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Date: Wed, 20 May 2009 14:38:04 +0200
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From: hugo rivera <uair00@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] plan 9 floating point representation
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thanks, I'll study it with care.
Saludos

2009/5/20, Jonas Amoson <jonas.amoson@home.se>:
>
>  Hello Hugo,
>
>
>  Done some experiments with the indivudual
>  bits in Lunix, and would be very surprised
>  if it is not handled the same under Plan 9,
>  given the same hardware architecture.
>
>  The exponent is stored in base 2, but What
>  might be a bit confusing, is that it is not
>  stored using two's complement, but rather
>  using a bias. If you have an exponent of 8
>  bits (in a 32-bit IEEE float) an exponent of
>  zero is represented by '10000000' or 127.
>  Simply add the desired exponent, whether pos
>  or neg. -1 will be 126, +1 will be 128.
>
>  This link explains the whole thing in more detail:
>  http://steve.hollasch.net/cgindex/coding/ieeefloat.html
>
>  /jonas
>
>  <-----Ursprungligt Meddelande----->
>    From: hugo rivera [uair00@gmail.com]
>  Sent: 20/5/2009 11:50:51 AM
>  To: 9fans@9fans.net
>  Subject: [9fans] plan 9 floating point representation
>
>  Hi,
>  I am learning a bit about floating point representation and I am
>  wondering about how plan 9 does this.
>  According to IEEE 754 (I think) the convention used by C for single
>  precision floating point numbers is to use 24 of the 32 bits available
>  for the significand and 8 bits for the exponent. It seems to me that
>  plan 9 follows this convention but I am still kind of puzzled about
>  the base of the exponent. I've been experimenting (on a 386) a while
>  and it looks like a base 4 to me, which is kind of strange, since I
>  was expecting a base 2 or 10. I think I got something wrong, but I
>  would appreciate if someone can explain this to me to have a better
>  idea of how this works. It looks to me that this stuff is very machine
>  dependent (or language?), is it?
>  The point of all this is to classify raw data (4 byte length)
>  according to their magnitude, I don't really care about the
>  significant. This is just an exercise for me, since there are other
>  easier ways to do it.
>
>  Saludos
>  --
>  Hugo
>
>  .
>
>
>
>
> _______________________________________________________________
> Eniro Supers=C3=B6k - =C3=A4r vad det heter
>
>


--=20
Hugo