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-rw-r--r--sys/arch/wgrisc/include/endian.h9
1 files changed, 8 insertions, 1 deletions
diff --git a/sys/arch/wgrisc/include/endian.h b/sys/arch/wgrisc/include/endian.h
index 1ec9259725a..b8899c077cf 100644
--- a/sys/arch/wgrisc/include/endian.h
+++ b/sys/arch/wgrisc/include/endian.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: endian.h,v 1.3 1997/06/25 12:32:54 downsj Exp $ */
+/* $OpenBSD: endian.h,v 1.4 1997/06/25 12:52:11 grr Exp $ */
/* $NetBSD: endian.h,v 1.4 1994/10/26 21:09:38 cgd Exp $ */
/*
@@ -75,6 +75,13 @@ __END_DECLS
/*
* Macros for network/external number representation conversion.
+ *
+ * The way this works is that HTONS(x) modifies x and *can't* be used as
+ * and rvalue i.e. foo=HTONS(bar) is wrong. Likewise x=htons(x) should
+ * never be used where HTONS(x) will serve i.e. foo=htons(foo) is wrong.
+ * Failing to observe these rule will result in code that appears to work
+ * and probably does work, but generates gcc warnings on architectures
+ * where the macros are used to optimize away an unneeded conversion.
*/
#if BYTE_ORDER == BIG_ENDIAN && !defined(lint)
#define ntohl(x) (x)