* Re: Record rep-clauses [not found] <30F1418B.33CB@kiemw.ericsson.se> @ 1996-01-08 0:00 ` Robert A Duff 1996-01-08 0:00 ` Robert Dewar 0 siblings, 1 reply; 3+ messages in thread From: Robert A Duff @ 1996-01-08 0:00 UTC (permalink / raw) In article <30F1418B.33CB@kiemw.ericsson.se>, Magnus Ericson <emwmei@kiemw.ericsson.se> wrote: >I believe I have seen a paper (or article) about how to best write >record-rep clauses when you need to port your software between little- >and big-endian system but I don't know where! Sorry, I don't know of the article. But one technique for Ada 83 is to define a bunch of subtypes representing the ranges (e.g. all possible subranges of 0..31), and write all your rep clauses in terms of those. Then, when you switch to a machine with different endian-ness, change the subtypes, but not the rep clauses. (I.e. keep two different versions of the same package, defining all the subtypes.) It's a lot of subtypes, but if you're writing many rep clauses, it might be worth it. >I am not using Ada 95 but information about how to solve it with this >revision of the language is also of interest (at least in order to plan >for transitioning the software we are writing now to Ada 95 later on). Look at RM95-13.5.3, "Bit Ordering". - Bob ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Record rep-clauses 1996-01-08 0:00 ` Record rep-clauses Robert A Duff @ 1996-01-08 0:00 ` Robert Dewar 1996-01-09 0:00 ` Magnus Ericson 0 siblings, 1 reply; 3+ messages in thread From: Robert Dewar @ 1996-01-08 0:00 UTC (permalink / raw) Magnus asked: >I believe I have seen a paper (or article) about how to best write >record-rep clauses when you need to port your software between little- >and big-endian system but I don't know where! This is too vague, these endian questions can be very confusing, and there are at least three quite different problems that the above question might be referring to. Magnus, can you be very precise in exactly what you are trying to do, and we will try to help! ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Record rep-clauses 1996-01-08 0:00 ` Robert Dewar @ 1996-01-09 0:00 ` Magnus Ericson 0 siblings, 0 replies; 3+ messages in thread From: Magnus Ericson @ 1996-01-09 0:00 UTC (permalink / raw) Cc: emwmei Robert Dewar wrote: > This is too vague, these endian questions can be very confusing, and there > are at least three quite different problems that the above question might > be referring to. Magnus, can you be very precise in exactly what you are > trying to do, and we will try to help! I am working in a project where we need to define a protocol on two machines, one of them is a Motorola 68040 and the other is a Pentium PC. We have started to write rep-clauses for the Motorola machine and realized how difficult it will be to make and maintain a parallell package with declarations and rep-specs with all bits reversed etc for the Intel machine. The questions are what coding-techniques that can be used to make this as "painles" as possible. Can you please elaborate on what "three" problems that you are thinking about? Since the protocol is packed tightly (possibly crossing storage unit boundaries) I (unfortunatly) suspect that all of them might apply... One posibility for us (that I actually like a lot) is to describe the messages of the protocol in for instance a relational data base and then write a piece of code that auto-generate the record declarations and rep-specs for both the Intel and Motorola machine from this description. In this case no measures need to be taken to simplify the maintanence of the two parallell packages but other language issues might still apply! Hope this is specific enough, I am trying to learn a bit more about this issue before finding the problems "the hard way"... When it comes to Ada 95 I am not sure if all of the new pragmas about bit-ordering are informational only or if it actually is possible to select what bit-numbering scheme that is used by the copmiler when interpreting rep-clauses? Regards Magnus Ericson -- Magnus Ericson M.Sc, Ericsson Microwave Systems Torshamnsgatan 32C, S-164 84 STOCKHOLM Tel: +46 8 757 35 38 Fax: +46 8 750 74 42 Disclaimer: "The opinions expressed here are my own, and not those of my employer." ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~1996-01-09 0:00 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <30F1418B.33CB@kiemw.ericsson.se> 1996-01-08 0:00 ` Record rep-clauses Robert A Duff 1996-01-08 0:00 ` Robert Dewar 1996-01-09 0:00 ` Magnus Ericson
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