Apparently HPUX runs the IA64 in big-endian mode.

tglsfdc · tglsfdc · commit cb792343074d · 2004-09-02T21:03:30.000Z
diff --git a/src/include/port/hpux.h b/src/include/port/hpux.h
@@ -16,8 +16,9 @@
 
 #elif defined(__ia64)
 
+/* HPUX runs IA64 in big-endian mode */
 #ifndef			BYTE_ORDER
-#define			BYTE_ORDER		LITTLE_ENDIAN
+#define			BYTE_ORDER		BIG_ENDIAN
 #endif
 
 #else
