Provide an MD 64-bit byteswapping function build on 32-bit swaps

as we do on arm and i386.  Copied from arm.

If there are no MD byteswapping functions, MI macros are used.
These are wrapped by static inline functions to prevent multiple
evaluation of their argument.  If there are MD functions, they are
used directly and therefore we must implicitly guarantee that they
are safe from multiple evaluation.  Defining an MD function to an
MI macro breaks this promise.

ok deraadt@

1 files changed, 11 insertions, 2 deletions

diff --git a/sys/arch/sh/include/endian.h b/sys/arch/sh/include/endian.h
index ef0050be1ad..b80fbe6a1f2 100644
--- a/sys/arch/sh/include/endian.h
+++ b/sys/arch/sh/include/endian.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: endian.h,v 1.6 2018/10/02 21:30:44 naddy Exp $	*/
+/*	$OpenBSD: endian.h,v 1.7 2018/10/05 15:13:55 naddy Exp $	*/
 /*	$NetBSD: endian.h,v 1.4 2000/03/17 00:09:25 mycroft Exp $	*/
 
 /* Written by Manuel Bouyer. Public domain */
@@ -31,7 +31,16 @@ __swap32md(__uint32_t _x)
 	return (_rv);
 }
 
-#define	__swap64md	__swap64gen
+static __inline __uint64_t
+__swap64md(__uint64_t _x)
+{
+	__uint64_t _rv;
+
+	_rv = (__uint64_t)__swap32md(_x >> 32) |
+	    (__uint64_t)__swap32md(_x) << 32;
+
+	return (_rv);
+}
 
 /* Tell sys/endian.h we have MD variants of the swap macros.  */
 #define __HAVE_MD_SWAP