[illumos-Developer] Ugh... xdr_{float,double} problems

[Garrett D'Amore]

I think that largely sums my feeling of floating point in general....

Bill Sommerfeld <sommerfeld at hamachi.org> wrote:

>On 01/31/11 15:34, Garrett D'Amore wrote:
>> It sounds like all the main CPU targets support IEEE 754. The only
>> reasonable (?) question IMO is S390. Roland? Neale?
>
>There is an extensive discussion of floating point formats at:
>
>http://www.quadibloc.com/comp/cp0201.htm
>
>There is definitely a least one "IBM" floating point encoding out there.
>
>Apollo's NCS RPC protocol (which is about as old as xdr) supported four 
>different floating point format tags: IEEE, Vax, Cray, and IBM (mainframe).
>
>My conclusion from the time I spent working in the group at apollo that 
>did NCS is that you're generally better off avoiding the use of floating 
>point numbers in wire protocols if at all humanly possible.  Lossless 
>conversion between formats is often impossible, and a round-trip 
>conversion between formats is likely to give you back a slightly 
>different number.
>
>Probably best to let sleeping dogs lie here..
>
>						- Bill
>
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