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7170: [MUD-Dev] Re: [CODE QUESTION] How to encode floats into bytes?
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From: Ben Greear <greear@cyberhighway.net>
Newsgroups: nu.kanga.list.mud-dev
Date: Mon, 7 Sep 1998 10:45:18 -0700 (MST)
References: [1]
Organization: Kanga.Nu
On Mon, 7 Sep 1998, T. Alexander Popiel wrote:
> In message: <Pine.LNX.3.96.980906215952.30075A-100000@shamen.cyberhighway.net>
> Ben Greear <greear@cyberhighway.net> writes:
> >
> >What is the standard way (if there is one) to encode floating
> >point numbers (double too I guess) into bytes for transport accross
> >the network.
> >
> >I'm using c++, on both ends (encode/decode).
> >
> >It would seem like there would be a method to do this somewhere!
>
> Standard is to send raw IEEE format across the wire; just about
> everyone uses IEEE internally these days, and those who don't
> know how to convert, so they can talk with those that do.
>
> IEEE 32-bit format is bigendian: 1 sign bit, 8 bits exponent in
> offset 127 notation, implied 1 (not stored), 23 bits mantissa.
> Special codes are used in the exponent to denote NaN, +/-Inf,
> and reduced-precision numbers between 2^-128 and 2^-152.
>
> IEEE 64-bit is similar, with 16 bits exponent and 47 bits
> mantissa.
>
> If you do the conversion manually, actually check the standard;
> I prolly have an off-by-one error in the above (which was taken
> from memory).
I was looking at the standard last night.. You are at least
very close :) (Don't remember all the details myself.)
I'm going to play around with bit-masking and casting to see if
I can get at the bits w/out turning the target into an integer!
Thanks,
Ben
>
> - Alex
>
> --
> MUD-Dev: Advancing an unrealised future.
>
Ben Greear (greear@cyberhighway.net) http://www.primenet.com/~greear
Author of ScryMUD: mud.primenet.com 4444
http://www.primenet.com/~greear/ScryMUD/scry.html