From 2ce238984ca466ebb50070cf88d80244dc767774 Mon Sep 17 00:00:00 2001
From: Matteo Cypriani <matteo.cypriani@univ-fcomte.fr>
Date: Thu, 7 Apr 2011 14:31:31 +0200
Subject: [PATCH] [lib] Add float endianess converters

---
 libowlps/libowlps.c | 29 +++++++++++++++++++++++++++++
 libowlps/owlps.h    | 12 ++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/libowlps/libowlps.c b/libowlps/libowlps.c
index ad77de0..c11aea9 100644
--- a/libowlps/libowlps.c
+++ b/libowlps/libowlps.c
@@ -17,6 +17,8 @@
 #include <net/if.h>
 #include <iwlib.h>
 
+#include <assert.h>
+
 #define DEBUG
 
 
@@ -237,6 +239,10 @@ owl_timestamp owl_time_elapsed(const owl_timestamp d1,
 }
 
 
+
+/* *** Endianess *** */
+
+
 /*
  * Converts a owl_timestamp from host endianess to network endianess.
  */
@@ -261,6 +267,29 @@ owl_timestamp owl_ntoh_timestamp(const owl_timestamp d)
 }
 
 
+/*
+ * Swap bytes composing a float.
+ * You probably want to use the macros owl_htonf() and owl_ntohf()
+ * instead of this function.
+ */
+float owl_swap_float(const float f)
+{
+  float ret ;
+  char
+    *f_bytes = (char*) &f,
+    *ret_bytes = (char*) &ret ;
+
+  assert(sizeof(float) == 4) ;
+
+  ret_bytes[0] = f_bytes[3] ;
+  ret_bytes[1] = f_bytes[2] ;
+  ret_bytes[2] = f_bytes[1] ;
+  ret_bytes[3] = f_bytes[0] ;
+
+  return ret ;
+}
+
+
 
 /* *** Network *** */
 
diff --git a/libowlps/owlps.h b/libowlps/owlps.h
index a8dda9b..25e8700 100644
--- a/libowlps/owlps.h
+++ b/libowlps/owlps.h
@@ -252,8 +252,20 @@ uint_fast32_t owl_time_elapsed_ms(const owl_timestamp d1,
                                   const owl_timestamp d2) ;
 owl_timestamp owl_time_elapsed(const owl_timestamp d1,
                                const owl_timestamp d2) ;
+
+// Endianess
 owl_timestamp owl_hton_timestamp(const owl_timestamp d) ;
 owl_timestamp owl_ntoh_timestamp(const owl_timestamp d) ;
+float owl_swap_float(const float f) ;
+#if __BYTE_ORDER == __BIG_ENDIAN
+# define owl_htonf(f) (f)
+# define owl_ntohf(f) (f)
+#else // __BYTE_ORDER == __BIG_ENDIAN
+# if __BYTE_ORDER == __LITTLE_ENDIAN
+#  define owl_htonf(f) owl_swap_float(f)
+#  define owl_ntohf(f) owl_swap_float(f)
+# endif // __BYTE_ORDER == __LITTLE_ENDIAN
+#endif // __BYTE_ORDER == __BIG_ENDIAN
 
 // Network
 int owl_create_udp_trx_socket(const char *const server_address,