packing float as network long:
 +-----+    +-----------+    +------------+
 |float|--->|native long|--->|network long|
 +-----+    +-----------+    +------------+

 and unpacking network long back to float
 +------------+    +-----------+    +-----+
 |network long|--->|native long|--->|float|
 +------------+    +-----------+    +-----+