From: "Robert C. Leif, Ph.D." <rleif@rleif.com>
To: <comp.lang.ada@ada.eu.org>
Subject: RE: 3-bit array ...
Date: 1999/12/08
Date: 1999-12-09T03:24:09+00:00 [thread overview]
Message-ID: <NBBBJNOMKDIAJALCEFIJMEGJDGAA.rleif@rleif.com> (raw)
In-Reply-To: 384D4C8E.36174908@averstar.com
-----Original Message-----
From: USENET news [mailto:news@inmet.camb.inmet.com]On Behalf Of Tucker
Taft
Sent: Tuesday, December 07, 1999 10:06 AM
To: comp.lang.ada@ada.eu.org
Subject: Re: 3-bit array ...
SNIP
Robert Dewar wrote:
To: Tucker Taft et al.
From: Bob Leif
Amusingly, IBM has now created a super-computer for the human genome using a
large number of special RISC processors. Three and possibly two bit
operations on a very wide word (at least 128 bit) CPU probably would have
been a better approach. One of the main uses is determining the degree of
matching between various parts of these arrays. Bounded Arrays of generic
characters would cover both BCD arithmetic and genomics. The present
packages for 8 and 16 bit characters could be instantiations, in a similar
manner as as was done for Text_Io with integers and floats.
Bob mis-spoke. We only pack to "odd-ball" sizes if the user
explicitly requests it via a 'Component_Size clause. This
is important because there is existing Ada 95 code which we didn't
want to suddenly change behavior in a potentially surprising way.
> But the gods of legacy Ada 83 code definitely demand significant
> sacrifices, so this is one of them.
We chose to force these "legacy" users to put in a 'Component_Size clause
if they really need the 3-bit (in)efficiency.
> Bob, how far did Averstar go, did you just do 3 bits? In GNAt
> we close pack all sizes up to 64. (e.g. an array of Natural
> gets packed to 31, which can be quite a surprise, although the
> pragma Pack in this case is junk!)
We support any "odd-ball" 'component_size up to the maximum integer
size supported by the compiler on the target. That varies, from 24
bits up to 64 bits.
--
-Tucker Taft stt@averstar.com http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.) Burlington, MA USA
next prev parent reply other threads:[~1999-12-08 0:00 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-11-06 0:00 3-bit array porting problem from ADA83 to GreenHills ADA95 Darrell Higgins
1999-11-05 0:00 ` Jeff Creem
1999-11-06 0:00 ` Darrell Higgins
1999-11-06 0:00 ` Robert Dewar
1999-11-09 0:00 ` Steve Mossom
1999-11-09 0:00 ` Robert Dewar
1999-11-10 0:00 ` Gleason
1999-11-10 0:00 ` Ted Dennison
1999-11-10 0:00 ` David Botton
1999-11-12 0:00 ` Robert Dewar
1999-11-12 0:00 ` Preben Randhol
1999-11-14 0:00 ` David Botton
1999-11-13 0:00 ` Darrell Higgins
1999-12-03 0:00 ` Darrell Higgins
1999-12-02 0:00 ` Robert C. Leif, Ph.D.
1999-12-04 0:00 ` Robert Dewar
1999-12-03 0:00 ` 3-bit array Nick Roberts
1999-12-05 0:00 ` Gisle S�lensminde
1999-12-06 0:00 ` Robert A Duff
1999-12-06 0:00 ` Tucker Taft
1999-12-07 0:00 ` Robert Dewar
1999-12-07 0:00 ` Tucker Taft
1999-12-08 0:00 ` Robert Dewar
1999-12-08 0:00 ` Robert C. Leif, Ph.D. [this message]
1999-12-07 0:00 ` Robert A Duff
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