +#define BSWAP32(x) (((x << 24) & 0xff000000) | \ + ((x << 8) & 0x00ff0000) | \ + ((x >> 8) & 0x0000ff00) | \ + ((x >> 24) & 0x000000ff)) +#endif /* HAVE__BUILTIN_BSWAP32 */ + +#ifdef HAVE__BUILTIN_BSWAP64 +#define BSWAP64(x) __builtin_bswap64(x) +#else +#define BSWAP64(x) (((x << 56) & 0xff00000000000000UL) | \ + ((x << 40) & 0x00ff000000000000UL) | \ + ((x << 24) & 0x0000ff0000000000UL) | \ + ((x << 8) & 0x000000ff00000000UL) | \ + ((x >> 8) & 0x00000000ff000000UL) | \ + ((x >> 24) & 0x0000000000ff0000UL) | \ + ((x >> 40) & 0x000000000000ff00UL) | \ + ((x >> 56) & 0x00000000000000ffUL)) +#endif /* HAVE__BUILTIN_BSWAP64 */ + +#endif /* PG_BSWAP_H */ |