From a8f944cb6e6c75c1aac2500ccf1f3905c4c3fd7a Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Tue, 21 Mar 2000 15:51:30 +0000
Subject: Wrote real version of unaligned data access functions (needed for
 BGP).

---
 lib/unaligned.h | 48 +++++++++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

(limited to 'lib')

diff --git a/lib/unaligned.h b/lib/unaligned.h
index 53e32e5d..fa17a837 100644
--- a/lib/unaligned.h
+++ b/lib/unaligned.h
@@ -1,7 +1,7 @@
 /*
- *	Unaligned Data Accesses -- Generic Version
+ *	Unaligned Data Accesses -- Generic Version, Network Order
  *
- *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *	(c) 2000 Martin Mares <mj@ucw.cz>
  *
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -9,34 +9,44 @@
 #ifndef _BIRD_UNALIGNED_H_
 #define _BIRD_UNALIGNED_H_
 
-#if CPU_NEEDS_ALIGN_WORD != 1 || CPU_NEEDS_ALIGN_LONG != 1
+/*
+ *  We don't do any clever tricks with unaligned accesses since it's
+ *  virtually impossible to figure out what alignment does the CPU want
+ *  (unaligned accesses can be emulated by the OS which makes them work,
+ *  but unusably slow). We use memcpy and hope GCC will optimize it out
+ *  if possible.
+ */
+
 #include <string.h>
-#endif
 
-#if CPU_NEEDS_ALIGN_WORD == 1
-#define unaligned_u16(p) (*((u16 *)(p)))
-#else
 static inline u16
-unaligned_u16(void *p)
+get_u16(void *p)
 {
   u16 x;
-
-  memcpy(&x, p, sizeof(x));
-  return x;
+  memcpy(&x, p, 2);
+  return ntohs(x);
 }
-#endif
 
-#if CPU_NEEDS_ALIGN_LONG == 1
-#define unaligned_u32(p) (*((u32 *)(p)))
-#else
 static inline u32
-unaligned_u32(void *p)
+get_u32(void *p)
 {
   u32 x;
+  memcpy(&x, p, 4);
+  return ntohl(x);
+}
 
-  memcpy(&x, p, sizeof(x));
-  return x;
+static inline void
+put_u16(void *p, u16 x)
+{
+  x = htons(x);
+  memcpy(p, &x, 2);
+}
+
+static inline void
+put_u32(void *p, u32 x)
+{
+  x = htonl(x);
+  memcpy(p, &x, 4);
 }
-#endif
 
 #endif
-- 
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