Add BSWAP64 macro.

This is like BSWAP32, but for 64-bit values.  Since we've got two of
them now and they have use cases (like sortsupport) beyond CRCs, move
the definitions to their own header file.

Peter Geoghegan

4 files changed, 54 insertions, 10 deletions

diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index dda73a8b4ce..a20e0cd1d66 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -660,6 +660,9 @@
 /* Define to 1 if your compiler understands __builtin_bswap32. */
 #undef HAVE__BUILTIN_BSWAP32
 
+/* Define to 1 if your compiler understands __builtin_bswap64. */
+#undef HAVE__BUILTIN_BSWAP64
+
 /* Define to 1 if your compiler understands __builtin_constant_p. */
 #undef HAVE__BUILTIN_CONSTANT_P
 
diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 6f7a773c5be..8566065bc77 100644
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -508,6 +508,9 @@
 /* Define to 1 if your compiler understands __builtin_bswap32. */
 /* #undef HAVE__BUILTIN_BSWAP32 */
 
+/* Define to 1 if your compiler understands __builtin_bswap64. */
+/* #undef HAVE__BUILTIN_BSWAP64 */
+
 /* Define to 1 if your compiler understands __builtin_constant_p. */
 /* #undef HAVE__BUILTIN_CONSTANT_P */
 
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 */
diff --git a/src/include/port/pg_crc32c.h b/src/include/port/pg_crc32c.h
index c925c569014..35589c0c9be 100644
--- a/src/include/port/pg_crc32c.h
+++ b/src/include/port/pg_crc32c.h
@@ -33,6 +33,8 @@
 #ifndef PG_CRC32C_H
 #define PG_CRC32C_H
 
+#include "port/pg_bswap.h"
+
 typedef uint32 pg_crc32c;
 
 /* The INIT and EQ macros are the same for all implementations. */
@@ -71,16 +73,6 @@ extern pg_crc32c (*pg_comp_crc32c) (pg_crc32c crc, const void *data, size_t len)
 #define COMP_CRC32C(crc, data, len) \
 	((crc) = pg_comp_crc32c_sb8((crc), (data), (len)))
 #ifdef WORDS_BIGENDIAN
-
-#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
-
 #define FIN_CRC32C(crc) ((crc) = BSWAP32(crc) ^ 0xFFFFFFFF)
 #else
 #define FIN_CRC32C(crc) ((crc) ^= 0xFFFFFFFF)