From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,8201deea80f1752a X-Google-Attributes: gid103376,public From: "Robert C. Leif, Ph.D." Subject: RE: 3-bit array ... Date: 1999/12/08 Message-ID: #1/1 X-Deja-AN: 558410612 Content-Transfer-Encoding: 7bit References: <384D4C8E.36174908@averstar.com> To: X-Priority: 3 (Normal) Content-Type: text/plain; charset="iso-8859-1" X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 X-Complaints-To: usenet@enst.fr Importance: Normal X-Trace: menuisier.enst.fr 944709850 30403 137.194.161.2 (9 Dec 1999 03:24:09 GMT) Organization: ENST, France X-BeenThere: comp.lang.ada@ada.eu.org X-MSMail-Priority: Normal Mime-Version: 1.0 Reply-To: comp.lang.ada@ada.eu.org NNTP-Posting-Date: 9 Dec 1999 03:24:09 GMT Newsgroups: comp.lang.ada Date: 1999-12-09T03:24:09+00:00 List-Id: -----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