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| From: | anton@mips.complang.tuwien.ac.at (Anton Ertl) |
| Newsgroups: | comp.compilers |
| Date: | Wed, 08 Feb 2023 10:19:54 GMT |
| Organization: | Institut fuer Computersprachen, Technische Universitaet Wien |
| References: | 23-01-092 23-02-003 23-02-019 23-02-025 23-02-026 23-02-029 |
| Injection-Info: | gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="11788"; mail-complaints-to="abuse@iecc.com" |
| Keywords: | arithmetic, comment |
| Posted-Date: | 08 Feb 2023 11:49:47 EST |
Hans-Peter Diettrich <DrDiettrich1@netscape.net> writes:
>AFAIK use IEEE-754 floating point numbers still sign-magnitude
>representation.
>Then the same representation of integral numbers may have advantages in
>computations.
Such as? Anyway, whatever these advantages may be, they have not been
enough to prevent the extermination of sign-magnitude integers.
>[I presume the sign-magnitude is to enable the hidden bit trick,
>which doesn't apply in unscaled integers. -John]
With a ones-complement or two's-complement mantissa the hidden bit
would just have the same sign as the sign bit, so this trick is not
tied to sign-magnitude representation.
Some years ago someone sketched a two's-complement representation for
FP (that also includes the exponent), but I did not quite get the
details. Anyway, I expect that whatever the advantages of that
representation are, they are not enough to justify the transition
cost.
- anton
--
M. Anton Ertl
anton@mips.complang.tuwien.ac.at
http://www.complang.tuwien.ac.at/anton/
[PDP-6/10 floating point was two's complement. As someone else recently noted, that
meant they could use fixed point compare instructions. -John]
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