[Xapian-tickets] [Xapian] #673: Use IEEE-754 interchange format?

Xapian nobody at xapian.org
Wed Apr 8 13:23:00 BST 2015

#673: Use IEEE-754 interchange format?
        Reporter:  olly            |      Owner:  olly
            Type:  defect          |     Status:  new
        Priority:  normal          |  Milestone:  1.3.x
       Component:  Backend-Remote  |    Version:
        Severity:  normal          |   Keywords:
      Blocked By:                  |   Blocking:
Operating System:  All             |
 Most current platforms use IEEE-754 floating point formats, so using
 IEEE-754 interchange format in the remote protocol would be very efficient
 for such platforms.  For any other platforms, a bit more work would be
 needed, but probably similar to what we do to encode and decode the
 base-256 representation we currently use.

 The downsides I can see are that we'd lose precision or range if the
 native precision or range was better than IEEE (currently we should
 convert exactly), and that the current serialisation is more compact for
 some values (e.g. small integers) - it is bigger if all bits of the
 mantissa are used though, so might actually not be much different overall.
 In most cases weights aren't round numbers.

 One wrinkle is it seems IEEE doesn't specify the endianness, so I guess
 we'd have to pick one and then convert for platforms which don't use the
 same endianness.

Ticket URL: <http://trac.xapian.org/ticket/673>
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