COMEDI_DO_INSN(3)

💅 COMEDI_DO_INSN 💅

okay bestie, sit down, hydrate, and let me tell you about a lil function from the Comedi reference manual (section 3, library calls, iykyk). It's called comedi_do_insn and honestly? It does exactly the one thing it says it does. No cap.

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✨ NAME ✨

comedi_do_insn — perform instruction

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🦋 SYNOPSIS 🦋

#include <comedilib.h>

int comedi_do_insn(comedi_t * device, comedi_insn * instruction);

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🌸 DESCRIPTION 🌸

So like. The function comedi_do_insn performs a single instruction. That's it. One instruction. It's giving minimalism, it's giving main character, it's giving "I have one job and I slay at it." 🎀

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👑 RETURN VALUE 👑

If everything goes how we want it — which, bestie, we love to see — it returns a non-negative number. ✨

Now here's the specific tea for INSN_READ or INSN_WRITE instructions: comedi_do_insn returns the number of samples read or written, and heads up — that number may be less than the number you requested. Not a bug, just how it be. 💀

And if there's an error? -1 gets returned. Not the vibe, but at least it's honest. 😭

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💖 AUTHORS 💖

These iconic humans made this happen, show some respect:

• David Schleef <ds@schleef.org> — Author.
• Frank Mori Hess <fmhess@users.sourceforge.net> — Author.
• Herman Bruyninckx <Herman.Bruyninckx@mech.kuleuven.ac.be> — Author.
• Bernd Porr <tech@linux-usb-daq.co.uk> — Author.
• Ian Abbott <abbotti@mev.co.uk> — Author.
• Éric Piel <piel@delmic.com> — Author.

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🌈 COPYRIGHT 🌈

Copyright © 1998-2003 David Schleef Copyright © 2001-2003, 2005, 2008 Frank Mori Hess Copyright © 2002-2003 Herman Bruyninckx Copyright © 2012 Bernd Porr Copyright © 2012 Ian Abbott Copyright © 2012, 2015 Éric Piel

This document is part of Comedilib. In the context of this document, the term "source code" as defined by the license is interpreted as the XML source.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

fr fr, read the license before you redistribute, it's the law and also it's polite 🫶

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and that's the whole page, bestie, you ate that 🍓

Comedi · page updated 03/20/2026 · filed under COMEDI_DO_INSN(3) 💜🧚✨