types: Add big-endian 128-bit types and helpers.

These types will be used by the following patches to ensure a consistent
wire format for 128-bit connection tracking labels. Common functions for
comparison, endian translation, etc. are provided.

Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

include/openvswitch/types.h

@@ -84,10 +84,24 @@ typedef struct {
 typedef union {
     uint32_t u32[4];
     struct {
+#ifdef WORDS_BIGENDIAN
+        uint64_t hi, lo;
+#else
         uint64_t lo, hi;
+#endif
     } u64;
 } ovs_u128;
 
+typedef union {
+    ovs_be32 be32[4];
+    struct {
+        ovs_be64 hi, lo;
+    } be64;
+} ovs_be128;
+
+#define OVS_U128_MAX (ovs_u128) { .u64 = { UINT64_MAX, UINT64_MAX } }
+#define OVS_BE128_MAX (ovs_be128) { .be64 = { OVS_BE64_MAX, OVS_BE64_MAX } }
+
 /* A 64-bit value, in network byte order, that is only aligned on a 32-bit
  * boundary. */
 typedef struct {