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,ffdd4d59cbfb4caf X-Google-Attributes: gid103376,public From: stt@houdini.camb.inmet.com (Tucker Taft) Subject: Re: Ada 95 Numerics questions for the experts Date: 1997/08/29 Message-ID: #1/1 X-Deja-AN: 268930799 Sender: news@inmet.camb.inmet.com (USENET news) X-Nntp-Posting-Host: houdini.camb.inmet.com References: Organization: Intermetrics, Inc. Newsgroups: comp.lang.ada Date: 1997-08-29T00:00:00+00:00 List-Id: Robert Dewar (dewar@merv.cs.nyu.edu) wrote: : <> : SOunds like a bug to me, since these compilers say they support : annex C, this means that the implementation advice in chapter 13 (13.2(9)) : ... Sounds like a misconception to me. The compiler supports packing to the bit level. It would be helpful if the actual source code that illustrated the problem were posted, because we have never had a bug report relating to an inability to pack. As far as packing to an array of 3-bits per element versus 4-bits per element, we have generally chosen to follow the recommendations of the RM. Going beyond the RM is not always in the customer's interest, as they may have to move to another Ada compiler at some point, and one of the goals of standardization is portability between implementations. For example, we used to support very long source lines, though the actual limit was a bit hard to define. We now support exactly 200 as the maximum length of a line (which is the length guaranteed by the RM), because supporting something like 256 or some other number chosen by us did not seem to be doing the customer a great favor. Of course, if a customer was willing to pay extra to get tighter packing, perhaps in the presence of some special pragma Jam_Packed(xxx), we would be happy to accommodate them (I think this general "disclaimer" applies to ACT as well ;-). However, as mentioned above, we have currently chosen to follow the RM recommendations as closely as possible for the "standard" pragma Pack, and if you find that we don't, please file a bug report. -- -Tucker Taft stt@inmet.com http://www.inmet.com/~stt/ Intermetrics, Inc. Burlington, MA USA P.S. By the way, on our 24-bit-per-storage-unit target, we pack arrays to element sizes of 1, 2, 3, 4, 6, 8, and 12. I remember someone once arguing for a word size of 72 bits on the grounds that it had a lot of factors ;-).