From: Daniel Jacobowitz <drow@false.org>
To: Paul Schlie <schlie@comcast.net>
Cc: Richard Sandiford <rsandifo@redhat.com>, binutils@sources.redhat.com
Subject: Re: Bignums and .sleb128
Date: Tue, 01 Feb 2005 03:29:00 -0000 [thread overview]
Message-ID: <20050201032846.GA22855@nevyn.them.org> (raw)
In-Reply-To: <BE243D1B.8DB0%schlie@comcast.net>
On Mon, Jan 31, 2005 at 07:52:59PM -0500, Paul Schlie wrote:
> > Daniel Jacobowitz <drow@false.org> writes:
> > >> You said later that:
> > >>
> > >> > If we're going to use these semantics, at least the '-' case in
> > >> > operand() needs to be fixed.
> > >>
> > >> but I wasn't sure what you meant by "these semantics". Do you mean
> > >> treating bignums as signed, or treating them as unsigned? By my reading,
> > >> operand()'s current handling of '-' already assumes they are signed,
> > >> just like the sleb128 code does (and did ;).
> > > It doesn't work, because sometimes bignums are signed and sometimes
> > > they aren't. Consider -0xffffffffffff; the current code will return 1.
> > > If you want to treat the input as unsigned, then you need to add a new
> > > word with the sign bit. Note that with one less leading 'f', it
> > > suddenly works.
>
> Strongly suspect that the proper idiom to is to treat all non-explicitly
> negative constants as being unsigned values; where the point of confusion
This discussion is about the internal representation of bignums; the
user input is not ambiguous in any way. The meaning of
.sleb128 0xffffffffffffffff
is quite clear.
--
Daniel Jacobowitz
next prev parent reply other threads:[~2005-02-01 3:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-01 0:53 Paul Schlie
2005-02-01 1:09 ` Paul Schlie
2005-02-01 5:04 ` Paul Schlie
2005-02-01 3:29 ` Daniel Jacobowitz [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-01-31 19:54 Daniel Jacobowitz
2005-01-31 21:33 ` Richard Sandiford
2005-01-31 21:57 ` Daniel Jacobowitz
2005-01-31 22:18 ` Richard Sandiford
2005-01-31 22:22 ` Daniel Jacobowitz
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