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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,c98f618755b0ddcc X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII Path: g2news1.google.com!news3.google.com!feeder.news-service.com!cyclone01.ams2.highwinds-media.com!news.highwinds-media.com!npeersf02.ams.highwinds-media.com!newsfe26.ams2.POSTED!7564ea0f!not-for-mail From: John McCabe Newsgroups: comp.lang.ada Subject: Re: Thinking of using Ada for a job at home. Couple of questions first. Message-ID: <6ggto5p3g2p58839gdsut6idb2l621nv2c@4ax.com> References: X-Newsreader: Forte Agent 2.0/32.652 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit NNTP-Posting-Host: 80.176.146.77 X-Complaints-To: abuse@demon.net X-Trace: newsfe26.ams2 1267647434 80.176.146.77 (Wed, 03 Mar 2010 20:17:14 UTC) NNTP-Posting-Date: Wed, 03 Mar 2010 20:17:14 UTC Date: Wed, 03 Mar 2010 20:17:12 +0000 Xref: g2news1.google.com comp.lang.ada:9382 Date: 2010-03-03T20:17:12+00:00 List-Id: Hibou57 (Yannick Duch�ne) wrote: >Le Wed, 03 Mar 2010 17:19:31 +0100, John McCabe > a �crit: >Hello, >> So the first question is do any of you know of any bindings to MS >> Windows MIDI (presumably the multimedia system) functions that already >> exist and are open source or something like that? I searched on Google >> for "ada midi" but it looks like there's a product called that so it >> came up with loads of stuff. I'm aware there are some binding to Win32 >> from Ada but, as I've not been doing Ada in anger for a long time, I'm >> not sure if there's something for Ada 2005. >If there are possible funding, I would enjoy to re-organize my time to >honor this target under whatever license you may request. Unfortunately there's not funding available. I've found a library called libjdkmidi that, if it would look easier to bind to than direct to Win32's mmsystem functions, might be worth doing. I suspect though that it encapsulates some of the functionality you mention later in relation to tasking etc, although I haven't looked that closely yet. >If you ever you are interested in another stuff in the same area, I've >also started some times ago, but not terminated, an Ada binding to the VST >architecture. I've temporarily dropped the project for an undetermined >amount of time, because I need a project which could give me some earn. I >can't give a date, however, I'm pretty sure I will come back to it in the >future (at least, I hope I could) Thanks, I'll bear that in mind. >> The second question is related to the implementation of the System >> Exclusive messages. Basically this is part of the reason I thought Ada >> would be good for this task. The SysEx messages basically consist of a >> smallish header and a variety of different structures that are >> differentiated by the "Function" type in the header. Now I seem to >> remember from when I did use Ada that it's possible to define the >> record representation of a variant record such that the discriminant >> is held within the body of the record. This would mean (I think) that >> I could read a block of data from the synthesizer straight in to a >> buffer that overlaid the variant record and essentially automatically >> created a record that could be read as the particular variant related >> to the incoming data. However I also seem to remember that's not quite >> a 'recommended' way of doing that sort of thing. >Excuse me, I'm not sure I've understood your words. Could you give a >concrete example of a process ? Well basically you define a variant record that contains variants that apply to all the SysEx messages then (dodgily) locate a buffer (e.g. of bytes, integers, whatever) in the same place and write the incoming data in to the buffer. When you come to read it later as a record object rather than just as bytes it's essentially a valid variant record (at least, I believe from what I remember that it is!). I think Jeff's Unchecked_Conversion is a more appropriate way to do it though. >Just to tell about what immediately comes into my mind : I'm not sure >variant record would be Ok for whole MIDI data sequences, as it comes into >sequence and not as a single block. The content of some MIDI messages are >splitted into multiple units which comes as a sequence. A variant record, >to be coherent, must be a whole, you cannot have something related to a >discriminant which remains dangling until some more data later arrives. The application I'm trying to do is a patch editor so it will essentially deal only with expected messages that are sent from the synth in response to requests. I don't think the synth intersperses any other midi data within those messages. It's a Kawai K1 by the way. >All this comment provided I've understood a bit of what you were to mean >(I apologize if I'm wrong). No need to apologise; if it's not clear to you then I'm sure there are others in the same position. >> The other thing that >> guided me in Ada's direction is that the structure of the SysEx >> messages requires a lot of bit-fields and I'm well aware that Ada's >> representation clauses are fantastic for that sort of thing. >Another reason to use Ada : Ada is also a good choice in this area, due to >its tasking capabilities. This kind of application typically heavily >relies on multiple tasks (and even more heavily if you have to deal with >multiple synthesizers, what is a common case) I don't need to deal with multiple synthesizers but yes, the tasking was another reason Ada sounded appropriate as the synth sends all sorts of junk while it's idling that I need to be able to receive and just dump, and I need a GUI as well. >> So, in principle, would that be the way to do this, or would you be >> able to suggest a better mechanism? >> >> Finally, is there a straightforward way to do that sort of thing using >> tagged records? E.g. could I define a record which is the header >> format, then extend that in a number of different tagged extensions to >> create each individual message as a separate tagged record and use the >> OO and dispatching facilities to work with them? >I gonna go back to my docs to remind me about what's the layout of these >messages exactly. > >> Any advice you've got the time to give on this would be very much >> appreciated. >You're welcome Thanks for taking the time to respond. Hope I've made it a little clearer but if not, just let me know.