xtoxll: Add byte conversions macros for use in constant expressions.

[sliver-openvswitch.git] / lib / xtoxll.h

diff --git a/lib/xtoxll.h b/lib/xtoxll.h
index faf6c94..a3734f1 100644 (file)
--- a/lib/xtoxll.h
+++ b/lib/xtoxll.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008 Nicira Networks.
+ * Copyright (c) 2008, 2010 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,6 +18,7 @@
 
 #include <arpa/inet.h>
 #include <sys/types.h>
+#include <inttypes.h>
 
 static inline uint64_t
 htonll(uint64_t n)
@@ -31,4 +32,31 @@ ntohll(uint64_t n)
     return htonl(1) == 1 ? n : ((uint64_t) ntohl(n) << 32) | ntohl(n >> 32);
 }
 
+/* These macros may substitute for htons(), htonl(), and htonll() in contexts
+ * where function calls are not allowed, such as case labels.  They should not
+ * be used elsewhere because all of them evaluate their argument many times. */
+#ifdef WORDS_BIGENDIAN
+#define CONSTANT_HTONS(VALUE) ((uint16_t) (VALUE))
+#define CONSTANT_HTONL(VALUE) ((uint32_t) (VALUE))
+#define CONSTANT_HTONLL(VALUE) ((uint64_t) (VALUE))
+#else
+#define CONSTANT_HTONS(VALUE)                       \
+        (((((uint16_t) (VALUE)) & 0xff00) >> 8) |   \
+         ((((uint16_t) (VALUE)) & 0x00ff) << 8))
+#define CONSTANT_HTONL(VALUE)                           \
+        (((((uint32_t) (VALUE)) & 0x000000ff) << 24) |  \
+         ((((uint32_t) (VALUE)) & 0x0000ff00) <<  8) |  \
+         ((((uint32_t) (VALUE)) & 0x00ff0000) >>  8) |  \
+         ((((uint32_t) (VALUE)) & 0xff000000) >> 24))
+#define CONSTANT_HTONLL(VALUE)                                           \
+        (((((uint64_t) (VALUE)) & UINT64_C(0x00000000000000ff)) << 56) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x000000000000ff00)) << 40) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x0000000000ff0000)) << 24) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x00000000ff000000)) <<  8) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x000000ff00000000)) >>  8) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x0000ff0000000000)) >> 24) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0x00ff000000000000)) >> 40) | \
+         ((((uint64_t) (VALUE)) & UINT64_C(0xff00000000000000)) >> 56))
+#endif
+
 #endif /* xtoxll.h */