arduino_midi_library VS coreutils

That makes me wonder how often one runs across a synth that doesn't support running status. I'm working on a MIDI controller myself, and that's a thing I probably ought to enable if I want the lowest latency.

It seems the standard MIDI libraries that Arduino uses don't enable it by default, but it's a configuration option you can turn on, along with a note not to try to use it with USB[1].

[1] https://github.com/FortySevenEffects/arduino_midi_library/bl...

take a look here

The Arduino MIDI Library [1]. Back in 2009, I learned C++ to build it and control my guitar effects pedals with custom electronics as part of my engineering degree.

[1] https://github.com/FortySevenEffects/arduino_midi_library

Your project can be broken up into a number of subprojects. For keyscanning you don't need additional hardware, just the pins from the ribbon cables going to the arduino's digital pins and ground. Since the keys are just switches (two per key, the time difference between the two switches closing giving the source of velocity), you could start with some examples from the Arduino MIDI library (https://github.com/FortySevenEffects/arduino_midi_library). To test MIDI sending you don't even need to start from the keybed just yet, and if you do, you can start with a single key. Once you've got that part figured out end to end (key press/release generates note on/off events) you can work on iterating through the matrix, CC controls etc. MIDI out can be done in different ways. With a 5 pin DIN plug you'd just need two 220 ohm resistors.

On an Arduino compatible platform the configuration of the baud rate at the bare metal layer is taken care of by the library when you call its begin() method. Looking at the example code included with the library it appears that there are no timer interrupts or anything like that required of you in order to use it. Another thing that jumps out is that the call to read() returns a non-zero value if anything has been received that you should use to predicate whether any further attention needs to be spent on it by your code. You may know this but it wasn't apparent from the loop() { MIDI.read\`() }` example that you gave above.

As i have started to combine this with Midi Implementation from FourtySevenEffects lib, i only have done a quick test with two/three strips and did discover follwing issue(s):

Using a library for the midi shield you can register two functions as callbacks. One callback for NoteOn(...) messages and one for NoteOff(...) messages. But thre is much more. In the end the source of truth should always be the docs for the library itself.

Click the link to github (second link in the article) and there's all the source code: https://github.com/FortySevenEffects/arduino_midi_library

Here’s a library that might work.

https://github.com/coreutils/coreutils/commit/fcfba90d0d27a1...

A summary of other changes just released in GNU coreutils 9.5 are:

* mv accepts --exchange to swap files

> some are simple like yes(1)

Not that simple: https://github.com/coreutils/coreutils/blob/master/src/yes.c

The -S / --split-string option[1] of /usr/bin/env is a relatively recent addition to GNU Coreutils. It's available starting from GNU Coreutils 8.30[2], released on 2018-07-01.

Beware of portability: it relies on a non-standard behavior from some operating systems. It only works for OS's that treat all the text after the first space as argument(s) to the shebanged executable; rather than just treating the whole string as an executable path (that can happen to contain spaces).

Fortunately this non-standard behavior is more the norm than the exception: it works at least on modern GNU/Linux, BSDs, and macOS.

[1] https://www.gnu.org/software/coreutils/manual/html_node/env-...

[2] https://github.com/coreutils/coreutils/blob/b09dc6306e7affaf...

> building a cat from scratch

> That would be an interesting project.

Here is the source code of the OpenBSD implementation of cat:

> https://github.com/openbsd/src/blob/master/bin/cat/cat.c

and here of the GNU coreutils implementation:

> https://github.com/coreutils/coreutils/blob/master/src/cat.c

Thus: I don't think building a cat from scratch or creating a tutorial about that topic is particularly hard (even though the HN audience would likely be interested in it). :-)

the yes command, writing to /dev/null, is making IO calls, which interfere with predictable scheduling.

If you look at the source code for yes, https://github.com/coreutils/coreutils/blob/master/src/yes.c

it builds a buffer of output and then writes that in a for loop

  while (full_write (STDOUT_FILENO, buf, bufused) == bufused)

Looking at the source of nohup, if the execvp() of the child happens then it _must_ have already done the signal (SIGHUP, SIG_IGN) so - WTF?

This got me wondering so I went and looked and it seems like lo and behold there was actually a commit to the GNU ls source just 2 weeks ago.

https://github.com/coreutils/coreutils/blob/master/src/ls.c

"maint: prefer char32_t to wchar_t"

even an empty file? Yes. so now it was a file with a copyright disclaimer and nothing else. And the koan-like question comes to mind is "Can you copyright nothing?" well AT&T sure tried.

Then somebody said our programs should be well defined and not depend on a fluke of unix, which at this point was probable a good idea. so it became "exit 0"

Then somebody said we should write our system utilities in C instead of shell so it runs faster. openbsd still has a good example of how this would look.

http://cvsweb.openbsd.org/cgi-bin/cvsweb/~checkout~/src/usr....

At some point gnu bureaucracy got involved and said all programs must support the '-h' flag. so that got added, then they said all programs must support locale so that got added. now days gnu true is an astonishing 80 lines long.

https://github.com/coreutils/coreutils/blob/master/src/true....

http://trillian.mit.edu/~jc/humor/ATT_Copyright_true.html

> Yes, ls is maintained. Although, maintained is a very strong word. It exists.

Why would it be a strong word? Here it is, in src/ls.c: https://github.com/coreutils/coreutils

It is then packaged by tens of operating system distributions, who themselves maintain extra patchsets, some of which are then upstreamed.

It is installed and used on millions (billions?) of devices, for 3 decades.

It's a very reliable and trusty "sharp stick of metal" :)