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From: Frank Buss <fb@frank-buss.de>
Newsgroups: comp.lang.ada
Subject: Re: quiz for Sequential_IO Read
Date: Mon, 4 Sep 2017 23:51:55 +0200
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Date: 2017-09-04T23:51:55+02:00
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On 09/04/2017 10:55 PM, Dmitry A. Kazakov wrote:
> On 2017-09-04 21:58, Frank Buss wrote:
>> Would this be portable on all systems (assuming they provide FIFO
>> files) ?
>
> You probably mean a pipe here?

No, I'm using a FIFO file, created like this in Linux:

mkfifo a=rw midi

I need this, because I use the program "amdidi" to receive data from the 
MIDI port.

It makes the whole process really easy, without the need for the Ada 
program to interface to any special sound driver library. With "amidi 
-l" you get a list of available MIDI interfaces, and then you can let it 
write data to the FIFO file like this:

amidi -p "hw:2,0,0" -r midi

Any other program can read from it, as if it were a normal file.

> And it is not a good idea to pass each octet to the task. A better
> design is to have a FIFO (ring buffer) to be filled by one task and read
> by another.

Thanks, this looks interesting for more data, like audio input. The MIDI 
input is just some piano key presses and rotary encoder changes, max a 
few bytes per seconds, depending on how fast I can play :-) so I think 
not that many messages that it would justify the more complicated usage 
of an Ada FIFO buffer.

-- 
Frank Buss, http://www.frank-buss.de
electronics and more: http://www.youtube.com/user/frankbuss